EVALUATION OF THE SEATTLE ENERGY CODEIS MAJOR PROJECTS REQUIREMENT FOR NEW COMMERCIAL BUILOINGS Bri an Coates and Davi d Sumi Seattle City Light

Transcription

1 EVALUATION OF THE SEATTLE ENERGY CODEIS MAJOR PROJECTS REQUIREMENT FOR NEW COMMERCIAL BUILOINGS Bri an Coates and Davi d Sumi Seattle City Light ABSTRACT An evaluation was conducted on the Seattle Energy Codels Major Projects Requirement. Under this Requirement, designers must demonstrate with computer simulations that, as a result of conservation measures, the projected energy consumption for the proposed building is 10 percent less than the consumption for a standard building. It was found, first, that commercial buildings can be designed to exceed the energy savings requirement. The average projected savings for the 13 buildings were 6.09 kwh/sq. ft./year (20,785 Btu/sq. ft./year), a percent savings when compared to the standard building. Second, only a portion of these savings can be attributed to the Requirement. About three-fifths of the designers said that the conservation measures were in response to the Requirement. Third, the projected energy savings were obtained without the designers being compelled to use highly innovative conservation strategies. Instead, off-the-she lf. conservation measures were used to comply with the Requirement. In interviews 61 designers assessed these measures as only somewhat innovative

2 " INTRODUCTION EVALUATION OF THE SEATTLE ENERGY CODEIS MAJOR PROJECTS REQUIREMENT FOR NEW COMMERCIAL BUILDINGS Brian Coates and David Sumi Seattle City Light The purpose of the Seattle Energy Code, which was enacted by the Seattle City Council on August 20, 1979, is to promote energy efficiency in buildings (City of Seattle, 1986). This efficiency is facilitated through the City of Seattlels regulation of the building envelope design and the design 'and selection of the buildingis mechanical, electrical, and water heating systems. The Code, which is based on the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 90-80, applies to all new or remodeled buildings which are served by electricalor nonelectrical fuels. With two exceptions, the commercial requirements of the Seattle Energy Code are similar to the regional Model Conservation Standards (Northwest Power Planning Council, 1987). First, several of the lighting power budgets in the Seattle Energy Code differ slightly from the budgets in the Model Conservation Standards. Overall, the Code is slightly less stringent than the Model Conservation Standards on lighting power budgets. Seéond, the Seattle Energy Code has a Major Project Requirement for construction projects which exceed 50,000 square feet of conditioned space. These requirements, which took effect in April, 1984, are not in the Model Conservation Standards. Under the Major Projects Requirement, designers are to conduct an energy consumption analysis during the building permit process. In this analysis the designer has to demonstrate with computer simulations that the projected energy consumption for the proposed building is 10 percent less than the 'consumption for a standard building. The energy savings for the proposed building occur as a result of the application of conservation measures to the computer simulation of the energy consumption in the standard building. The building of standard design is one that just meets the prescriptive requirements of the Seattle Energy Code (City of Seattle, 1984a). The primary purpose of this evaluation was to assess the impact of the Major Projects Requirement on both the design strategies and projected energy consumption for 13 buildings proposed under the Requirement. These buildings, which included 10 office buildings and 3 other buildings, were the initial 13 commercial building projects that complied with the Requirement. Theevaluation had three specific objectives. The first was to determine which building design features were changed in order to comply with the Major Projects Requirement. Conservation strategies which were identified for the projects and that received credit toward the 10 percent savings could be attributed to the Requirement or to other factors. To determine the extent to which the strategies are a consequence of the amended Seattle Energy Code, Major Projects Requirement designers were interviewed and asked: "Which of 5.47

3 the energy efficient design strategies (in the building) were included in response to the Major Projects Requirement?" A second objective of the evaluation was to assess the impact of the Major Projects Requirement on the innovativeness of design strategies adopted for the 13 buildings. The reason for assessing design innovation in this evaluation is as follows. At the time that the Major Projects Requirement was adopted, it was unclear whether it would be difficult for designers to meet the Requirement. If designers had difficulty in meeting the Requirement, then they would have to use innovative design strategies to meet the Requirement. On the other hand, i f it was rel at i ve 1 y easy to meet the Requ i rement, then designers could use off-the-shelf conservation technologies to meet the Requirement. To address the question of innovation, two groups of designers, Major Projects Requirement designers in Seattle and non-major Projects Requirement designers in Seattle and Portland, Oregon, were asked to assess two dimensions of the i nnovat i on concept. These two dimensions were: (1) frequency of the design communities' use of the proposed conservation strategies in similar buildings; and (2) an assessment on a 0-10 scale of the overall innovativeness of the package of conservation strategies used in a project. The final objective of the evaluation was t~ provide information on the projected/actual energy consumption for the bui ldings constructed under the Major Projects Requirement. Since many of the building projects that complied with the Requirement are still under construction or only recently completed, an evaluation based on actual energy consumption in the buildings cannot be done until a later time. Instead, descriptive information is presented from computer simulations on the projected energy consumption in the standard and proposed buildings, and on the projected energy savings that result from the application of conservation measures to the standard building. METHOD This section covers the methods used to obtain information on the characteristics of the Major Projects Requirement buildings, the conservation strategies used by designers to meet the requirements, and the projected energy savings for these strategies. Building Characteristics The energy ana lys i s report prepared by the des i gner was the primary source of information on the characteristics of Major Project Requirement buildings. Data were collected from these reports on the building type for the projects that complied with the requirement; square footage for these buildings; fuel sources for heating, cool ing, and hot water; and number of stories. 5.48

4 Conservation Strategies In the energy analysis reports designers presented the conservation strategies for meeting the Major Projects Requirement's 10 percent energy savings requirement. Information on these strategies was obtained from the report and organized into eight strategy categories. These categories were: glazing; walls, roof, and floors; interior lighting; exterior lighting for covered garages; heating and cool ing systems; fan systems; heat recovery systems; and garage vent il ation. The conservation strategies information was used to answer two of the major questions in the evaluation. The first question was whether designers changed the design features of the building in order to comply with the Major Projects Requirement. This question was answered by interviewing 31 designers (architects, mechanical engineers, and electrical engineers) of Major Projects Requirement buildings. These designers were asked: "Did the Major Projects Amendment 10 percent requirement make a difference in the way this project was designed?" and "Which of the energy efficient design strategies were included in response to the Major Projects Amendment?" The second question was whether the Major Projects Requirement design strategies are innovative. The evaluation design called for the 31 Major Projects Requirement designers and 30 non-major Projects Requirement designers in Seattle and Portland, Oregon, to each review three Major Projects Requirement projects on the innovativeness of the project's conservation strategies. To ensure that the project assessments were balanced between the Major Projects Requirement and non-major Projects Requirement designer groups, the 183 project assessments, minus 38 assessments done on projects by project designers, were randomly allocated across all 61 designers. Also, the order of presentation of the three projects to the interviewee was randomly determined. As descri bed earl ier, the des i gners assessed two aspects of i nnovat i on for each project. These were: (1) the frequency (very frequent, of ten, occasionally, never) with which designers and firms in their metropolitan area used the conservation strategies proposed to comply with the Major Projects Requirement; and (2) the designer's opinion on whether the package of conservation strategies for the project was innovative. Projected Energy Savings Under the Major Projects Requirement the designer was obliged to demonstrate with hourly computer simulations that the projected energy consumption for the proposed building was 10 percent less than the consumption for a standard building. The standard building was a buildihg that just met the prescriptive requirements for commercial buildings in the Seattle Energy Code. Data on projected energy consumption in the standard and proposed buildings were collected from the- computer simulations in the designers' energy analysis reports

5 RESULTS Building Characteristics Since all new construction in Seattle with more than 50,000 square feet of conditioned space must comply with the Requirement, the projects are large with the gross square footage ranging from 50,000 to 952,000 square feet (medi an gross square footage = 147,000 square feet). The conditioned square footage for the 13 projects ranges from 50,000 to 862,000 square feet (median conditioned square footage = 106,000 square feet). In addition, the median number of stories in the buildings is 12 stories with a range of 2 to 41 stories. The Seattle Energy Code regulates energy efficiency in buildings that use electricalor non-electrical fuels. Eight of the thirteen projects use el ectri c i ty for both space heat i ng and hot water. Space heat i ng for the remaining five projects is accomplished with purchased steam in two projects, a combination of electricity and natural gas in two projects, and natural gas in one project. Hot water for these projects is from purchased steam in two projects, electricity in two projects, and natural gas in one project. Cooling for all buildings was from electricity. Many of the 13 building projects had multiple uses. Three of the ten office buildings had specialized uses, including a medicallaboratory, residential apartments, and space for telephone equipment. Four other office buildings had retail space. The three "other" buildings consisted of a convention center, bus maintenance facility, and a television station. Conservation Strategies Table I presents data on the bui 1 di ng envelope conservation strategies used by designers to meet the Major Projects Requirement's 10 percent energy savings requirement. As shown in this table, the 13 buildings had lower glazing U-values and shading coefficients then those required in the Seattle Energy Code. In addition, for other buildings the average amount of glass was 16 percent of the exterior wall, well below the Seattle Energy Code maximum of 40 percent. Double glazing was used in most of the office and other buildings with extensive use of tinted and thermal break windows. Table I also shows that the U-values for walls, roof, and floors in eight office and three other buildings were lower than the U-values in the Seattle Energy Code. The me an U-values were somewhat lower for the other buildings than for the office buildings. The Seattle Energy Code requirement for interior lighting is given in the lighting power budget, which is the watts of electrical power devoted to illumination of conditioned space (watts/sq.ft.). All but two of the office and other buildings earned energy savings credit toward the Major Projects Requirement on the basis of the proposed lighting budget "...

6 '. COATES AND SUMI Table I. Mean values for building envelope conservation strategies. U-Value Glazing Glazing as Shading % of Type of Building Glazing Wall Roof Floor Coefficient Wall Area 1984 Seattle Energy Code, ~ 3 stories % 1984 Seattle Energy Code, > 3 stories % Office (N=10) % Other (N=3) % Note: The U-value and shading coefficient are measures, respectively, of the insulating value of building materials and the solar heat gain for a buildingis windows and doors~ The lower the value for these measures, the better the insulation value or the buildïngls resistance to heat gaine The 1984 Seattle Energy Code specified a maximum of 2.0 watts/sq. ft. for office space. The average power budget for office space across 11 Major Projects Requirement buildings was 1.73 watts/sq.ft. For retail spaces, the power budget values tended to match the Code requirements which vary by the square footage of the retail space. The average for all retail spaces in the office and other buildings was 3.30 watts/sq.ft. Five of the thirteen projects received credit for exterior lighting strategies. In each case the lighting was for covered garages with the average per building being 0.20 watts/sq.ft. compared to the Code maximum of 0.30 watts/sq.ft. Table II presents a comparison of the efficiency of the heating, ventilating, and air conditioning systems in the 13 buildings with the Seattle Energy Code requirements. As shown in the table, the ten office and three other buildings exceeded the code values for heating and cool ing efficiency. Eight office and two other buildings also exceeded the code values for air transport factor, a measure of fan motor efficiency. For 7 of the 13 buildings these efficiencies in the heating, ventilating, and air conditioning system were achieved through a variable air volume system with reheat. Four buildings also had heat recovery systems. 5.51

7 Table II. Mean values for heating, ventilating, and air conditioning conservation strategies. Type of Building Heating Efficiency % Cool ing Coefficient of Performance Air Transport Factor 1984 Seattle Energy Code Value 96% Office (N=10) 194% Other (N=3) 133% Note: Air transport factor is the ratio of the rate of heat removal from a conditioned space to the energy input for the fan motors. More efficient fan equipment has a higher air transport factor. An important objective of the evaluation was' to determine which design strategies were changed in order to comply with the Major Projects Requirement. In response to the question, "Did the Major Projects Amendment make a difference in the way this project was designed?," designers representing half of the office projects and all of the other projects said "yes." Those designers who said that the Requirement made a difference provided information on which design strategies changed in response to the Requirement. These data are presented in Table III. Table III. Number of design strategies changed in response to the Major Projects Requirement. Type of Building Glazing Building Envelope Interi or Lighting Exterior Garage Lighting HVAC Fans Ventilation Office Other 3 o o o 3 1 Total

8 ". COATES AND SUMI A comparison of the strategy data in Table III with the strategies proposed toward compliance reveals an emphasis on garage ventilation and interior and exterior lighting as tho se strategies most affected by the Major Projects Requirement. For the eight projects indicating that the Requirement had an effect on the design strategies, designers said that lighting and garage ventilation were changed in response to the Requirement in nearly every case where these strategies were proposed toward compliance. Building envelope measures were also likely to have been changed in response to the Major Projects Requirement. Less 1 i kely to change were strategies with the fan and heating, ventilating, and air conditioning systems. A major question in this study was whether the conservation strategies used by designers to comply with the Major Projects Requirement were innovative. This question was answered through interviews with Major Projects Requirement designers and non-major Projects Requirement designers in Seattle and Portland, Oregon. Table IV shows the mean innovation score for the three groups by the office and other sectors. -Analysis of variance revealed that the differences between the three designer groups in their innovation scores were not statistically significant. In addition, the higher innovation scores for other projects than for office projects was not statistically reliable. Overall, the mean innovation score for all of the designer assessments on the 10 point scale (zero being not innovative and 10 being highly innovative) was 4.6. Table IV. Mean innovations scores. Non-MPR Non-MPR Type of MPR Designers Designers Buil di ng Designers (Seattle) (Portland) Office (N=59) (N=36) (N=20) Other (N=15) (N=9) (N=5) Note: Thirty-nine assessments were also done on the innovativeness of the conservation strategies used in five apartment projects to comply with the Major Projects Requirement. The results for these assessments are presented in Coates and Sumi (1987). 5.53

9 Designers were also asked in the interviews to provide information on the frequency Qf use for strategies proposed to comply with the Major Projects Requirement. In general, these data support the finding from the innovation score ratings that the conservation strategies used to comply with the Major Projects Requirement were only moderately innovative. Strategies which \'Iere seen of ten or frequently by the designers, and thus would be interpreted as not innovative, were in glazing, building envelope, interior lighting, and fans. Strategies which were seen only occasionally or at most of ten, and thus would be somewhat innovative, were in exterior lighting, heat recovery, garage ventilation, and the heating, ventilating, and air conditioning system. In one part of the interviews, designers were asked how satisfied they were with the Major Projects Requirement. It was found that more than two-thirds of the designers were very or somewhat dissatisfied with the required meetings with City of Seattle staff and with the computer simulations of energy consumption in the proposed and standard bui lding. On the other hand, three-fifths of the designers were very or somewhat satisfied with the required energy analysis report (Coates and Sumi, 1987). Projected Energy Savings Table V presents the projected energy consumption in the standard and proposed buildings for the office and other sectors. The average projected consumption for the standard building in the office sector is kwh/sq. ft./year (65,018 Btu/sq. ft./year). This consumption is consistent with the actual consumption for 14 current practice office buildings in the Pacific Northwest (Northwest Power Planning Council, 1986). Table V. Mean number of projected kilowatt-hours/square foot/year for Major ProJects Requirement Buildings. Type of % Energy Buil di ng Standard Proposed Energy Savings Savings Office % (65,018) (52,936) 02,082) Other % (189,933 ) (140,206 ) (49,727) Note: The numbers in parentheses are projected energy savings Btus/sq. ft./year. in 5.54

10 .. COATES AND SUMI Table V also presents the projected energy savings for the office and other sectors. These savings occur because the designer is required to apply a set of conservation measures to the computer simul ation of the standard buildingis energy consumption. Each designer met the Major Projects Requirement's minimum requirement of a 10 percent savings. The median percentage savings for the 13 projects was 18 percent with 10 of the 13 projects having energy savings between 10 and 20 percent. Three projects had energy savings that exceeded 25 percent. The average projected energy savings for the 13 projects was 6.09 kwh/sq. ft./year (20,785 Stu/sq. ft./year), with the savings ranging from 1.33 kwh/sq. ft./year (4,539 Stu/sq. ft./year) to kwh/sq. ft./year (115,155 Stu/sq. ft./year). More than 98 percent of the savings were achieved in three end-uses: interior lighting (15 percent), space heating (64 percent), and fans (19 percent). There were almost no savings in exterior lighting, space cool ing, water heating, miscellaneous, and other. In complying with the Major Projects Requirement, designers incurred costs for the computer simulations of the projected energy consumption in the proposed and standard building, preparation of a written report summarizing the results of these simulations, and meeting with City of Seattle staff to discuss the simulations. Although designers did not have cost information that was subdivided by, for example, computer simulation costs, it was possible to obtain estimates of total compliance costs for all projects. These costs for the 13 projects ranged from $3,500-to $52,500 with a median cost of $11,500. The developers also incurred costs for the design of the conservation measures that were used to meet the Major Projects Requirement's 10 percent energy savings rule and the capital and installation costs for these measures. These costs for the conservation measures were not available for this paper. DISCUSSION It was found in this evaluation that commercial buildings in Seattle can be designed to exceed the Major Projects Requirement IS 10 percent energy savings requirement. These savings were achieved both for office and other buildings. The average projected savings for the 10 office buildings were 3.54 kilowatt-hours/square foot/year (12,082 Stu/sq. ft./year), an percent savings when compared to the energy consumption in the standard bui 1 di ngs. The average projected savi ngs for th ree other bui 1 di ngs were kwh/sq. ft./year (49,727 Stu/sq. ft./year), a percent savings. These projected energy savings resulted from designers receiving credit toward meeting the 10 percent savings requirement for two types of measures: measures that were already in the building design prior to their complying with the Requirement and measures that were specifically in response to the Requirement. Since many of the measures were already in the building design, designers stated in the interviews.that only a portion of the measures could be attributed to the Major Projects Requirement. For the designers, the measures that were most affected by the Requirement were for interior and exterior lighting and garage ventilation. 5.55

11 The savings for the buildings were obtained without the designers being compelled to use highly innovative conservation strategies. Interviews with Major Projects Requirement and non-major Projects Requirement designers revealed that the strategies used to meet the Requirement were only somewhat innovative. On a lo-point scale, with zero being not innovative and 10 being highly innovative, the average designer ratings for office and other projects was 4.6. Instead of using highly innovative conservation strategies, designers were able to comply with the Major Projects Requirement with off-the-shelf conservation technologies. These strategies included double glazing; improved shading coefficients for the glazing; fluorescent lighting (e.g., 3 tube parabolic with efficient ballasts and tubes) for producing lighting power budgets in office space that averaged 1.73 watts/square foot; using fanpowered variable air volume or hydronic heat pumps for the heating, ventilating, and air conditioning system; and carbon monoxide sensors for garage ventilation. Although limited in number, there are instances of innovative conservation strategies being used to meet the Major Projects Requirement. For example, designers assessed the package of conservation strategies for two buildings as above six on the 10 point innovativeness scale. In one building, which has offices and telephone equipment, the assessment was based in part on the heat recovery system with centrifugal and reciprocating chillers. In a second building, a maintenance and operation building for a bus system, a heat recovery wheel was used to transfer interior heat to the supply air in winter and dehumidify this air in summer. The energy savings presented in this paper are projections based on hcurly computer simulations of the energy consumption in the standard and proposed buildings. Since it is of considerable value to determine what the actual energy savings are for Major Projects Requirement buildings (Wagner, 1984), Seattle City Light is currently engaged in a study of the energy savings for the buildings. In this analysis energy consumption in Major Projects Requirement buildings will be compared with the energy consumption in buildings outside Seattle which are not affected by the Requirement. 5.56

12 REFERENCES City of Seattle, Department of Construction and Land Use, 1984a. Design Building for Energy Code Analysis, February. Seattle. City of Seattle, Department of Construction and Land Use, 1984b. Energy Code, April. Seattle. City of Seattle, Department of Construction and Land Use, Energy Code, October. Seattle. Standard Seattle 1986 Seattle Coates, B. and D. Sumi, Evaluation of the Seattle Energy Codels Major Projects Amendment. In Major Projects Requirement Report. Seattle: Seattle City Light. Northwest Power Planning Council, Power Plan. Vol. 2. Portland. Northwest Conservation and Electric Northwest Power Planning Council, History and Status of Energy Conservation Standards for New Commercial Buildings in the Northwest. Portland. Wagner, B.S. Comparisons of Predicted and Measured Energy Use in Occupied Buildings. ASHRAE Transactions, 1984, V. 90, Pt