2013 California Building Energy Efficiency Standards Architectural Energy Corporation, March 7, 2011

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1 Measure Information Template DRAFT Nonresidential Fenestration Requirements 2013 California Building Energy Efficiency Standards Architectural Energy Corporation, March 7, 2011 CONTENTS 1. Purpose Overview Methodology Definitions Research Product selection Product combination research Alternative generation Alternative properties Product cost collection Product cost synthesis Alternative cost Alternative modeling subset Modeling parameter generation Energy model Curve fit research Curve fit trials Life-cycle cost Cost-effectiveness Proposed new VT requirement Code simplification Analysis and Results Methodology research Product selection and cost research Product combination selection Alternative modeling subset Curve fit Cost-effectiveness Proposed new VT requirement Code simplification Recommended Language for the Standards Document, ACM Manuals, and the Reference Appendices Table 143-A Table 143-B Table 146-C Nonresidential Alternative Calculation Manual Approval Method Bibliography and Other Research Appendices... 18

2 Nonresidential Fenestration Requirements Page 2 FIGURES Figure 4-1 Products Considered in the Analysis and Their Costs Figure 4-2 Description of Window Alternatives in the Modeling Subset Figure 4-3 Window Cost-effectiveness Results Figure 5-1 Table 143-A Proposed Update... 16

3 Nonresidential Fenestration Requirements Page 3 1. Purpose Fenestration requirements in Title 24 were last updated in the 2001 Standards. Significant changes in pricing and technology have occurred since then allowing for an update to the Standards. In addition, the effect of solar angle of incidence was considered for accuracy. This document presents the work done towards incorporating these criteria and proposed changes to the Standard.

4 Nonresidential Fenestration Requirements Page 4 2. Overview Complete the following table, providing responses for each category of information. a. Measure Nonresidential Fenestration Requirements Title b. The proposed update would change the required NFRC performance ratings for Description nonresidential buildings.

5 Nonresidential Fenestration Requirements Page 5 3. Methodology This section describes the research, tools and steps taken to determine the non-residential fenestration requirements. The basic approach was to determine the life-cycle cost of all fenestration alternatives applicable to California nonresidential construction, then to use the NFRC performance parameters of cost-effective fenestration to update the fenestration requirements for the 2013 Standard. Notable goals within this structure were the use of: EnergyPlus for more accurate simulations The Component Modeling Approach Software Tool (CMAST) to attain consistency between the Standard and NFRC ratings Window6 data files to include angle of incidence in the analysis 3.1 Definitions product category A generic title for products of similar purpose and characteristic (e.g. Nonmetal spacers) fenestration alternative A unique, complete fenestration assembly including frame, lites, gas and spacers as applicable. fenestration ratio The ratio of window area to wall area or skylight area to roof area. performance parameters the NFRC rated U-factor, SHGC and VT for fenestration. 3.2 Research Interviews Codes and Standards developers, window manufacturers and fabricators, window product manufacturers, window trade organizations and energy and environmental technical experts were interviewed to determine: Developments in the fenestration industry since the previous fenestration code update. Market studies, research reports or other pertinent resources that they recommend Their opinion on what would be important considerations for this study Whether they would like to be considered a stakeholder in the process or whether they recommend another resource for this role Who the major companies in the industry were Literature review The previous fenestration code and its associated reports, other fenestration codes and online resources of current technology were reviewed. Market studies Reports on the nonresidential fenestration market were studied. 3.3 Product selection To select applicable products, the below criteria were considered. Note that although a product may not have been considered in the analysis to determine cost-effectiveness for this analysis that does not imply that the product cannot be used to meet the Standard. It only implies that it was not used in the analysis to determine cost-effective fenestration. Market place availability Reliability Verifiability of performance data State and local building code compliance Applicability to all nonresidential construction

6 Nonresidential Fenestration Requirements Page 6 Performance versus cost comparison If a product was more expensive and lower performing than another product in the same product category, it was not selected. Visibility: Fenestration must be transparent and have a visible transmittance greater than 30%. Extreme conditions test Life-cycle cost of certain products were determined in climate zones 14 and 16 at the maximum fenestration ratio only. They were compared to the next, lower costing product in the same product category (e.g. Krypton compared to Argon). If the lifecycle cost was higher, no further analysis was performed. 3.4 Product combination research Research was conducted to determine which products were not compatible with other products and therefore should not be included in combinations together to form a fenestration alternative. 3.5 Alternative generation Using an indexing algorithm a list of all possible fenestration alternatives was generated considering the above product and product combination selection criteria. 3.6 Alternative properties So as to create consistency between T and NFRC ratings, CMAST was used to generate the performance parameters for all fenestration alternatives. CMAST contains a database of fenestration products. However, not all products needed for the analysis are in the database. Therm6 was used to create the needed products and then imported into CMAST. Once these were created the performance parameters for all fenestration alternatives were determined. 3.7 Product cost collection A cost survey was used to collect the data. The survey was structured such that a complete baseline fenestration alternative was presented to the surveyee. Then the surveyee was requested to provide the cost premium for simple swaps of one product for another, for example, swapping the baseline aluminum frame for a poured and debridged thermally broken aluminum frame. 85% of the data was obtained window manufacturers. The remaining data was collected from product manufacturers and glazing contractors. Note that initially an online survey of over 300 glazing contractors was conducted but the response was less than 1%. Surveys were able to obtain at least three cost data points per product category for 90% of the products. The remaining products were of low cost consequence to the overall fenestration alternative cost. 3.8 Product cost synthesis Costs were adjusted according to the following schedule: 35% profit: product manufacturer to glazing contractor 20% markup: glazing contractor to general contractor 10% markup: general contractor to owner Non-California data adjusted for California using RS Means.

7 Nonresidential Fenestration Requirements Page 7 Median costs were calculated for each product category for use in the life-cycle cost analysis. Median costs typically represent a real price and are better with outliers (e.g. special pricing structures). The median costs did not differ significantly from the average cost. 3.9 Alternative cost A simple cost model was used. The fenestration alternative cost was calculated as the sum of the products costs used in that alternative Alternative modeling subset From the Section 3.6 Alternative properties the minimum and maximum performance parameters of all fenestration alternatives were calculated. Then evenly distributed intervals were calculated within the range of a performance parameter. Fenestration alternatives were selected for the modeling subset if one of their performance parameters was the closest to one of the intervals. For example, if an SHGC interval were to be at 0.30, then the fenestration alternative that fell closest to 0.3 would be selected. CMAST was then used on these modeling subset alternatives to create Window6 files so that the analysis would take angle of incidence into account. NOTE: For the preliminary analysis presented here only the following products were considered: Layers: single- and double-pane Substrate: clear, standard or high-performance tints. Coatings: 2nd surface only Frames: Single-pane: aluminum with and without thermal break. Double-pane: aluminum with thermal break Spacers: aluminum, stainless steel (done before eliminated) and non-metal Gases: air and argon 3.11 Modeling parameter generation Using an indexing algorithm a list was generated comprised of all fenestration alternatives in all climate zones at fenestration ratios from 0 40% at 10% intervals Energy model An attempt was made to be consistent with the previous fenestration code update, but to incorporate EnergyPlus, CMAST NFRC ratings, Window6 data files and other pertinent changes in the code since the previous fenestration code update. The output of the model was annual TDV energy use. The basic inputs are given here: Software: EnergyPlus Environment Weather and TDV Updated weather and TDV developed outside this analysis Design days From the EnergyPlus website for California climate zones. NOTE: For the preliminary analysis presented here, only 5 representative climate zones were modeled: CZ03, CZ07, CZ12, CZ14 and CZ16. Envelope 130 X 130, single-story, Title minimally compliant steel-frame exterior walls, adiabatic roof and floor, directly facing the cardinal directions.

8 Nonresidential Fenestration Requirements Page 8 4 X 5 windows per NFRC 100. The model used Window6 data files to consider angle of incidence in the analysis. Fenestration parametrics As defined in section 3.11 Modeling parameter generation. Zones 4, 15 deep perimeter zones and a 100 X 100 core zone. Occupancy Loads T office minimally compliant lighting, equipment and outside air. Automatic daylighting controls were included for the primary and secondary daylit zones. NOTE: For the preliminary analysis presented here high-rise residential loads were not modeled although they will be for the final analysis. Schedules T Nonresidential. NOTE: For the preliminary analysis presented here, the high-rise residential schedule was not modeled although it will be for the final analysis. Systems T Nonresidential ACM compliant System Curve fit research Once the results from the energy model were assembled, curve fit research was conducted so that the fenestration alternatives could be analyzed outside the time-consuming task of energy modeling. Note that if every alternative had been analyzed via the energy model it is estimated that computer run time would be on the order of 6 months. The research for determining the structure of the curve fit included the following: Previous fenestration code update The curve fit used in the previous fenestration code update was applied to the results with some success, but errors were outside preferred tolerances. Data inspection The data was inspected to look for patterns that corresponded to changes in window performance parameters. Physical laws The physics of the effects of changes in the window performance parameters was analyzed to gain insight as to possible forms for the curve fit. This included a study of physical analogies such as decay phenomenon Curve fit trials Using the information from section 3.13 Curve fit research, several curve fit structures were tested and optimized using an iterative procedure on the parameters of the curve fits to minimize their discrepancies with the energy model. The optimal curve fit resembled the previous fenestration code update s curve fit, but with the addition of exponents to performance parameters and fenestration ratios. The details are given in the Analysis and Results section Life-cycle cost The life-cycle cost of a particular fenestration alternative was calculated as the sum of the fenestration alternative cost and annual energy cost as follows Fenestration alternative cost As described in section 3.9 Alternative cost. Annual energy cost The annual TDV energy use multiplied by the 30-year nonresidential cost per TDV as determined outside this analysis Cost-effectiveness All fenestration alternatives that have a lower life-cycle cost than the previous code requirements are considered cost-effective. Typically the minimum life-cycle cost alternative is chosen as the

9 Nonresidential Fenestration Requirements Page 9 alternative to determine the updated fenestration requirements. However, this may be modified for code simplification if it respects the constraints of cost-effectiveness Proposed new VT requirement A new VT requirement will be analyzed for the update to the Standard. Given that high-performance sputter coatings are proving to be cost-effective, it may not be sufficient to only specify SHGC as with previous code cycles. The daylighting benefit brought about by the VT may also be included in the requirements. Otherwise, dark windows, which could meet a stand-alone SHGC requirement, would lose lighting energy savings in comparison to the higher VT sputter-coated fenestration Code simplification In addition to the cost-effectiveness consideration there is the move toward simplification of the Standards. In the interest of code simplification, if a reduced set of requirements was found to be cost-effective it would be included in the code. Possible code simplification could include: A single SHGC and VT for all fenestration ratios up to the maximum fenestration ratio A single U-factor, SHGC and VT for all climate zones A single SHGC and VT for all orientations

10 Nonresidential Fenestration Requirements Page Analysis and Results This section presents the analysis and results from the Methodology section. 4.1 Analysis Methodology research Research provided information on the methodology, analysis and results of the previous Title 24 fenestration update and the ASHRAE fenestration update. A similar approach to these code updates was used to determine the cost-effective fenestration performance parameters. This approach used an energy model with representative fenestration to produce data points of annual energy use. These data points were then used to determine a curve of annual energy use versus fenestration performance parameters. From this, the CEC cost-effectiveness calculation was performed.

11 Plastic Fenest ration Glass Fenestration Nonresidential Fenestration Requirements Page Product selection and cost research Research also resulted in a comprehensive list of nonresidential fenestration products. Figure 4-1 lists these and any rationale for elimination from the analysis. Note that green standard and high-performance tints had the highest VT of all other tints in that product category and were therefore chosen for the analysis. Product Category Cost Elimination rationale Coating Uncoated (Baseline) $- Low-e with a low SHGC $6.78 /sq ft Low-e with a medium SHGC $4.12 /sq ft Low-e with a high SHGC $2.75 /sq ft Low-reflectance reflective coating $2.56 /sq ft Visibility Pyrolytic $4.24 /sq ft Substrate Clear (Baseline) $- Suspended film $8.42 /sq ft Standard tint (Green) $1.27 /sq ft High-performance tint (Green) $5.53 /sq ft Electrochromic TBD Extreme CA climate test (TBD) Thermochromic TBD Extreme CA climate test (TBD) Building-integrated photovoltaics Non-verifiable performance Diffusive (Kalwall, nano-gel) Visibility Angularly dependent diffusivity Non-verifiable performance Light redirective Non-verifiable performance Frames Standard Aluminum (Baseline) $- Poured and debridged thermal break $1.79 /lin ft Polyamide thermal break $3.53 /lin ft More expensive, lower performing than Poured and debridged thermal break Vinyl frames Building code Fiberglass frames Building code Low-e painted Market availability Spacers Standard Aluminum (Baseline) $- Mild Steel $0.02 /lin ft SST $0.21 /lin ft More expensive, lower performing than Mild Steel Hybrid Steel $0.11 /lin ft Hybrid SST $0.21 /lin ft Thermal break $0.42 /lin ft More expensive, lower performing than Hybrid SST Non-metal $0.48 /lin ft Gases Air (Baseline) $- Argon $0.03 /sq ft Krypton $2.12 /sq ft Extreme CA climate test Xenon $7.23 /sq ft Extreme CA climate test Layers Single-pane (Baseline) $- Double-pane $3.83 /sq ft Triple-pane $11.18 /sq ft Quadruple-pane TBD Extreme CA climate test (TBD) Substrate Clear (Baseline) $- Bronze tint acrylic TBD /sq ft High white pigment acrylic TBD /sq ft

12 Nonresidential Fenestration Requirements Page 12 Product Category Cost Elimination rationale Medium white pigment acrylic TBD /sq ft Low white pigment acrylic TBD /sq ft Frame Standard Aluminum (Baseline) $- Aluminum with thermal break TBD /lin ft Vinyl frame TBD /lin ft Layers Single-pane (Baseline) $- An additional pane of clear acrylic TBD /sq ft Two additional panes of clear acrylic TBD /sq ft Figure 4-1 Products Considered in the Analysis and Their Costs 4.3 Product combination selection The following criteria were considered to determine which products were used in combinations with other products: Only the outside lite was ever tinted An indoor surface low-e coating was only ever used if there was already an even-surfaced inter-lite coating (e.g. a 4 th surface indoor coating was used on an alternative only if there was already a 2 nd surface coating.) For triple-pane fenestration, the assumption was made that the gas fills, spacers, and air gap dimensions were the same for each air gap. 3 rd surface coatings were only used for passive solar fenestration Only clear substrates were used on passive solar fenestration For the sputter coatings, only Low-e with a high SHGC was used for passive solar fenestration because the other sputter coatings were more expensive, with comparable U-factors. 4.4 Alternative modeling subset Figure 4-2 presents the fenestration alternatives that were selected for the energy model runs per the criteria in section 3.10 Alternative modeling subset. Note: In the final analysis, skylights will be included and low-reflectance reflective coatings and SST spacers will be eliminated per section 4.2 Product selection and cost research. Also, for the preliminary analysis presented here, only poured and debridged thermal break frames were available for double-pane. Aluminum will be available in the final analysis.

13 Reference Number Uncoated (Baseline) Low-e with a low SHGC Low-e with a medium SHGC Low-e with a high SHGC Low-reflectance reflective coating Pyrolytic Clear (Baseline) Standard tint High-performance tint Standard Aluminum (Baseline) Poured and debridged thermal break Standard Aluminum (Baseline) SST Non-metal Air (Baseline) Argon Single-pane (Baseline) Double-pane 1 X X X X 2 X X X X 3 X X X X 4 X X X X 5 X X X X 6 X X X X 7 X X X X 8 X X X X 9 X X X X 10 X X X X 11 X X X X X X 12 X X X X X X 13 X X X X X X 14 X X X X X X 15 X X X X X X 16 X X X X X X 17 X X X X X 18 X X X X X 19 X X X X X 20 X X X X X 21 X X X X X 22 X X X X X Figure 4-2 Description of Window Alternatives in the Modeling Subset

14 4.5 Curve fit The following curve fit structure proved optimal for agreement with the energy model results. fu pu fs ps fv pv Cu FR U - factor Cs FR SHGC CV FR VT Where: C X, f X and p X are constants that vary by climate zone. They are determined by minimizing the discrepancy between the modeled TDV annual energy use and the TDV energy use calculated by this formula as applies. X is a subscript that references a performance parameter of the fenestration alternative. FR = the fenestration ratio Using this curve fit structure, the agreement metrics between modeled and calculated TDV annual energy use were as follows: R 2 : Average error: 0.321% % Maximum error: 1.15% % Details of the curve fit, including constants by climate zone and agreement metrics are listed in section (TBD) of the Appendices. 4.6 Cost-effectiveness The curve fits yielded the life-cycle cost for each fenestration alternative. Cost-effectiveness results are presented in Figure 4-3. NOTE: For this preliminary analysis only representative climate zones and vertical fenestration were analyzed. 4.7 Proposed new VT requirement If the VT requirement is not included in the update the estimated loss of benefit is presented in Figure 4-3. In the ACM a credit/penalty system will be used for VTs that are higher or lower than the prescriptive VT. The credit/penalty system will be similar to the current effective aperture credit. However, the credit/penalty will apply to all spaces in primary and secondary daylit areas. 4.8 Code simplification As presented in Figure 4-3, if the requirements for all climate zones and all fenestration ratios are set to a single set of performance parameters, the update will still be cost-effective. Therefore, in the interest of code simplification, a proposed single U-factor, SHGC and VT requirement across all climate zones is being proposed. NOTE: For this preliminary analysis, only windows are included. In the final analysis, skylights will be included as well.

15 Nonresidential Fenestration Requirements Page 15 Cost-effectiveness (Life-cycle cost savings per sq ft) WWR U- SHGC VT With VT Without % loss U/SHGC/VT = factor VT (vs. With VT) 0.35/0.25/ % $ $ % $ % 20% $ $ % $ % 30% $ $ % $ % 40% $ $ % $ % Climate Zone % loss (vs. With VT) 7 10% $ $ % $ % 20% $ $ % $ % 30% $ $ % $ % 40% $ $ % $ % 12 10% $ $ % $ % 20% $ $ % $ % 30% $ $ % $ % 40% $ $ % $ % 14 10% $ $ % $ % 20% $ $ % $ % 30% $ $ % $ % 40% $ $ % $ % 16 10% $ $(0.0991) 115% $ % 20% $ $ % $ % 30% $ $ % $ % 40% $ $ % $ % Figure 4-3 Window Cost-effectiveness Results

16 Nonresidential Fenestration Requirements Page Recommended Language for the Standards Document, ACM Manuals, and the Reference Appendices 5.1 Table 143-A RSHG represents the effect of shading. Therefore, for the translation of the analysis results to the code requirements, RSHG is equivalent to SHGC. Windows All Climate Zones U-factor 0.35 RSHG 0.25 VT 0.53 Figure 5-1 Table 143-A Proposed Update 5.2 Table 143-B TBD. 5.3 Table 146-C TBD. A lighting credit and penalty system, similar to the current credit method, will give credit to VTs greater than the prescriptive VT and a penalty to VTs less than the prescriptive VT. 5.4 Nonresidential Alternative Calculation Manual Approval Method TBD. A lighting credit and penalty system will be applied using the values in Table 146-C.

17 Nonresidential Fenestration Requirements Page Bibliography and Other Research 1. California Code of Regulations (CCR), Title California Code of Regulations (CCR), Title ASHRAE Standard Data from the ASHRAE Standard fenestration update 5. A Characterization of the Nonresidential Fenestration Market, Assembly Bill 970 Emergency Rulemaking 2001 Update of California Nonresidential Energy Standards, Volume I Measure Analysis, November 17, Emerging Technologies Index, g%20technologies%20index.htm 8. The Efficient Windows Collaborative, 9. Charles Eley, Architectural Energy Corporation. 10. Leonard Sciarra, ASHRAE 90.1 Envelope Committee. 11. John Hogan, City of Seattle, ASHRAE 90.1 Board member. 12. Steve Nelson, Cardinal Corporation. 13. Jim Benney, National Fenestration Rating Council. 14. John Lewis, National Fenestration Rating Council. 15. Bill Lingnell, Insulating Glass Manufacturers Alliance. 16. Zack Rogers, Daylighting Innovations. 17. Chris McMahon, Technoform. 18. Jason Theios, Guardian Industries. 19. Galen Burrell, ARUP.

18 Nonresidential Fenestration Requirements Page Appendices TBD.