PASSIVE AND LOW ENERGY ARCHITECTURE - THE ISRAELI APPROACH WITHIN THE SUSTAINABLE BUILDING STANDARD

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1 PASSIVE AND LOW ENERGY ARCHITECTURE - THE ISRAELI APPROACH WITHIN THE SUSTAINABLE BUILDING STANDARD Edna Shaviv Faculty of Architecture & Town Planning Technion - Israel Institute of Technology, Technion City, Haifa, Israel eshaviv@technion.ac.il ABSTRACT The new Israeli Sustainable Building (Green Building) Standard SI 5281 puts an emphasis in the energy chapter on Bio-Climatic and passive solar Architecture. As buildings are designed to outlive the services systems by a large margin, the Energy Chapter is divided into two parts; Building energy performance and Building services systems. A minimum credit points from each subchapter is obligatory in order to win each Green Grade level as well as predefined Energy Rating of the building should be obtained. Moreover, Bioclimatic analysis is a prerequisite and Passive systems for heating and cooling are encouraged and credited. Moreover, the standard tries to make the Building performance points easier to handle at the early design stages by using simple CAD tools for the performance based method, as well as providing design guidelines for the prescriptive-based method. Thus, the Israeli "Green buildungs" standard is unique in encouraging passive and low energy Architecture. 1. INTRODUCTION Green Architecture has recently gained momentum to become the trendy fashion and mainstream architectural practice. Hence, one expected bioclimatic, passive and low energy architecture to expand with the Green Architecture movement. However, it did not happen. A former paper presented in PLEA 2008 (1) examined carefully different examples of LEED accredited buildings and found that almost no improvement in the energy performance of the building was achieved (Fig. 1). Moreover, even when energy efficiency was considered, it could be achieved merely by improving the mechanical, electrical and hot water systems since these are easier issues to handle than designing low energy buildings. This is in contrast with the fact that buildings are designed to last 50 to 100 years and the mechanical systems only 10 to 20 years, at most. Fig. 1: Berkeley Lab's Molecular Foundry. Left: West and North Elevations. Right: Contrast obtained in the main working cubical space by the unshaded West Elevation. Consequently, the author of this paper, who was a member of the expert committee of the revision of the Energy Chapter of the Israeli Green Building Standard, has put an emphasis on the design of Passive and low energy architecture buildings, at each Green grad level. The paper presents the criteria and rules that the Israeli Green Building standard applied in order to guarantee that green buildings will be designed as a low energy one. 2. ARE GREEN BUILDINGS DESIGNED AS PASSIVE AND LOW ENERGY ONE? To answer the above question we focus on LEED that was established by US Green Building Council (2). This is because it is the most common one and therefore the 1

2 momentum of the Green Building Movement in the USA, as well as worldwide, has been achieved largely through it. LEED has the following faults: LEED, as most current environmental assessment methods uses simple point hunting approach. The tendency is to choose "cheap and easy points in order to collect enough points to be labelled Green Building. The points for reducing the energy consumption of the building are, in general, neither "cheap" nor easy. However, in order to achieve LEED Silver, the most common goal, one can get the minimum score required for it with almost no improvement in energy performance of the building. Moreover, energy efficiency can be achieved merely by improving the systems of the building. There is no need to improve the architectural design from bio-climatic and passive solar aspects, as happened in Intel Haifa that got even LEED GOLD with only 5 points in Minimizing Energy Performance, and without improving the building design (Fig. 2). In LEED the use of renewable energy, like solar energy for hot water, PV, or even buying Green Power, is awarded twice: once, as it reduces the amount of the total purchased energy and again, as it contributes to the "On Site Renewable Energy" credit, or to the "Green Power" credit. However, Passive Solar Energy is not considered as "On Site Renewable Energy". Consequently, LEED does not reward passive solar design. The energy calculations in LEED for minimizing energy performance are based on appendix G of ASHRAE 90.1 (3), which can t be used for buildings without mechanical systems. Therefore, if the building is an innovative Passive Solar and Bio- climatic one that doesn t require any mechanical heating or cooling, it can t be assessed and graded by ASHRAE and hence, cannot be credited for Minimizing Energy Performance. In other words, the best design fails! (4). It might even lose the possibility of achieving Green Building accreditation, as happened (first) to the SF Federal Building (Fig.3). If this is not a paradox, what is it? 3. ENSURING LOW ENERGY BUILDING DESIGN IN THE ISRAELI GREEN BUILDING STANDARD The Israeli Green Building Standard SI 5281 was first published on November 2005 (5) and consisted of only one part that included Residential Buildings, as well as Office Buildings. After three years it was decided to review periodically this standard at least every five years, in order to adapt it to technological developments. This paper refers to the revision of SI 5281 Standard that was published in July 2011 (6). SI 5281 includes eight parts, which are: Part 1: general requirements and parts 2 to 8: specific requirements for different building types including: Residential, office, education, hotels, healthcare, retail and public buildings. All types of buildings contain the same categories, but the sections and points allocated to each section and category are not always the same. In this paper all the examples brought are from the SI 5281 Part 2: Residential Buildings and Part 3: Office Buildings. SS 8 p 19% LEED 2.2 Intel Building ID 4 p 10% WE 4 p 10% MR 6 p 15% EA 5p 12% EQ 14 p 34% Fig. 2: Intel Haifa - The first LEED GOLD Green Building in Israel. Left: West elevation without sunshades. Right - Points achieved to obtained LEED 2.2 Gold Accreditation. Fig. 3: SF Federal Building, Up: Sunshades to protect the windows. Left: South Elevation - horizontal perforated metal skin as sunshades. Up right: North Elevation - vertical glass fins Sunshades. Bottom right: Daylighting. SI 5281 for residential includes the categories: EA-Energy (37%), SS-Land (17%), WE-Water (17%), MR-Materials (6%), H&WB-Health & Well being (10%), WMT-includes: Waist (4%), Management (4%) and Transportation (2%), ID- Innovation (3%). The differences between Residential and Office buildings are small and in both cases the Energy chapter is 37% (Fig. 4). These categories and points allocated to the energy category are also very similar to LEED 3.0's categories and points. 2

3 H&WB 10% MR 6% Residential WTM 10% ID 3% WE 17% SS 17% EA 37% H&WB 11% Office Building MR 8% WTM 10% ID 4% WE 15% SS 15% EA 37% SS 26 p 24% WE 10 p 9% LEED 3.0 Fig. 4: Left: SI Max. total possible points (= %). Left: LEED Max. total possible points & %. Like other environmental assessment methods, SI 5281 uses simple point hunting approach. According to the number of points achieved, the building is labelled as a green building on five Green Grade levels. In order to avoid the above mentioned deficiencies, the emphasis in the suggested revision has been laid on the improvement of the architectural design, i.e. the design of the building itself as bio-climatic and passive solar in order to minimize the energy consumption of the building. The HVAC performance is not evaluated together with the building energy performance, but is rated according to the COP of each piece of equipment. Therefore, the Energy Chapter (chapter 1) is divided into two subchapters: 1.1. Building energy performance: Only Bioclimatic and PLEA aspects are considered under this title and 1.2 Building services systems: including HVAC and other mechanical systems, as well as solar water heating and PV. A minimum awarded number of points from each subchapter is required, in order to reach a certain level of Green Grade (Table 1). The energy rating of the proposed building design should reach at least level C, according to SI 5282 (7), which guarantees energy saving of 20% or 28% in residential or in office buildings, respectively, compared with the performance of a reference building. Moreover, contrary to LEED, the use of renewable energy like solar energy for hot water (that is compulsory in Israel), or PV (that is highly subsidized) is not credited twice. Instead, passive solar design and low cooling energy design, are awarded and encouraged by SI TABLE 1: MINIMUM REQUIRED ENERGY POINTS FOR EACH GREEN GRADE LEVEL Rating of Building No of Stars & Total Points 1.1 Building 1.2 Systems ID 6 p 5% Rg 4 p 3% MR 14 p 13% EA 35 p 32% EQ 15 p 14% At least Level According to SI 5282 R O R O 1* C 2* B 3* A 4* A+ 5* A+ Remark: R: Residential Building, O: Office Building. The author of this paper, was in charge of the revision of the building energy performance subchapter. The rest of the paper will be devoted to present this subchapter. 4. THE SUBCHAPTER BUILDING ENERGY PERFORMANCE The sections defined in the the subchapter 1.1 Building energy performance for residential buildings and the points allocated to them are: Bioclimatic Design Passive heating and cooling (5pt), Bioclimatic Design Sun and shade (6.3pt), Energy Efficiency according to SI 5282 (20pt), Daylighting of public indoor areas (1pt), Drying Space (1pt). The maximnum allocated points in residential building to this subchapter is 29 and 21 points in office buildings, which includes less sections: Bioclimatic Design Passive heating and cooling (4pt), Bioclimatic Design Sun and shade (7pt) Energy Efficiency according to SI 5282 (17pt) ), Daylighting of public indoor areas (1pt). 4.1 Bioclimatic Design Passive heating and cooling The intent of this section is to encourage energy efficient building design using passive heating and cooling techniques including natural ventilation. The first part of this section includes Bioclimatic analysis and the determination of design strategies that fit best the location of the project. The requirement is to present the climatic conditions; temperature and relative humidity on a Bioclimatic Chart, in order to understand the local climate and to determine the suitable passive and low energy strategies (Fig. 5). The Bioclimatic analysis is a prerequisite without awarding any points. It may be carried out manually, or by using computer programs like PASYS (8). The second part includes the physical application of passive systems for heating, cooling and ensuring natural ventilation in the building, according to the Bio-climatic design strategies that were found appropriate for the building site. There is an emphasis on passive systems in which special effort was needed to bring the solar passive heating to spaces that cannot get direct sun, like Northern rooms, or lower rooms that are shaded by the surrounding, or when direct sun may cause too much brightness and glare (Fig. 6). These include for example Vented Wall or Sunspace for space heating, or Wind Chimney and Thermal Chimney for cooling by natural ventilation. The vented wall or Sunspace, for example, may serve also as Thermal Chimney, as was designed and built in Shaviv 3

4 House (9). Hence, they are considered as two systems (Fig. 6). allows him to know, at the early design stage, the required size of each passive system, according to the floor area it should serve. Fig. 6: Vented Sunspace for heating the first floor that is shaded by neighbouring building, which also serves as Wind Chimney for cooling and for natural ventilation. (From Appendix A of SI 5281). Fig. 5: Bioclimatic analysis using PASYS program. The passive systems to be applied in the project and the building area served by each system should be documented and presented by schematic drawings. The points are determined according to the floor area of the building devoted to the primary functions that are served by the passive systems for heating or for cooling. The contribution of the passive systems for heating and cooling to minimize the energy consumption of the building, as well as direct solar gain and cross ventilation are calculated by using computer simulation programs like EnergyPlus (10). However, to encourage the architect to design a passive building a prescription approach is presented in Appendix A of the SI 5281 (11). This Appendix presents the passive systems, like Sunspace, or Vented wall, as well as specifies the percentage of the required system area in relation to the floor area it serves (Fig. 7). The user can also use CAD tools like PASYS (12) to learn at the early design stage about the best passive systems suitable for the specific project and their recommended size. The prescription approach was developed by using the LCR method derived by Balcomb et al. after running many simulations (13). This method was adapted to the Israeli climate and building technology by Shaviv (14,11). Thus, the architect has a simple and easy to use design tool that ss = sunspace c = common o = opaque g = glass 5 = = = 90 0 m = Thermal Mass L = Light Climate Zone A B C Climate Zone A B C Single Glazing Double Glazing SS5om SS5om SS5oL SS5oL SS5gm SS5gm SS5gL SS5gL SS5om SS5om SS5oL SS5oL SS5gm SS5gm SS5gL SS5gL SS9cm SS9cm SS9cL SS9cL SS5cm SS5cm SS5cL SS5cL SS3cm SS3cm SS3cL SS3cL Figure 7: The LCR method for Sunspace. Up: Different Configurations of Sunspace Systems (13) Down: The required % of system area relative to the floor area it serves. (From Appendix A of SI 5281). 4

5 4.2 Bioclimatic Design Sun and shade The building density in Israel is one of the highest in the world. The green code should ensure suitable environmental conditions to the surrounding buildings, sidewalks and open spaces, as well as the proposed projet in regards to the sun and winds. (Winds analysis was first included in this chapter but was moved later to the chapter Health and Wellbeing ). Therefore, the intent of this section is to maintain the solar rights of the proposed project and of the buildings and open areas in its close environment, and in addition to carfully shade the open spaces and sidewalks in summer, without depriving winter insolation. required insolation. This may be achieved by fixed shading devices or evergreen trees, in areas that are anyhow shaded during winter by sourounding buildings, or by dynamic shading devices or deciduous trees, in areas that insolated to winter sun, like horizontal shading devices that protect the open space from the summer high sun, but allows the winter low sun to reach this area. Analyzing the shadow cast by the surrounding buildings and objects and the shadow cast by the proposed building on its close environment is a prerequisite, which does not carry any bonus points. This analysis can be carried out manually, according to a prescription/description approach (15,16) or by using computer aided design programs like SUSTARC (17,18) or SHADING (19) (Figs. 8-10). Points are awarded according to the achieved predefined amount of solar exposure of the proposed project and the nearby environment according to the requirements in Apendix B of SI 5281, including: the solar systems (PV and water heating solar collectors), the building elevations, the open spaces of the proposed designed project. Moreover, the building should should not ciolete the solar rights of the neighbouring buildings and open spaces (12). The last requirement is mandatory for buildings taller than 90m or taller and longer than 45m. An additional point is awarded when 20% of the main open area is shaded during summer, while keeping the winter Zone A Zone C Zone B Zone D Fig. 9: Solar rights design - the description approach: Using the lines obtained according to SustArc model. (From Appendix B of SI 5281). Fig. 8: Solar rights design - the description approach: Using SustArc model to create the Solar Envelope. Fig. 10: Haifa Auditorium: Solar rights design - the performance approach. Using SHADING as a design tool. 5

6 4.3 Energy Efficiency according to SI 5282 Achieving points for minimizing the energy required for heating, cooling and lighting, is based on the Israeli Standard SI 5282 (7). This Standard offers prescription/description methods, as well as performance one, to evaluate the building energy consumption. The energy performance method defines a reference building that complies with the mandatory Israeli Standard SI 1045 that prescribes the required insulation and the solar heat gain coefficient of the building envelope and windows (20). The energy rating includes 5 grades. The per cent of the required energy saving for achieving grades D and C is the same in all four climatic zones of Israel. However, to be awarded grades B, A or A+ the requirments for saving are not the same in the four climatic zones. This is because the hotter the climate is, the less saving could be achieved relative to the standard building practice today. Yet, energy rating of A+ provides a new building with 17 green points in all climatic zones and 21 for retrofitting, while energy rating of C in new buildings, or D for retrofitting existing buildings, wins only 5 points in all climatic zones. Achieving the same level of energy efficiency in existing buildings is more difficult. Hence each energy rating grade gets a higher score in renovation (Table 2). This interface includes the requirements of how to use the performance approach and how to define the reference building, which the interface builds automatically. It also creats automatically the building database required to run EnergyPlus (Fig. 11). Thus, EnergyUI allows the Architect to run the heavy simulation model at the early design Stages. TABLE 2: ENERGY RATING OF OFFICE BUILDINGS IN SI 5282 AND SI 5281 Energy Saving Compliance (%) Credit points In SI Level in Climatic Zones New Existing SI A, D B,C Building Building Level D 20%< - 5 Level C 28%< 5 9 Level B 34%< 36%< 9 13 Level A 44%< 40%< Level A+ 46%< 52%< In order to improve the building energy performace according to the performance approach, one should run a heavy simulation models like EnergyPlus that requires high experties to run it. Therfore, the tendency is to use such models only at the very advanced design stages, when it is almost impossible to change the geometry of the building or to perform other major changes. We know that a good energy counsious building design, like decisions about the building mass and orientation should be carried on at the early design stages. Hence, it is important to be able to evaluate the building performance already at the conceptual design stage. To solve this problem, an easy to use interface EnergyUI was written as part of the SI 5282 standard (21). Fig. 11: The interface EnergyUI. Up: Output presented as Energy Rating produced automatically for the whole building as well as for each apartment or office unit. Down: The main input menu. The Israeli standard SI 5282 emphasizes the building architecture and its architectural details including: the building geometry, compactness and proportions, windows size and orientation, window shading and glazing type, envelope insulation and thermal mass, as well as night ventilation for passive cooling and comfort ventilation. The reference building in SI 5282 is defined with fixed geometry and depth that allows daylighting. For this reason, the geometry of the proposed building affects the results. The calculations of the energy consumption for heating, cooling and daylighting for a proposed building, as well as for the reference one, are performed according to the electricity consumption of the same predefined aircondition unit, even if the proposed building will not have any mechanical systems. Thus, only the building energy performance is considered under SI This is in contrast to ASHRAE 90.1 that requires the proposed building to have mechanical systems as written: the provisions of this standard do not apply to: buildings that do not use either electricity or fossil fuel (3). As the emphasis in ASHRAE 6

7 90.1 is put on improving the mechanical systems and not on the architectural design, the reference building in appendix G is defined according to the geometry of the proposed building, and thus the influence of the building s geometry is eliminated. Another simple way to start a good energy consious building design is to follow the requirements of the prescriptive, or the descriptive approach (Fig 12), derived from summarizing the results obtained from running a large number of cases (22) using the simulation model ENERGY (23, 24). 4.5 Drying Space (only in residential buildings) The intent of this issue is to encourage energy saving for drying laundry by providing an adequate space for it (Fig. 14). Tel Aviv A South 8.20 Climate zone Orientation Unit Depth Orientation Infiltration Night Ventilation W.T.Mass W. U Value W. Albedo Electricity Consumption/Life Cycle Cost Or Inf NV TM Ins Al Dp Wa Glz Blnd SunShd Ctrl Tot CTot Sensitivity Analysis St1045: SS Light U= DgCl IntBld OnOn Tel Aviv Basic: SS Light U= LE01 NoBlnd Hs Ls Onf Glazing Type Blinds Sun Shades Glazing Size Light Cont. Fig. 12: Energy Rating of office building - the descriptive approach. The dark bar is a semi-optimal low energy. solution, S.T. economical constrains. The Energy Grade is defined on the sensitivity analysis graph. 4.4 Daylighting of public indoor areas The intent of this issue is to reduce energy for electric lighting in all public indoor spaces that are in daily use, like lobbies, stairways, etc. (Fig. 13). Fig. 13: Double atrium to daylit the circulation area of a residential building, as well as the lobby of an hotel below.. Fig. 14: Hidden Space for drying laundry adjacent to a utility balcony in each floor of a High rise residential building. 5. SUMMARY AND CONCLUSIONS This paper reveals the faults that exist in point hunting' Green Buildings assessment methods rating schemes, like LEED, and presents how they are solved in the Israeli new green building standard SI The disturbing phenomena discussed in the paper are: 1. Attempts to get only cheap and easy points. As Energy points are neither cheap nor easy, and consequently are avoided. 2. Attempt to improve only the systems of the building and not the building itself, as this is easier and cheaper. 3. Optimizing the energy consumption of the building according to Appendix G of ASHRAE takes into consideration mainly the performance of the systems and not of the architectural design of the building. Hence, improving the geometry of the building is neglected. 4. Renewable energy systems are rewarded twice while passive solar systems are not considered renewable energy and consequently are not awarded. The Israeli Green Building Standard is also based on a point hunting' method. Therefore, to avoid the abovementioned faults, and in order to guarantee that Green Buildings will be designed as Low Energy Buildings the Energy Committee for the Israeli Green Building Standard used the following criteria: a. The Energy Chapter should get sufficiently more points than other green categories in order to increase the weight of energy saving. 7

8 b. The Energy Chapter is devided into two parts: Building Energy Performance and Buildigs Services Systems and a minimum required points from each subchapter should be obligatory in order to achieve each Green Grade level. This separation is important because the building is designed to outlive the services systems by a large margin. c. Low energy building design requirements should be imposed for achieving a minimum required predefined Energy Rating of the building for each Green Grade level according to SI d. Bioclimatic analysis should be a prerequisite without awarded points for it. e. Passive and Low Energy Building Design should be awarded and treated separately from hot water systems (that is mandatory in Israel) and from mechanical systems (AC and others, like elevators). However, it is not sufficient to impose requirements in order to achieve Low Energy Green Buildings. One should remember that the Green Building standard is a voluntary one; hence, we should make it easy to implement. Therefore, all the sections in the Building Performance subchapter include (on top of a performance approach that required expert professional stuff to run the heavy simulation models) prescription or description methods, which were derived by running many simulations in advance. It also refers to simple CAD tools that can be used in the early design stages. Even the heavy energy simulation model EnergyPlus may be run by using a simple CAD tool EnergyUI, as a user interface. 6. REFERENCES (1) Shaviv E., Passive and Low Energy Architecture (PLEA) VS Green Architecture (LEED), Proceeding of the 25th PLEA 2008 Conference, 2008 (2) LEED for New Construction & Major Renovations, (3) ASHRAE Standard 90.1, Energy Standard for Buildings except Low-Rise Residential Buildings, ISSN , 2007 (4) Stamp J. Greener Than Thou: Fed Building Too Green For LEED, 2008 (5) SI 5281, Buildings with reduced environmental impact ( Green Buildings ), The Standards Institution of Israel, (6) SI 5281, Sustainable Buildings ( Green Buildings ), The Standards Institution of Israel, 2011 (7) SI 5282, Energy Rating of Buildings, The Standards Institution of Israel, 2011 (8) Yezioro A., Shaviv E., A Knowledge Based CAD System for Determining Thermal Comfort Design Strategies. Renewable Energy 8: Pergamom Press, (9) Shaviv, E., The Performance of a Passive Solar House with Window Sunspace Systems. "Energy & Buildings", 7, Elsevier Sequoia, 1984 (10) EnergyPlus, US Department of Energy, (11) Shaviv E., Appendix A of SI 5281a Prescriptive/ Descriptive Approach (Normative): Part 1: Passive Systems for heating, Part 2: Passive Systems for Cooling and Natural Ventilation, The Standards Institution of Israel, 2011 (12) Yezioro A., E. Shaviv, A KB CAAD System for the Pre-Conceptual Design Of Bio-Climatic and Low Energy Buildings, Proceeding of CAAD Futures 97 Conference, 1997 (13) Balcomb J.D., Jones R. W., Kosiewicz C.E., Lazarus G.S., McFarland R. D., Wray W. A., Passive Solar Design Handbook. Vol. III, American Solar Energy Society, 1983 (14) Shaviv E., Design of Passive Solar Buildings, Lectures Notes, Faculty of Architecture & Town Planning, Technion, 1995 (15) Yezioro, A, I. G. Capeluto, T. Bleiberg, E. Shaviv, Regulations for Solar Rights in Urban Areas, Renewable Energy Yearly magazine, 2008 (16) Shaviv E., Appendix B of SI 5281(Normative): Solar Rights in Urban Design, The Standards Institution of Israel, 2011 (17) Capeluto I.G. and E. Shaviv, On the Use of Solar Volume for Determining the Urban Fabric, Solar Energy, Vol. 70, No. 3, Elsevier Science Ltd., 2001 (18) Shaviv E., Capeluto G., Yezioro A., Sun and Winds in a New Business District in Tel Aviv, Proceeding of IBPSA - Building Simulation Conference, 2001 (19) Yezioro A., Shaviv E., SHADING: A Design tool for Analyzing Mutual Shading Between Buildings. Solar Energy. Vol. 52, No. 1, Pergamom Press Ltd., USA, (20) SI 1045, Thermal Insulation of Buildings, The Standards Institution of Israel, 2011 (21) Yezioro A., Shapir O., and Capeluto, G., A Simple User Interface for Energy Rating of Buildings. Proceeding of IBPSA - Building Simulation Conference, 2011 (22) Shaviv E., A. Yezioro, I. G. Capeluto, Energy Code for Office Buildings in Israel, Renewable Energy, Vol 33/1, Elsevier Science Ltd., GB, (23) Shaviv E., Shaviv G., Designing of Buildings for Minimal Energy Consumption. CAD Journal, Vol. 10, 1978 (24) Shaviv E., The Integration of Passive Cooling, Heating and Daylighting in the Design of an Intelligent Energy Conscious Building Design, Proceeding of EuroSun 98, the 2nd ISES-Europe Solar Congress,