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Architectural Energy Retrofit (AER): An alternative building’s deep energy retrofit strategy
Accepted Manuscript Title: Architectural Energy Retrofit (AER): An alternative building’s deep energy retrofit strategy Authors: Eftychia Eliopoulou, Eleni Mantziou PII: DOI: Reference:
S0378-7788(17)31561-X http://dx.doi.org/doi:10.1016/j.enbuild.2017.05.001 ENB 7582
To appear in:
ENB
Received date: Revised date: Accepted date:
28-10-2016 14-2-2017 1-5-2017
Please cite this article as: Eftychia Eliopoulou, Eleni Mantziou, Architectural Energy Retrofit (AER): An alternative building’s deep energy retrofit strategy, Energy and Buildingshttp://dx.doi.org/10.1016/j.enbuild.2017.05.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Architectural Energy Retrofit (AER). An alternative building’s deep energy retrofit strategy Eftychia Eliopoulou1,*, Eleni Mantziou2 1. Architect Eng. NTUA, M.Sc. in Environmental Design of Buildings W.S.A., Ph.D. Researcher, School of Architecture, Department of Architectural Design D1, National Technical School of Athens, Greece 2. Dr. Architect Eng. NTUA, Associate Professor, School of Architecture, Department of Architectural Design D1, National Technical School of Athens, Greece *corresponding author. E-mail address:[email protected]
Abstract The refinement of architectural space plays a catalytic role in the building’s energy balance. A different configuration on the deep energy building retrofit is presented on this paper, by proposing mainly strategies that hierarchize in a high position the invigoration of the building’s architectural design principals. These space qualities enable diversity of occupancy, environmental variability and facilitate the building envelope to operate efficiently as climate moderator. The main working hypothesis claims that bioclimatic trends, derived from primary architectural decisions of the early design phase, predispose the final energy performance of the existing building.Based on that, the alternative retrofit proposal called Architectural Energy Retrofit (AER) strategy, focuses on the energy genetic code of these basic architectural features. It argues that their holistic revival and refinement, indoors and outdoors will pave the way for the building’s energy retrofit and the space’s regeneration. As a case study to test this theory, an old and energy-consuming school complex is selected. By applying solely architectural interventions, a reduction of 44% energy demands was achieved. The results highlighted the challenges of “quantifying” the energy efficiency of architecture. However, by exploring and focusing on the non-energy, co-benefits, it also seeks to expand the perspective of energy efficiency beyond the traditional measures, by identifying and measuring its impacts across many different spheres. AER, as a counterproposal, wishes to add a new base of discussion on deep energy retrofit strategies as it follows a diametrically opposed direction than the typical practices. The building instead of being “sealed”and its environment kept strictly controlled, it “opens” and interacts with its surroundings.
Research highlights ► Architectural Energy Retrofit is an alternative building’s energy retrofit proposal ► Early architectural design phase predispose building’s final energy performance ► Linking building’s energy retrofit with its primary architectural principals ►Challenges on quantifying the energy efficiency of architecture ►Non-Energy benefits of Architectural Energy Retrofit (AER)
Keywords Deep energy retrofit; energy-demand control; sustainable rehabilitation practices; quantifying architectural disciplines; non-energy benefits; added-value; Architectural Energy Retrofit; 1
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2.1 Introduction Designing spaces daylit and naturally ventilated, by taking into account the microclimatic conditions, have been among the main objectives for architects [1] [2]. Bioclimatic design’s importance in the early design phase of new buildings is not only indisputable, but it is also required according to the European [3] and National energy legislative framework [4]. However, when it comes to deep energy retrofit of existing buildings, the typical practices leave out the architect’s perspective. Architectural design although it affects dramatically the energy needs, it is not yet fully implemented in the assessment of energy use. The highenergy efficiency performance of the building sector, according to the contemporary high standards of European and national legislative framework, mainly focuses on the use of renewable sources, efficient technologies and insulating building materials, hierachized with cost-optimal terms [5]. The specific energy behavior pattern derived from the architectural form of the examined building and the microclimate of its surroundings, are often disregarded. They are usually more related with the user’s thermal comfort conditions [6], rather than capitalized at the final energy performance of the building. The present paper intends to value the final energy gains by invigorating the architectural qualities of the building during the energy renovation. This practice, described as Architectural Energy Retrofit (AER), interlinks the building’s final energy needs with the architectural concept’s bioclimatic potential. By tracing, the architectural desciplines of the examined building and profiling those architectural elements that affect its internal and surrounding external conditions, an environmental post-occupancy evaluation analysis of the building is performed. This evaluation, that includes both energy efficiency and architectural perspectives, forms the basis of an energy retrofit proposal that sets as priority to fix, restore, modificate and update these architectural elements and structures to minimize building’s energy demands along with achieving the revival of the microclimatic conditions and the non-energy benefits of a well-designed space. By using the term architectural qualities, we refer to the basic design’s principals that articulate the built indoor and surrounding outdoor environment and shape the final space’s geometry. They originate from archetype forms and generate the structure of the architectural concept, aiming at the satisfaction of physical, aesthetic and psychological needs of the users. We are talking about primary design elements such as atriums, arcades, enclosed and in-between spaces, open plan arrays, arrangemet of the circulation, open space’s propotions and façade defining features [7]. These elements have genetic characteristics that dispose their potential as microclimate modulator and influence dramatically the environamental variability. This genetic disposition is passed to the structure and the building order of the building, which is not influenced dramatically by any changes in the use pattern [8]. Thus, the environmental conditions diversity, the visual, thermal and acoustic comfort of the users derive from this basic architectural concept. This dynamic, so far overlooked, could play a catalytic role in the building’s energy retrofit if we recharge it. The operational configuration of the building service systems follows that special pattern the architectural space has formulated. Therefore, it is debatable how efficient it is to propose the same set of energy retrofit measures to treat radically different “pathologies”. The present research does not firmly oppose to the strategies developed so far, but wants to contribute to the open dialogue of building’s energy retrofit with alternative architecturally oriented proposal that broaden the benefits of retrofit actions. Apart from the solely energy viewpont, the strategic advantage of Architectural Energy Retrofit (AER) is described with the non-energy benefits (NEBs). Non-energy benefits (NEBs) or non-energy impacts (NEIs) are generally defined as any real or perceived, financial or intangible benefit accrued by an energy efficiency project. They are effects that are omitted from traditional energy evaluation work, which focuses on impacts on energy savings [9]. 2
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“Non-energy benefits [10,11]”,“Co-benefits”, “ancillary benefits”, “non-energy impacts” and “multiple benefits [12]”are equivalent terms used to describe these positive and negative effects beyond energy savings and energy bill savings that are attributable to energy efficiency programs. In energy efficiency economy, the values of NEBs gain ground at the policy makers and market transformation communities. NEB of energy efficiency programs have been studied as early as 1993, and there have been hundreds of papers and reports published since then, many of them finding that NEB are significant [13]. A strength of the multiple benefits approach is that it encourages cross-sectoral collaboration in policymaking. By optimizing the intellectual, technical and financial resources available, it allows decision-makers to tackle more complex issues in a more holistic manner, as it broadens their perpestive on energy- retrofit impact xi.
Figure 1: ECD/IEA)
The multiple benefits of energy efficiency improvements, ( International Energy Agency,
Highly efficient buildings, additionally characterized with AER terms, infer a range of co-benefits that could motivate decision-making process when it comes to energy retrofit investment. Societalperspective benefits such as infrastructure savings for energy and controlling local air pollution, Participant non-energy impact such as health and well-being, added asset values such as improved aesthetics and increased comfort, are strongly pursued in this alternative proposal. However, the broader impacts of energy efficiency have not been systematically assessed in practice. The main reasons are their indirect nature that makes them hard to measure or value in a robust and objective manner like other measurements associated with energy efficiency programs. Therefore, their evaluation is another open challenge for Architectural Energy Retrofit.
1.2 Methodology description The proposed methodology, firstly explores how the original architectural qualities (both indoor and outdoor) affect the operational pattern and shape the microclimate conditions. The second step of the methodology evaluates their implementation to the building’s final energy balance. The third proposes tailoring measures for maximizing their environmental variability and energy-efficiency potential along with enabling their occupancy diversity, before any other typical retrofit action taken, synthesizes the AER methodology. As the scope of this study is to produce robust, applicable and valid results, the achievement of 3
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substantial energy conservation with the implementation of solely architectural interventions, after multidirctional information procession, should follow a simplified and efficient methodology. One of the main challenges that arise from the AER concept, is the need to assess how “correct” and “feasible” is to “quantify” architectural concepts with contemporary energy efficiency terms, in order to be verified by the rest of the stakeholders. It is not a common practice for architecture to play a catalytic role in energy retrofit of building stock. Therefore, there is lack of confidence and high risk of non-generating clear proposals by getting “lost in translation” among theoretical architectural disciplines and technical calculations. A first step of this research is to test AER working hypothesis in a real case study and attempt to produce numeric values by using Building Performance and Analysis tools. An old school building complex in Athens’ city centre is used for this preliminary research. It has architectural form and space articulation, characterized by strong architectural concept. In combination with its contemporary poor energy performance and user’s comfort levels, indoors and outdoors, it provides a solid working base and a good starting point for AER. As it is already described, the original architectural concept was explored and linked with the building’s final energy use. The current indoor and outdoor conditions, the users’ thermal and visual comfort status from the on-site visit and the past 3-year energy bills gave feedback for building up the profile of the current energy use distribution and the indoors and outdoors thermal and visual conditions, with the help of dynamic modelling. Next phase included the set-up of architectural-based retrofit scenarios that aimed at the optimum environmental conditions of the architectural space potential and the increase of the end user’s thermal and visual comfort -indoors and outdoors-. The final energy saving benefit and the revitalization of the outdoor surrounding were also estimated and gave a comparative numeric analysis before and after the retrofit. Behind of the apparent technical measures that were finally proposed at the final step of the AER analysis, the intention of restoring and enhancing the space with polyvalence that meets the user’s comfort, physocological and aesthetic needs, were set high at the hierarchy in the decision-making process. The estimation tools included a group of energy design software, according to the multi-orientated perspectives of AER. Each of it estimated different aspects and contributed to the qualitative and quantitave required assessment. Energy demands and efficiency of bioclimatic features of the examined school were compared before and after applying the retrofit scenario. Energy Plus software estimated the final energy demands, Envi-Met software described microclimatic outdoor conditions and students’ thermal comfort, CFD software demonstrated the air movement of the tested ventilation scenarios and Ecotect software simulated the performance of the shading devices. The weather files were loaded from the International Weather for Energy Calculation (IWEC) files for Athens. It was also taken into account the Greek Regulation on the Energy Performance of Buildings (K.E.N.A.K) [14] the operational scenario of schools. So, cooling point temperature was set to 26°C and heating set point temperature was set to 20°C. The cooling period for Athens (Greek climate zone B) starts at mid of May until September and the heating period is from November until April. The school year lasts from mid of September until mid of June. The operation scenario described a full school year, the typical school day that starts at 08:00 a.m. and ends at 16:00 p.m., the 45 minutes’ duration of the course, the 15 minutes’ brakes and the internal gains from the pupils and the use of the current lighting system.
1.3 The case study The school complex that was selected as the case study for this report is an elementary school in Athens’ city centre next to Lycabettus hill. A famous Greek architect Dimitris Pikionis designed it in 1931. It 4
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is one of the first samples of modernism and stands out as a reference of contemporary Greek architecture. It is a well-known architectural reference due to the successful adjustment of the building complex to the site’s steep landscape and the mild climatic conditions of Attica. Its space diversity generated by the terrace array of the classrooms provides private mini-courtyards and offers the pioneer option of outdoor classes during midseasons. (Fotos 1, 2, 3) Today, the school is protected as an architectural monument of Modernism under austere morphological restrictions that do not allow any radical alterarions of the envelope, a typical deep energy retrofit would require. However, its current condition needs extensive renovation. First raw data from the on-site visit and the end users’ opinion indicated thermal discomfort especially during the heating period. The classroom’s light conditions were described as constantly gloomy leading to extensive use of electrical lighting of old technology. Heating is provided with an uninsulated central system and radiators are misplaced next to the regurarly open entrance. There are no any heating or lighting control systems. Masonry walls and concrete roof provide high thermal capacity but they do not have any thermal insulation and neither has the floor, which is in direct contact with the ground. The vast classroom’s façade exposed to the southwest, retains the original iron-framed, single-pane, frosted-glass, sliding opening, from the 30’s. The classroom’s mini courtyards are lacking greenery and shadow and the terrain is covered by asphalt, resulting in problematic microclimatic conditions. (Fotos 4, 5) 251658240
Fotos 1, 2, 3: Panoramic view of the school complex and classroom interior when it was finished in1933, and architectural plan of the typical classroom, (Antonakakis)
Fotos 4, 5: The school complex today, outdoors and indoors The annual heating consumption –bill based– using natural gas is around 74 kWh/m² final energy. This rate is much higher than the average rate for the non-insulated Greek schools of the same climatic zone that is estimated 46 kWh/m² [15] . Greek school buildings’ energy is mainly used for heating and lighting 5
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needs. Energy for cooling purposes is limited in the personnel office areas where split A/C units are used. Accordingly, to energy consumption data collected through energy surveys performed in 320 schools in Greece the typical Greek school uses annually 57 kWh/m² for heating and 20 kWh/m² for electricity final energy [16]. According to another study, there is a considerable potential for energy conservation in heating loads ranging from 36% to 72% compared to the present state for the Greek school buildings [17]. The modelling simulation of the indoors temperature conditions in the typical classroom, verified the pupil’s thermal discomfort complaints. The classroom’s operative temperature on an hour basis was simulated with Energy Plus under free-running conditions (Fig. 2) .The high frequency of the indoors temperature values that fall behind the heating set point and exceed the cooling set pont, except from the midseasons, is presented at Table 1. The chart also gives an indicative qualitative aspect of the excessed heating demands in comparison with the moderate cooling demands during the school year. 251658240
Figure 2: Sketch Up model of the classrooms array used in Energy Plus calculations Fotos 6,7: Current view of the classroom, aerial view of the school building complex.
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Table 1: Annual current classroom’s operative temperature and outdoor air temperatre
2.1 Architectural Energy Retrofit (AER) scenario As the scope of this report is to identify the potential energy efficiency by invigorating architectural qualities, the energy retrofit scenario will propose measures focused on optimizing the passive energy behaviour of the envelope that derive from its architectural desciplines and building order. In the Pikionis’ school, despite of the problematic current conditions of the school complex, it is apparent that the original architectural concept of the child-scale classrooms and their own courtyards’ articulation, qualifies with flexibility and polyvalence the open spaces. According to the occupancy pattern, these spaces have the right dimensions and the potential of outdoor educational activities that agree with contemporary educational and pedagogical theories. From the energy efficiency point of view, the repeated classroom and mini courtyard cluster encourages the autonomous operation scenario, compatible with the modern energy design standards. Therefore, in the Architectural Energy Retrofit scenario, the above architectural qualities will be designated to pave the way for high-energy efficiency operation. The study on the work of Pikionis, by professor architect Dimitris Antonakakis, will be used as a guide for the selection of the architecturally oriented retrofit measures. In his thorough analysis [18] on the design and manufacturing phases of the examined school, he presents strong evidence that certify that the original architectural proposal was never fully realized. The design that was finally built had significant modifications from the architect’s concept resulting in partial malfunction of the user’s energy behavior and of the envelope as climate moderator. The original proposal included various openings for cross ventilation of the classrooms, an extensive pergola over their mini-courtyard for shading of the outdoor space and the glaze façade and an entrance booth at the side of the classrom that served as a buffer zone between indoors and outdoors during wintertime (Fotos 8, 9). 7
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The retrofit scenario took into account the above along with the mild microclimatic conditions due to the surrounding greenery, the open terrain, the seasonal and daytime school operation and the modern energyefficiency materials and pracrices. The proposed measures included: ● Partial thermal insulation of the masonry envelope, ● Optimization of daylighting and filtering to avoid glare, ● Seasonal modification of classroom’s heated volume, ● Use of buffer zone entrance during wintertime ● Restoring cross ventilation, night-ventilation and façade shading for efficient cooling ● Shading pergola seasonally covered with greenery and using cool paving materials for the courtyard’s surface. The following analysis demonstrates the energy-efficiency benefits by modificating, restoring, and redesigning of architectural structural elements and explains the necessity of those actions for the holistic space revival. Finally, a numeric estimation of the energy demand reduction capitalizes the retrofit with AER terms.
251658240 Fotos 8, 9: Section, 3d model and plan of the typical classroom and its courtyard according the architect’s original concept, (Antonakakis)
2.1.1. Thermal insulation impact High thermal insulation of the envelope in new and deep renovated buildings is obligatory according to contemporary Greek Energy Building Regulations. In the case of the typical classroom structure, the very high thermal inertia the masonry walls and the envelope’s contact with the ground offer provides stable internal conditions during the day. However, the low surface temperatures during wintertime have a negative affect on the thermal comfort of the students and the envelope responses very slow when the heating system is on. The AER defined the classroom unit as one thermal zone and proposed the selective application of internal thermal insulation, considering the daily 8-hour operation and the monument’s morhological restrictions (Fig. 3). Although the building elements lose their thermal capacity in this case, they response faster to heating when the system is on, which is compatible with the school program. Thus, it was suggested only the external walls, the roof and the internal walls adjacent to the non-thermal storage room to be insulated with panels of 10cm EPS as it is described at the table 2. All surfaces in contact with the ground (floor surface and open cloakroom’s corner walls) were left uninsulated. It was estimated that it is more beneficial for cooling purposes (as it will be described later), without significant heat losses during heating period.
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Figure 3: 3d Section of the typical classroom illustrating the thermal insulation proposal
U values (W/m²*K)*
current situation
Greek energy regulation standards **
retrofit scenario proposal
insulation details
60cm width external plastered stone walls
2,13
0,5
0,26
10cm Mineral wool (thermal onductivity=0,031 W/m*K) in the internal side of the classroom
60cm width stone walls to the ground
2,28
1
-
no insulation
60cm width stone walls to the north storage corridor -non thermal zone-
2,13
1
0,2
10cm Mineral wool conductivity=0,031 W/m*K) in the internal side of the classroom
60cm width stone walls to the next classroom -thermal zone-
-
-
-
no insulation
20cm concrete roof with 10cm lightweight concrete and wateproof asphalt membrane on the top
1
0,45
0,2
12cm EPS (thermal conductivity=0,031 W/m*K) with light beize ceramic tiles (SR=0,58), on the existing roof
mosaic floor to the ground
3,5
0,9
3,5
no insulation
* based on energy plus computer model
**according to the climatic zone of Athens
Table 2: Thermophysical characteristics of the building envelope before and after the AER
2.1.2. Openings displacement The concept of the internal insulated envelope from the previous stage is repeated in the energyconsuming single glaze metal façade. Due to the monument’s restrictions, the original opening must not be replaced (Foto 10). Only the frosted glass can be replaced with clear glass, according to the original proposal. Therefore, a double window that meets the contemporary energy efficient standards was proposed at the internal side of the 50cm stonewall behind of the preserved façade (Fig. 4). Double pane clear glass with low– e coating would allow natural light in the classroom and the original metal façade could function as a movable extra glass layer during heating period, supporting the energy performance of the opening. Infiltration rates would be minimized. The significant benefit in providing flourishing daylit in the classroom from the clear glass, apart from minimizing the use of electric lights, is the promotion of morning circadian stimulation in students. According to the latest researches, the students who were not exposed to morning light or daylight that would stimulate the circadian system experience a more pronounced delayed circadian phase, which results in later bedtimes, and possibly chronic sleep deprivation, stress or mood disorders. If the lighted environment in schools can promote circadian entrainment by delivering light that will shift the 9
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biological clock to an earlier time, students will fall asleep earlier at night and sleep deprivation will be reduced. In turn, students should feel better and perform better in school. [19] 251658240
Foto 10: The original façade of the 30’s ,as it is today. Figure 4: 3d section of the typical classroom illustrating the façade retrofit proposal
Openings
current situation (single pane frosted glass and steel frame)
retrofit scenario proposal (double pane clear glass low-e and aluminum frame with thermal brakes + current glaze façade with clear glass)
U value (W/m²*K)
6
2
Solar heat gain coefficient
0,3
0,6
Transmittance visibility
0,3
0,65
**according to the climatic zone of Athens
Table 3. Thermophysical characteristics of the openings
2.1.3. Seasonal redefining of the size and the volume of the classroom as a thermal zone The proposed partial thermal wall and roof insulation in combination with the new opening in the internal side of the façade, synthesizes a thermal cell that includes the core of the classroom and leaves out the supplementary rooms like the cloakroom and the storage room (Fig. 5). This concept was further organized in seasonal redefining of the size and the size of the classroom unit. An architectural volumetric rearrangement of the classroom that responds better to the heating, cooling and functional demands was proposed that also has the right dimensions as it contracts in wintertime and expands, in summertime copying the human adaptation model. At the backside of the classroom, there is an open cloakroom (approx. 10m²), with its masonry walls in contact with the ground. As it was reported earlier, these walls are left uninsulated by choice. At Table 4, it was estimated that their inside surface temperature always stays stable lower -approx. 3,5 °C-, than the internally insulated walls. Therefore, they can contribute to cool down the classroom’s operative temperature 10
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during cooling period. During the heating period, in order to prevent thermal discomfort and heat losses, a movable partition that separates the cloakroom from the rest classroom was proposed. As a result, a thermal cell enclosed by insulated masonry walls and roof, consist the classroom’s thermal zone. Subsequently, less volume (approx. 20m³) is heated there is faster response to the mechanical heating system (Fig. 6, 7, 8). 251658240
Figure 5: Seasonal redefining of the size and the volume of the classroom 251658240
Table 4: Annual hourly classroom’s operative temperature, outdoor air temperatre and wall to ground inside surface temperature 251658240
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Figures 6, 7, 8: Seasonal redefining of the size and the volume of the classroom limits surfaces and volume to minimize heat losses like the human body when it feels cold. The opposite happens when it is hot.
2.1.4. Natural Ventilation optimization Establishing Indoor Air Quality (IAQ) within the classroom is essential as it relates to the well-being, the health and comfort of occupants. Many studies have proved that indoor environmental conditions strongly influence the well-being in buildings and the productivity in working and educational environments. Children must attend schools even when the air quality and thermal conditions in the classrooms are unsuitable, because they cannot easily choose to attend another school and they have fewer ways of registering complaints than adults have. The work that children are obliged to perform in school is almost always new to them, while adults frequently perform routine, well- practiced tasks [20] . Good IAQ contributes to a favorable environment for students, performance of teachers and staff. It reduces absenteeism, improves test scores and enhances student and staff productivity [21] [22] In the examined school, the only openable window, which also serves as an entrance, is one part of the sliding metal façade. It provides moderate side ventilation during summertime and its frequent use results in severe energy penalty during winter. Rearrangement of windows’ opening area was essential in combination with the introduction of the entrance booth according to the original architectural proposal. Two natural ventilation scenarios for heating and cooling period were proposed, based on the geometry of the classroom, the existing top fenestration and the high potential of air movement by pressure from the open terrain of the site. During cooling period, two passive strategies were proposed, compatible with the Athenian mild climatic conditions and the high thermal inertia of the masonry structure. At daytime, cross natural ventilation was restored, by opening the classroom’s top windows to the north non-thermal zone storage room, which is also cross ventilated. Openable window area was maximized to the 50% of the total glaze surface, including the top fenestration and the sliding panel of the façade and the top windows of the opposite internal wall. According to the CFD model where the openings array, the classroom geometry and the climatic conditions of warm day, were simulated, it is shown that cross ventilation scenario could work efficiently (Fig. 9, 11, 12). Field studies find that people in naturally ventilated indoor environments are comfortable within a range of microclimatic values that is larger than in fully conditioned indoor environments [23] . At nightime, night ventilation for cooling was also applied, in combination with the expanded size and the increased thermal inertia of the classroom –as it was described earlier-. It was estimated with Energy Plus that in order to prevent overcooling and low indoor temperatures during morning hours, it is recommended to keep the top windows open when the outside temperature is over 22°C. During heating period, a buffer zone entrance according to the initial plans was proposed. Apart from its catalytic role as a buffer zone, AER focus on the significance as the necessary in-between space 12
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–with the minimum dimensions-, in order welcome and prepare the pupils to enter into the classrooom’s cell (Fotos 11, 12). As far as the air quality, the option of single sided ventilation from the façade during brakes is open (Fig. 10). It is reported that teaching staff and pupils control the ventilation into the classrooms by thermal comfort rather than air quality [24]. However, use of CO2 sensors fans during the courses for acceptable IAQ levels with minimum ventilation rates are also recommended.
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Figures 9, 10: CFD model of the classroom and its adjacent storage room, Airflow potential in the classroom with single sided ventilation during heating period
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Figures 11, 12: Airflow potential in the classroom with cross ventilation according to the cooling period scenario
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Fotos 11,12 : Plan and detail from the entrance booth, the architect had proposed but it was not constructed, (Antonakakis)
2.1.5. Sun shading system The pergola has always been an intergral part of the architectural design, both for shading the classroom’s southwest façade and for the thermal, visual and acoustic comfort of the mini-courtyard. AER proposal restored this structural element, according to the architect’s original proposal (Fotos 13, 14, 15, 16). The same dimensions and proportions of the solid surfaces of the pergola geometry were repeated in detail, as they credit the underlying courtyard with the qualities of a semi-enclosed space. The semi-open or semi-enclosed space is an archetypical form in architecture that is embedded in the architecture of southern climates. It intervenes between the inside and the outside and reconciles the two spaces as concerns the light, the natural forces, the view of the outside world. Its transitional character generates thoughts concerning the relation of the built space with the man and the nature [25]. From the environmental design aspect, that architectural diversity modulates also a thermal diversity. Spaces with different characteristics result in a variety of thermal conditions, which in turn create a more variable environment [26]. Therefore, a pergola with an overhang of 1 meter above the facade and an array of light beams was proposed. The voids between the beams, were suggested to be covered with deciduous “plant roof”, typical of the Mediterranean traditional architecture. The segmentation of the shelter into many smaller parts of variable height and geometry allows the movement of the cooling air breeze during the warm days xxii (Fotos 17, 18). This alive canopy is also ideal for diffusing the light and protecting the courtyard and the classroom interior from glare. The shading study with Ecotect, illustrates the efficiency of pergola as it blocks out the sun from the façade during cooling periods and allows sun to penetrate in winter. The beams and the canopy of the deciduous plants, extend the shadow/light filtering effect during all school day (Fig. 13, 14, 15). 251658240
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Fotos 13, 14, 15, 16: Aspects of the pergola, as it was proposed in the original architectural proposal of the 30’s, (Antonakakis) 251658240
Fotos 17, 18: plant roof as element of climatic control (Mantziou) 251658240
Figures 13, 14, 15: Shading masks of the Ecotect Model, of the metal façade before and after the restored pergola
2.1.6. Improving the classroom’s courtyard microclimate 15
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AER supports that outdoor microclimatic conditions are substantially interlinked with the environmental conditions of indoors. Therefore, the energy retrofit scenario proposes revival actions of the surroundings that improve thermal comfort conditions of the open spaces by decreasing the ambient air temperature during the cooling period. This also proves to be beneficial for the condition of the ambient airflow that naturally ventilates the indoor spaces. In the AER proposed scenario, the potential of outdoors courses at the mini-courtyard under the pergola, during the midseasons, gives a robust evidence of the strong eternal connection between Greeks and life in the open space. The original architectural design proposes the extensive glass façade to be completed removed during warm days. Sliding panels can be stored in the entrance booth. Both spaces, classroom and minicourtyard, are unified in one and so do their environmental conditions. Envi–met software was used to simulate the micro urban environmental conditions before and after the retrofit proposal and estimate the thermal comfort conditions during a typical late morning in June. The AER scenario of the moderate revitalization of the school mini-courtyards included replacement of the asphalt terrain with stone paving blocks, cool material coating on the roofs and on the pergola and deciduous greenery as an extra summer canopy. In order to estimate the Predicted Mean Vote (PMV) of a typical student, the Fanger model was used. It refers to a thermal scale that runs from Cold (-3) to Hot (+3), originally developed by Fanger [27] and later adopted as an ISO standard 7730:2005. Six factors were taken into consideration: the metabolic rate (met) of light playing activities, the clothing insulation (clo) of summer clothing, the air temperature, the radiant temperature, the air velocity and the relative humidity of the open space before and after the AER, on a typical day of June. The Envi-met model included the school building complex with all its courtyards and its urban surroundings, as it is illustrated at Foto 7. The PMV analysis, focused at the typical classroom’s mini courtyard, designated the efficiency of the proposed measures. PMV factor at the miday of June before the micro urban revitalization proposal was ranging between 2.7 and 3.53 (hot), indicating strong thermal discomfort that deprives of any use of the mini courtyard, (Figure 16). After the AER, the PMV factor in the same position, was reduced in average to 1 (neutral to slightly warm), which offers satisfying conditions for the unification of indoors and outdoors scenario , (Figure 17). 251658240
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Figures 16, 17: Courtyard’s PMV factor at the miday of June before the micro urban revitalization proposal after the AER
3.1. Results Discussion 17
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Architectural Energy Retrofit aims at minimizing energy demands by optimizing firstly the good operation of the building based on its architectural disciplines and the well-being of the users, before proceeding in the typical energy retrofit actions. As a result, symbiotic strategies combine building retrofit and microclimate revival, derived from the energy behavior potetntial of the building order, the space’s articulation and the occupant’s pattern. Strong evidence that AER is a high energy efficiency retrofit strategy that paves the way for Nearly Zero Energy in existing buildings, were provided by the feedback from the quantitative analysis with Building Information Modeling tools. The most important energy-focused remarks are the following: ● Despite of the mild climate of Athens, during the school period, heating demands have the biggest share while cooling demands are limited (Table 1). However, the future scenario that includes further educational and community activities will extend the operational period of the school complex during summer months and holidays. As a result, cooling demands are expected to increase significantly and so do the positive impact of the cooling strategies. ● During the heating period, the set of the AER measures further increase the indoors operative temperature 1, 5 – 2o C in average. During the cooling period the indoors operative temperature is lower 2- 2,5 o C than the current conditions. At Table 5, the diurnal hourly temperature fluctuation for a typical heating period day and a cooling period day, shows during school day (08:00-16:00), the final piled-up set of measures (described as daylight optimization because it was the last action to add in the tested scenario) reach the operative temperature very close to the 20 o C heating point. In summer time, during the school day, the operative does not exceed the 26 o C cooling point. ● At Table 6, ventilation rates in Air Changes per Hour (ACH), show sufficient natural ventilation, 23 ACH, during winter courses with moderate use the top windows. Efficient cooling is achieved from end of May until start of October, with high night and day cross ventilation rates ranging from 3 to 11 ACH. ● During heating period, the reduce of the size of the classroom as a thermal zone, minimizing envelope’s heat losses and controlling airflow, will eventually contribute to less energy demands and to the best efficiency of the heating system’s performance. ● Night ventilation combined with high thermal capacity for precooling the envelope and applying cross ventilation during the day, can limit drastically the need for cooling system ● By piling up the tested measures into a complete proposal, the final energy demands of every phase were estimated with Energy Plus software. The final set reported a reduction of 44, 2 % of the total final energy demands for heating, cooling and lighting, paving the way for n ZEB retrofit, as it is shown at Table 7. 251658240
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Table 5: Indicative two days diurnal temperature fluctuation for a typical winter and summer day 251658240
Table 6: Annual classroom’s ACH based on natural ventilation scenario. Apart from the encouraging feedback, of the above quantitative computer analysis on the energy efficiency of the AER strategy, some very interesting qualitative values that could be qualified as nonenergy benefits, are accomplished: ● The restoration of in-between spaces that establish a smooth transition of the student from the outer world into the inner academic world of knowledge. This statement describes phsycological subconscious human needs that need to be satisfied in order the school fullfill its educational role. Transitional spaces have been a basic area of interest for Pedagogics and Environmental Psychology, due to the stimulative spatial variables they can offer to the children [28]. 19
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This concept stops being only symbolic and implements in the architectural built space and energy performance. The route from the noise and the chaos of the city to the silence and the order of the classroom is enriched and interconnected with the presence of the covered mini-courtyard and the entrance buffer zone. AER stimulates the transitional in-between spaces and routes, the students have to follow in order to leave the open space playing activities and enter in the classroom cell. The gradual shift from the exposed outdoor suuroundings into the protective environmentally controlled space is restored in theory and in practice. ● The experience of outdoor classes in the urban environment is re-established. By ensuring thermal, visual and acoustic comfort, the unification of the indoor classroom and outdoor minicourtyard, widens the range of educational activities and challenges for more experimental lerarning strategies (Fig. 18, 19, 20). From the start of the 20th century, the concept of open-air school combined student’s physical health with the learning environment, and suggested outdoor classes during mild season by providing a teaching verandah opening out of the classroom [29]. Nowadays, outdoor class is an option that is related with the environmentbased education. Studies have determined that environment-based education significantly raised motivation levels [30]. The results provide evidence of environment-based education’s ability to improve students’ achievement motivation and support [31], capturing the interest of alternative learning methods. .251658240
Figures 18, 19, 20: Architectural Sketches by D. Antonakakis visualizing the school life outdoors
● Participant-Perspective non-energy benefits, could also include reduced operational and maintenance costs due to the limited use of mechanical infrastructure for heating and lighting. Although a further technoeconomical study is needed to establish the above, the optimization of the envelope’s passive mechanisms to filter outdoor climatic conditions, strongly indicates that there is no need for severe and comlex heating, cooling, ventilating and lighting system that a typical energy retrofit measures often recomends.
Table 7 summarizes the analysis phases that pile up the final retrofit scenario, as they were described earlier. It estimates the percentage reduction in the total energy use reduction and gives information about how the energy demands are distributed. The last column refers to the non-energy benefits, the retrofit measures achieve. Although this kind of info is only indicative, it gives a hint of the holistic theory of AER.
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Measures Current situation
1.
Thermal impact *
insulation
Openings displacement*
REVISED VERSION
% Energy Demands Savings
Heating
Cooling
Electricity
Total
66.9
2.22
14.22
83.34
60
0.73
14.22
74.95
10.1
49.7
0.76
14.22
64.68
22.4
50.23
0.66
14.22
65.11
21.9
36.8
0.26
14.22
51.28
38.5
43.65
0.1
2.73
46.48
44.2
2. ( +measure 1)
3.
Sun shading system* +measures 1,2)
(
4. Natural Ventilation
control optimization *( +measures 1,2,3)
5.
Non-Energy Benefits
Educational related benefits, good IAQ, health and well-being, lower operating cost, flexibility in use, space enhancement, increase of funtionality, stimulative environment
Daylighting optimization* ( +measures 1,2,3,4,) * Seasonal redefining of the size and the volume of the classroom as a thermal zone is taken into account
Table 7: Estimation of the energy use distribution and energy demands savings and list of the non-energy benfits
3.2 Conclusions The present preliminary study, aims at establishing a holistic approach where energy balance, architectural disciplines, user’s behavior and microclimate’s revival, are interlinked and interacted. First reults provide strong evidence of its high-energy efficiency performance potential. Maximizing user’s and space’s options to adjust to different seasonally environmental conditions will lead evidently to the optimum operation of the designed space and to the best response of the end-user’s energy behaviour. Building’s Architectural Retrofit Scenario linkes indoors conditions with the microclimate’s revitalization, driving to the creation of micro urban energy oasis with symbiotic strategies. Nevertheless, AER theory also recharges basic open questions about the nature of the architect’s profession. Necessary condition for the applicability of AER’s working hypothesis is the architect to keep up with the dynamic progress in the energy design and management arena that influences dramatically the built environment. He needs to be scientifically updated, to capitalize the specialized technical information, to evaluate the upcoming directives and trends, in order to embed them in his designing practice. This statement is part of a wider introspective concerning the role of the architect in the modern world. He needs to feel some responsibility, like engineers and consultants who, laying claim and enter by the back door to steadily rob him of his freedom [32]. Another drawback of this alternative new approach is the lack of confidence, as there is no relative materialized background. Lack of standardization results in greater performance and execution risk. Therefore, a full systematic review should be carried on, in order to determine the the technical feasibility and 21
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the methodology of this strategy. The outcome benefits should also be compared with other typical retrofit practices, in cost-optimum terms. Long term potential paybacks from minimizing maintenance and upgrading building services systems and achieving better adjustment to future climate, building’s use and operational changes should be further studied in order to balance the high risk factor of the applied bioclimatic strategies. The outcome results are expected to be encouraging as the first step towards reducing the investment cost is to reduce energy demand in the first place [33]. Architectural Energy Retrofit strong point is the maximum added value it pursues in the energy retrofit scenario. It is commonly argued that non-energy benefits are difficult to aggregate, to monetize and to be verified by third party. However, they are a strong innovation in energy efficiency behavior. The term “added value” is on a “change of the way to think of the Environment” through anthropocentric proposals (reuse, awareness, and sustainability). Such a contribution cannot be evaluated by quantitative measurements, or a solely technical feasibility assessment today. The main goal is rather to start a process of "change of mentality" which may then "cultivate" further individual quantitative targets and technical solutions [34]. As an answer to this demand, more sophisticated valuation methods are being developed based on the “common good” balance, such as the Matrix of the Economy for the Common Good (ECG) movement [35]. A general remark to conclude with is that Architectural Energy Retrofit does not face energy retrofit as an end in itself. This innovative retrofit proposal demonstrates a diametrically opposed direction than the typical practices by promoting non-energy related factors as equal important with the energy balance. By developing mechanisms and symbiotic strategies based on the restoration of architectural qualities, the building“opens”at its surrounding environment instead of being “sealed”, responses to the user’s needs and adjustes to seasonal and environmental changes, resulting to a better operation of indoors and outdoors and a balanced energy performance. As a result, AER paves the way for the building’s deep energy retrofit with high-energy efficiency performance and multiple non-energy related benefits.
3.3 Acknowledgements This research’s working hypothesis is based on the outcome effort of professors architects Dimitris and Suzanna Antonakakis on intepreting Pikionis’ architectural work. The authors grateful acknowledge their valuable contribution.
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[1] Victor Olgay, “Design with Climate”, Princeton University Press, NJ 1963 [2] Baruch Givoni, “Man, Climate and Architecture”, Applied Science Publishers, London 1976 [3] EU, Directive 2012/27/EU, Official Journal of the European Union, October 2012 [4] Greek Regulation on the Energy Performance of Buildings, (K.E.N.A.K.), http://portal.tee.gr/ [5] Buildings Performance Institute Europe (BPIE), A Guide to developing Strategies for Building Energy Renovation, Brussels, February 2013
[6] Baruch Givoni, Comfort, climate analysis and building design guideline, Energy & Buildings, 18, 1992, pp.11-23 [7] Francis D.K. Ching, “Architecture. Form, space and order”, Willey Editions, New Jersey, 2015 [8] Herman Hertzberger,” Lessons for students in architecture” , 010 Publishers, Rotterdam 1993 [9] Skumatz Economic Research Associates (SERA), “Lessons Learned and Next Steps in Energy Efficiency Measurement and Attribution: Energy Savings, Net to Gross, Non-Energy Benefits, and Persistence of Energy Efficiency Behavior”, CIEE Behavior and Energy Program, California Institute for Energy and Environment, Berkeley, CA, 2009 [10] Jennifer Thorne Amann, “Valuation of Non-Energy Benefits to Determine Cost-Effectiveness of Whole-House Retrofits Programs: A Literature Review”, American Council for an Energy-Efficient Economy, 2006 [11] Erin Malone, “Driving Efficiency with Non-Energy Benefits”, ACEEENational Symposium on Market Transformation, Baltimore 2014, http://aceee.org/ [12] “ Capturing the Multiple Benefits of Energy Efficiency“, International Energy Agency, OECD/IEA, France 2014 [13] Michael Freed, Frank A. Felder, “Non-energy benefits: Workhorse or unicorn of energy efficiency programs?”, The Electricity Journal 30, 43–46, 2017 [14] Technical Guideline KENAK 20701-1/2010, Technical Chamber of Greece, Athens 2014 [15] Daskalaki, Elena & Sermpetzoglou Vasileios,”Energy performance and indoor environmental quality in Hellenic schools, Energy and Buildings”, 43, pp. 718–727, 2011 [16] Gaitani, N. et al, “Using principal component and cluster analysis in the heating evaluation of the school building sector”, Applied Energy, 87, pp.2079–2086, 2010 [17] Santamouris, Mattheos et al., Using intelligent clustering techniques to classify the energy performance of school buildings, Energy and Buildings, 39, pp.45–51, 2007 [18] Antonakakis, Dimitris, Two studies on Dimitris Pikionis, 1st Edition. Athens, Domes Edition, 2013 [19] Lighting Research Center, “Patterns to Daylight Schools for People and Sustainability”, Rensselaer Polytechnic Institute, NY 2010 [20] Corgnati, Stefano Paolo et al, 2009, Thermal comfort in Italian classrooms under free running conditions during midseasons: Assessment through objective and subjective approaches, Building and Environment, 44, 785–792 [21] Wargocki, Pawel et al, “Providing better thermal and air quality conditions in school classrooms would be costeffective”, Building and Environment, 59, pp. 581-589, 2013 [22] Wargocki, Pawel et al, “The Effects of Outdoor Air Supply Rate and Supply Air Filter Condition in Classrooms on the Performance of Schoolwork by Children”, HVAC&R RESEARCH, vol 13. number 2, 2007 [23] Brager, “Developing an adaptive model of thermal comfort and preference. ASHRAE Transactions: Research, RP884.”, 1998
[24] M. Griffiths , M. Eftekhari, “Control of CO2 in a naturally ventilated classroom”, Energy and Buildings, 40, pp. 555560, 2008
[25] Eleni Mantziou, “ΒΙΟ, Bioclimatic architecture in Greece”, Ergon IV publishers, Athens 2009 [26] Maria Sinou, “Design and Thermal Diversity of Semi-Enclosed Spaces”, Melrose Books, Cambridgeshire 2007 [27] P. O. Fanger, “Thermal comfort: Analysis and applications in environmental engineering”, Danish Technical Press, Copenhagen, 1970
[28] Tsoukala Kyriakí, “Trends in School Design “, Epikentro Editions, Thessaloniki, 2000 [29] Ralph Crowley, “The Open-Air School Movement”, British Journal of Tuberculosis, Volume 3, Issue 3, July 1909, Pages 188–190
[30] The National Environmental Education & Training Foundation, “Environment-based Education,Creating High Performance Schools and Students”, Washington, DC, 2000
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[31] Julie Athman, Martha Monroe, “The effect of Environment-Based Education on student’s achievement motivation”, Environmental Education Research 10(4):507-522 · November 2004
[32] Herman Hertzberger,” Space and the Architect. Lessons in architecture” 2, 010 Publishers, Rotterdam 2000 [33] Kapsalaki, Maria et al., “A methodology for economic efficient design of Net Zero Energy Buildings”, Energy & Buildings, 55, pp.765-778, 2012,
[34] Eleni Mantziou et al., "Cultural Landscapes as a Means of Energy Reduction at Global Warming", Energy, Transportation and Global Warming, pp. 223 -243, 2016
[35] Economy for the Common Good (ECG) movement, https://old.ecogood.org/
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S0378-7788(17)31561-X http://dx.doi.org/doi:10.1016/j.enbuild.2017.05.001 ENB 7582
To appear in:
ENB
Received date: Revised date: Accepted date:
28-10-2016 14-2-2017 1-5-2017
Please cite this article as: Eftychia Eliopoulou, Eleni Mantziou, Architectural Energy Retrofit (AER): An alternative building’s deep energy retrofit strategy, Energy and Buildingshttp://dx.doi.org/10.1016/j.enbuild.2017.05.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Architectural Energy Retrofit (AER). An alternative building’s deep energy retrofit strategy Eftychia Eliopoulou1,*, Eleni Mantziou2 1. Architect Eng. NTUA, M.Sc. in Environmental Design of Buildings W.S.A., Ph.D. Researcher, School of Architecture, Department of Architectural Design D1, National Technical School of Athens, Greece 2. Dr. Architect Eng. NTUA, Associate Professor, School of Architecture, Department of Architectural Design D1, National Technical School of Athens, Greece *corresponding author. E-mail address:[email protected]
Abstract The refinement of architectural space plays a catalytic role in the building’s energy balance. A different configuration on the deep energy building retrofit is presented on this paper, by proposing mainly strategies that hierarchize in a high position the invigoration of the building’s architectural design principals. These space qualities enable diversity of occupancy, environmental variability and facilitate the building envelope to operate efficiently as climate moderator. The main working hypothesis claims that bioclimatic trends, derived from primary architectural decisions of the early design phase, predispose the final energy performance of the existing building.Based on that, the alternative retrofit proposal called Architectural Energy Retrofit (AER) strategy, focuses on the energy genetic code of these basic architectural features. It argues that their holistic revival and refinement, indoors and outdoors will pave the way for the building’s energy retrofit and the space’s regeneration. As a case study to test this theory, an old and energy-consuming school complex is selected. By applying solely architectural interventions, a reduction of 44% energy demands was achieved. The results highlighted the challenges of “quantifying” the energy efficiency of architecture. However, by exploring and focusing on the non-energy, co-benefits, it also seeks to expand the perspective of energy efficiency beyond the traditional measures, by identifying and measuring its impacts across many different spheres. AER, as a counterproposal, wishes to add a new base of discussion on deep energy retrofit strategies as it follows a diametrically opposed direction than the typical practices. The building instead of being “sealed”and its environment kept strictly controlled, it “opens” and interacts with its surroundings.
Research highlights ► Architectural Energy Retrofit is an alternative building’s energy retrofit proposal ► Early architectural design phase predispose building’s final energy performance ► Linking building’s energy retrofit with its primary architectural principals ►Challenges on quantifying the energy efficiency of architecture ►Non-Energy benefits of Architectural Energy Retrofit (AER)
Keywords Deep energy retrofit; energy-demand control; sustainable rehabilitation practices; quantifying architectural disciplines; non-energy benefits; added-value; Architectural Energy Retrofit; 1
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2.1 Introduction Designing spaces daylit and naturally ventilated, by taking into account the microclimatic conditions, have been among the main objectives for architects [1] [2]. Bioclimatic design’s importance in the early design phase of new buildings is not only indisputable, but it is also required according to the European [3] and National energy legislative framework [4]. However, when it comes to deep energy retrofit of existing buildings, the typical practices leave out the architect’s perspective. Architectural design although it affects dramatically the energy needs, it is not yet fully implemented in the assessment of energy use. The highenergy efficiency performance of the building sector, according to the contemporary high standards of European and national legislative framework, mainly focuses on the use of renewable sources, efficient technologies and insulating building materials, hierachized with cost-optimal terms [5]. The specific energy behavior pattern derived from the architectural form of the examined building and the microclimate of its surroundings, are often disregarded. They are usually more related with the user’s thermal comfort conditions [6], rather than capitalized at the final energy performance of the building. The present paper intends to value the final energy gains by invigorating the architectural qualities of the building during the energy renovation. This practice, described as Architectural Energy Retrofit (AER), interlinks the building’s final energy needs with the architectural concept’s bioclimatic potential. By tracing, the architectural desciplines of the examined building and profiling those architectural elements that affect its internal and surrounding external conditions, an environmental post-occupancy evaluation analysis of the building is performed. This evaluation, that includes both energy efficiency and architectural perspectives, forms the basis of an energy retrofit proposal that sets as priority to fix, restore, modificate and update these architectural elements and structures to minimize building’s energy demands along with achieving the revival of the microclimatic conditions and the non-energy benefits of a well-designed space. By using the term architectural qualities, we refer to the basic design’s principals that articulate the built indoor and surrounding outdoor environment and shape the final space’s geometry. They originate from archetype forms and generate the structure of the architectural concept, aiming at the satisfaction of physical, aesthetic and psychological needs of the users. We are talking about primary design elements such as atriums, arcades, enclosed and in-between spaces, open plan arrays, arrangemet of the circulation, open space’s propotions and façade defining features [7]. These elements have genetic characteristics that dispose their potential as microclimate modulator and influence dramatically the environamental variability. This genetic disposition is passed to the structure and the building order of the building, which is not influenced dramatically by any changes in the use pattern [8]. Thus, the environmental conditions diversity, the visual, thermal and acoustic comfort of the users derive from this basic architectural concept. This dynamic, so far overlooked, could play a catalytic role in the building’s energy retrofit if we recharge it. The operational configuration of the building service systems follows that special pattern the architectural space has formulated. Therefore, it is debatable how efficient it is to propose the same set of energy retrofit measures to treat radically different “pathologies”. The present research does not firmly oppose to the strategies developed so far, but wants to contribute to the open dialogue of building’s energy retrofit with alternative architecturally oriented proposal that broaden the benefits of retrofit actions. Apart from the solely energy viewpont, the strategic advantage of Architectural Energy Retrofit (AER) is described with the non-energy benefits (NEBs). Non-energy benefits (NEBs) or non-energy impacts (NEIs) are generally defined as any real or perceived, financial or intangible benefit accrued by an energy efficiency project. They are effects that are omitted from traditional energy evaluation work, which focuses on impacts on energy savings [9]. 2
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“Non-energy benefits [10,11]”,“Co-benefits”, “ancillary benefits”, “non-energy impacts” and “multiple benefits [12]”are equivalent terms used to describe these positive and negative effects beyond energy savings and energy bill savings that are attributable to energy efficiency programs. In energy efficiency economy, the values of NEBs gain ground at the policy makers and market transformation communities. NEB of energy efficiency programs have been studied as early as 1993, and there have been hundreds of papers and reports published since then, many of them finding that NEB are significant [13]. A strength of the multiple benefits approach is that it encourages cross-sectoral collaboration in policymaking. By optimizing the intellectual, technical and financial resources available, it allows decision-makers to tackle more complex issues in a more holistic manner, as it broadens their perpestive on energy- retrofit impact xi.
Figure 1: ECD/IEA)
The multiple benefits of energy efficiency improvements, ( International Energy Agency,
Highly efficient buildings, additionally characterized with AER terms, infer a range of co-benefits that could motivate decision-making process when it comes to energy retrofit investment. Societalperspective benefits such as infrastructure savings for energy and controlling local air pollution, Participant non-energy impact such as health and well-being, added asset values such as improved aesthetics and increased comfort, are strongly pursued in this alternative proposal. However, the broader impacts of energy efficiency have not been systematically assessed in practice. The main reasons are their indirect nature that makes them hard to measure or value in a robust and objective manner like other measurements associated with energy efficiency programs. Therefore, their evaluation is another open challenge for Architectural Energy Retrofit.
1.2 Methodology description The proposed methodology, firstly explores how the original architectural qualities (both indoor and outdoor) affect the operational pattern and shape the microclimate conditions. The second step of the methodology evaluates their implementation to the building’s final energy balance. The third proposes tailoring measures for maximizing their environmental variability and energy-efficiency potential along with enabling their occupancy diversity, before any other typical retrofit action taken, synthesizes the AER methodology. As the scope of this study is to produce robust, applicable and valid results, the achievement of 3
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substantial energy conservation with the implementation of solely architectural interventions, after multidirctional information procession, should follow a simplified and efficient methodology. One of the main challenges that arise from the AER concept, is the need to assess how “correct” and “feasible” is to “quantify” architectural concepts with contemporary energy efficiency terms, in order to be verified by the rest of the stakeholders. It is not a common practice for architecture to play a catalytic role in energy retrofit of building stock. Therefore, there is lack of confidence and high risk of non-generating clear proposals by getting “lost in translation” among theoretical architectural disciplines and technical calculations. A first step of this research is to test AER working hypothesis in a real case study and attempt to produce numeric values by using Building Performance and Analysis tools. An old school building complex in Athens’ city centre is used for this preliminary research. It has architectural form and space articulation, characterized by strong architectural concept. In combination with its contemporary poor energy performance and user’s comfort levels, indoors and outdoors, it provides a solid working base and a good starting point for AER. As it is already described, the original architectural concept was explored and linked with the building’s final energy use. The current indoor and outdoor conditions, the users’ thermal and visual comfort status from the on-site visit and the past 3-year energy bills gave feedback for building up the profile of the current energy use distribution and the indoors and outdoors thermal and visual conditions, with the help of dynamic modelling. Next phase included the set-up of architectural-based retrofit scenarios that aimed at the optimum environmental conditions of the architectural space potential and the increase of the end user’s thermal and visual comfort -indoors and outdoors-. The final energy saving benefit and the revitalization of the outdoor surrounding were also estimated and gave a comparative numeric analysis before and after the retrofit. Behind of the apparent technical measures that were finally proposed at the final step of the AER analysis, the intention of restoring and enhancing the space with polyvalence that meets the user’s comfort, physocological and aesthetic needs, were set high at the hierarchy in the decision-making process. The estimation tools included a group of energy design software, according to the multi-orientated perspectives of AER. Each of it estimated different aspects and contributed to the qualitative and quantitave required assessment. Energy demands and efficiency of bioclimatic features of the examined school were compared before and after applying the retrofit scenario. Energy Plus software estimated the final energy demands, Envi-Met software described microclimatic outdoor conditions and students’ thermal comfort, CFD software demonstrated the air movement of the tested ventilation scenarios and Ecotect software simulated the performance of the shading devices. The weather files were loaded from the International Weather for Energy Calculation (IWEC) files for Athens. It was also taken into account the Greek Regulation on the Energy Performance of Buildings (K.E.N.A.K) [14] the operational scenario of schools. So, cooling point temperature was set to 26°C and heating set point temperature was set to 20°C. The cooling period for Athens (Greek climate zone B) starts at mid of May until September and the heating period is from November until April. The school year lasts from mid of September until mid of June. The operation scenario described a full school year, the typical school day that starts at 08:00 a.m. and ends at 16:00 p.m., the 45 minutes’ duration of the course, the 15 minutes’ brakes and the internal gains from the pupils and the use of the current lighting system.
1.3 The case study The school complex that was selected as the case study for this report is an elementary school in Athens’ city centre next to Lycabettus hill. A famous Greek architect Dimitris Pikionis designed it in 1931. It 4
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is one of the first samples of modernism and stands out as a reference of contemporary Greek architecture. It is a well-known architectural reference due to the successful adjustment of the building complex to the site’s steep landscape and the mild climatic conditions of Attica. Its space diversity generated by the terrace array of the classrooms provides private mini-courtyards and offers the pioneer option of outdoor classes during midseasons. (Fotos 1, 2, 3) Today, the school is protected as an architectural monument of Modernism under austere morphological restrictions that do not allow any radical alterarions of the envelope, a typical deep energy retrofit would require. However, its current condition needs extensive renovation. First raw data from the on-site visit and the end users’ opinion indicated thermal discomfort especially during the heating period. The classroom’s light conditions were described as constantly gloomy leading to extensive use of electrical lighting of old technology. Heating is provided with an uninsulated central system and radiators are misplaced next to the regurarly open entrance. There are no any heating or lighting control systems. Masonry walls and concrete roof provide high thermal capacity but they do not have any thermal insulation and neither has the floor, which is in direct contact with the ground. The vast classroom’s façade exposed to the southwest, retains the original iron-framed, single-pane, frosted-glass, sliding opening, from the 30’s. The classroom’s mini courtyards are lacking greenery and shadow and the terrain is covered by asphalt, resulting in problematic microclimatic conditions. (Fotos 4, 5) 251658240
Fotos 1, 2, 3: Panoramic view of the school complex and classroom interior when it was finished in1933, and architectural plan of the typical classroom, (Antonakakis)
Fotos 4, 5: The school complex today, outdoors and indoors The annual heating consumption –bill based– using natural gas is around 74 kWh/m² final energy. This rate is much higher than the average rate for the non-insulated Greek schools of the same climatic zone that is estimated 46 kWh/m² [15] . Greek school buildings’ energy is mainly used for heating and lighting 5
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needs. Energy for cooling purposes is limited in the personnel office areas where split A/C units are used. Accordingly, to energy consumption data collected through energy surveys performed in 320 schools in Greece the typical Greek school uses annually 57 kWh/m² for heating and 20 kWh/m² for electricity final energy [16]. According to another study, there is a considerable potential for energy conservation in heating loads ranging from 36% to 72% compared to the present state for the Greek school buildings [17]. The modelling simulation of the indoors temperature conditions in the typical classroom, verified the pupil’s thermal discomfort complaints. The classroom’s operative temperature on an hour basis was simulated with Energy Plus under free-running conditions (Fig. 2) .The high frequency of the indoors temperature values that fall behind the heating set point and exceed the cooling set pont, except from the midseasons, is presented at Table 1. The chart also gives an indicative qualitative aspect of the excessed heating demands in comparison with the moderate cooling demands during the school year. 251658240
Figure 2: Sketch Up model of the classrooms array used in Energy Plus calculations Fotos 6,7: Current view of the classroom, aerial view of the school building complex.
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Table 1: Annual current classroom’s operative temperature and outdoor air temperatre
2.1 Architectural Energy Retrofit (AER) scenario As the scope of this report is to identify the potential energy efficiency by invigorating architectural qualities, the energy retrofit scenario will propose measures focused on optimizing the passive energy behaviour of the envelope that derive from its architectural desciplines and building order. In the Pikionis’ school, despite of the problematic current conditions of the school complex, it is apparent that the original architectural concept of the child-scale classrooms and their own courtyards’ articulation, qualifies with flexibility and polyvalence the open spaces. According to the occupancy pattern, these spaces have the right dimensions and the potential of outdoor educational activities that agree with contemporary educational and pedagogical theories. From the energy efficiency point of view, the repeated classroom and mini courtyard cluster encourages the autonomous operation scenario, compatible with the modern energy design standards. Therefore, in the Architectural Energy Retrofit scenario, the above architectural qualities will be designated to pave the way for high-energy efficiency operation. The study on the work of Pikionis, by professor architect Dimitris Antonakakis, will be used as a guide for the selection of the architecturally oriented retrofit measures. In his thorough analysis [18] on the design and manufacturing phases of the examined school, he presents strong evidence that certify that the original architectural proposal was never fully realized. The design that was finally built had significant modifications from the architect’s concept resulting in partial malfunction of the user’s energy behavior and of the envelope as climate moderator. The original proposal included various openings for cross ventilation of the classrooms, an extensive pergola over their mini-courtyard for shading of the outdoor space and the glaze façade and an entrance booth at the side of the classrom that served as a buffer zone between indoors and outdoors during wintertime (Fotos 8, 9). 7
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The retrofit scenario took into account the above along with the mild microclimatic conditions due to the surrounding greenery, the open terrain, the seasonal and daytime school operation and the modern energyefficiency materials and pracrices. The proposed measures included: ● Partial thermal insulation of the masonry envelope, ● Optimization of daylighting and filtering to avoid glare, ● Seasonal modification of classroom’s heated volume, ● Use of buffer zone entrance during wintertime ● Restoring cross ventilation, night-ventilation and façade shading for efficient cooling ● Shading pergola seasonally covered with greenery and using cool paving materials for the courtyard’s surface. The following analysis demonstrates the energy-efficiency benefits by modificating, restoring, and redesigning of architectural structural elements and explains the necessity of those actions for the holistic space revival. Finally, a numeric estimation of the energy demand reduction capitalizes the retrofit with AER terms.
251658240 Fotos 8, 9: Section, 3d model and plan of the typical classroom and its courtyard according the architect’s original concept, (Antonakakis)
2.1.1. Thermal insulation impact High thermal insulation of the envelope in new and deep renovated buildings is obligatory according to contemporary Greek Energy Building Regulations. In the case of the typical classroom structure, the very high thermal inertia the masonry walls and the envelope’s contact with the ground offer provides stable internal conditions during the day. However, the low surface temperatures during wintertime have a negative affect on the thermal comfort of the students and the envelope responses very slow when the heating system is on. The AER defined the classroom unit as one thermal zone and proposed the selective application of internal thermal insulation, considering the daily 8-hour operation and the monument’s morhological restrictions (Fig. 3). Although the building elements lose their thermal capacity in this case, they response faster to heating when the system is on, which is compatible with the school program. Thus, it was suggested only the external walls, the roof and the internal walls adjacent to the non-thermal storage room to be insulated with panels of 10cm EPS as it is described at the table 2. All surfaces in contact with the ground (floor surface and open cloakroom’s corner walls) were left uninsulated. It was estimated that it is more beneficial for cooling purposes (as it will be described later), without significant heat losses during heating period.
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Figure 3: 3d Section of the typical classroom illustrating the thermal insulation proposal
U values (W/m²*K)*
current situation
Greek energy regulation standards **
retrofit scenario proposal
insulation details
60cm width external plastered stone walls
2,13
0,5
0,26
10cm Mineral wool (thermal onductivity=0,031 W/m*K) in the internal side of the classroom
60cm width stone walls to the ground
2,28
1
-
no insulation
60cm width stone walls to the north storage corridor -non thermal zone-
2,13
1
0,2
10cm Mineral wool conductivity=0,031 W/m*K) in the internal side of the classroom
60cm width stone walls to the next classroom -thermal zone-
-
-
-
no insulation
20cm concrete roof with 10cm lightweight concrete and wateproof asphalt membrane on the top
1
0,45
0,2
12cm EPS (thermal conductivity=0,031 W/m*K) with light beize ceramic tiles (SR=0,58), on the existing roof
mosaic floor to the ground
3,5
0,9
3,5
no insulation
* based on energy plus computer model
**according to the climatic zone of Athens
Table 2: Thermophysical characteristics of the building envelope before and after the AER
2.1.2. Openings displacement The concept of the internal insulated envelope from the previous stage is repeated in the energyconsuming single glaze metal façade. Due to the monument’s restrictions, the original opening must not be replaced (Foto 10). Only the frosted glass can be replaced with clear glass, according to the original proposal. Therefore, a double window that meets the contemporary energy efficient standards was proposed at the internal side of the 50cm stonewall behind of the preserved façade (Fig. 4). Double pane clear glass with low– e coating would allow natural light in the classroom and the original metal façade could function as a movable extra glass layer during heating period, supporting the energy performance of the opening. Infiltration rates would be minimized. The significant benefit in providing flourishing daylit in the classroom from the clear glass, apart from minimizing the use of electric lights, is the promotion of morning circadian stimulation in students. According to the latest researches, the students who were not exposed to morning light or daylight that would stimulate the circadian system experience a more pronounced delayed circadian phase, which results in later bedtimes, and possibly chronic sleep deprivation, stress or mood disorders. If the lighted environment in schools can promote circadian entrainment by delivering light that will shift the 9
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biological clock to an earlier time, students will fall asleep earlier at night and sleep deprivation will be reduced. In turn, students should feel better and perform better in school. [19] 251658240
Foto 10: The original façade of the 30’s ,as it is today. Figure 4: 3d section of the typical classroom illustrating the façade retrofit proposal
Openings
current situation (single pane frosted glass and steel frame)
retrofit scenario proposal (double pane clear glass low-e and aluminum frame with thermal brakes + current glaze façade with clear glass)
U value (W/m²*K)
6
2
Solar heat gain coefficient
0,3
0,6
Transmittance visibility
0,3
0,65
**according to the climatic zone of Athens
Table 3. Thermophysical characteristics of the openings
2.1.3. Seasonal redefining of the size and the volume of the classroom as a thermal zone The proposed partial thermal wall and roof insulation in combination with the new opening in the internal side of the façade, synthesizes a thermal cell that includes the core of the classroom and leaves out the supplementary rooms like the cloakroom and the storage room (Fig. 5). This concept was further organized in seasonal redefining of the size and the size of the classroom unit. An architectural volumetric rearrangement of the classroom that responds better to the heating, cooling and functional demands was proposed that also has the right dimensions as it contracts in wintertime and expands, in summertime copying the human adaptation model. At the backside of the classroom, there is an open cloakroom (approx. 10m²), with its masonry walls in contact with the ground. As it was reported earlier, these walls are left uninsulated by choice. At Table 4, it was estimated that their inside surface temperature always stays stable lower -approx. 3,5 °C-, than the internally insulated walls. Therefore, they can contribute to cool down the classroom’s operative temperature 10
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during cooling period. During the heating period, in order to prevent thermal discomfort and heat losses, a movable partition that separates the cloakroom from the rest classroom was proposed. As a result, a thermal cell enclosed by insulated masonry walls and roof, consist the classroom’s thermal zone. Subsequently, less volume (approx. 20m³) is heated there is faster response to the mechanical heating system (Fig. 6, 7, 8). 251658240
Figure 5: Seasonal redefining of the size and the volume of the classroom 251658240
Table 4: Annual hourly classroom’s operative temperature, outdoor air temperatre and wall to ground inside surface temperature 251658240
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Figures 6, 7, 8: Seasonal redefining of the size and the volume of the classroom limits surfaces and volume to minimize heat losses like the human body when it feels cold. The opposite happens when it is hot.
2.1.4. Natural Ventilation optimization Establishing Indoor Air Quality (IAQ) within the classroom is essential as it relates to the well-being, the health and comfort of occupants. Many studies have proved that indoor environmental conditions strongly influence the well-being in buildings and the productivity in working and educational environments. Children must attend schools even when the air quality and thermal conditions in the classrooms are unsuitable, because they cannot easily choose to attend another school and they have fewer ways of registering complaints than adults have. The work that children are obliged to perform in school is almost always new to them, while adults frequently perform routine, well- practiced tasks [20] . Good IAQ contributes to a favorable environment for students, performance of teachers and staff. It reduces absenteeism, improves test scores and enhances student and staff productivity [21] [22] In the examined school, the only openable window, which also serves as an entrance, is one part of the sliding metal façade. It provides moderate side ventilation during summertime and its frequent use results in severe energy penalty during winter. Rearrangement of windows’ opening area was essential in combination with the introduction of the entrance booth according to the original architectural proposal. Two natural ventilation scenarios for heating and cooling period were proposed, based on the geometry of the classroom, the existing top fenestration and the high potential of air movement by pressure from the open terrain of the site. During cooling period, two passive strategies were proposed, compatible with the Athenian mild climatic conditions and the high thermal inertia of the masonry structure. At daytime, cross natural ventilation was restored, by opening the classroom’s top windows to the north non-thermal zone storage room, which is also cross ventilated. Openable window area was maximized to the 50% of the total glaze surface, including the top fenestration and the sliding panel of the façade and the top windows of the opposite internal wall. According to the CFD model where the openings array, the classroom geometry and the climatic conditions of warm day, were simulated, it is shown that cross ventilation scenario could work efficiently (Fig. 9, 11, 12). Field studies find that people in naturally ventilated indoor environments are comfortable within a range of microclimatic values that is larger than in fully conditioned indoor environments [23] . At nightime, night ventilation for cooling was also applied, in combination with the expanded size and the increased thermal inertia of the classroom –as it was described earlier-. It was estimated with Energy Plus that in order to prevent overcooling and low indoor temperatures during morning hours, it is recommended to keep the top windows open when the outside temperature is over 22°C. During heating period, a buffer zone entrance according to the initial plans was proposed. Apart from its catalytic role as a buffer zone, AER focus on the significance as the necessary in-between space 12
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–with the minimum dimensions-, in order welcome and prepare the pupils to enter into the classrooom’s cell (Fotos 11, 12). As far as the air quality, the option of single sided ventilation from the façade during brakes is open (Fig. 10). It is reported that teaching staff and pupils control the ventilation into the classrooms by thermal comfort rather than air quality [24]. However, use of CO2 sensors fans during the courses for acceptable IAQ levels with minimum ventilation rates are also recommended.
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Figures 9, 10: CFD model of the classroom and its adjacent storage room, Airflow potential in the classroom with single sided ventilation during heating period
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Figures 11, 12: Airflow potential in the classroom with cross ventilation according to the cooling period scenario
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Fotos 11,12 : Plan and detail from the entrance booth, the architect had proposed but it was not constructed, (Antonakakis)
2.1.5. Sun shading system The pergola has always been an intergral part of the architectural design, both for shading the classroom’s southwest façade and for the thermal, visual and acoustic comfort of the mini-courtyard. AER proposal restored this structural element, according to the architect’s original proposal (Fotos 13, 14, 15, 16). The same dimensions and proportions of the solid surfaces of the pergola geometry were repeated in detail, as they credit the underlying courtyard with the qualities of a semi-enclosed space. The semi-open or semi-enclosed space is an archetypical form in architecture that is embedded in the architecture of southern climates. It intervenes between the inside and the outside and reconciles the two spaces as concerns the light, the natural forces, the view of the outside world. Its transitional character generates thoughts concerning the relation of the built space with the man and the nature [25]. From the environmental design aspect, that architectural diversity modulates also a thermal diversity. Spaces with different characteristics result in a variety of thermal conditions, which in turn create a more variable environment [26]. Therefore, a pergola with an overhang of 1 meter above the facade and an array of light beams was proposed. The voids between the beams, were suggested to be covered with deciduous “plant roof”, typical of the Mediterranean traditional architecture. The segmentation of the shelter into many smaller parts of variable height and geometry allows the movement of the cooling air breeze during the warm days xxii (Fotos 17, 18). This alive canopy is also ideal for diffusing the light and protecting the courtyard and the classroom interior from glare. The shading study with Ecotect, illustrates the efficiency of pergola as it blocks out the sun from the façade during cooling periods and allows sun to penetrate in winter. The beams and the canopy of the deciduous plants, extend the shadow/light filtering effect during all school day (Fig. 13, 14, 15). 251658240
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Fotos 13, 14, 15, 16: Aspects of the pergola, as it was proposed in the original architectural proposal of the 30’s, (Antonakakis) 251658240
Fotos 17, 18: plant roof as element of climatic control (Mantziou) 251658240
Figures 13, 14, 15: Shading masks of the Ecotect Model, of the metal façade before and after the restored pergola
2.1.6. Improving the classroom’s courtyard microclimate 15
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AER supports that outdoor microclimatic conditions are substantially interlinked with the environmental conditions of indoors. Therefore, the energy retrofit scenario proposes revival actions of the surroundings that improve thermal comfort conditions of the open spaces by decreasing the ambient air temperature during the cooling period. This also proves to be beneficial for the condition of the ambient airflow that naturally ventilates the indoor spaces. In the AER proposed scenario, the potential of outdoors courses at the mini-courtyard under the pergola, during the midseasons, gives a robust evidence of the strong eternal connection between Greeks and life in the open space. The original architectural design proposes the extensive glass façade to be completed removed during warm days. Sliding panels can be stored in the entrance booth. Both spaces, classroom and minicourtyard, are unified in one and so do their environmental conditions. Envi–met software was used to simulate the micro urban environmental conditions before and after the retrofit proposal and estimate the thermal comfort conditions during a typical late morning in June. The AER scenario of the moderate revitalization of the school mini-courtyards included replacement of the asphalt terrain with stone paving blocks, cool material coating on the roofs and on the pergola and deciduous greenery as an extra summer canopy. In order to estimate the Predicted Mean Vote (PMV) of a typical student, the Fanger model was used. It refers to a thermal scale that runs from Cold (-3) to Hot (+3), originally developed by Fanger [27] and later adopted as an ISO standard 7730:2005. Six factors were taken into consideration: the metabolic rate (met) of light playing activities, the clothing insulation (clo) of summer clothing, the air temperature, the radiant temperature, the air velocity and the relative humidity of the open space before and after the AER, on a typical day of June. The Envi-met model included the school building complex with all its courtyards and its urban surroundings, as it is illustrated at Foto 7. The PMV analysis, focused at the typical classroom’s mini courtyard, designated the efficiency of the proposed measures. PMV factor at the miday of June before the micro urban revitalization proposal was ranging between 2.7 and 3.53 (hot), indicating strong thermal discomfort that deprives of any use of the mini courtyard, (Figure 16). After the AER, the PMV factor in the same position, was reduced in average to 1 (neutral to slightly warm), which offers satisfying conditions for the unification of indoors and outdoors scenario , (Figure 17). 251658240
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Figures 16, 17: Courtyard’s PMV factor at the miday of June before the micro urban revitalization proposal after the AER
3.1. Results Discussion 17
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Architectural Energy Retrofit aims at minimizing energy demands by optimizing firstly the good operation of the building based on its architectural disciplines and the well-being of the users, before proceeding in the typical energy retrofit actions. As a result, symbiotic strategies combine building retrofit and microclimate revival, derived from the energy behavior potetntial of the building order, the space’s articulation and the occupant’s pattern. Strong evidence that AER is a high energy efficiency retrofit strategy that paves the way for Nearly Zero Energy in existing buildings, were provided by the feedback from the quantitative analysis with Building Information Modeling tools. The most important energy-focused remarks are the following: ● Despite of the mild climate of Athens, during the school period, heating demands have the biggest share while cooling demands are limited (Table 1). However, the future scenario that includes further educational and community activities will extend the operational period of the school complex during summer months and holidays. As a result, cooling demands are expected to increase significantly and so do the positive impact of the cooling strategies. ● During the heating period, the set of the AER measures further increase the indoors operative temperature 1, 5 – 2o C in average. During the cooling period the indoors operative temperature is lower 2- 2,5 o C than the current conditions. At Table 5, the diurnal hourly temperature fluctuation for a typical heating period day and a cooling period day, shows during school day (08:00-16:00), the final piled-up set of measures (described as daylight optimization because it was the last action to add in the tested scenario) reach the operative temperature very close to the 20 o C heating point. In summer time, during the school day, the operative does not exceed the 26 o C cooling point. ● At Table 6, ventilation rates in Air Changes per Hour (ACH), show sufficient natural ventilation, 23 ACH, during winter courses with moderate use the top windows. Efficient cooling is achieved from end of May until start of October, with high night and day cross ventilation rates ranging from 3 to 11 ACH. ● During heating period, the reduce of the size of the classroom as a thermal zone, minimizing envelope’s heat losses and controlling airflow, will eventually contribute to less energy demands and to the best efficiency of the heating system’s performance. ● Night ventilation combined with high thermal capacity for precooling the envelope and applying cross ventilation during the day, can limit drastically the need for cooling system ● By piling up the tested measures into a complete proposal, the final energy demands of every phase were estimated with Energy Plus software. The final set reported a reduction of 44, 2 % of the total final energy demands for heating, cooling and lighting, paving the way for n ZEB retrofit, as it is shown at Table 7. 251658240
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Table 5: Indicative two days diurnal temperature fluctuation for a typical winter and summer day 251658240
Table 6: Annual classroom’s ACH based on natural ventilation scenario. Apart from the encouraging feedback, of the above quantitative computer analysis on the energy efficiency of the AER strategy, some very interesting qualitative values that could be qualified as nonenergy benefits, are accomplished: ● The restoration of in-between spaces that establish a smooth transition of the student from the outer world into the inner academic world of knowledge. This statement describes phsycological subconscious human needs that need to be satisfied in order the school fullfill its educational role. Transitional spaces have been a basic area of interest for Pedagogics and Environmental Psychology, due to the stimulative spatial variables they can offer to the children [28]. 19
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This concept stops being only symbolic and implements in the architectural built space and energy performance. The route from the noise and the chaos of the city to the silence and the order of the classroom is enriched and interconnected with the presence of the covered mini-courtyard and the entrance buffer zone. AER stimulates the transitional in-between spaces and routes, the students have to follow in order to leave the open space playing activities and enter in the classroom cell. The gradual shift from the exposed outdoor suuroundings into the protective environmentally controlled space is restored in theory and in practice. ● The experience of outdoor classes in the urban environment is re-established. By ensuring thermal, visual and acoustic comfort, the unification of the indoor classroom and outdoor minicourtyard, widens the range of educational activities and challenges for more experimental lerarning strategies (Fig. 18, 19, 20). From the start of the 20th century, the concept of open-air school combined student’s physical health with the learning environment, and suggested outdoor classes during mild season by providing a teaching verandah opening out of the classroom [29]. Nowadays, outdoor class is an option that is related with the environmentbased education. Studies have determined that environment-based education significantly raised motivation levels [30]. The results provide evidence of environment-based education’s ability to improve students’ achievement motivation and support [31], capturing the interest of alternative learning methods. .251658240
Figures 18, 19, 20: Architectural Sketches by D. Antonakakis visualizing the school life outdoors
● Participant-Perspective non-energy benefits, could also include reduced operational and maintenance costs due to the limited use of mechanical infrastructure for heating and lighting. Although a further technoeconomical study is needed to establish the above, the optimization of the envelope’s passive mechanisms to filter outdoor climatic conditions, strongly indicates that there is no need for severe and comlex heating, cooling, ventilating and lighting system that a typical energy retrofit measures often recomends.
Table 7 summarizes the analysis phases that pile up the final retrofit scenario, as they were described earlier. It estimates the percentage reduction in the total energy use reduction and gives information about how the energy demands are distributed. The last column refers to the non-energy benefits, the retrofit measures achieve. Although this kind of info is only indicative, it gives a hint of the holistic theory of AER.
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Measures Current situation
1.
Thermal impact *
insulation
Openings displacement*
REVISED VERSION
% Energy Demands Savings
Heating
Cooling
Electricity
Total
66.9
2.22
14.22
83.34
60
0.73
14.22
74.95
10.1
49.7
0.76
14.22
64.68
22.4
50.23
0.66
14.22
65.11
21.9
36.8
0.26
14.22
51.28
38.5
43.65
0.1
2.73
46.48
44.2
2. ( +measure 1)
3.
Sun shading system* +measures 1,2)
(
4. Natural Ventilation
control optimization *( +measures 1,2,3)
5.
Non-Energy Benefits
Educational related benefits, good IAQ, health and well-being, lower operating cost, flexibility in use, space enhancement, increase of funtionality, stimulative environment
Daylighting optimization* ( +measures 1,2,3,4,) * Seasonal redefining of the size and the volume of the classroom as a thermal zone is taken into account
Table 7: Estimation of the energy use distribution and energy demands savings and list of the non-energy benfits
3.2 Conclusions The present preliminary study, aims at establishing a holistic approach where energy balance, architectural disciplines, user’s behavior and microclimate’s revival, are interlinked and interacted. First reults provide strong evidence of its high-energy efficiency performance potential. Maximizing user’s and space’s options to adjust to different seasonally environmental conditions will lead evidently to the optimum operation of the designed space and to the best response of the end-user’s energy behaviour. Building’s Architectural Retrofit Scenario linkes indoors conditions with the microclimate’s revitalization, driving to the creation of micro urban energy oasis with symbiotic strategies. Nevertheless, AER theory also recharges basic open questions about the nature of the architect’s profession. Necessary condition for the applicability of AER’s working hypothesis is the architect to keep up with the dynamic progress in the energy design and management arena that influences dramatically the built environment. He needs to be scientifically updated, to capitalize the specialized technical information, to evaluate the upcoming directives and trends, in order to embed them in his designing practice. This statement is part of a wider introspective concerning the role of the architect in the modern world. He needs to feel some responsibility, like engineers and consultants who, laying claim and enter by the back door to steadily rob him of his freedom [32]. Another drawback of this alternative new approach is the lack of confidence, as there is no relative materialized background. Lack of standardization results in greater performance and execution risk. Therefore, a full systematic review should be carried on, in order to determine the the technical feasibility and 21
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the methodology of this strategy. The outcome benefits should also be compared with other typical retrofit practices, in cost-optimum terms. Long term potential paybacks from minimizing maintenance and upgrading building services systems and achieving better adjustment to future climate, building’s use and operational changes should be further studied in order to balance the high risk factor of the applied bioclimatic strategies. The outcome results are expected to be encouraging as the first step towards reducing the investment cost is to reduce energy demand in the first place [33]. Architectural Energy Retrofit strong point is the maximum added value it pursues in the energy retrofit scenario. It is commonly argued that non-energy benefits are difficult to aggregate, to monetize and to be verified by third party. However, they are a strong innovation in energy efficiency behavior. The term “added value” is on a “change of the way to think of the Environment” through anthropocentric proposals (reuse, awareness, and sustainability). Such a contribution cannot be evaluated by quantitative measurements, or a solely technical feasibility assessment today. The main goal is rather to start a process of "change of mentality" which may then "cultivate" further individual quantitative targets and technical solutions [34]. As an answer to this demand, more sophisticated valuation methods are being developed based on the “common good” balance, such as the Matrix of the Economy for the Common Good (ECG) movement [35]. A general remark to conclude with is that Architectural Energy Retrofit does not face energy retrofit as an end in itself. This innovative retrofit proposal demonstrates a diametrically opposed direction than the typical practices by promoting non-energy related factors as equal important with the energy balance. By developing mechanisms and symbiotic strategies based on the restoration of architectural qualities, the building“opens”at its surrounding environment instead of being “sealed”, responses to the user’s needs and adjustes to seasonal and environmental changes, resulting to a better operation of indoors and outdoors and a balanced energy performance. As a result, AER paves the way for the building’s deep energy retrofit with high-energy efficiency performance and multiple non-energy related benefits.
3.3 Acknowledgements This research’s working hypothesis is based on the outcome effort of professors architects Dimitris and Suzanna Antonakakis on intepreting Pikionis’ architectural work. The authors grateful acknowledge their valuable contribution.
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[1] Victor Olgay, “Design with Climate”, Princeton University Press, NJ 1963 [2] Baruch Givoni, “Man, Climate and Architecture”, Applied Science Publishers, London 1976 [3] EU, Directive 2012/27/EU, Official Journal of the European Union, October 2012 [4] Greek Regulation on the Energy Performance of Buildings, (K.E.N.A.K.), http://portal.tee.gr/ [5] Buildings Performance Institute Europe (BPIE), A Guide to developing Strategies for Building Energy Renovation, Brussels, February 2013
[6] Baruch Givoni, Comfort, climate analysis and building design guideline, Energy & Buildings, 18, 1992, pp.11-23 [7] Francis D.K. Ching, “Architecture. Form, space and order”, Willey Editions, New Jersey, 2015 [8] Herman Hertzberger,” Lessons for students in architecture” , 010 Publishers, Rotterdam 1993 [9] Skumatz Economic Research Associates (SERA), “Lessons Learned and Next Steps in Energy Efficiency Measurement and Attribution: Energy Savings, Net to Gross, Non-Energy Benefits, and Persistence of Energy Efficiency Behavior”, CIEE Behavior and Energy Program, California Institute for Energy and Environment, Berkeley, CA, 2009 [10] Jennifer Thorne Amann, “Valuation of Non-Energy Benefits to Determine Cost-Effectiveness of Whole-House Retrofits Programs: A Literature Review”, American Council for an Energy-Efficient Economy, 2006 [11] Erin Malone, “Driving Efficiency with Non-Energy Benefits”, ACEEENational Symposium on Market Transformation, Baltimore 2014, http://aceee.org/ [12] “ Capturing the Multiple Benefits of Energy Efficiency“, International Energy Agency, OECD/IEA, France 2014 [13] Michael Freed, Frank A. Felder, “Non-energy benefits: Workhorse or unicorn of energy efficiency programs?”, The Electricity Journal 30, 43–46, 2017 [14] Technical Guideline KENAK 20701-1/2010, Technical Chamber of Greece, Athens 2014 [15] Daskalaki, Elena & Sermpetzoglou Vasileios,”Energy performance and indoor environmental quality in Hellenic schools, Energy and Buildings”, 43, pp. 718–727, 2011 [16] Gaitani, N. et al, “Using principal component and cluster analysis in the heating evaluation of the school building sector”, Applied Energy, 87, pp.2079–2086, 2010 [17] Santamouris, Mattheos et al., Using intelligent clustering techniques to classify the energy performance of school buildings, Energy and Buildings, 39, pp.45–51, 2007 [18] Antonakakis, Dimitris, Two studies on Dimitris Pikionis, 1st Edition. Athens, Domes Edition, 2013 [19] Lighting Research Center, “Patterns to Daylight Schools for People and Sustainability”, Rensselaer Polytechnic Institute, NY 2010 [20] Corgnati, Stefano Paolo et al, 2009, Thermal comfort in Italian classrooms under free running conditions during midseasons: Assessment through objective and subjective approaches, Building and Environment, 44, 785–792 [21] Wargocki, Pawel et al, “Providing better thermal and air quality conditions in school classrooms would be costeffective”, Building and Environment, 59, pp. 581-589, 2013 [22] Wargocki, Pawel et al, “The Effects of Outdoor Air Supply Rate and Supply Air Filter Condition in Classrooms on the Performance of Schoolwork by Children”, HVAC&R RESEARCH, vol 13. number 2, 2007 [23] Brager, “Developing an adaptive model of thermal comfort and preference. ASHRAE Transactions: Research, RP884.”, 1998
[24] M. Griffiths , M. Eftekhari, “Control of CO2 in a naturally ventilated classroom”, Energy and Buildings, 40, pp. 555560, 2008
[25] Eleni Mantziou, “ΒΙΟ, Bioclimatic architecture in Greece”, Ergon IV publishers, Athens 2009 [26] Maria Sinou, “Design and Thermal Diversity of Semi-Enclosed Spaces”, Melrose Books, Cambridgeshire 2007 [27] P. O. Fanger, “Thermal comfort: Analysis and applications in environmental engineering”, Danish Technical Press, Copenhagen, 1970
[28] Tsoukala Kyriakí, “Trends in School Design “, Epikentro Editions, Thessaloniki, 2000 [29] Ralph Crowley, “The Open-Air School Movement”, British Journal of Tuberculosis, Volume 3, Issue 3, July 1909, Pages 188–190
[30] The National Environmental Education & Training Foundation, “Environment-based Education,Creating High Performance Schools and Students”, Washington, DC, 2000
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Elsevier – Call for papers- Special Issue on Nearly Zero Energy in existing buildings
REVISED VERSION
[31] Julie Athman, Martha Monroe, “The effect of Environment-Based Education on student’s achievement motivation”, Environmental Education Research 10(4):507-522 · November 2004
[32] Herman Hertzberger,” Space and the Architect. Lessons in architecture” 2, 010 Publishers, Rotterdam 2000 [33] Kapsalaki, Maria et al., “A methodology for economic efficient design of Net Zero Energy Buildings”, Energy & Buildings, 55, pp.765-778, 2012,
[34] Eleni Mantziou et al., "Cultural Landscapes as a Means of Energy Reduction at Global Warming", Energy, Transportation and Global Warming, pp. 223 -243, 2016
[35] Economy for the Common Good (ECG) movement, https://old.ecogood.org/
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