Comparing LEED certified and Conventional Schools ...

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Comparing LEED certified and Conventional Schools in Houston, Texas, USA: Environmental Performance TANVI DHAR1, IHAB ELZEYADI1 1

University of Oregon, Eugene, USA.

ABSTRACT: LEEDTM for schools was introduced in response to research that showed the influence of classroom environment on energy savings and students’ performance. There is however a need to investigate the relationship between credits achieved by the LEEDTM for schools rating system and its impact on building performance. This study quantifies and analyses resource consumption of two LEEDTM certified elementary schools in Houston, Texas by comparing them to their conventional counterparts. Year-long metered data for 2015 was analysed for resource consumption. Both LEEDTM schools had greater energy savings compared to their conventional counterparts but the water consumption savings varied by each school. Also, the LEEDTM Gold School didn’t exhibit higher energy and water consumption savings than the LEEDTM Silver School. Keywords: energy consumption, EUI, LEEDTM credits, BELSTM, elementary schools.

INTRODUCTION Currently out of 129,189 K-12 schools, over 3000 are LEEDTM certified (Census 2015; USGBC, 2015). The United States Green Building Council’s (USGBC) Center for Green schools claims that LEEDTM schools use 33% less energy and 32% less water than their conventional counterparts (USGBC, 2015). Previous studies, such as Benchmarking and Evaluation for LEEDTM Schools (BELSTM) (Elzeyadi, 2012) have investigated these metrics with post occupancy evaluations, for LEEDTM schools in the Pacific Northwest and in California schools (Elzeyadi, 2015), However, there’s a lack of replicating studies investigating similar issues in other geographical locations of the USA, and specifically in the southern climatic zone. Therefore, this study aims to expand on the case-study pool for the BELSTM project by investigating the environmental performance of schools in Houston, Texas. As a follow-up to previous BELSTM investigations, this study compares actual performance of two LEEDTM and two conventional schools from the same district with comparable student population, ethnicity and income group. Based on the BELSTM research framework, data on energy and water consumption were collected and analysed for the 2015 calendar year.

PROBLEM STATEMENT There are many green building rating systems in addition to LEEDTM which require rigorous evaluations, especially since they are blindly adopted by architects and clients without being informed about the proven

benefits on energy consumption, occupant health and building performance (Bosch et al., 2003). It is often stated that LEEDTM is used as a stamp for point chasing, where easily attainable points are achieved to get higher certification level instead of employing points for integrated design strategies that result in cost effective and high performing buildings (Eijadi, Vaidya, Reinsertsen & Kumar, 2002). Due to few Post Occupancy Evaluation (POE) studies of LEEDTM for schools certification system, there is a gap in knowledge about the performance and energy savings that LEEDTM schools have claimed to achieve. This study addressed this knowledge gap by assessing and comparing resource consumption and energy utilization of LEEDTM and conventional elementary schools in Houston, Texas. Moreover, schools may conform to the ideas of green rating systems but in practice may not perform to their full potential. These errors can only be corrected and brought out if POE studies address these issues and the results are verified and openly publicized (Meir, Garb, Jiao & Cicelsky, 2009). POE studies have the ability to clarify discrepancies, loopholes, and problems by measuring actual conditions of the existing building design. They can indicate problems in the design process (for the architect and related disciplines), the operation (for the occupant, user and building manager) or in the building as a system (Elzeyadi, 2012; Meir et al., 2009).

SIGNIFICANCE AND RESEARCH OBJECTIVE As per American Council for an Energy-Efficient Economy (ACEEE’s) state energy score card, Texas dropped eight positions in the nations least energy

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consuming states (ACEEE, 2015). In addition, Houston Independent School District (HISD) has the second largest number of LEEDTM registered schools across the nation (HISD, 2015). Therefore, replication of previous studies of LEEDTM schools’ performance assessments and verification in the state of Texas would guide further development of its green school program to catch-up with the green building movement. Moreover, for every new sustainable school being constructed, there are thousands of existing schools with plenty of life left in them. These schools have the potential to be far more energy and water efficient with comfortable learning spaces. Therefore, existing conventional school buildings were used for the comparison so as to add to the knowledge of future retrofit opportunities. HISD is the largest school district in Texas and the seventh-largest in the USA. It serves approximately 215,000 students at 283 campuses (HISD, 2015). This study aims to inform the HISD about the environmental performance of their existing schools (LEEDTM and conventional) so as to take informed decisions for future retrofit opportunities. Moreover, this study provides a framework for the HISD to perform similar studies on other schools’ campuses as well. In 2007, Governor Perry signed HB 3693 in Houston – an omnibus energy efficiency bill, which established energy efficiency provisions applicable to school districts and to certain institutions of higher education and executive branch state agencies, requiring them to establish a goal of reducing their annual electricity consumption by 5% for six consecutive years beginning September 1, 2007 (House Bill 3693, 2007). As a result of which, in 2007, Houston passed a green building policy that set a target of LEEDTM silver or higher certification for city owned and funded new construction and renovation. Therefore, this study will provide analysis on the impact of credits achieved by LEEDTM for schools on energy conservation. In addition, this study aims to replicate the BELSTM study for a subtropical climate so as to add to the POE case study pool for future amendments to the LEEDTM certification system.

RESEARCH METHODS The methodology and results presented in this paper were developed within the framework of the BELSTM extended research program which aims to quantify resource consumption impacts of LEEDTM credits achieved in elementary schools and compare it to nonLEED schools (Elzeyadi, 2013). This was achieved by using a comparative case study method where two LEEDTM schools were selected and compared with their conventional counterparts. The first step was the selection of schools which was based on rigorous

selection criteria. After the school selection process, a comparative case study analysis method was used, where data were collected for the LEEDTM and conventional schools. Archival Data: Information on utility bills for the 2015 calendar year and information on the number of students, grade level, project size etc. were collected offsite through the HISD sustainability office, HISD library and the official HISD website respectively. In addition, data were collected on the Environment and Energy and Water Conservation credits achieved by the LEEDTM certified schools from the USGBC website.

HYPOTHESIS There are two main hypothesis that the study tested: 1. Based on the credits achieved for Energy and Atmosphere, LEEDTM schools should outperform their comparatives in energy savings, showing a reduction in Energy Use Intensity (EUI) of 25% or more (Elzeyadi, 2015). 2. LEED schools with higher Water Conservation credits should have higher water consumption savings as compared to the non-LEED school.

LIMITATIONS While modifying the research framework of BELSTM for this study, following restrictions were imposed by the researcher: • As a geographical extension to the BELSTM study, Houston was selected as the case study location for a humid subtropical climate. • Considering the ease of availability of data and the maximum number of student population, elementary public schools were selected from the HISD. • BELSTM study was carried out for sixteen comparative pairs of LEEDTM and non-LEED schools for multiple seasons and classrooms. It studied multiple factors such as resource consumption, transportation, energy expenditure, health and performance of students in terms of LEEDTM credits achieved for K-12 schools (Elzeyadi, 2013). However, due to time constraints and the scope of this research, only two LEEDTM and two non-LEED schools are studied and compared for the summer season based on data collected on resource consumption. • As per the school selection process, LEEDTM for schools version 2007 was studied. • Occupant surveys and interviews were not a part of the POE method. • Metrics used to benchmark energy standards are based on the BELSTM study.


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The client (HISD) wasn’t able to provide the LEEDTM certification binder, construction drawings and the details on the Heating Ventilating and Air Conditioning (HVAC) system used. The researcher wasn’t able to establish contact with the project architects to understand the design intent or gather detailed drawings, and specifications.

EXISTING COMPARATIVE CASE STUDIES In 2007, USGBC launched LEEDTM for schools rating system to address issues such as classroom acoustics, master planning, mould prevention, and environmental site assessment (USGBC, 2007). By addressing the uniqueness of school spaces and children’s health issues, LEEDTM for schools aimed to provide a unique and comprehensive tool to build green with measureable results (USGBC, 2007). LEEDTM schools claim to be high performing buildings that are healthy for students, comfortable for teachers, and cost effective for clients (USGBC, 2007). This certification system has become a prominent feature for new construction and renovation for existing schools. Therefore, in order to assess its impact before the rapid replication it’s important to measure the impact of this rating system on buildings’ performance for future amendments. LEEDTM schools were chosen as a benchmark of “green buildings” for this research as they are designed on a set of guidelines which can be compared and evaluated across schools. The following sections describe the literature review undertaken to understand how LEEDTM schools compare to conventional schools, factors which need to be included in addition to energy cost savings for better user experience and the BELSTM study which the current study builds on. One of the major hypothesis for this research is that if scored correctly, LEEDTM certified buildings can be energy efficient and comfortable as compared to conventional buildings. The first step for this study was to review existing literature on post occupancy evaluations and performance studies that targeted schools and other buildings. Specifically, studies that have a comparative analysis between LEEDTM and conventional buildings. To assess how much energy is consumed by LEEDTM buildings USGBC commissioned the National Building Institute (NBI), to measure the post-occupancy energy performance of LEEDTM buildings against their commercial counterparts (Turner & Frankel, 2008). They used the Energy Use Index (EUI), the Energy Star Rating, and the actual measured performance versus modelled designed performance as the basis for comparison. The results indicated that the LEEDTM buildings were delivering the claimed savings, they showed average energy use of 25 to 30% better than the national average (Turner & Frankel, 2008).

To further assess this data, in 2009, Newsham analysed the same buildings and found that the LEEDTM buildings used 18-39% less energy per floor than their conventional counterparts (Newsham, Mancini & Benjamin, 2009). However, while assessing the same data for the building itself, LEEDTM buildings had a 2835% increase over the same period of time (Newsham et al., 2009). In addition, Newsham found that there was no direct correlation to the energy consumption and the LEEDTM certification level of these 100 buildings (Newsham et al., 2009). Moreover, in 2009, Scofield discounted previous finding on these LEEDTM buildings as he focused on source energy, which consist of energy used on site with site losses and generation and distribution (Scofield, 2009). This study found no energy savings for the LEEDTM buildings as compared to their commercial counterparts. Furthermore, in 2006, a study by Turner (2006) analysed the building performance by evaluating the postoccupancy data. She emphasized the importance of gathering utility data to compare and generate meaningful results. A comparison to the study done by Newsham on 21 LEEDTM and conventional office buildings in New York showed varied savings in terms of energy consumption. LEEDTM Gold buildings outperformed conventional buildings by 20% (Scofield, 2013). However, LEEDTM silver and lower certified buildings underperformed. The average Energy Performance Ratio for LEEDTM was 78 points i.e. 10 points higher than all other non-LEEDTM buildings (Scofield, 2013). All LEEDTM certified buildings performed 3% worse and LEEDTM silver and higher were 6% better than conventional buildings (Scofield, 20013). But neither of these differences are statistically significant. The study concluded by saying that LEEDTM certification is not moving the city of New York towards climate neutrality (Scofield, 2013).

BELSTM STUDY The BELSTM study reported on a comprehensive multiyear comparative study evaluating the performance of sixteen LEEDTM and non-LEED schools in the Pacific Northwest. The study employed a multiple methods approach to collect data on resource consumption, transportation, energy expenditure, and human impacts (Elzeyadi, 2013, 2015). The methods included a 12 month survey of actual building resource consumption (electricity, natural gas and water), geographic information systems analysis of transportation networks, transportation behavior audits and questionnaires, parent’s survey of children health records and behavior patterns and field observations of the neighborhood and classroom environments across the sixteen paired LEEDTM and non-LEED schools (Elzeyadi, 2013, 2015).


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The result of BELS study supported the hypothesis that LEEDTM schools outperformed the comparative non-LEED schools in terms of energy consumption and indoor comfort and students’ health. LEEDTM schools had a reduction in EUI between 25% to 60% compared to non-LEED schools (Elzeyadi, 2013, 2015). However, LEEDTM schools that achieved fewer energy and atmosphere credits performed similar to the non-LEED schools and sometimes underperformed (Elzeyadi, 2013, 2015). The study results support the continuous use and development of green design practices and certification system. Moreover, the study stresses on the fact that school districts need to implement practices and policies that support the design and operation of better schools for future generations (Elzeyadi, 2013, 2015).

SCHOOL SELECTION PROCESS The first step for the school selection process was to develop a data base for all LEEDTM silver and higher rated schools from the Houston Independent School District (HISD) (Fig. 1). These schools were classified in a matrix based on achieved certification date and level, year opened and achievements, project architect, project size, budget, school level, number of students, gender ratio, and ethnicity. This data were collected for schools certified till the year 2015 from the USGBC and HISD website. From this matrix, schools with the highest achievements for reduction in energy and water consumption were studied in greater detail. Another criteria was to choose schools which achieved the same certification version (For example LEEDTM for schools v2007). As per this criteria, Cunningham Elementary (LEEDTM Gold) and Patterson Elementary (LEEDTM Silver) were selected as the “green schools” for the comparative case study.

Figure 1: Google Map showing all LEEDTM silver or higher certified schools in Houston, Texas.

The next step was to create parameters to select the conventional schools. Based on comparable building form, orientation, proximity to LEEDTM School, number of students, school level, and ethnicity; McNamara Elementary and Bonner Elementary were chosen as

comparatives for Cunningham and Patterson Elementary respectively (Fig. 2).

Figure 2: District maps showing the proximity of the selected schools: Green box-LEEDTM schools, Black box – conventional schools.

DATA COLLECTION PROCESS As per the preliminary archival data collection, all the selected schools had a U-shape typology with the longer axis oriented along the east-west axis, providing maximum sun exposure to the north and south facades. The utility bills from the HISD sustainability office for the 2015 calendar year were collected and analysed for energy (electricity and gas) and water consumption. Energy Consumption: Energy Use Intensity (EUI) was used as a benchmark to compare the energy consumptions for the schools. The kilowatt hour (KWH) values for electricity and the hundred cubic feet (ccf) values for gas from the utility bills were converted to thousand British thermal units (kBtu), based on which EUI was calculated for each school. Environment Protection Agency’s (EPA) Target Finder was used for the corresponding median property and Architecture 2030 design challenge EUI values for comparison. Target Finder generates these results by accounting for building and operating characteristics, as well as 30-year weather data for the project site. This data is then compared to actual energy consumption of real buildings, as collected by nationally representative surveys such as Department of Energy’s (DOE) Commercial Building Energy Consumption Survey (CBECS). Based on information for the project location, gross floor area, year of construction completion, project type (K-12 school), number of buildings, and ENERGY STAR score of 90 on 100 for Architecture 2030 challenge, Target Finder calculated the base and target EUI values to compare with the actual achieved EUI by the each school. Water Consumption: The generic water consumption metrics established by the Federal Energy Management Program (FEMP) were used to analyse water consumption in each school. An assumed baseline was


interpolated that was based on the number of occupants and school facilities. Metrics assumed for the indoor water consumption baseline for each school with a cafeteria and gym was 10gals/student/day. Building off the baseline assumptions, the benchmark figures represent the performance established by the FEMP of 16% water reduction from the baseline as 8.4gals/student/day. To compare the water utility bills, the benchmark and baseline values were calculated for a year of school working days i.e. 175 days (HISD, 2015).

The calculated EUI from the utility bills met the claimed EUI value of the LEEDTM score card. In addition, it had a 40.68% decrease in the EUI as compared to its Bonner (conventional counterpart). Patterson needs a 23.35% reduction in EUI to meet the architecture 2030 challenge. McNamara Elementary had an increase of 0.57%, 38.32% and Bonner Elementary had an increase of 27.2%, 54.93% from the median property and Architecture 2030 challenge respectively (Table 1). Table 1: Percentage change in EUI for each school

FINDINGS Energy Consumption: Cunningham (LEEDTM Gold) had a total of 53.21 EUI with 3.57 kBtu/ft2 for gas and 49.64 kBtu/ft2 for electricity. The LEEDTM Gold School attained six points for Energy and Atmosphere credit. McNamara had a total of 65 EUI with 9.17 kBtu/ft2 for gas and 56 kBtu/ft2 for electricity. Patterson (LEEDTM Silver) had a total of 44.49 EUI with 1.55 kBtu/ft2 for gas and 42.94 kBtu/ft2 for electricity. The LEEDTM Silver School attained five points for Energy and Atmosphere credit. Bonner had a total of 75 EUI with 6 kBtu/ft2 for gas and 69 kBtu/ft2 for electricity (Fig. 2).

Water Consumption: Cunningham consumed 868 Tgals of water with 709 student population. McNamara consumed 844 Tgals of water with 789 student population. Patterson consumed 1,171 Tgals of water with 946 students. Lastly, Bonner consumed 1,600 Tgals of water with 992 students. All the schools had reduced water consumption compared to the baseline and benchmark, except Bonner, which had an increase in water consumption as compared to the benchmark (Fig. 4).

Figure 3: Energy consumption in EUI of each school v/s Energy & Atmosphere credits achieved.

Out of a possible seventeen Energy and Atmosphere points, LEEDTM gold certified, Cunningham achieved six points for Optimize Energy Performance (EAc1), Enhanced Commissioning (EAc3), Enhanced refrigerant management (EAc4) and Measurement and Verification (EAc5) credits. The LEEDTM score card for Cunningham claims to have a 20% reduction in energy consumption from the baseline. However, as per the utility bills calculation, it shows a 6.98% reduction. As compared to McNamara (conventional counterpart), Cunningham showed an 18.35% reduction in EUI. Cunningham needs a reduction in EUI of 33.28% to meet the Architecture 2030 challenge (Table 1). Patterson (LEEDTM Silver), achieved five points for Energy and Atmosphere credits on Optimize Energy Performance (EAc1), Enhanced Commissioning (EAc3) and Enhanced Refrigerant Management (EAc4) credits.

Figure 4: Water consumption of each school v/s Water Conservation credits achieved.

Out of a possible 7 points for Water Efficiency credit, Cunningham Elementary (LEEDTM Gold) achieved 2 points for Water Use Reduction (WEc3.1). The LEEDTM for schools guidelines claim that if this credit is achieved, the building should have a 20% decrease from the baseline. The LEEDTM score card values states that the measured reduction was 34% but as per the utility bills calculation, the actual reduction was 30%. As compared to its non-LEED counterpart (McNamara Elementary), Cunningham had a 2.76% increase in


water consumption. McNamara also had a 27.23% reduction in water consumption from the benchmark (Table 2). Table 2: Percentage change in water consumption savings.

Patterson Elementary (LEEDTM Silver) attained five points for Water Efficiency credit out of a possible 7 points by earning the Water Efficient Landscaping (WEc1.1), (WEc1.2) and Process Water Use Reduction (WEc4) credits. As per the LEEDTM for schools guidelines, by achieving these credits the building should have a 70% reduction in water consumption. The LEEDTM score card values indicate that the building has a 37% reduction, however, as calculated from the utility bills, the actual reduction in water consumption is 29.27%. Moreover, the percentage decrease in consumption as compared to the non-LEED school (Bonner Elementary) is 26.81%. Patterson also had a 15.79% reduction in water consumption as compared to the benchmark (Table 4). McNamara had a 38.87% and 27.23% decrease from the baseline and benchmark respectively. Bonner had a 7.83% decrease and an 8.86% increase from the baseline and benchmark respectively (Table 2).

CONCLUSIONS One of the important observations from this study has been that the conventional schools haven’t paid much attention to energy efficiency. Therefore, in order to achieve better building performance, reduction in energy consumption in the existing buildings should be the main criteria for future retrofits. The study results partially prove both the hypothesis. Both the LEEDTM schools performed better in terms of energy consumption based on the Energy and Atmosphere credits achieved. Following the BELSTM study results, Patterson Elementary (LEEDTM Silver) had a EUI reduction above 25% as compared to its conventional counterpart. However, even though Cunningham Elementary (LEEDTM Gold) achieved higher Energy and Atmosphere credits as compared to Patterson Elementary, the EUI reduction compared to its comparative conventional school was less than 25%.

Patterson Elementary achieved seven points for water consumption and thus performed better than its conventional counterpart and the LEEDTM gold school. Cunningham elementary only attained two points for water consumption and underperformed compared to its conventional counterpart. Thus, achieving LEEDTM credits does not always impact the actual building performance. Attention should be given on the performance of the LEEDTM credit achieved. In addition, it can be concluded that higher LEEDTM rating doesn’t necessarily mean better building performance in terms of environmental impact. Even though Cunningham Elementary had a higher rating, its environmental impact was higher than the LEEDTM Silver School (Patterson Elementary) and comparable to its conventional counterpart in terms of water consumption.

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