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Energy performance of buildings: The evaluation of design and construction measures concerning building energy efficiency in Iran
Energy and Buildings 75 (2014) 456–464
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Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild
Energy performance of buildings: The evaluation of design and construction measures concerning building energy efficiency in Iran Gholamreza Heravi ∗ , Mahsa Qaemi School of Civil Engineering, College of Engineering, University of Tehran, 16 Azar Ave. , Tehran, P.O. Box 11155-4563, Iran
a r t i c l e
i n f o
Article history: Received 11 September 2013 Received in revised form 8 February 2014 Accepted 12 February 2014 Keywords: Sustainability Energy consumption Renewable energy system Energy-efficient building Design and construction measures Energy simulation Developing countries
a b s t r a c t The main purpose of this study is to identify and evaluate the design and construction measures concerning building energy efficiency in Iran. In this regard, reducing energy consumption and using renewable energies are the main approaches of this paper. Thus, firstly, the most applicable renewable energy system in building industry has been identified; then, the design and construction measures have been identified and evaluated with respect to their effects on the building energy-performance; utilization of renewable energy systems as well as energy consumption patterns. In this way, utilization of renewable energy has been evaluated on the basis of experts’ opinion and energy consumption has been evaluated on the basis of energy simulation. The primary result of this research revealed that, passive solar energy is the most applicable renewable energy system in urban areas and buildings in Iran. Furthermore, 23 design and construction measures were identified and categorized into 12 groups. Finally, the groups of measures are evaluated and classified into three levels of high, medium, and low importance with respect to their effects on buildings energy-performance. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Sustainability in construction developments has to result in the creation and responsible maintenance of a healthy built environment, based on ecological principles, and through an efficient use of resources. Buildings not only use the existing resources such as energy and raw materials but they also generate the waste and potentially harmful atmospheric emissions [1]. Clearly, sustainability in the construction industry offers an outstanding response to the current environmental and socio-economic problems [2]. In this regard, green building is now becoming a flagship of sustainable development in this century that takes the responsibility for balancing long-term economic, environmental and social health. Green building offers a considerable opportunity to create environmentally efficient buildings by using an integrated approach for design so that the deteriorative impacts and devastating effects of buildings on the environment and public health can be diminished. Green building does not only reduce the deteriorative impact of buildings on public health and environment, it also cuts operating costs, enhances occupant productivity and facilitates sustainable development of the society.
∗ Corresponding author. Tel.: +98 21 6111 2852; fax: +98 21 6646 1024. E-mail addresses: [email protected] (G. Heravi), [email protected] (M. Qaemi). http://dx.doi.org/10.1016/j.enbuild.2014.02.035 0378-7788/© 2014 Elsevier B.V. All rights reserved.
In the present time, one of the most critical global issues is the pollution caused by the consumption of fossil fuels. Buildings are the largest consumer of energy and decisive factor in greenhouse gas emissions. Buildings operation accounts for about 40% of global energy and carbon dioxide emissions. Therefore, sustainability in general, and energy efficiency in particular have become the key measures of building performance [3]. Because of a great amount of fossil fuel consumption in non-energy-efficient buildings, environmental pollution has increased notably. In order to reduce the energy used in buildings and the relative effects on the climate, several strategies seem to be necessary, including energy demand reduction, adoption of passive systems and improvement energy efficiency [4]. Implementing such strategies in a green building would normally raise the initial capital costs of the building compared with a conventional home. Yet, the added benefits regarding energy savings over the time are believed to collectively offset part of this increased capital cost [5]. Motawa and Carter [3] emphasized that with a slight increase in up front building cost of 2%, a lifecycle savings of about 20% of the initial building cost can be achieved. Energy consumption in households is a focus in many countries [5]. The main purpose of this study is to identify and evaluate the design and construction measures concerning building energy efficiency in Iran. In this context, firstly, the most applicable renewable energy system in building industry is identified, then, the design and construction measures are identified, validated and evaluated with respect to their effects on the building energy-performance;
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renewable energy systems utilization and energy consumption. In this way, utilization of renewable energy is evaluated on the basis of experts’ opinion and energy consumption is evaluated on the basis of energy simulation. 2. Literature review There are numerous studies related to energy and energy efficiency, which emphasize on various optimal strategies to improve energy performance and design and construct sustainable buildings. A review of literature showed that the studies related to the purpose of this research can be classified into the following two categories: • Building efficient energy performance. Balaras et al. [6] assessed and compared the influence of envelope thermal insulation, age and conditions of the heating system on the heating energy consumption and the resulting environmental impacts on buildings; based on 193 case studies. They concluded that approximately 38% of the audited buildings have the annual heating energy consumption higher than the average European consumption. Saroni and Hestnes [7] evaluated and compared the lifecycle energy consumption in a typical as well as an optimized building. The results of their research clarified the important difference in energy consumption due to the differences in the design and construction practices of buildings. Ramesh et al. [8] evaluated and compared the lifecycle energy consumption in both residential and office buildings. The findings of their research disclosed that the operating and embodied phases of energy usage are significant contributors to the buildings’ lifecycle energy demand. Furthermore, the buildings’ life cycle energy demand can be lowered by reducing the operating energy significantly through application of passive and active technologies even if it would lead to a slight increase in embodied energy. Taleb and Sharples [9] provided an overview of the current situation of buildings and identified some measurements for increasing the energy and water consumption in order to develop sustainable residential buildings in Saudi Arabia. They defined and applied some energy optimization criteria on simulated model using Design Builder (an energy simulation software), to propose the number of effective criteria on reducing energy consumption. In another research, Chang et al. [5] developed an optimal design for water conservation and energy saving. The plan suggests utilizing green roofs in green buildings. More recently, Qaemi and Heravi [10] carried out an investigation to find the most feasible renewable energies in Iran. They studied renewable energies in respect a couple of major approaches: (1) The feasibility and economic justification of using renewable energy systems (such as the applicability in urban areas, reducing fossil fuels consumption, the effects on the initial construction costs, and the effects on operations and maintenance costs); and (2) The existing obstacles for using renewable energy systems (including lack of government support, awareness, technical technologies, appropriate facilities and planning approaches, in addition to significant initial costs). • Building energy performance criteria. Juan et al. [11] studied several systems including Leadership in Energy and Environmental Design (LEED) [12], Building Research Establishment Environmental Assessment Method (BREEAM) [13], and Green Building Tool (GB Tool). Their purpose was renovating and improving energy performance of office buildings. Soussi et al. [14] studied the energy performance of a solar cooled office building located in Tunisia using the TRNSYS software. The simulations assessed the real case study and analyzed the impact of its architectural characteristics and passive techniques on its
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energy requirements in order to analyze the effect of these passive techniques and propose solutions to take advantage of them in winter and prevent their overheating effect in summer. They analyzed isolation of the wall and cool roof, window glazing type, trombe walls and shading. In another research, Yoo et al. [15] evaluated some measures to reduce energy consumption in construction sector. They emphasized that high-efficiency window systems can play an important role in reducing energy consumption in buildings. They measured the thermal performance (U-factor) of different window systems and analyzed their effects on energy savings in the central and southern regions in South Korea. Mwasha et al. [4] focused to explore the principal sustainable energy performance indicators in order to model the energy performance of the residential building envelope and develop an approach for determining the most appropriate sustainable energy performance indicators. Gong et al. [16] studied passive design, as the most economical effective strategy for reducing energy consumption inside residential buildings. This paper presented an approach in which the orthogonal method and the listing method were integrated to explore how energy consumption is minimized in residential buildings by optimizing seven passive design measures. They asserted that the passive design could reduce annual thermal load of building considerably. This paper indicated that the external wall insulation thickness and the sunroom depth are the two most important parameters affect the annual thermal load. 3. Methodology As shown in Fig. 1, the methodology of this research comprises six main stages as follows: • Identifying the most applicable renewable energy system in building industry in Iran. • Identifying the design and construction measures concerning building energy efficiency (i.e., non-renewable energy consumption and renewable energy system utilization). • Validating the design and construction measures based on the Green Globes rating system. • Evaluating the measures with respect to energy consumption, by utilizing energy simulation. • Evaluating the measures with respect to passive solar energy utilization, as a renewable energy system, by using experts’ opinion. • Determining the most effective design and construction measures concerning building energy efficiency. The above mentioned stages are explaining through the following subsections: 3.1. Identifying the most applicable renewable energy system As the economy expands and population continues to rise, designers and builders are facing a unique challenge to meet the demands of new and renovated facilities that could be accessible, secure, healthy, and productive while minimizing their impacts on the environment [1]. In the past decade, the emphasis on green building design has directed mainly to the development of energy saving technologies such as solar panels and wind farms [5]. The purpose of this section is to identify the most applicable renewable energy system in Iran, as a developing country. Currently, several types of renewable energies are used for different applications. However, in this paper, the renewable energy systems that are more common, accessible, and useful for buildings have been surveyed, including: active solar energy, passive solar energy, wind energy, geothermal energy, and fuel cell.
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Fig. 1. The flow chart of the research methodology.
This section, in one hand, evaluates the five mentioned renewable energy systems considering the following items: (1) applicability in urban areas and buildings, (2) effects on fossil fuel consumption, (3) influences on the initial construction costs, and (4) influences on the maintenance and operation costs. On the other side, the renewable energy systems are evaluated with consideration of several identified obstacles preventing the development of such systems in building industry in Iran. The individual interview technique has been employed in this research to make use of the experts’ opinion from Iran Renewable Energy Organization. The interviewees were 16 experts, whose characteristics are depicted in Table 1. The mean score (MS) method [17] was applied to determine the relative importance of each renewable energy system considering the evaluation factors. The five point scale ranged from very low (1), to very high (5) importance was adopted to calculate the MS for each factor by using the following equation:
MS =
(f × s) N
where MS = relative importance for each factor, s = score given to each factor by the respondents, ranging from 1 to 5; f = frequency of
Table 1 A brief summary of experts’ characteristics. General information Department Solar energy Wind energy Fuel cell Geothermal energy Biomass Work experience Under 2 years 2–5 years 5–10 years Over 10 years Education level Bachelor’s degree Master’s degree
Frequency
Percent
3 5 5 1 2
19 31 31 7 12
0 3 6 7
0 19 37 44
0 16
0 100
each rating (1–5) for each factor; and N = total number of responses concerning a particular factor. Table 2 shows the results of the conducted opinion survey considering the feasibility and economic justification for using renewable energy systems. Based on the mean scores which are depicted in this table, active and passive solar energy systems are evaluated as the most applicable systems.
Table 2 Evaluating renewable energy systems considering feasibility and economic justification of such systems. Renewable energy systems
Active solar energy Passive solar energy Wind energy Geothermal energy Fuel cell *
Mean score* (rank) The feasible usage in urban areas and buildings
The amount of reduction in fossil fuel consumption
The amount of initial construction costs enhancement
The amount of reduction in maintenance and operation costs
4.21 (2) 4.50 (1) 3.00 (4) 2.67 (5) 3.71 (3)
4.40 (1) 4.36 (3) 4.38 (2) 3.97 (5) 4.06 (4)
3.50 (3) 2.83 (1) 3.60 (4) 3.27 (2) 3.50 (3)
3.38 (1) 3.31 (2) 3.00 (3) 3.00 (3) 2.82 (4)
The best possible score is 5.00; the worst possible score is 1.00.
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Table 3 Evaluating renewable energy systems considering obstacles preventing the development of such systems. Renewable energy systems
Passive solar energy Wind energy Active solar energy Geothermal energy Fuel cell *
Normalized score* (rank)
High initial costs
Lack of government support
Lack of public awareness
Lack of technology
Lack of proper and required equipment
Poor planning approach
0.43(1)
0.88(4)
0.75(3)
0.71(1)
0.33(1)
0.78(3)
0.57(2) 1.00(5) 0.79(3) 0.93(4)
0.38(1) 1.00(5) 0.63(2) 0.75(3)
0.38(1) 1.00(4) 1.00(4) 0.63(2)
0.86(2) 0.86(2) 1.00(3) 1.00(3)
0.78(3) 0.67(2) 0.89(4) 1.00(5)
0.44(1) 1.00(4) 0.44(1) 0.67(2)
xi /xmax ; the best possible score is 0.20; the worst possible score limit is 1.00.
Table 3 shows the results of the conducted opinion survey considering the obstacles preventing the development of such systems. Based on the normalized scores which are depicted in this table, passive solar energy and wind energy systems are facing to the obstacles that removing them is easier than the other systems in building industry in Iran. Consequently, solar energy (active and passive forms) has the highest priority, best advantage, and most useful application to be used in urban areas and buildings. The most important advantages for active solar energy are the fossil fuel consumption reduction and added the reduction in maintenance and operation costs. The major advantages of passive solar energy are the applicability in urban areas and buildings and the low initial construction costs. Regarding advantages (Table 2) and obstacles (Table 3) for developing active and passive solar energy systems, passive solar energy is selected as the most applicable renewable energy system to be used in building industry in Iran. 3.2. Identifying and validating the design and construction measures Energy performance in the building life cycle may be affected by several factors [18]: • • • •
geographical location and climate region; material production and transportation; construction methods; existing mechanical and electrical facilities (e.g., optimizing thermal cooling and lighting systems, increasing the share of renewable energy in buildings, etc.); • sociocultural energy consumption patterns (related to behavioral patterns and norms of citizens in consuming energy, e.g., citizens’ economic concerns, lifestyles, etc.); and • design and construction measures (e.g., using architectural design adoptive with climate circumstances, increasing the building envelope thermal resistance, increasing airtightness, etc.).
This study has focused on design and construction measures of building as important effective measures of energy performance (i.e., passive solar energy, as renewable energy system utilization and energy consumption). Based on library studies and the collected experts’ opinions, 23 measures are selected towards the energy-efficient building. As shown in Table 4, the identified measures have been classified into 12 groups. The Green Globes [19] provides an assessment tool for characterizing a building’s energy efficiency and environmental performance. The system also provides guidance for green building design, operation and management and provides constant, longitudinal monitoring of energy efficiency or building performance. The Green Globes software tools and ratings/certification system use a recognized and proven assessment protocol in order to comprehensively assess environmental impacts on a 1000 point
scale in multiple categories for both existing and new buildings. The categories and the relative assigned points for new building are as follows: (1) Energy: 380 points, (2) Water: 85 points, (3) Resources: 100 points, (4) Emissions: 70 points, (5) Indoor Environment: 200 points, (6) Project Management: 50 points, and (7) Site: 115 points. This study focuses on the energy category of Green Globes rating system; 380 out of the total 1000 points [19]. The measures, Table 4, earned 56% of the total scores of the energy category (213 out of 380 points), as detailed below (Table 5): • Building energy performance and energy saving: 100 points. • Measures (wall, roof, opening and accessories, materials and building plan specifications): 103 points. • Integration of renewable energy system sources in buildings: 10 points. 3.3. Evaluating the measures with respect to energy consumption Recently, some researches [9,20] have been done on energy simulation by Design Builder, as energy simulation software, for optimizing energy consumption and proposing the optimization measurements. 3.3.1. Design Builder as energy simulation software Design Builder (version 3.0.0.105), is a commercially available software package, with three-dimensional interface, that provides dynamic and comprehensive energy simulation for buildings. The simulation is based on real hourly weather data, and takes into consideration of both solar gains through windows, as well as heat conduction and convection between the zones with different temperature. The accuracy of the Design Builder is validated using the Building Energy Simulation TEST procedure originally developed by the International Energy Agency [9]. Utilizing the Design Builder, the energy consumption within a building may be analyzed on daily, weekly, monthly and yearly bases. The results included: energy consumption, indoor air quality and thermal comfort, heating and cooling loads, heat loss, and so on. The annual-based results are generally more useful for comparing the electricity and gas consumption and heating and cooling energy. The utilizing indicators are as follows: • Zone sensible heating: The amount of heating energy needed to provide thermal comfort in winter. • Zone sensible cooling: The amount of heating energy needed to provide thermal comfort in summer. • Fuel totals: The average annual gas and electricity consumption. 3.3.2. Energy simulation by Design Builder The analysis objective is assessing the potential improvements in terms of energy consumption within buildings in Iran, with
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Table 4 The design and construction measures toward energy-efficient building. Groups
Measures
Remarks
Increasing solar energy and sunlight utilization.
Setting up building orientation (South*) Laying out building elongation (East–West* ) Locating common spaces on the southern side* Reducing story height
Building plan
Story height
Increasing roof slope Increasing external walls thickness
Roof slope External wall dimensions
Increasing solar energy and sunlight utilization. Optimal utilization of solar energy and sunlight in the interior spaces of the building. Reducing energy consumption, by decreasing the building total volume. Increasing solar energy utilization in winter. Increasing wall isolation as a thermal mass (thermal storage). Reducing heat transfer through external walls. Increasing solar energy and sunlight utilization (absorbing and distributing solar energy through building’s thermal mass). Storing excess solar energy during the winter day which is then re-radiated during the night. Reducing energy loss by improving window isolation. Reducing energy loss by improving window isolation. Preventing energy loss per opening and closing the door, due to protected space between the interior and exterior spaces. Reducing energy loss by improving window’s isolation. Reducing solar heat gain through windows. Controlling solar heat gain and glare. Controlling solar heat gain and glare face to different occasions (external forms are better for preventing the entrance energy). Reducing amount of energy needed for air conditioning. Improving thermal isolation and reducing heat loss. Controlling absorption of solar energy. Improving thermal isolation and reducing heat loss. Controlling reflection or absorption of sunlight. Improving thermal isolation and reducing heat loss. Controlling reflection or absorption of sunlight. Improving thermal isolation, reducing heat loss, and improving urban environment.
Reducing external walls surface to volume ratio Increasing windows area on the south face* Using thermal storage behind the windows Improving windows frames thermal resistance Improving windows air tightness Using protected entrance door
Opening location and accessories
Opening thermal resistance
Using windows multiple glazing
Widows glazing
Using fixed internal shading Using movable external shading
Shading
Using natural ventilation
Natural ventilation
Using thermal resistant materials Increasing the surface reflectivity of materials Increasing wall thermal isolation Using external wall thermal resistance paint Increasing ceiling thermal isolation Using the roof thermal resistance paint Using green roof
Materials thermal specifications
Wall thermal isolation
Roof thermal isolation
* These measures are related to specific geographical locations and climate regions (Tehran, capital of Iran: Elevation: 1190 m, Latitude: 35 41N, Longitude: 051 12E, Mediterranean Climate, The annual average temperature: 17.8 ◦ C).
respect to the considered measures. In order to apply the factors, a typical official building in Tehran, capital of Iran, is selected as a case study.
3.3.2.1. Geographical location and the climate conditions. The geographical location and the climate conditions of Tehran are listed below:
• Elevation: 1190 m, Latitude: 35 41N, Longitude: 051 12E. • Köppen Classification: Mediterranean Climate. • Average annual temperature: 17.8 ◦ C, warmest month: 31.1 ◦ C, coolest month: 1.7 ◦ C. 3.3.2.2. Building description. The 2040-m2 building includes four floors, a parking floor and a basement (340 m2 per each floor).
Table 5 The design and construction measures with respect to Green Globes energy category. Green Globes rating system
Design and construction measures
Energy category
The most important items in each group
Building energy performance
Building energy performance Energy savings compared to the reference base building CO2 emissions reduction Space optimization Integration of micro climate and topography Integration of day lighting Building envelope Energy metering Usage of energy-efficient equipment Renewable energy will supply a percentage of the building total load Public transportation Cycling facilities
Energy demand minimization
Energy-efficient systems Renewable sources of energy Energy-efficient transportation
Reduction in energy consumption
All measures related to: Building Plan Openings Materials
Passive solar energy utilization
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Table 6 The Materials have been used in Simulated Building. Material
Category
Conductivity (W/m ◦ K)
Specific heat (J/kg ◦ K)
Density (kg/m3 )
Bitumen/felt layers Asphalt Brick Cement mortar Concrete cast, lightweight Concrete slab Air Plaster and soil Plaster Granite stone Mosaic Ceramic–Porcelain Ceramic–Clay tiles Oily paint
Asphalt and other roofing finishes Asphalt and other roofing finishes Brick and Block work Concrete Concrete Concrete Gases Plaster Plaster Sands, stones, and soils Sands, stones, and soils Tiles Tiles Plastic, and solid
0.25 1.15 1 1.15 0.34 1.75 0.3 1.15 0.7 2.9 1.4 2.3 0.7 0.1
1000 1000 840 920 840 1000 1000 840 1000 840 1000 840 850 1500
1700 2110 1900 2000 1300 2300 1000 1000 1300 2500 3000 2300 2000 1000
• The ceilings are composite; all perimeter walls have a thickness of 20 cm and all interior walls have a thickness of 10 cm; all exterior doors are steel; all existing windows are made by aluminum, double glazing with air layer (6 mm); and HVAC building system is fan coil. • The materials specifications as input data of Design Builder are depicted in Table 6. 3.4. Evaluating the measures with respect to passive solar energy utilization The design and construction measures may be evaluated based on renewable energy system efficiency by utilizing the experts’ opinion. An opinion survey, using a structured interview, is used to evaluate the measures with respect to utilizing Passive Solar Energy as a Renewable Energy system in building projects. Survey participants were the experts with experience in building construction projects. In this survey, the respondents were asked to rate the importance of 23 measures with respect to utilizing Passive Solar Energy as a key performance evaluation criteria. After adjusting the developed questionnaire based on a pilot study, 58 interviews were conducted with eligible experts. The demographic profiles of the respondents are given in Table 7. The mean score (MS) method is applied to determine relative importance of each measures. The five point scale ranged from very low (1), to very high (5) importance is adopted to calculate the MS for each measures, using Eq. (1). 3.5. Determining the most effective measures concerning building energy efficiency Based on the relative effects of groups of the design and construction measures on reducing energy consumption as well as Table 7 A brief summary of respondents’ characteristics. General information Job title Energy consultant Energy-architectural Building contractor Work experience Under 2 years 2–5 years 5–10 years Over 10 years Education level Bachelor’s degree Master’s degree
Frequency
Percent
35 17 6
60 29 11
6 17 25 10
11 29 43 17
4 54
7 93
their relative effects on increasing the efficiency of passive solar energy, groups of energy-efficient buildings’ measures are evaluated and ranked through two steps:
- Step 1: Classifying groups of energy-efficient buildings’ measures based on their normalized energy consumption efficiency weights, as energy consumption reduction factors, into three categories: - I: High level of energy consumption reduction: 0.70 < Energy Consumption Reduction Factor < 1.00 - II: Medium level of energy consumption reduction: 0.40 < Energy Consumption Reduction Factor < 0.70 - III: Low level of energy consumption reduction: 0.00 < Energy Consumption Reduction Factor < 0.40 - Step 2: Ranking groups of energy-efficient buildings’ measures in each of main groups based on the amount of the following production for each groups in each categories: - Importance Factor = (Energy Consumption Reduction Factor)*(Passive Solar Energy Utilization Factor)
4. Results 4.1. Measures with respect to energy consumption The measures were simulated independently by Design Builder software. The values as well as the ranges of the simulated measures are shown in the third and fourth columns of Table 8, respectively. In addition, according to the outcomes of simulation, the reduction values of energy consumption due to the improvement of measures are depicted in the fifth and sixth columns of Table 8. Overall, it was revealed that, “Roof Thermal Isolation”, “Material Thermal Specification” and “Wall Thermal Isolation” are the most effective groups with respect to building energy consumption. Increasing the roof thermal isolation by using suitable roof thermal resistance paint, green roof and increasing the ceiling thermal isolation by using rock wool, as the most common isolation in building industry in Iran, can reduce the building energy consumption by 13.8%. Moreover, considering the thermal specification of materials can decrease building energy consumption by 13.03%. Increasing thermal resistance of the wall, ceiling and roof materials with respect to their surface reflectivity are accounted as the most effective measures to improve the building energy performance. Furthermore, increasing the wall thermal isolation by using suitable wall thermal resistance paint and using rock wool can reduce the building energy consumption by 12.16%.
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Table 8 Values and ranges of energy simulated measures and the reduction of rnergy consumption. Groups
Building plan
Story height Roof slope
External wall Dimensions Opening location and accessories
Opening thermal resistance
Widows Glazing Shading Natural ventilation Materials thermal specifications
Wall thermal isolation Roof thermal isolation
Values and ranges of measures
‘Groups’ energy ‘Groups’ energy consumption reduction consumption source
Initial
Improved
%
Normalized
Setting up building orientation (South* )
Main side: Facing north
Main side: Facing south
2.07
0.15
Mostly heating
Laying out building elongation (East–West* ) Locating common spaces on the southern side* Reducing story height Increasing roof slope Increasing external walls thickness
–
–
–
–
3.2 m Flat roof Int. wall: 10 cm Ext. wall: 20 cm –
2.8 m Slope: 30 degrees Int. wall: 15 cm Ext. wall: 30 cm –
11.38 8.03 11.60
0.83 0.58 0.84
Heating/cooling Heating/cooling Heating/cooling
20% for all faces
5.93
0.43
Mostly heating
–
30% South, 20% East and West, 10% North –
Aluminum frame
UPVC frame
7.45
0.54
Mostly heating
– – Single gazing Without shading – Without ventilation Wall: 0.514, Ceiling: 1.702, Roof: 1.806(m2 K/w)
– – Triple glazing With external shading – With ventilation Wall: 0.903, Ceiling: 2.202, Roof: 1.493(m2 K/w)
9.97 4.46
0.72 0.32
Mostly heating Cooling
2.76 13.03
0.20 0.94
Ventilation Heating/cooling
Without thermal insulation – Without thermal insulation – –
Rock wool insulation: 10 cm – Rock wool insulation: 20 cm – –
12.16
0.88
Heating/cooling
13.80
1.00
Heating/cooling
Measures
Reducing external walls surface to volume ratio Increasing windows area on the south face* Using thermal storage behind the windows Improving windows frames thermal resistance Improving windows air tightness Using protected entrance door Using windows multiple glazing Using fixed external shading Using movable internal shading Using natural ventilation Using thermal resistant materials
Increasing surface reflectivity of materials Increasing wall thermal isolation Using external wall thermal resistance paint Increasing ceiling thermal isolation Using roof thermal resistance paint Using green roof
*
These measures are related to geographical locations and climate regions.
4.2. Measures with respect to passive solar energy utilization The normalized results of the survey with respect to maximum efficiency of utilizing passive solar energy as a renewable energy system are illustrated in Table 9. As result, “Opening Location and Accessories”, “Building Plan” and “Roof Slope” are the most effective groups regarding renewable energy system efficiency. Increasing windows area on the south face and using thermal storage behind them is the most important factor in building to receive and absorb more solar energy through windows and furthermore provide the required heating and lighting of buildings. Considering different aspects of building plan such as building orientation, elongation and locating common spaces on the southern side can increase and optimize solar energy and sunlight utilization in building. In addition, increasing the roof slope can lead to increasing solar energy utilization in winter and decreasing cooling needs in summer. 4.3. The most effective measures concerning building energy efficiency Based on the developed approach in Section 3.5, considering normalized values of the sixth column of Table 8 and the fifth column of Table 9, 12 groups of energy-efficient buildings’ measures are evaluated and ranked through steps 1 and 2. The results are depicted in Table 10.
The table provides the following information: • Most of the measures which have been placed in the high level of energy efficiency are related to materials and isolation. • Most of the measures which have been placed in the medium level of energy efficiency are related to opening and accessories. • Most of the measures which have been placed in the low level of energy efficiency are related to building shape and shading. • Most effective measures with respect to efficiency of passive solar energy system as a renewable energy system are placed in the medium and the low levels categories. As depicted in Table 10, “Roof Thermal Isolation” includes increasing ceiling thermal isolation; using roof thermal resistance paint and using green roof earned the top spot. It is followed by “Materials Thermal Specifications” which includes using thermal resistant materials and increasing surface reflectivity of materials. Moreover, the next place is for “Reducing Story Height” earned the third spot. These measures can improve thermal isolation and reduce heat loss, control reflection or absorption of sunlight, and reduce energy consumption, by decreasing building volume. Also, the most important concerns related to the design and construction measures concerning building energy efficiency are as follows: • Passive solar energy is selected as the most applicable renewable energy system for using in building industry in Iran.
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Table 9 The relative importance of measures with respect to passive solar energy performance. Groups
Measures
Building plan
Story height Roof slope External wall Dimensions Opening location and accessories Opening thermal resistance
Widows glazing Shading Natural ventilation Materials thermal specifications Wall thermal isolation Roof thermal isolation
*
Passive solar energy performance Measures’ importance weight
Groups’ importance weight
Normalized
Setting up building orientation (South* ) Laying out building elongation (East–West* ) Locating common spaces on the southern side* Reducing story height Increasing roof slope Increasing external walls thickness
0.49 0.49 0.50 0.05 0.42 0.00
0.49
0.79
0.05 0.42 0.00
0.08 0.67 0.00
Reducing external walls surface to volume ratio Increasing windows area on the south face*
0.00 0.67
0.63
1.00
Using thermal storage behinds the windows Improving windows frames thermal resistance
0.58 0.00
0.01
0.02
Improving windows air tightness Using protected entrance door Using windows multiple glazing Using fixed external shading Using movable internal shading Using natural ventilation Using thermal resistant materials
0.04 0.00 0.05 0.32 0.32 0.00 0.08
0.05 0.32
0.08 0.51
0.00 0.08
0.00 0.13
Increasing surface reflectivity of materials Increasing wall thermal isolation Using external wall thermal resistance paint Increasing ceiling thermal isolation Using roof thermal resistance paint Using green roof
0.08 0.00 0.00 0.00 0.00 0.36
0.00
0.00
0.12
0.19
These measures are related to geographical locations and climate regions.
Table 10 The evaluation of groups of energy-efficient buildings’ measures. Class
High
Med.
Low
Groups of energy-efficient buildings’ measures
Roof thermal isolation Materials thermal specifications Story height Widows glazing Wall thermal isolation External wall dimensions Opening location and accessories Roof slope Opening thermal resistance Shading Building plan Natural ventilation
Energy performance Step 1 (1)Energy consumption reduction
Step 2 (2)Passive solar energy utilization
(1)*(2)
1.00 0.94
0.19 0.13
0.19 0.13
H1 H2
0.82 0.72 0.88 0.84 0.43
0.08 0.08 0.00 0.00 1.00
0.06 0.06 0.00 0.00 0.43
H3 H4 H5 H6 M1
0.58 0.54 0.32 0.15 0.20
0.67 0.02 0.51 0.79 0.00
0.39 0.01 0.16 0.12 0.00
M2 M3 L1 L2 L3
• Considering the geographical locations and climate regions is essential for design of energy-efficient buildings. • Most of the measures reduce energy consumption for heating and cooling by increasing isolation and utilizing solar energy. • There are some defects beside the measures’ benefits such as decreasing residents’ level of comfort due to reducing story height and increasing dead load and reducing area of building due to increasing external wall dimensions. • Utilizing the measures in accompanied may provide better results due to the synergism, such as “Opening Thermal Resistance” which may improve “Widows Glazing” effectiveness. 5. Conclusions This paper studied the renewable energy system application and energy performance measures in concerned with building
Rank
design and construction as important effective measures in developing country of Iran. In this research, first, passive solar energy was evaluated as the most applicable renewable energy system in building industry in Iran. Then, 23 energy performance measures were identified, validated and categorized into 12 groups, as the most effective designing and construction requirements. Finally, the groups of measures were evaluated and classified into high, medium and low levels of importance with respect to their effects on buildings energy-performance. Accordingly, the most effective design and construction measures concerning building energy efficiency were determined. As result, “Roof thermal isolation”, “Materials Thermal Specifications”, “Story Height” and “Widows Glazing” as the most effective groups of measures should be considered in designing and construction of buildings. Despite “Building Plan” has not earned the top spot in the groups of measures, it should be considered in designing and
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construction of buildings. Furthermore, utilizing the measures in accompanied may provide better results due to the synergism. Despite essential role of geographical location and climate region for design of energy-efficient buildings, findings from this research can be used by others who seek to build energy-efficient building in developing countries. References [1] N.W. Alnaser, R. Flanagan, W.E. Alnaser, Model for calculating the sustainable building index (SBI) in the kingdom of Bahrain, Journal of Energy and Buildings 40 (2008) 2037–2043. [2] R. Yunus, J. Yang, Sustainability criteria for industrialized building systems (IBS) in Malaysia, The Twelfth East Asia-Pacific Conference on structural engineering and construction, Procedia Engineering, 2011, pp. 1590–1598, 14. [3] I. Motawa, k. Carter, Sustainable BIM-based evaluation of buildings, 26th IPMA World Congress Crete Greece, Procedia—Social and Behavioral Sciences, 2013, pp. 419–428, 74. [4] A. Mwasha, R.G. Williams, J. Iwaro, Modeling the performance of residential building envelope: the role of sustainable energy performance indicators, Journal of Energy and Buildings 43 (9) (2011) 108–2117. [5] N.B. Chang, B.J. Rivera, M.P. Wanielista, Optimal design for water conservation and energy savings using green roofs in a green building under mixed uncertainties, Journal of Cleaner Production 19 (11) (2011) 1180–1188. [6] C.A. Balaras, K. Droutsa, E. Dascalaki, S. Kontoyiannidis, Heating energy consumption and resulting environmental impact of European apartment buildings, Energy and Buildings 37 (5) (2005) 429–442. [7] I. Sartori, A.G. Hestnes, Energy use in the life cycle of conventional and lowenergy buildings: a review article, Energy and Buildings 39 (2007) 249–257.
[8] T. Ramesh, R. Prakash, K.K. Shukla, Life cycle energy analysis of buildings: An overview, Energy and Buildings 42 (2010) 1592–1600. [9] H.M. Taleb, S. Sharples, Developing sustainable residential buildings in Saudi Arabia: a case study, Applied Energy 88 (1) (2011) 383–391. [10] M. Qaemi, G. Heravi, Sustainable Energy Performance Indicators of Green Building in Developing Countries, Construction Research Congress (ASCE 2012), 2012, pp. 1961–1970. [11] Y.K. Juan, P. Gao, J. Wang, A hybrid decision support system for sustainable office building renovation and energy performance improvement, Energy and Buildings 42 (3) (2010) 290–297. [12] LEED—Leadership in Energy and Environmental Design. USA, LEED for New Construction and Major Renovation 2009, Developed by US Green Building Council. [13] BREEAM—Building Research Establishment Environmental Assessment Method, 1990, UK, Developed by Building Research Establishment. [14] M. Soussi, M. Balghouthi, A. Guizani, Energy performance analysis of a solar-cooled building in Tunisia: passive strategies impact and improvement techniques, Energy and Buildings 67 (2013) 374–386. [15] S. Yoo, H. Jeong, B. Ahn, H. Han, D. Seo, J. Lee, C.H. Jang, Thermal transmittance of window systems and effects on building heating energy use and energy efficiency ratings in South Korea, Energy and Buildings 67 (2013) 236–244. [16] X. Gong, Y. Akashi, D. Sumiyoshi, Optimization of passive design measures for residential buildings in different Chinese areas, Building and Environment 58 (2012) 46–57. [17] D.M. Chan, M.M. Kumaraswamy, An evaluation of construction time performance in the building industry, Building and Environment 31 (6) (1996) 569–578. [18] Iranian Fuel Conservation Company. http://www.ifco.ir, 2012. [19] The Green Building Initiative (GBI). http://www.thegbi.org, 2012. [20] A.A. Chowdhury, M.G. Rasul, M.M.K. Khan, Thermal-comfort analysis and simulation for various low-energy cooling-technologies applied to an office building in a subtropical climate, Applied Energy 85 (6) (2008) 449–462.
Contents lists available at ScienceDirect
Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild
Energy performance of buildings: The evaluation of design and construction measures concerning building energy efficiency in Iran Gholamreza Heravi ∗ , Mahsa Qaemi School of Civil Engineering, College of Engineering, University of Tehran, 16 Azar Ave. , Tehran, P.O. Box 11155-4563, Iran
a r t i c l e
i n f o
Article history: Received 11 September 2013 Received in revised form 8 February 2014 Accepted 12 February 2014 Keywords: Sustainability Energy consumption Renewable energy system Energy-efficient building Design and construction measures Energy simulation Developing countries
a b s t r a c t The main purpose of this study is to identify and evaluate the design and construction measures concerning building energy efficiency in Iran. In this regard, reducing energy consumption and using renewable energies are the main approaches of this paper. Thus, firstly, the most applicable renewable energy system in building industry has been identified; then, the design and construction measures have been identified and evaluated with respect to their effects on the building energy-performance; utilization of renewable energy systems as well as energy consumption patterns. In this way, utilization of renewable energy has been evaluated on the basis of experts’ opinion and energy consumption has been evaluated on the basis of energy simulation. The primary result of this research revealed that, passive solar energy is the most applicable renewable energy system in urban areas and buildings in Iran. Furthermore, 23 design and construction measures were identified and categorized into 12 groups. Finally, the groups of measures are evaluated and classified into three levels of high, medium, and low importance with respect to their effects on buildings energy-performance. © 2014 Elsevier B.V. All rights reserved.
1. Introduction Sustainability in construction developments has to result in the creation and responsible maintenance of a healthy built environment, based on ecological principles, and through an efficient use of resources. Buildings not only use the existing resources such as energy and raw materials but they also generate the waste and potentially harmful atmospheric emissions [1]. Clearly, sustainability in the construction industry offers an outstanding response to the current environmental and socio-economic problems [2]. In this regard, green building is now becoming a flagship of sustainable development in this century that takes the responsibility for balancing long-term economic, environmental and social health. Green building offers a considerable opportunity to create environmentally efficient buildings by using an integrated approach for design so that the deteriorative impacts and devastating effects of buildings on the environment and public health can be diminished. Green building does not only reduce the deteriorative impact of buildings on public health and environment, it also cuts operating costs, enhances occupant productivity and facilitates sustainable development of the society.
∗ Corresponding author. Tel.: +98 21 6111 2852; fax: +98 21 6646 1024. E-mail addresses: [email protected] (G. Heravi), [email protected] (M. Qaemi). http://dx.doi.org/10.1016/j.enbuild.2014.02.035 0378-7788/© 2014 Elsevier B.V. All rights reserved.
In the present time, one of the most critical global issues is the pollution caused by the consumption of fossil fuels. Buildings are the largest consumer of energy and decisive factor in greenhouse gas emissions. Buildings operation accounts for about 40% of global energy and carbon dioxide emissions. Therefore, sustainability in general, and energy efficiency in particular have become the key measures of building performance [3]. Because of a great amount of fossil fuel consumption in non-energy-efficient buildings, environmental pollution has increased notably. In order to reduce the energy used in buildings and the relative effects on the climate, several strategies seem to be necessary, including energy demand reduction, adoption of passive systems and improvement energy efficiency [4]. Implementing such strategies in a green building would normally raise the initial capital costs of the building compared with a conventional home. Yet, the added benefits regarding energy savings over the time are believed to collectively offset part of this increased capital cost [5]. Motawa and Carter [3] emphasized that with a slight increase in up front building cost of 2%, a lifecycle savings of about 20% of the initial building cost can be achieved. Energy consumption in households is a focus in many countries [5]. The main purpose of this study is to identify and evaluate the design and construction measures concerning building energy efficiency in Iran. In this context, firstly, the most applicable renewable energy system in building industry is identified, then, the design and construction measures are identified, validated and evaluated with respect to their effects on the building energy-performance;
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renewable energy systems utilization and energy consumption. In this way, utilization of renewable energy is evaluated on the basis of experts’ opinion and energy consumption is evaluated on the basis of energy simulation. 2. Literature review There are numerous studies related to energy and energy efficiency, which emphasize on various optimal strategies to improve energy performance and design and construct sustainable buildings. A review of literature showed that the studies related to the purpose of this research can be classified into the following two categories: • Building efficient energy performance. Balaras et al. [6] assessed and compared the influence of envelope thermal insulation, age and conditions of the heating system on the heating energy consumption and the resulting environmental impacts on buildings; based on 193 case studies. They concluded that approximately 38% of the audited buildings have the annual heating energy consumption higher than the average European consumption. Saroni and Hestnes [7] evaluated and compared the lifecycle energy consumption in a typical as well as an optimized building. The results of their research clarified the important difference in energy consumption due to the differences in the design and construction practices of buildings. Ramesh et al. [8] evaluated and compared the lifecycle energy consumption in both residential and office buildings. The findings of their research disclosed that the operating and embodied phases of energy usage are significant contributors to the buildings’ lifecycle energy demand. Furthermore, the buildings’ life cycle energy demand can be lowered by reducing the operating energy significantly through application of passive and active technologies even if it would lead to a slight increase in embodied energy. Taleb and Sharples [9] provided an overview of the current situation of buildings and identified some measurements for increasing the energy and water consumption in order to develop sustainable residential buildings in Saudi Arabia. They defined and applied some energy optimization criteria on simulated model using Design Builder (an energy simulation software), to propose the number of effective criteria on reducing energy consumption. In another research, Chang et al. [5] developed an optimal design for water conservation and energy saving. The plan suggests utilizing green roofs in green buildings. More recently, Qaemi and Heravi [10] carried out an investigation to find the most feasible renewable energies in Iran. They studied renewable energies in respect a couple of major approaches: (1) The feasibility and economic justification of using renewable energy systems (such as the applicability in urban areas, reducing fossil fuels consumption, the effects on the initial construction costs, and the effects on operations and maintenance costs); and (2) The existing obstacles for using renewable energy systems (including lack of government support, awareness, technical technologies, appropriate facilities and planning approaches, in addition to significant initial costs). • Building energy performance criteria. Juan et al. [11] studied several systems including Leadership in Energy and Environmental Design (LEED) [12], Building Research Establishment Environmental Assessment Method (BREEAM) [13], and Green Building Tool (GB Tool). Their purpose was renovating and improving energy performance of office buildings. Soussi et al. [14] studied the energy performance of a solar cooled office building located in Tunisia using the TRNSYS software. The simulations assessed the real case study and analyzed the impact of its architectural characteristics and passive techniques on its
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energy requirements in order to analyze the effect of these passive techniques and propose solutions to take advantage of them in winter and prevent their overheating effect in summer. They analyzed isolation of the wall and cool roof, window glazing type, trombe walls and shading. In another research, Yoo et al. [15] evaluated some measures to reduce energy consumption in construction sector. They emphasized that high-efficiency window systems can play an important role in reducing energy consumption in buildings. They measured the thermal performance (U-factor) of different window systems and analyzed their effects on energy savings in the central and southern regions in South Korea. Mwasha et al. [4] focused to explore the principal sustainable energy performance indicators in order to model the energy performance of the residential building envelope and develop an approach for determining the most appropriate sustainable energy performance indicators. Gong et al. [16] studied passive design, as the most economical effective strategy for reducing energy consumption inside residential buildings. This paper presented an approach in which the orthogonal method and the listing method were integrated to explore how energy consumption is minimized in residential buildings by optimizing seven passive design measures. They asserted that the passive design could reduce annual thermal load of building considerably. This paper indicated that the external wall insulation thickness and the sunroom depth are the two most important parameters affect the annual thermal load. 3. Methodology As shown in Fig. 1, the methodology of this research comprises six main stages as follows: • Identifying the most applicable renewable energy system in building industry in Iran. • Identifying the design and construction measures concerning building energy efficiency (i.e., non-renewable energy consumption and renewable energy system utilization). • Validating the design and construction measures based on the Green Globes rating system. • Evaluating the measures with respect to energy consumption, by utilizing energy simulation. • Evaluating the measures with respect to passive solar energy utilization, as a renewable energy system, by using experts’ opinion. • Determining the most effective design and construction measures concerning building energy efficiency. The above mentioned stages are explaining through the following subsections: 3.1. Identifying the most applicable renewable energy system As the economy expands and population continues to rise, designers and builders are facing a unique challenge to meet the demands of new and renovated facilities that could be accessible, secure, healthy, and productive while minimizing their impacts on the environment [1]. In the past decade, the emphasis on green building design has directed mainly to the development of energy saving technologies such as solar panels and wind farms [5]. The purpose of this section is to identify the most applicable renewable energy system in Iran, as a developing country. Currently, several types of renewable energies are used for different applications. However, in this paper, the renewable energy systems that are more common, accessible, and useful for buildings have been surveyed, including: active solar energy, passive solar energy, wind energy, geothermal energy, and fuel cell.
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Fig. 1. The flow chart of the research methodology.
This section, in one hand, evaluates the five mentioned renewable energy systems considering the following items: (1) applicability in urban areas and buildings, (2) effects on fossil fuel consumption, (3) influences on the initial construction costs, and (4) influences on the maintenance and operation costs. On the other side, the renewable energy systems are evaluated with consideration of several identified obstacles preventing the development of such systems in building industry in Iran. The individual interview technique has been employed in this research to make use of the experts’ opinion from Iran Renewable Energy Organization. The interviewees were 16 experts, whose characteristics are depicted in Table 1. The mean score (MS) method [17] was applied to determine the relative importance of each renewable energy system considering the evaluation factors. The five point scale ranged from very low (1), to very high (5) importance was adopted to calculate the MS for each factor by using the following equation:
MS =
(f × s) N
where MS = relative importance for each factor, s = score given to each factor by the respondents, ranging from 1 to 5; f = frequency of
Table 1 A brief summary of experts’ characteristics. General information Department Solar energy Wind energy Fuel cell Geothermal energy Biomass Work experience Under 2 years 2–5 years 5–10 years Over 10 years Education level Bachelor’s degree Master’s degree
Frequency
Percent
3 5 5 1 2
19 31 31 7 12
0 3 6 7
0 19 37 44
0 16
0 100
each rating (1–5) for each factor; and N = total number of responses concerning a particular factor. Table 2 shows the results of the conducted opinion survey considering the feasibility and economic justification for using renewable energy systems. Based on the mean scores which are depicted in this table, active and passive solar energy systems are evaluated as the most applicable systems.
Table 2 Evaluating renewable energy systems considering feasibility and economic justification of such systems. Renewable energy systems
Active solar energy Passive solar energy Wind energy Geothermal energy Fuel cell *
Mean score* (rank) The feasible usage in urban areas and buildings
The amount of reduction in fossil fuel consumption
The amount of initial construction costs enhancement
The amount of reduction in maintenance and operation costs
4.21 (2) 4.50 (1) 3.00 (4) 2.67 (5) 3.71 (3)
4.40 (1) 4.36 (3) 4.38 (2) 3.97 (5) 4.06 (4)
3.50 (3) 2.83 (1) 3.60 (4) 3.27 (2) 3.50 (3)
3.38 (1) 3.31 (2) 3.00 (3) 3.00 (3) 2.82 (4)
The best possible score is 5.00; the worst possible score is 1.00.
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Table 3 Evaluating renewable energy systems considering obstacles preventing the development of such systems. Renewable energy systems
Passive solar energy Wind energy Active solar energy Geothermal energy Fuel cell *
Normalized score* (rank)
High initial costs
Lack of government support
Lack of public awareness
Lack of technology
Lack of proper and required equipment
Poor planning approach
0.43(1)
0.88(4)
0.75(3)
0.71(1)
0.33(1)
0.78(3)
0.57(2) 1.00(5) 0.79(3) 0.93(4)
0.38(1) 1.00(5) 0.63(2) 0.75(3)
0.38(1) 1.00(4) 1.00(4) 0.63(2)
0.86(2) 0.86(2) 1.00(3) 1.00(3)
0.78(3) 0.67(2) 0.89(4) 1.00(5)
0.44(1) 1.00(4) 0.44(1) 0.67(2)
xi /xmax ; the best possible score is 0.20; the worst possible score limit is 1.00.
Table 3 shows the results of the conducted opinion survey considering the obstacles preventing the development of such systems. Based on the normalized scores which are depicted in this table, passive solar energy and wind energy systems are facing to the obstacles that removing them is easier than the other systems in building industry in Iran. Consequently, solar energy (active and passive forms) has the highest priority, best advantage, and most useful application to be used in urban areas and buildings. The most important advantages for active solar energy are the fossil fuel consumption reduction and added the reduction in maintenance and operation costs. The major advantages of passive solar energy are the applicability in urban areas and buildings and the low initial construction costs. Regarding advantages (Table 2) and obstacles (Table 3) for developing active and passive solar energy systems, passive solar energy is selected as the most applicable renewable energy system to be used in building industry in Iran. 3.2. Identifying and validating the design and construction measures Energy performance in the building life cycle may be affected by several factors [18]: • • • •
geographical location and climate region; material production and transportation; construction methods; existing mechanical and electrical facilities (e.g., optimizing thermal cooling and lighting systems, increasing the share of renewable energy in buildings, etc.); • sociocultural energy consumption patterns (related to behavioral patterns and norms of citizens in consuming energy, e.g., citizens’ economic concerns, lifestyles, etc.); and • design and construction measures (e.g., using architectural design adoptive with climate circumstances, increasing the building envelope thermal resistance, increasing airtightness, etc.).
This study has focused on design and construction measures of building as important effective measures of energy performance (i.e., passive solar energy, as renewable energy system utilization and energy consumption). Based on library studies and the collected experts’ opinions, 23 measures are selected towards the energy-efficient building. As shown in Table 4, the identified measures have been classified into 12 groups. The Green Globes [19] provides an assessment tool for characterizing a building’s energy efficiency and environmental performance. The system also provides guidance for green building design, operation and management and provides constant, longitudinal monitoring of energy efficiency or building performance. The Green Globes software tools and ratings/certification system use a recognized and proven assessment protocol in order to comprehensively assess environmental impacts on a 1000 point
scale in multiple categories for both existing and new buildings. The categories and the relative assigned points for new building are as follows: (1) Energy: 380 points, (2) Water: 85 points, (3) Resources: 100 points, (4) Emissions: 70 points, (5) Indoor Environment: 200 points, (6) Project Management: 50 points, and (7) Site: 115 points. This study focuses on the energy category of Green Globes rating system; 380 out of the total 1000 points [19]. The measures, Table 4, earned 56% of the total scores of the energy category (213 out of 380 points), as detailed below (Table 5): • Building energy performance and energy saving: 100 points. • Measures (wall, roof, opening and accessories, materials and building plan specifications): 103 points. • Integration of renewable energy system sources in buildings: 10 points. 3.3. Evaluating the measures with respect to energy consumption Recently, some researches [9,20] have been done on energy simulation by Design Builder, as energy simulation software, for optimizing energy consumption and proposing the optimization measurements. 3.3.1. Design Builder as energy simulation software Design Builder (version 3.0.0.105), is a commercially available software package, with three-dimensional interface, that provides dynamic and comprehensive energy simulation for buildings. The simulation is based on real hourly weather data, and takes into consideration of both solar gains through windows, as well as heat conduction and convection between the zones with different temperature. The accuracy of the Design Builder is validated using the Building Energy Simulation TEST procedure originally developed by the International Energy Agency [9]. Utilizing the Design Builder, the energy consumption within a building may be analyzed on daily, weekly, monthly and yearly bases. The results included: energy consumption, indoor air quality and thermal comfort, heating and cooling loads, heat loss, and so on. The annual-based results are generally more useful for comparing the electricity and gas consumption and heating and cooling energy. The utilizing indicators are as follows: • Zone sensible heating: The amount of heating energy needed to provide thermal comfort in winter. • Zone sensible cooling: The amount of heating energy needed to provide thermal comfort in summer. • Fuel totals: The average annual gas and electricity consumption. 3.3.2. Energy simulation by Design Builder The analysis objective is assessing the potential improvements in terms of energy consumption within buildings in Iran, with
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Table 4 The design and construction measures toward energy-efficient building. Groups
Measures
Remarks
Increasing solar energy and sunlight utilization.
Setting up building orientation (South*) Laying out building elongation (East–West* ) Locating common spaces on the southern side* Reducing story height
Building plan
Story height
Increasing roof slope Increasing external walls thickness
Roof slope External wall dimensions
Increasing solar energy and sunlight utilization. Optimal utilization of solar energy and sunlight in the interior spaces of the building. Reducing energy consumption, by decreasing the building total volume. Increasing solar energy utilization in winter. Increasing wall isolation as a thermal mass (thermal storage). Reducing heat transfer through external walls. Increasing solar energy and sunlight utilization (absorbing and distributing solar energy through building’s thermal mass). Storing excess solar energy during the winter day which is then re-radiated during the night. Reducing energy loss by improving window isolation. Reducing energy loss by improving window isolation. Preventing energy loss per opening and closing the door, due to protected space between the interior and exterior spaces. Reducing energy loss by improving window’s isolation. Reducing solar heat gain through windows. Controlling solar heat gain and glare. Controlling solar heat gain and glare face to different occasions (external forms are better for preventing the entrance energy). Reducing amount of energy needed for air conditioning. Improving thermal isolation and reducing heat loss. Controlling absorption of solar energy. Improving thermal isolation and reducing heat loss. Controlling reflection or absorption of sunlight. Improving thermal isolation and reducing heat loss. Controlling reflection or absorption of sunlight. Improving thermal isolation, reducing heat loss, and improving urban environment.
Reducing external walls surface to volume ratio Increasing windows area on the south face* Using thermal storage behind the windows Improving windows frames thermal resistance Improving windows air tightness Using protected entrance door
Opening location and accessories
Opening thermal resistance
Using windows multiple glazing
Widows glazing
Using fixed internal shading Using movable external shading
Shading
Using natural ventilation
Natural ventilation
Using thermal resistant materials Increasing the surface reflectivity of materials Increasing wall thermal isolation Using external wall thermal resistance paint Increasing ceiling thermal isolation Using the roof thermal resistance paint Using green roof
Materials thermal specifications
Wall thermal isolation
Roof thermal isolation
* These measures are related to specific geographical locations and climate regions (Tehran, capital of Iran: Elevation: 1190 m, Latitude: 35 41N, Longitude: 051 12E, Mediterranean Climate, The annual average temperature: 17.8 ◦ C).
respect to the considered measures. In order to apply the factors, a typical official building in Tehran, capital of Iran, is selected as a case study.
3.3.2.1. Geographical location and the climate conditions. The geographical location and the climate conditions of Tehran are listed below:
• Elevation: 1190 m, Latitude: 35 41N, Longitude: 051 12E. • Köppen Classification: Mediterranean Climate. • Average annual temperature: 17.8 ◦ C, warmest month: 31.1 ◦ C, coolest month: 1.7 ◦ C. 3.3.2.2. Building description. The 2040-m2 building includes four floors, a parking floor and a basement (340 m2 per each floor).
Table 5 The design and construction measures with respect to Green Globes energy category. Green Globes rating system
Design and construction measures
Energy category
The most important items in each group
Building energy performance
Building energy performance Energy savings compared to the reference base building CO2 emissions reduction Space optimization Integration of micro climate and topography Integration of day lighting Building envelope Energy metering Usage of energy-efficient equipment Renewable energy will supply a percentage of the building total load Public transportation Cycling facilities
Energy demand minimization
Energy-efficient systems Renewable sources of energy Energy-efficient transportation
Reduction in energy consumption
All measures related to: Building Plan Openings Materials
Passive solar energy utilization
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Table 6 The Materials have been used in Simulated Building. Material
Category
Conductivity (W/m ◦ K)
Specific heat (J/kg ◦ K)
Density (kg/m3 )
Bitumen/felt layers Asphalt Brick Cement mortar Concrete cast, lightweight Concrete slab Air Plaster and soil Plaster Granite stone Mosaic Ceramic–Porcelain Ceramic–Clay tiles Oily paint
Asphalt and other roofing finishes Asphalt and other roofing finishes Brick and Block work Concrete Concrete Concrete Gases Plaster Plaster Sands, stones, and soils Sands, stones, and soils Tiles Tiles Plastic, and solid
0.25 1.15 1 1.15 0.34 1.75 0.3 1.15 0.7 2.9 1.4 2.3 0.7 0.1
1000 1000 840 920 840 1000 1000 840 1000 840 1000 840 850 1500
1700 2110 1900 2000 1300 2300 1000 1000 1300 2500 3000 2300 2000 1000
• The ceilings are composite; all perimeter walls have a thickness of 20 cm and all interior walls have a thickness of 10 cm; all exterior doors are steel; all existing windows are made by aluminum, double glazing with air layer (6 mm); and HVAC building system is fan coil. • The materials specifications as input data of Design Builder are depicted in Table 6. 3.4. Evaluating the measures with respect to passive solar energy utilization The design and construction measures may be evaluated based on renewable energy system efficiency by utilizing the experts’ opinion. An opinion survey, using a structured interview, is used to evaluate the measures with respect to utilizing Passive Solar Energy as a Renewable Energy system in building projects. Survey participants were the experts with experience in building construction projects. In this survey, the respondents were asked to rate the importance of 23 measures with respect to utilizing Passive Solar Energy as a key performance evaluation criteria. After adjusting the developed questionnaire based on a pilot study, 58 interviews were conducted with eligible experts. The demographic profiles of the respondents are given in Table 7. The mean score (MS) method is applied to determine relative importance of each measures. The five point scale ranged from very low (1), to very high (5) importance is adopted to calculate the MS for each measures, using Eq. (1). 3.5. Determining the most effective measures concerning building energy efficiency Based on the relative effects of groups of the design and construction measures on reducing energy consumption as well as Table 7 A brief summary of respondents’ characteristics. General information Job title Energy consultant Energy-architectural Building contractor Work experience Under 2 years 2–5 years 5–10 years Over 10 years Education level Bachelor’s degree Master’s degree
Frequency
Percent
35 17 6
60 29 11
6 17 25 10
11 29 43 17
4 54
7 93
their relative effects on increasing the efficiency of passive solar energy, groups of energy-efficient buildings’ measures are evaluated and ranked through two steps:
- Step 1: Classifying groups of energy-efficient buildings’ measures based on their normalized energy consumption efficiency weights, as energy consumption reduction factors, into three categories: - I: High level of energy consumption reduction: 0.70 < Energy Consumption Reduction Factor < 1.00 - II: Medium level of energy consumption reduction: 0.40 < Energy Consumption Reduction Factor < 0.70 - III: Low level of energy consumption reduction: 0.00 < Energy Consumption Reduction Factor < 0.40 - Step 2: Ranking groups of energy-efficient buildings’ measures in each of main groups based on the amount of the following production for each groups in each categories: - Importance Factor = (Energy Consumption Reduction Factor)*(Passive Solar Energy Utilization Factor)
4. Results 4.1. Measures with respect to energy consumption The measures were simulated independently by Design Builder software. The values as well as the ranges of the simulated measures are shown in the third and fourth columns of Table 8, respectively. In addition, according to the outcomes of simulation, the reduction values of energy consumption due to the improvement of measures are depicted in the fifth and sixth columns of Table 8. Overall, it was revealed that, “Roof Thermal Isolation”, “Material Thermal Specification” and “Wall Thermal Isolation” are the most effective groups with respect to building energy consumption. Increasing the roof thermal isolation by using suitable roof thermal resistance paint, green roof and increasing the ceiling thermal isolation by using rock wool, as the most common isolation in building industry in Iran, can reduce the building energy consumption by 13.8%. Moreover, considering the thermal specification of materials can decrease building energy consumption by 13.03%. Increasing thermal resistance of the wall, ceiling and roof materials with respect to their surface reflectivity are accounted as the most effective measures to improve the building energy performance. Furthermore, increasing the wall thermal isolation by using suitable wall thermal resistance paint and using rock wool can reduce the building energy consumption by 12.16%.
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Table 8 Values and ranges of energy simulated measures and the reduction of rnergy consumption. Groups
Building plan
Story height Roof slope
External wall Dimensions Opening location and accessories
Opening thermal resistance
Widows Glazing Shading Natural ventilation Materials thermal specifications
Wall thermal isolation Roof thermal isolation
Values and ranges of measures
‘Groups’ energy ‘Groups’ energy consumption reduction consumption source
Initial
Improved
%
Normalized
Setting up building orientation (South* )
Main side: Facing north
Main side: Facing south
2.07
0.15
Mostly heating
Laying out building elongation (East–West* ) Locating common spaces on the southern side* Reducing story height Increasing roof slope Increasing external walls thickness
–
–
–
–
3.2 m Flat roof Int. wall: 10 cm Ext. wall: 20 cm –
2.8 m Slope: 30 degrees Int. wall: 15 cm Ext. wall: 30 cm –
11.38 8.03 11.60
0.83 0.58 0.84
Heating/cooling Heating/cooling Heating/cooling
20% for all faces
5.93
0.43
Mostly heating
–
30% South, 20% East and West, 10% North –
Aluminum frame
UPVC frame
7.45
0.54
Mostly heating
– – Single gazing Without shading – Without ventilation Wall: 0.514, Ceiling: 1.702, Roof: 1.806(m2 K/w)
– – Triple glazing With external shading – With ventilation Wall: 0.903, Ceiling: 2.202, Roof: 1.493(m2 K/w)
9.97 4.46
0.72 0.32
Mostly heating Cooling
2.76 13.03
0.20 0.94
Ventilation Heating/cooling
Without thermal insulation – Without thermal insulation – –
Rock wool insulation: 10 cm – Rock wool insulation: 20 cm – –
12.16
0.88
Heating/cooling
13.80
1.00
Heating/cooling
Measures
Reducing external walls surface to volume ratio Increasing windows area on the south face* Using thermal storage behind the windows Improving windows frames thermal resistance Improving windows air tightness Using protected entrance door Using windows multiple glazing Using fixed external shading Using movable internal shading Using natural ventilation Using thermal resistant materials
Increasing surface reflectivity of materials Increasing wall thermal isolation Using external wall thermal resistance paint Increasing ceiling thermal isolation Using roof thermal resistance paint Using green roof
*
These measures are related to geographical locations and climate regions.
4.2. Measures with respect to passive solar energy utilization The normalized results of the survey with respect to maximum efficiency of utilizing passive solar energy as a renewable energy system are illustrated in Table 9. As result, “Opening Location and Accessories”, “Building Plan” and “Roof Slope” are the most effective groups regarding renewable energy system efficiency. Increasing windows area on the south face and using thermal storage behind them is the most important factor in building to receive and absorb more solar energy through windows and furthermore provide the required heating and lighting of buildings. Considering different aspects of building plan such as building orientation, elongation and locating common spaces on the southern side can increase and optimize solar energy and sunlight utilization in building. In addition, increasing the roof slope can lead to increasing solar energy utilization in winter and decreasing cooling needs in summer. 4.3. The most effective measures concerning building energy efficiency Based on the developed approach in Section 3.5, considering normalized values of the sixth column of Table 8 and the fifth column of Table 9, 12 groups of energy-efficient buildings’ measures are evaluated and ranked through steps 1 and 2. The results are depicted in Table 10.
The table provides the following information: • Most of the measures which have been placed in the high level of energy efficiency are related to materials and isolation. • Most of the measures which have been placed in the medium level of energy efficiency are related to opening and accessories. • Most of the measures which have been placed in the low level of energy efficiency are related to building shape and shading. • Most effective measures with respect to efficiency of passive solar energy system as a renewable energy system are placed in the medium and the low levels categories. As depicted in Table 10, “Roof Thermal Isolation” includes increasing ceiling thermal isolation; using roof thermal resistance paint and using green roof earned the top spot. It is followed by “Materials Thermal Specifications” which includes using thermal resistant materials and increasing surface reflectivity of materials. Moreover, the next place is for “Reducing Story Height” earned the third spot. These measures can improve thermal isolation and reduce heat loss, control reflection or absorption of sunlight, and reduce energy consumption, by decreasing building volume. Also, the most important concerns related to the design and construction measures concerning building energy efficiency are as follows: • Passive solar energy is selected as the most applicable renewable energy system for using in building industry in Iran.
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Table 9 The relative importance of measures with respect to passive solar energy performance. Groups
Measures
Building plan
Story height Roof slope External wall Dimensions Opening location and accessories Opening thermal resistance
Widows glazing Shading Natural ventilation Materials thermal specifications Wall thermal isolation Roof thermal isolation
*
Passive solar energy performance Measures’ importance weight
Groups’ importance weight
Normalized
Setting up building orientation (South* ) Laying out building elongation (East–West* ) Locating common spaces on the southern side* Reducing story height Increasing roof slope Increasing external walls thickness
0.49 0.49 0.50 0.05 0.42 0.00
0.49
0.79
0.05 0.42 0.00
0.08 0.67 0.00
Reducing external walls surface to volume ratio Increasing windows area on the south face*
0.00 0.67
0.63
1.00
Using thermal storage behinds the windows Improving windows frames thermal resistance
0.58 0.00
0.01
0.02
Improving windows air tightness Using protected entrance door Using windows multiple glazing Using fixed external shading Using movable internal shading Using natural ventilation Using thermal resistant materials
0.04 0.00 0.05 0.32 0.32 0.00 0.08
0.05 0.32
0.08 0.51
0.00 0.08
0.00 0.13
Increasing surface reflectivity of materials Increasing wall thermal isolation Using external wall thermal resistance paint Increasing ceiling thermal isolation Using roof thermal resistance paint Using green roof
0.08 0.00 0.00 0.00 0.00 0.36
0.00
0.00
0.12
0.19
These measures are related to geographical locations and climate regions.
Table 10 The evaluation of groups of energy-efficient buildings’ measures. Class
High
Med.
Low
Groups of energy-efficient buildings’ measures
Roof thermal isolation Materials thermal specifications Story height Widows glazing Wall thermal isolation External wall dimensions Opening location and accessories Roof slope Opening thermal resistance Shading Building plan Natural ventilation
Energy performance Step 1 (1)Energy consumption reduction
Step 2 (2)Passive solar energy utilization
(1)*(2)
1.00 0.94
0.19 0.13
0.19 0.13
H1 H2
0.82 0.72 0.88 0.84 0.43
0.08 0.08 0.00 0.00 1.00
0.06 0.06 0.00 0.00 0.43
H3 H4 H5 H6 M1
0.58 0.54 0.32 0.15 0.20
0.67 0.02 0.51 0.79 0.00
0.39 0.01 0.16 0.12 0.00
M2 M3 L1 L2 L3
• Considering the geographical locations and climate regions is essential for design of energy-efficient buildings. • Most of the measures reduce energy consumption for heating and cooling by increasing isolation and utilizing solar energy. • There are some defects beside the measures’ benefits such as decreasing residents’ level of comfort due to reducing story height and increasing dead load and reducing area of building due to increasing external wall dimensions. • Utilizing the measures in accompanied may provide better results due to the synergism, such as “Opening Thermal Resistance” which may improve “Widows Glazing” effectiveness. 5. Conclusions This paper studied the renewable energy system application and energy performance measures in concerned with building
Rank
design and construction as important effective measures in developing country of Iran. In this research, first, passive solar energy was evaluated as the most applicable renewable energy system in building industry in Iran. Then, 23 energy performance measures were identified, validated and categorized into 12 groups, as the most effective designing and construction requirements. Finally, the groups of measures were evaluated and classified into high, medium and low levels of importance with respect to their effects on buildings energy-performance. Accordingly, the most effective design and construction measures concerning building energy efficiency were determined. As result, “Roof thermal isolation”, “Materials Thermal Specifications”, “Story Height” and “Widows Glazing” as the most effective groups of measures should be considered in designing and construction of buildings. Despite “Building Plan” has not earned the top spot in the groups of measures, it should be considered in designing and
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