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The influence of the atrium geometry on the building energy performance
Energy and Buildings 57 (2013) 1–5
Contents lists available at SciVerse ScienceDirect
Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild
The influence of the atrium geometry on the building energy performance Abdelsalam Aldawoud ∗ College of Environmental Design, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
a r t i c l e
i n f o
Article history: Received 18 September 2012 Accepted 10 October 2012 Keywords: Atrium Computer simulation Energy efficiency Computer modeling
a b s t r a c t In this study, the thermal performance of various shapes and geometries of atriums in buildings is examined under various conditions. The goal of the study is to assess the impact of the atrium shape on the building total energy consumption and to identify the most energy-efficient atrium design. The study focuses on four different central atriums types with square and rectangular geometries which have same areas, use, schedule, controls, occupancy, and construction. The atriums exhibit different aspect ratios (length to width). Four cities in United States are selected to represent primary climatic regions of hotdry, hot-humid, cold, and temperate. Besides, the atrium height, the atrium glazing type, and the glazing ratio are varied throughout the simulation process. Buildings models are constructed using the DOE-2.1E building energy simulation program. The results of this study indicate that in general, the total energy consumption of the narrow, elongated atrium or the rectangular atrium with high ratio of length to width is significantly greater than the square shaped atrium. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Buildings sector is responsible for at least 40% of energy use in most countries worldwide. In the United States, buildings consume about 67% of the total electricity used each year and produce 35% of US and 9% of global carbon dioxide (CO2 ) emissions. The future energy consumption trends in this sector continue to increase and according to the United States Energy Information Administration (EIA) [1], the total energy consumption in 2035 will increase about a 20% from current consumption levels. As a result, it is important to incorporate energy-efficient strategies into designs to minimize the buildings energy usage, while at the same time improving the levels of comfort within buildings. For buildings in general, the artificial lighting loads is considered a major problem which significantly contribute to building cooling and heating loads requirements [2]. In recent years, the atrium design becomes popular for purpose of esthetics, daylighting, and solar heating. Good atrium design will specifically bring natural lighting into the interior spaces of the building and therefore minimize depending on artificial lighting loads and reduce the demand for space conditioning. Despite numerous studies demonstrating the atriums benefits, including their energy significant potential in reducing the building artificial lighting demand and as a result lowering the thermal loads [3], their thermal performance is extremely difficult to predict [4]. Atria present some very unique design concerns for architects because there are many key factors that can be associated with
∗ Tel.: +001 7736252620. E-mail address: [email protected] 0378-7788/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.enbuild.2012.10.038
the use of this element in buildings and influence its energy performance. All aspects of the atrium in buildings such as atrium proportion, orientation, shape and size, height, shading control of the atrium, atrium’s glazing type and ratio, and the thermal mass of the atrium’s walls, need careful design consideration. Poor or inappropriate design may create challenges for controlling temperature, glare, and energy consumption. This causes even more energy to be used significantly and will result in poor indoor environment for occupants. Dealing with atrium buildings is complicated due to the lack of adequate and a comprehensive design tools capable of determining the impact of such spaces on the building energy performance in the early stages of the design process. Architects and designers also face a more difficult challenge represented in quantifying and accurately measuring the energy consumption that requires specifically awareness and knowledge of relevant energy efficiency issues [5]. Lacking a strong background to identify potential strategies could cause unanticipated consequences that considerably reduce the energy performance of any design. Following a careful atrium design guidelines produce buildings that use substantially less energy without compromising occupant comfort. It is important to examine the influence of all parameters in order to maximize the thermal comfort characteristics of an atrium in a building. This analysis aims to investigate how different atrium forms and geometries respond to various conditions. It clarifies the relationship between the thermal performance of an atrium and its size and geometry. The analysis results and findings help architects and designers to identify the most energy efficient atrium building type. It enhances their understanding of the effect of different parameters on the inner atrium environment and provides them with wide
2
A. Aldawoud / Energy and Buildings 57 (2013) 1–5
Fig. 2. Variations in the geometry of the atrium types.
Fig. 1. Typical atrium model.
range of strategies which could ultimately lead toward optimizing atrium design.
2. Modeling development approach In order to investigate the energy performance of the suggested atrium building types, four computer models are created using the computer simulation program DOE-2.1E. All models represent realistic commercial office buildings characteristics. Design requirements including occupancy, lighting and equipment power, HVAC operation schedule are considered in the simulation process. For the purpose to assess the impact of the atrium geometry on the building energy performance level, the atrium skylight in each model is considered the only access point to the exterior environment. The models envelopes including all exterior surfaces, floors, and walls are considered adiabatic to prohibit the heat transfer with the surrounding environment. The spaces within all models are assumed to be fully conditioned with a set temperature of 75 ◦ F (24 ◦ C). The conditioned spaces are in thermal equilibrium so there are no thermal transfers among them (see Fig. 1). The interior walls of each atrium for all models are clear single glazed curtain wall system. The ratio of glazed to opaque surfaces is 67% and this parameter is held constant throughout the simulation process. Weather data for four principal climatic zones in United States is used. Simulation weather files contain hourly weather data for one year (8760 h) are selected for four cities to represent hot-dry, hot-humid, cold, and temperate climates. In the simulation process, for each model which represents an atrium type, the energy performance is evaluated and compared with the measurements of other models under the same conditions (see Fig. 2).
In the study the model parameters are modified in each simulation run. Total of 4320 simulation runs are conducted for each model type. The main modified parameters in this study are: • Geometry: four different geometries of atria are tested. They all have same areas with different length-to-width ratio. Table 1 and Fig. 3 shows the dimensions and the area of each atrium type and the ratio of length to width compared to the length and width of Model (1) as a reference model for the analysis and comparison. ◦ Model (1) has a squared-shaped atrium plan and the ratio of length to width is 1:1. Model (1) length and width are the standard reference measurements for other models. ◦ Model (2) has a rectangular shaped atrium plan and is oriented east–west. The atrium area is exactly same as the atrium of Model (1), but the ratio of length to width is 1 1/4: 0.8 of the reference measurements of Model (1). ◦ Model (3) has a rectangular shaped atrium plan and is oriented east–west. It has same exact area of the atrium in Model (1). The atrium’s ratio of length to width is 1 2/3: 0.6 of the reference measurements of Model (1). ◦ Model (4) atrium is rectangular in plan and elongated east to west. The atrium has the same exact area of the atrium in Model (1). The ratio of length to width is 2 1/2 × 0.4 of the reference measurements of Model (1). • Glazing types: for each model alternative, four different glazing types are used for the atrium skylight. The glazing types variations are: ◦ Single layer of clear glass ◦ Double layers of clear glass ◦ Double layers of tinted glass ◦ Triple layers of clear glass. • Glazing ratio: for each model alternative, three different glazing ratios are investigated for the atrium skylight. The glazing ratios are: ◦ Glazing ratio of 30% ◦ Glazing ratio of 50%
Table 1 The atrium dimensions and the proportion of length to width compared to Model (1) as reference model for the analysis and comparison. Model
Atrium dimensions (m)
Floor area of atrium (m2 )
Ratio length × width
Model (1) Model (2) Model (3) Model (4)
15.24 × 15.24 19.05 × 12.19 25.40 × 9.14 38.10 × 6.10
232. 2 232. 2 232. 2 232. 2
1.0 × 1.0 1 1/4 × 0.8 1 2/3 × 0.6 2 1/2 × 0.4
A. Aldawoud / Energy and Buildings 57 (2013) 1–5
3
Fig. 3. The atrium ratio of length to width compared to the length and width of Model (1) atrium as a reference for the analysis and comparison.
◦ Glazing ratio of 80%. • Model height (number of floors): throughout the simulation process, the overall height of each alternative is modified from one to twenty stories. • Climate: four climatic regions are selected based on the climate classification criterion derived from Victor [6]. The United States consists of four primary climatic zones. A city from each climatic zone is selected; the representative cities are: ◦ Phoenix, Arizona (hot-dry climate region). ◦ Miami, Florida (hot-humid climate region). ◦ Chicago, Illinois (temperate climate region). ◦ Minneapolis, Minnesota (cold climate region). 3. Results The simulations results show that thermal performance of an atrium building is greatly affected by the atrium geometry and this effect varies widely by different conditions primarily the climate. • In general, with all glazing types and 30% glazing ratio, as demonstrated in Fig. 4, the four model types show significant energy saving in temperate and cold climates as a low rise building, while it is more energy efficient in hot humid and hot dry climates as a high rise building.
• Increasing the atrium skylight glazing ratio to 50% and 80%, as shown in Fig. 5, boost the atrium energy efficiency in temperate and cold climates. Energy efficiency in the hot-dry and hot-humid climatic conditions is better as high rise office building. • The geometry has a considerable influence on the rate of the energy usage for each model. In all climatic regions, Model (4) shows the worst energy performance. ◦ Elongated atrium shapes with high length to width ratios are less energy efficient than other tested shapes. As an example, Model (4) which has the highest aspect ratio of length to width shows a poor energy performance in all climatic regions. Despite the fact that it generally performs better in hot-humid and hot dry climates as a high rise building, but its total annual energy consumption rate is much higher than Model (1) energy consumption in these climates. ◦ Model (1) with square-shaped atrium is the most ideal shape among all tested atriums in all climatic regions. It shows the lowest energy consumption rate compared to all other atriums in all climatic regions. • The effect of the climatic changes on the total annual energy consumption of the models is noticeable. When modifying the climate, but leave other variable unchanged, the rate of the annual
Fig. 4. Total cooling and heating energy consumption using single clear glass 30%.
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A. Aldawoud / Energy and Buildings 57 (2013) 1–5
Fig. 5. Total cooling and heating energy consumption using single clear glass 80%.
Fig. 6. Total energy consumption using single clear glass and 30% glazing ratio.
energy consumption of all models compared to Model (1) energy performance varies according to the climate region. Fig. 6 shows the energy performance of the tested models compared to Model (1) energy performance in each climatic region.
◦ In temperate climates, for example, the annual energy consumption of Model (4) is up by 25.5% compared to the annual energy consumption of Model (1) when using single clear glass with 30% glazing ratio for the atrium skylight in that climate, at twenty floors. ◦ In hot-dry and hot-humid climatic regions, when using the same glazing type and glazing ratio for the atrium skylight, Model (4) consumes more than 30% of energy compared to the annual energy consumption of Model (1) at twenty floors. ◦ In cold climates, using the same criteria of glazing type and ratio, resulted in more energy consumption of about 24% for Model (4) compared to the annual energy consumption of Model (1) at twenty floors. ◦ In general, the energy performance of the atrium at twenty floors height is the best in hot-humid climates and the worst in cold climates. Table 2 shows the energy performance of the four tested models in each climate compared to their energy performance in temperate climate using double clear glass with 80% glazing ratio at twenty floors height.
• Depending on the atrium skylight glazing type and ratio and compared to the annual energy consumption of Model (1) in temperate climates as a reference and a method of evaluation, the same model annual energy consumption rate in hot-dry climates is less by approximately 13–22%. In hot-humid climates, the same model annual energy consumption rate is less by approximately 16–24%. Whereas in cold climates, the same model annual energy consumption rate is more by approximately 5–8%. • Compared to the annual energy performance of Model (2) in temperate climates as a reference for the evaluation, Model (2) annual energy consumption rate in hot-dry climates is less by approximately 13–21%. The same model in hot humid climates consumes less energy by the rate of approximately 16–22%. Meanwhile, in cold climates, Model (3) energy consumption rate increases by about 5–8% compared with the rate of the energy consumption of the same model in temperate climates. • Model (4) shows the best energy performance in hot-humid climates. Its energy consumption rate is less by about 15–17% than the energy consumption rate of Model (4) in temperate climates. The same model, in hot-dry climates consumes less energy by the rate of approximately 10–16% than Model (4) in temperate climates. The annual energy consumption rate in cold climates for the same model is
Table 2 Energy performance of tested models in each climate compared to their energy performance in temperate climate using double clear glass with 80% glazing ratio at twenty floors height. Model type Model (1) Model (2) Model (3) Model (4)
Temperate climate
Hot-dry climate (%)
Hot-humid climate (%)
Cold climate (%)
−12.89 −13.51 −12.23 −10.09
−16.09 −16.07 −15.65 −15.59
5.40 5.20 5.64 4.62
A. Aldawoud / Energy and Buildings 57 (2013) 1–5
5
Fig. 7. Total cooling and heating energy consumption in temperate climate using single clear glass and 50% skylight glazing ratio.
higher by approximately 4–6% than Model (4) in temperate climates. • In all climates, the increasing in cooling loads is mainly responsible for intensifying the rate of the total energy consumption in all models. ◦ Cooling loads demands in Models (2), (3), and (4) compared to Model (1) are generally 1–35% higher in all climates depending on other variables. Model (4) cooling demand is the highest among all tested models. For example, Fig. 7 shows the rate of cooling and heating energy consumption in temperate climates using single clear glass with 50% glazing ratio for the atrium skylight. Model (2) consumes about 2% more of cooling than Model (1), while there is no need for additional heating. Model (3) consumes about 5% more cooling and about 1% of heating. Model (4) consumes about 33% of cooling and 2% of heating more than the energy consumption of Model (1). 4. Conclusion In conclusion, the study shows that the atrium geometry is an important factor to consider from a design and an energy efficiency perspective. It impacts the heating and cooling loads which determine the overall energy performance of the building. In all climatic regions, the effect of the atrium geometry has been found to be more evident in the elongated atrium shapes and this is due to the size of the skylight exposed to environmental conditions. The
atrium which elongated along an east west axis with the long sides facing south and north will likely have greater exposure to direct solar radiation and the influence of the other weather conditions. Therefore, depending on the climate and the glazing type and ratio, buildings will typically require more heating and cooling capacity and use more energy annually. The findings of this study contribute to a better understanding of atrium geometry and its impact on heating and cooling requirements and energy use. This understanding can be used to better estimate the effectiveness of certain atrium geometries which can help to avoid underestimation as well as overestimation of the potential for energy use which could ultimately lead toward optimizing atrium design. References [1] “U.S. Energy Information Administration, – EIA – Independent Statistics and Analysis.” U.S. Energy Information Administration (EIA). N.p., n.d. Web. 13 Aug. 2012.
Contents lists available at SciVerse ScienceDirect
Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild
The influence of the atrium geometry on the building energy performance Abdelsalam Aldawoud ∗ College of Environmental Design, King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia
a r t i c l e
i n f o
Article history: Received 18 September 2012 Accepted 10 October 2012 Keywords: Atrium Computer simulation Energy efficiency Computer modeling
a b s t r a c t In this study, the thermal performance of various shapes and geometries of atriums in buildings is examined under various conditions. The goal of the study is to assess the impact of the atrium shape on the building total energy consumption and to identify the most energy-efficient atrium design. The study focuses on four different central atriums types with square and rectangular geometries which have same areas, use, schedule, controls, occupancy, and construction. The atriums exhibit different aspect ratios (length to width). Four cities in United States are selected to represent primary climatic regions of hotdry, hot-humid, cold, and temperate. Besides, the atrium height, the atrium glazing type, and the glazing ratio are varied throughout the simulation process. Buildings models are constructed using the DOE-2.1E building energy simulation program. The results of this study indicate that in general, the total energy consumption of the narrow, elongated atrium or the rectangular atrium with high ratio of length to width is significantly greater than the square shaped atrium. © 2012 Elsevier B.V. All rights reserved.
1. Introduction Buildings sector is responsible for at least 40% of energy use in most countries worldwide. In the United States, buildings consume about 67% of the total electricity used each year and produce 35% of US and 9% of global carbon dioxide (CO2 ) emissions. The future energy consumption trends in this sector continue to increase and according to the United States Energy Information Administration (EIA) [1], the total energy consumption in 2035 will increase about a 20% from current consumption levels. As a result, it is important to incorporate energy-efficient strategies into designs to minimize the buildings energy usage, while at the same time improving the levels of comfort within buildings. For buildings in general, the artificial lighting loads is considered a major problem which significantly contribute to building cooling and heating loads requirements [2]. In recent years, the atrium design becomes popular for purpose of esthetics, daylighting, and solar heating. Good atrium design will specifically bring natural lighting into the interior spaces of the building and therefore minimize depending on artificial lighting loads and reduce the demand for space conditioning. Despite numerous studies demonstrating the atriums benefits, including their energy significant potential in reducing the building artificial lighting demand and as a result lowering the thermal loads [3], their thermal performance is extremely difficult to predict [4]. Atria present some very unique design concerns for architects because there are many key factors that can be associated with
∗ Tel.: +001 7736252620. E-mail address: [email protected] 0378-7788/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.enbuild.2012.10.038
the use of this element in buildings and influence its energy performance. All aspects of the atrium in buildings such as atrium proportion, orientation, shape and size, height, shading control of the atrium, atrium’s glazing type and ratio, and the thermal mass of the atrium’s walls, need careful design consideration. Poor or inappropriate design may create challenges for controlling temperature, glare, and energy consumption. This causes even more energy to be used significantly and will result in poor indoor environment for occupants. Dealing with atrium buildings is complicated due to the lack of adequate and a comprehensive design tools capable of determining the impact of such spaces on the building energy performance in the early stages of the design process. Architects and designers also face a more difficult challenge represented in quantifying and accurately measuring the energy consumption that requires specifically awareness and knowledge of relevant energy efficiency issues [5]. Lacking a strong background to identify potential strategies could cause unanticipated consequences that considerably reduce the energy performance of any design. Following a careful atrium design guidelines produce buildings that use substantially less energy without compromising occupant comfort. It is important to examine the influence of all parameters in order to maximize the thermal comfort characteristics of an atrium in a building. This analysis aims to investigate how different atrium forms and geometries respond to various conditions. It clarifies the relationship between the thermal performance of an atrium and its size and geometry. The analysis results and findings help architects and designers to identify the most energy efficient atrium building type. It enhances their understanding of the effect of different parameters on the inner atrium environment and provides them with wide
2
A. Aldawoud / Energy and Buildings 57 (2013) 1–5
Fig. 2. Variations in the geometry of the atrium types.
Fig. 1. Typical atrium model.
range of strategies which could ultimately lead toward optimizing atrium design.
2. Modeling development approach In order to investigate the energy performance of the suggested atrium building types, four computer models are created using the computer simulation program DOE-2.1E. All models represent realistic commercial office buildings characteristics. Design requirements including occupancy, lighting and equipment power, HVAC operation schedule are considered in the simulation process. For the purpose to assess the impact of the atrium geometry on the building energy performance level, the atrium skylight in each model is considered the only access point to the exterior environment. The models envelopes including all exterior surfaces, floors, and walls are considered adiabatic to prohibit the heat transfer with the surrounding environment. The spaces within all models are assumed to be fully conditioned with a set temperature of 75 ◦ F (24 ◦ C). The conditioned spaces are in thermal equilibrium so there are no thermal transfers among them (see Fig. 1). The interior walls of each atrium for all models are clear single glazed curtain wall system. The ratio of glazed to opaque surfaces is 67% and this parameter is held constant throughout the simulation process. Weather data for four principal climatic zones in United States is used. Simulation weather files contain hourly weather data for one year (8760 h) are selected for four cities to represent hot-dry, hot-humid, cold, and temperate climates. In the simulation process, for each model which represents an atrium type, the energy performance is evaluated and compared with the measurements of other models under the same conditions (see Fig. 2).
In the study the model parameters are modified in each simulation run. Total of 4320 simulation runs are conducted for each model type. The main modified parameters in this study are: • Geometry: four different geometries of atria are tested. They all have same areas with different length-to-width ratio. Table 1 and Fig. 3 shows the dimensions and the area of each atrium type and the ratio of length to width compared to the length and width of Model (1) as a reference model for the analysis and comparison. ◦ Model (1) has a squared-shaped atrium plan and the ratio of length to width is 1:1. Model (1) length and width are the standard reference measurements for other models. ◦ Model (2) has a rectangular shaped atrium plan and is oriented east–west. The atrium area is exactly same as the atrium of Model (1), but the ratio of length to width is 1 1/4: 0.8 of the reference measurements of Model (1). ◦ Model (3) has a rectangular shaped atrium plan and is oriented east–west. It has same exact area of the atrium in Model (1). The atrium’s ratio of length to width is 1 2/3: 0.6 of the reference measurements of Model (1). ◦ Model (4) atrium is rectangular in plan and elongated east to west. The atrium has the same exact area of the atrium in Model (1). The ratio of length to width is 2 1/2 × 0.4 of the reference measurements of Model (1). • Glazing types: for each model alternative, four different glazing types are used for the atrium skylight. The glazing types variations are: ◦ Single layer of clear glass ◦ Double layers of clear glass ◦ Double layers of tinted glass ◦ Triple layers of clear glass. • Glazing ratio: for each model alternative, three different glazing ratios are investigated for the atrium skylight. The glazing ratios are: ◦ Glazing ratio of 30% ◦ Glazing ratio of 50%
Table 1 The atrium dimensions and the proportion of length to width compared to Model (1) as reference model for the analysis and comparison. Model
Atrium dimensions (m)
Floor area of atrium (m2 )
Ratio length × width
Model (1) Model (2) Model (3) Model (4)
15.24 × 15.24 19.05 × 12.19 25.40 × 9.14 38.10 × 6.10
232. 2 232. 2 232. 2 232. 2
1.0 × 1.0 1 1/4 × 0.8 1 2/3 × 0.6 2 1/2 × 0.4
A. Aldawoud / Energy and Buildings 57 (2013) 1–5
3
Fig. 3. The atrium ratio of length to width compared to the length and width of Model (1) atrium as a reference for the analysis and comparison.
◦ Glazing ratio of 80%. • Model height (number of floors): throughout the simulation process, the overall height of each alternative is modified from one to twenty stories. • Climate: four climatic regions are selected based on the climate classification criterion derived from Victor [6]. The United States consists of four primary climatic zones. A city from each climatic zone is selected; the representative cities are: ◦ Phoenix, Arizona (hot-dry climate region). ◦ Miami, Florida (hot-humid climate region). ◦ Chicago, Illinois (temperate climate region). ◦ Minneapolis, Minnesota (cold climate region). 3. Results The simulations results show that thermal performance of an atrium building is greatly affected by the atrium geometry and this effect varies widely by different conditions primarily the climate. • In general, with all glazing types and 30% glazing ratio, as demonstrated in Fig. 4, the four model types show significant energy saving in temperate and cold climates as a low rise building, while it is more energy efficient in hot humid and hot dry climates as a high rise building.
• Increasing the atrium skylight glazing ratio to 50% and 80%, as shown in Fig. 5, boost the atrium energy efficiency in temperate and cold climates. Energy efficiency in the hot-dry and hot-humid climatic conditions is better as high rise office building. • The geometry has a considerable influence on the rate of the energy usage for each model. In all climatic regions, Model (4) shows the worst energy performance. ◦ Elongated atrium shapes with high length to width ratios are less energy efficient than other tested shapes. As an example, Model (4) which has the highest aspect ratio of length to width shows a poor energy performance in all climatic regions. Despite the fact that it generally performs better in hot-humid and hot dry climates as a high rise building, but its total annual energy consumption rate is much higher than Model (1) energy consumption in these climates. ◦ Model (1) with square-shaped atrium is the most ideal shape among all tested atriums in all climatic regions. It shows the lowest energy consumption rate compared to all other atriums in all climatic regions. • The effect of the climatic changes on the total annual energy consumption of the models is noticeable. When modifying the climate, but leave other variable unchanged, the rate of the annual
Fig. 4. Total cooling and heating energy consumption using single clear glass 30%.
4
A. Aldawoud / Energy and Buildings 57 (2013) 1–5
Fig. 5. Total cooling and heating energy consumption using single clear glass 80%.
Fig. 6. Total energy consumption using single clear glass and 30% glazing ratio.
energy consumption of all models compared to Model (1) energy performance varies according to the climate region. Fig. 6 shows the energy performance of the tested models compared to Model (1) energy performance in each climatic region.
◦ In temperate climates, for example, the annual energy consumption of Model (4) is up by 25.5% compared to the annual energy consumption of Model (1) when using single clear glass with 30% glazing ratio for the atrium skylight in that climate, at twenty floors. ◦ In hot-dry and hot-humid climatic regions, when using the same glazing type and glazing ratio for the atrium skylight, Model (4) consumes more than 30% of energy compared to the annual energy consumption of Model (1) at twenty floors. ◦ In cold climates, using the same criteria of glazing type and ratio, resulted in more energy consumption of about 24% for Model (4) compared to the annual energy consumption of Model (1) at twenty floors. ◦ In general, the energy performance of the atrium at twenty floors height is the best in hot-humid climates and the worst in cold climates. Table 2 shows the energy performance of the four tested models in each climate compared to their energy performance in temperate climate using double clear glass with 80% glazing ratio at twenty floors height.
• Depending on the atrium skylight glazing type and ratio and compared to the annual energy consumption of Model (1) in temperate climates as a reference and a method of evaluation, the same model annual energy consumption rate in hot-dry climates is less by approximately 13–22%. In hot-humid climates, the same model annual energy consumption rate is less by approximately 16–24%. Whereas in cold climates, the same model annual energy consumption rate is more by approximately 5–8%. • Compared to the annual energy performance of Model (2) in temperate climates as a reference for the evaluation, Model (2) annual energy consumption rate in hot-dry climates is less by approximately 13–21%. The same model in hot humid climates consumes less energy by the rate of approximately 16–22%. Meanwhile, in cold climates, Model (3) energy consumption rate increases by about 5–8% compared with the rate of the energy consumption of the same model in temperate climates. • Model (4) shows the best energy performance in hot-humid climates. Its energy consumption rate is less by about 15–17% than the energy consumption rate of Model (4) in temperate climates. The same model, in hot-dry climates consumes less energy by the rate of approximately 10–16% than Model (4) in temperate climates. The annual energy consumption rate in cold climates for the same model is
Table 2 Energy performance of tested models in each climate compared to their energy performance in temperate climate using double clear glass with 80% glazing ratio at twenty floors height. Model type Model (1) Model (2) Model (3) Model (4)
Temperate climate
Hot-dry climate (%)
Hot-humid climate (%)
Cold climate (%)
−12.89 −13.51 −12.23 −10.09
−16.09 −16.07 −15.65 −15.59
5.40 5.20 5.64 4.62
A. Aldawoud / Energy and Buildings 57 (2013) 1–5
5
Fig. 7. Total cooling and heating energy consumption in temperate climate using single clear glass and 50% skylight glazing ratio.
higher by approximately 4–6% than Model (4) in temperate climates. • In all climates, the increasing in cooling loads is mainly responsible for intensifying the rate of the total energy consumption in all models. ◦ Cooling loads demands in Models (2), (3), and (4) compared to Model (1) are generally 1–35% higher in all climates depending on other variables. Model (4) cooling demand is the highest among all tested models. For example, Fig. 7 shows the rate of cooling and heating energy consumption in temperate climates using single clear glass with 50% glazing ratio for the atrium skylight. Model (2) consumes about 2% more of cooling than Model (1), while there is no need for additional heating. Model (3) consumes about 5% more cooling and about 1% of heating. Model (4) consumes about 33% of cooling and 2% of heating more than the energy consumption of Model (1). 4. Conclusion In conclusion, the study shows that the atrium geometry is an important factor to consider from a design and an energy efficiency perspective. It impacts the heating and cooling loads which determine the overall energy performance of the building. In all climatic regions, the effect of the atrium geometry has been found to be more evident in the elongated atrium shapes and this is due to the size of the skylight exposed to environmental conditions. The
atrium which elongated along an east west axis with the long sides facing south and north will likely have greater exposure to direct solar radiation and the influence of the other weather conditions. Therefore, depending on the climate and the glazing type and ratio, buildings will typically require more heating and cooling capacity and use more energy annually. The findings of this study contribute to a better understanding of atrium geometry and its impact on heating and cooling requirements and energy use. This understanding can be used to better estimate the effectiveness of certain atrium geometries which can help to avoid underestimation as well as overestimation of the potential for energy use which could ultimately lead toward optimizing atrium design. References [1] “U.S. Energy Information Administration, – EIA – Independent Statistics and Analysis.” U.S. Energy Information Administration (EIA). N.p., n.d. Web. 13 Aug. 2012.