- Email: [email protected]
Energy and environment in an architectural design application
PERGAMON
Renewable
Energy
I5 (1998) 445-450
ENERGY AND ENVIRONMENT IN AN ARCHITECTURAL DESIGN APPLICATION
Silvia de Schiller and John Martin Evans. Centro de Investigation Habitat y Energia, Facultad de Arquitectura, Disefio y Urbanismo, Universidad de Buenos Aires. CC 1765, Correo Central ( 1000) Capital Federal, Argentina. Fax: (+541) 782-8871 E-mail: [email protected]
ABSTRACT Office buildings with important administrative functions can produce high energy demands for lighting, cooling and heating. However, appropriate architectural design decisions can achieve significant energy savings and improve environmental conditions, without sacrificing architectural quality. Intense solar radiation and high temperature swings in dry continental climates favour deep plan offices, though natural daylight requires limited depth. This paper presents a case study of a large administrative complex project for the Justice Palace, Neuquen Province, in the cold windy semi-desert climate in the Northern Patagonia Region of Argentina, demonstrating the relevance of specialized advisory services in the architectural field. $> 1998 Published by Elsevier Science Ltd. All rights reserved.
KEYWORDS Bioclimatic Design; Energy Efficiency; Natural Daylight.
INTRODUCTION Oftice buildings, with high internal loads, can produce high energy consumption for lighting and cooling. Intense solar radiation and high temperature swings in dry continental climates also increase the cooling load which coincides with the indoor peaks. Appropriate architectural design decisions, incorporating strategies to reduce or delay thermal impacts, can achieve significant energy savings and improve environmental conditions without sacrificing architectural quality. Deep plan offtces reduce the incidence of external peaks, though these increase the demand due to additional artificial light and limited opportunities for natural cooling. This paper presents a case study of a large administrative complex project for the Palace of Justice, Province of Neuquen, in the cold windy semi-desert climate in the Northern Patagonia Region of Argentina, where the severe meteorological conditions provide an important limitation for energy efficiency. Table 1 summarises some of these climatic variables and the resulting design requirements (de Schiller et al, 1997a). The specific strategies incorporated during the design process also demonstrates the relevance of interaction between clients, designers and specialists, while the application of energy efficiency measures is developed in an architectural project. 0960-1481/98/ssee front matter PII: SO960-1481(98)00202-X
0
1998 Published
by Elsevier Science Ltd. All rights reserved
WREC
446
1998
The project, designed by the architects Bischof-Egozcue-Vidal, won first prize in a national architectural competition with the advice on bioclimatic design and energy efficiency from the authors. The following characteristics of the project and it’s location were critical for the bioclimatic recommendations proposed: continental climate with strong westerly winds, intense solar radiation, large daily and annual thermal swings and limited rainfall. exposed site with a shaded slope facing south, with views over the city. large scale project with a floor area of 6000 m2, divided in three main buildings, with strict height from planning regulation controls. Table 1 Climatic variable Latitude Summer temperatures Winter temperatures Summer temp. swing
Values 380 s 14,6’a 3 1,3” I-O,5 a 13,1 1l6,7’
1Design requirements Modest south overhangs protect from high summer sun (76’) Solar protection, especially from western a&noon sun Heating, thermal insulation and a compact plan Compact building form with high internal thermal mass and
The interaction between the designers and the bioclimatic advisors covers three main stages and scales of the design process which were considered: ??
??
??
initial design decisions of the building form, orientation and layout, with verifications and adjustments using a solar simulator and wind tunnel. aspects of the facade design, including window sizing, thermal properties of external elements, lighting and sun shading, using thermal simulations, model studies and solar simulator. design and measurement of natural lighting and solar protection in the indoor pedestrian street using models in an artificial sky
In all cases, the bioclimatic advice follows a series of similar steps: initial advice based on analysis of the climatic variables and the environmental requirements of the building characteristics. interaction with the designers ‘on the drawing board’ and the computer, and the evaluation of the initial and subsequent design proposals. verification of the final project, taking into account the integration in the design, the requirements of the client and the coherence of the architectural concept. The first two steps apply to stages of the project before the detailed design decision have been taken, when there is often insufftcient information to make detailed simulations or evaluations of energy requirements. The LT method (CEC, 1995), developed by the Martin Centre, Cambridge, and applied in this case, provides a useful guide at these stages, though the symmetrical results for east and west orientations do not correspond with the signifkant difference found in practice. The general conclusions are a valuable guide for the design but do not cover special conditions such as top-lit glazed spaces with sun protection.
4
WREC 1998
441
Only in the final stage is there sufficient data to realise simulations, although by that stage many of the important design decisions have already been made. Comparisons to evaluate energy saving or relative comfort conditions will also be influenced by the initial design decisions.
Figure 1. Model of the building complex for the Neuquen Palace of Justice, showing the location of the top lighting in the central circulation of the deep plan Court Building.
Detailed studies carried out in the three areas mentioned previously, are presented in this paper with special emphasis in different aspects of natural lighting in mid latitudes with hot summers and the interrelation of this factor with other bioclimatic variables. The problem of roof-lights in atrium spaces is presented with measurements made in models and actual spaces, to show methods of achieving adequate daylight while controlling direct solar radiation in summer months. Simple daylight analysis programs do not allow the study of complex three-dimensional toglit spaces, while complex ray-tracing programs require considerable time and detailed design data. In this case, the same model was used for studies of the shading from direct sunlight and daylighting distribution in indoor spaces. Although the architectural brief, the local building regulations and the climatic conditions favour a deep plan building, this solution can also produce high energy demand for lighting and subsequent airconditioning loads. Top-lit atriums can introduce lighting into indoor communal spaces but will also produce very high solar gains on the frequent cloudless summer days at this latitude (38” S). A special design for the roof of a top-lit internal street was developed to achieve adequate natural lighting and protection form direct summer solar radiation, while allowing controlled sun penetration in winter.
448
WREC IYYcl
The section of the indoor space is designed to allow daylight to the centre of the deep plan. However, this top-lit space requires protection from the overhead summer sun to avoid overheating. The use of natural ventilation, without air conditioning, as originally proposal for the conditioning of this space, would have provided the following benefits: ?? ?? ?? ?? ??
direct extraction of heated air to the outside reduces cooling demand in summer intermediate temperatures and reduced volume also reduce the cooling load wider air temperature variations are acceptable in a space used principally for circulation. the space is partially conditioned using extract air from adjacent conditioned spaces stratification, due to rising hot air, reduces discomfort in summer
Unfortunately the client, the provincial administration, required full air conditioning for this internal pedestrian street, so the shading became more critical to avoid a substantial increase in the heat load in the peak hours of summer afternoons. This load will determine the electricity tarrifs which are related to this peak. At the same time, adequate daylighting must be assured to reduce the need for artificial light which can also increase the heating load and peak power requirements. The heliodon, which simulates the apparent movement of the sun, and the artificial sky, were used in model tests to visualize and measure sun penetration and natural light distribution. This Heliodon shows the extent of shadows and direct sun penetration according to the latitude, season of the year and hour of day, while the artificial sky allows measurements and subjective evaluation of daylight levels and distribution in the internal spaces under study. The same model was used for both studies. A section of the building’s central circulation space was constructed in 1:50 scale, with the internal surfaces carefully matched to reproduce the planned reflectances. To avoid constructing a very large model of this long pedestrian indoor street, a small sector was built with a mirror at each end to simulate the longer space with multiple reflections. The light levels were measured at seven critical points at different locations: to the north and south side of each of the three floors, as well as the centre of the circulation space on the ground floor. The external unobstructed light levels were measured at the same time in order to obtain the daylight factors. Some 12 different alternative roof systems were tested as shown in Figure 2. Table 2 shows a synthesis of the measurements results made in the artificial sky. The considerable variation is a result of the strong directional effects of certain roof alternatives, the different patterns of light penetration as well as the difftculty of positioning the sensors in exactly the same position in spaces with a strong daylight gradient. Despite these experimental difficulties, the values allow both general and specific observasions: ??
??
??
the roofed space with controlled daylighting can result in substandard light levels, even in the central space below the partially glazed roof. the ground floor spaces to the south and north of the central circulation space are difficult to light as they do not receive any direct light. As is to be expected, on the upper levels, the levels of daylight improve. diferent roof shapes and shading strategies produce excentic internal light distribution
449
WREC 1998
Evaluation Poor 1 Good 1 Poor 1 Good 1 Poor 1 Good 1 Good INote: the numbers in bold type indicate inadecuate light levels in critical positions. Table 3. Scheme of the alternative sections Section 11 Section 2 1
I
Section 5
Section 9 1
Section 3 1
I
Section 4
I
Section 6
Section 7
Section 8
Section 10 1
Section 11 1
Section
CONCLUSIONS The principal contribution of this study is the development of strategies to define and explain appropriate bioclimatic design resources in order to achieve an effective application in a specific architectural context. These are related to the stages of the design process, with increasing levels of design definition and reduced opportunities for change. The detailed tests of design alternatives allowed a comparison of diferent solutions to the conflicting requiremens of sun protection and use of daylight This study also had to take into account architectural criteria for the visual appearance of this central space
WREC
450
1998
Figure 2. Example of shadow study for 13.00 hours in mid-winter
ACKNOWLEDGEMENTS The authors appreciate the permision given by the architects Bishof-Egozcue-Vidal to publish this study, based on the fruitful1 interactive experience of design development. Model studies and measurements in the artificial sky were carried out by Christel Bienner during her fellowship awarded by the Carl Duisberg Gesellschafi, while Alejandro Perez developed design alternatives and daylight availability. The artificial sky used in the daylight studies was built with support from the Secretary of Science and Technology, Buenos Aires University
REFERENCES de Schiller, S., Evans, J. M., Femandez, A., Leveratto, M. J., Delbene, C., Eguia, S. (1997a) Applicot~on of bioclrmatlc design strategres in the proJ’ectfor the Provincial Education Council, Neuqkn, Argentina. In Proceedings of PLEA’97, Sustainable Communities and Architecture, Kushiro, Japan. de Schiller, S., Evans, J. M., et all. (1997b) Compatibilizaci6n de variables energitico-ambientales en arquitectura. In Avarices en Energias Renovables y Medio Ambiente, Revista de la Asociacion Argentina de Energia Solar, Nro 1, Vol. 1, pages 117- 120. The Commission of the European Communities (1995). The LT Method 3.0. An Energy Design Tool for Buildings in Southern Europe.
Renewable
Energy
I5 (1998) 445-450
ENERGY AND ENVIRONMENT IN AN ARCHITECTURAL DESIGN APPLICATION
Silvia de Schiller and John Martin Evans. Centro de Investigation Habitat y Energia, Facultad de Arquitectura, Disefio y Urbanismo, Universidad de Buenos Aires. CC 1765, Correo Central ( 1000) Capital Federal, Argentina. Fax: (+541) 782-8871 E-mail: [email protected]
ABSTRACT Office buildings with important administrative functions can produce high energy demands for lighting, cooling and heating. However, appropriate architectural design decisions can achieve significant energy savings and improve environmental conditions, without sacrificing architectural quality. Intense solar radiation and high temperature swings in dry continental climates favour deep plan offices, though natural daylight requires limited depth. This paper presents a case study of a large administrative complex project for the Justice Palace, Neuquen Province, in the cold windy semi-desert climate in the Northern Patagonia Region of Argentina, demonstrating the relevance of specialized advisory services in the architectural field. $> 1998 Published by Elsevier Science Ltd. All rights reserved.
KEYWORDS Bioclimatic Design; Energy Efficiency; Natural Daylight.
INTRODUCTION Oftice buildings, with high internal loads, can produce high energy consumption for lighting and cooling. Intense solar radiation and high temperature swings in dry continental climates also increase the cooling load which coincides with the indoor peaks. Appropriate architectural design decisions, incorporating strategies to reduce or delay thermal impacts, can achieve significant energy savings and improve environmental conditions without sacrificing architectural quality. Deep plan offtces reduce the incidence of external peaks, though these increase the demand due to additional artificial light and limited opportunities for natural cooling. This paper presents a case study of a large administrative complex project for the Palace of Justice, Province of Neuquen, in the cold windy semi-desert climate in the Northern Patagonia Region of Argentina, where the severe meteorological conditions provide an important limitation for energy efficiency. Table 1 summarises some of these climatic variables and the resulting design requirements (de Schiller et al, 1997a). The specific strategies incorporated during the design process also demonstrates the relevance of interaction between clients, designers and specialists, while the application of energy efficiency measures is developed in an architectural project. 0960-1481/98/ssee front matter PII: SO960-1481(98)00202-X
0
1998 Published
by Elsevier Science Ltd. All rights reserved
WREC
446
1998
The project, designed by the architects Bischof-Egozcue-Vidal, won first prize in a national architectural competition with the advice on bioclimatic design and energy efficiency from the authors. The following characteristics of the project and it’s location were critical for the bioclimatic recommendations proposed: continental climate with strong westerly winds, intense solar radiation, large daily and annual thermal swings and limited rainfall. exposed site with a shaded slope facing south, with views over the city. large scale project with a floor area of 6000 m2, divided in three main buildings, with strict height from planning regulation controls. Table 1 Climatic variable Latitude Summer temperatures Winter temperatures Summer temp. swing
Values 380 s 14,6’a 3 1,3” I-O,5 a 13,1 1l6,7’
1Design requirements Modest south overhangs protect from high summer sun (76’) Solar protection, especially from western a&noon sun Heating, thermal insulation and a compact plan Compact building form with high internal thermal mass and
The interaction between the designers and the bioclimatic advisors covers three main stages and scales of the design process which were considered: ??
??
??
initial design decisions of the building form, orientation and layout, with verifications and adjustments using a solar simulator and wind tunnel. aspects of the facade design, including window sizing, thermal properties of external elements, lighting and sun shading, using thermal simulations, model studies and solar simulator. design and measurement of natural lighting and solar protection in the indoor pedestrian street using models in an artificial sky
In all cases, the bioclimatic advice follows a series of similar steps: initial advice based on analysis of the climatic variables and the environmental requirements of the building characteristics. interaction with the designers ‘on the drawing board’ and the computer, and the evaluation of the initial and subsequent design proposals. verification of the final project, taking into account the integration in the design, the requirements of the client and the coherence of the architectural concept. The first two steps apply to stages of the project before the detailed design decision have been taken, when there is often insufftcient information to make detailed simulations or evaluations of energy requirements. The LT method (CEC, 1995), developed by the Martin Centre, Cambridge, and applied in this case, provides a useful guide at these stages, though the symmetrical results for east and west orientations do not correspond with the signifkant difference found in practice. The general conclusions are a valuable guide for the design but do not cover special conditions such as top-lit glazed spaces with sun protection.
4
WREC 1998
441
Only in the final stage is there sufficient data to realise simulations, although by that stage many of the important design decisions have already been made. Comparisons to evaluate energy saving or relative comfort conditions will also be influenced by the initial design decisions.
Figure 1. Model of the building complex for the Neuquen Palace of Justice, showing the location of the top lighting in the central circulation of the deep plan Court Building.
Detailed studies carried out in the three areas mentioned previously, are presented in this paper with special emphasis in different aspects of natural lighting in mid latitudes with hot summers and the interrelation of this factor with other bioclimatic variables. The problem of roof-lights in atrium spaces is presented with measurements made in models and actual spaces, to show methods of achieving adequate daylight while controlling direct solar radiation in summer months. Simple daylight analysis programs do not allow the study of complex three-dimensional toglit spaces, while complex ray-tracing programs require considerable time and detailed design data. In this case, the same model was used for studies of the shading from direct sunlight and daylighting distribution in indoor spaces. Although the architectural brief, the local building regulations and the climatic conditions favour a deep plan building, this solution can also produce high energy demand for lighting and subsequent airconditioning loads. Top-lit atriums can introduce lighting into indoor communal spaces but will also produce very high solar gains on the frequent cloudless summer days at this latitude (38” S). A special design for the roof of a top-lit internal street was developed to achieve adequate natural lighting and protection form direct summer solar radiation, while allowing controlled sun penetration in winter.
448
WREC IYYcl
The section of the indoor space is designed to allow daylight to the centre of the deep plan. However, this top-lit space requires protection from the overhead summer sun to avoid overheating. The use of natural ventilation, without air conditioning, as originally proposal for the conditioning of this space, would have provided the following benefits: ?? ?? ?? ?? ??
direct extraction of heated air to the outside reduces cooling demand in summer intermediate temperatures and reduced volume also reduce the cooling load wider air temperature variations are acceptable in a space used principally for circulation. the space is partially conditioned using extract air from adjacent conditioned spaces stratification, due to rising hot air, reduces discomfort in summer
Unfortunately the client, the provincial administration, required full air conditioning for this internal pedestrian street, so the shading became more critical to avoid a substantial increase in the heat load in the peak hours of summer afternoons. This load will determine the electricity tarrifs which are related to this peak. At the same time, adequate daylighting must be assured to reduce the need for artificial light which can also increase the heating load and peak power requirements. The heliodon, which simulates the apparent movement of the sun, and the artificial sky, were used in model tests to visualize and measure sun penetration and natural light distribution. This Heliodon shows the extent of shadows and direct sun penetration according to the latitude, season of the year and hour of day, while the artificial sky allows measurements and subjective evaluation of daylight levels and distribution in the internal spaces under study. The same model was used for both studies. A section of the building’s central circulation space was constructed in 1:50 scale, with the internal surfaces carefully matched to reproduce the planned reflectances. To avoid constructing a very large model of this long pedestrian indoor street, a small sector was built with a mirror at each end to simulate the longer space with multiple reflections. The light levels were measured at seven critical points at different locations: to the north and south side of each of the three floors, as well as the centre of the circulation space on the ground floor. The external unobstructed light levels were measured at the same time in order to obtain the daylight factors. Some 12 different alternative roof systems were tested as shown in Figure 2. Table 2 shows a synthesis of the measurements results made in the artificial sky. The considerable variation is a result of the strong directional effects of certain roof alternatives, the different patterns of light penetration as well as the difftculty of positioning the sensors in exactly the same position in spaces with a strong daylight gradient. Despite these experimental difficulties, the values allow both general and specific observasions: ??
??
??
the roofed space with controlled daylighting can result in substandard light levels, even in the central space below the partially glazed roof. the ground floor spaces to the south and north of the central circulation space are difficult to light as they do not receive any direct light. As is to be expected, on the upper levels, the levels of daylight improve. diferent roof shapes and shading strategies produce excentic internal light distribution
449
WREC 1998
Evaluation Poor 1 Good 1 Poor 1 Good 1 Poor 1 Good 1 Good INote: the numbers in bold type indicate inadecuate light levels in critical positions. Table 3. Scheme of the alternative sections Section 11 Section 2 1
I
Section 5
Section 9 1
Section 3 1
I
Section 4
I
Section 6
Section 7
Section 8
Section 10 1
Section 11 1
Section
CONCLUSIONS The principal contribution of this study is the development of strategies to define and explain appropriate bioclimatic design resources in order to achieve an effective application in a specific architectural context. These are related to the stages of the design process, with increasing levels of design definition and reduced opportunities for change. The detailed tests of design alternatives allowed a comparison of diferent solutions to the conflicting requiremens of sun protection and use of daylight This study also had to take into account architectural criteria for the visual appearance of this central space
WREC
450
1998
Figure 2. Example of shadow study for 13.00 hours in mid-winter
ACKNOWLEDGEMENTS The authors appreciate the permision given by the architects Bishof-Egozcue-Vidal to publish this study, based on the fruitful1 interactive experience of design development. Model studies and measurements in the artificial sky were carried out by Christel Bienner during her fellowship awarded by the Carl Duisberg Gesellschafi, while Alejandro Perez developed design alternatives and daylight availability. The artificial sky used in the daylight studies was built with support from the Secretary of Science and Technology, Buenos Aires University
REFERENCES de Schiller, S., Evans, J. M., Femandez, A., Leveratto, M. J., Delbene, C., Eguia, S. (1997a) Applicot~on of bioclrmatlc design strategres in the proJ’ectfor the Provincial Education Council, Neuqkn, Argentina. In Proceedings of PLEA’97, Sustainable Communities and Architecture, Kushiro, Japan. de Schiller, S., Evans, J. M., et all. (1997b) Compatibilizaci6n de variables energitico-ambientales en arquitectura. In Avarices en Energias Renovables y Medio Ambiente, Revista de la Asociacion Argentina de Energia Solar, Nro 1, Vol. 1, pages 117- 120. The Commission of the European Communities (1995). The LT Method 3.0. An Energy Design Tool for Buildings in Southern Europe.