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Proposed Modification to the Florida Building Code Modification #: Name: Address: E-mail: Phone: Fax: Code: Section #: Section 553.73, Fla Stat Garrett A. Stone BBRS 1025 Thomas Jefferson St., NW Eighth Floor, West Washington, DC 20007 [email protected] 202-342-0800 202-342-0807 Florida Building Code, Building 13-601.1.A Text of Modification [additions underlined; deletions stricken]: 13-601.1.A Prescriptive requirements specific to Method A. Windows shall meet the air infiltration requirements in Section 606.1 The area weighted average maximum SHGC for all glazed fenestration products (windows, doors and skylights) shall be 0.50. Fiscal Impact Statement [Provide documentation of the costs and benefits of the proposed modifications to the code for each of the following entities. Cost data should be accompanied by a list of assumptions and supporting documentation. Explain expected benefits.]: A. Impact to local entity relative to enforcement of code: There should be virtually no impact on local code enforcement since it is necessary to determine window areas and SHGCs (whether labeled or default values) for code compliance already. This proposal would merely require that an area-weighted average of such SHGCs be calculated by the builder and determined to be equal or less than 0.50. This calculation can and should be incorporated in the software and on the forms for compliance. B. Impact to building and property owners relative to cost of compliance with code: This proposal does not increase (or decrease) the overall baseline home energy points required by the code. In fact, this maximum SHGC level (0.50) is 25% higher than the baseline SHGC level of 0.40. However, this requirement will ensure that windows with excessive solar gain are not used extensively throughout the home, which will increase occupant comfort, reduce the size and cost of air conditioning units, and potentially save energy. Owners will also be benefited by the installation of more efficient windows versus other trade-off options since windows have longer average useful lives than other efficiency measures (like HVAC equipment). While it is possible that under some circumstances the first cost of such windows could be greater than some other option that might be Official Form 9B-3.047-2004 565339566 selected to meet the code requirements (although this is unlikely since the reduced cost of HVAC due to smaller size alone should offset any increased cost), no other option would provide the offsetting long-term benefits of this measure as identified above. C. Impact to industry relative to cost of compliance with code: This proposal will slightly reduce the builder’s flexibility in choosing options for code compliance. However, this proposal still leaves reasonable flexibility since: (a) the maximum SHGC level (0.50) is 25% higher than the baseline SHGC level of 0.40 and (b) the weighted average will allow a wide choice of windows and design flexibility so long as the glazing collectively meets the 0.50 SHGC maximum. This proposal does not increase (or decrease) the overall baseline home energy points required by the code. While it is possible that under some circumstances the builder’s cost of windows to meet this requirement could be greater than some other option that might be selected to meet the code requirements, the reduced costs from the commensurate reduction in the size of HVAC units permitted by lower SHGC windows should more than offset any increased cost. Moreover, the additional benefits of energy efficient windows addressed above more than justify this restriction. Finally, reducing or eliminating poorly performing windows from production and inventories will result in reduced costs to suppliers and increased economies of scale in producing more efficient products, benefits likely to be passed along to builders due to competition. Rationale [Provide an explanation of why you would like this Proposed Modification to the Florida Building Code.]: This proposal is intended to establish a prescriptive provision that requires collectively, on a weighted-average basis, that glazed fenestration (windows, doors and skylights) meet a maximum 0.50 SHGC. The purpose of this provision is to ensure that windows, glazed doors and skylights installed in homes incorporate reasonable solar protection. The need for reasonable solar protection in windows is already recognized in the overall baseline (0.40 SHGC), but this prescriptive provision will ensure that poorly-performing windows are not installed extensively throughout a home under the performance path. The code already establishes prescriptive requirements for window air infiltration. This proposal builds on that requirement, recognizing that in Florida, solar gain protection is actually even more important than air infiltration. This proposal will also make the code consistent with the national model code. This provision is already included in the 2004 IECC and will be included in the 2006 IECC. This proposal will provide numerous benefits. Occupant comfort during summer days is a primary consideration, along with electrical peak demand savings (reduced air conditioner sizing and reduced demands on the power grid at the time when the system is most strained), reduced environmental impacts associated Official Form 9B-3.047-2004 565339566 with electric generation, and potential energy savings. None of these issues is presently accounted for in the performance path, which would allow the use of the worst-performing glass. As a result, some reasonable limit on glazing SHGC under the performance method is not only reasonable but absolutely necessary. The following graph was prepared by Lawrence Berkeley National Laboratory and posted on the Efficient Window Collaborative website (a non-profit project of the Alliance to Save Energy), quantifying the probability of discomfort with various glass products due to unwanted solar heat gain: This graph clearly indicates that occupant comfort is tied directly to the solar heat transmitted through windows. For example, for the windows with no solar control (single and double clear), the probability of discomfort is over 60%, meaning that more than 6 of 10 people would be uncomfortable in homes incorporating these windows. On the other hand, both the double tint and double low-E windows, which will meet the proposed maximum 0.50 SHGC limit, show a slightly more than 20% probability of discomfort. This huge difference in comfort alone justifies the proposed limitation. Occupant comfort is also critical to energy use, since overheated occupants are likely to use a thermostat adjustment (decrease the thermostat and increase cooling energy) to mitigate the impact of unwanted solar gain, substantially increasing energy use and cost. A reasonable estimate of reduced peak demand per home from reasonable solar control is around 1 kW and one ton reduction in cooling capacity. A conservative estimate of the cost of a ton of cooling capacity is around $500. A reasonable estimate of the cost of upgrading from clear to solar control windows is less than $1/square foot of windows. It is readily apparent that the reduced cost of cooling equipment capacity alone can offset the cost of improved solar control in windows, not to mention the energy savings and other benefits from the more efficient windows. Moreover, assuming 100,000 housing starts per year, the electrical peak demand savings would amount to avoiding a 100 MW power plant each year. Please explain how the proposed modification meets the following requirements: 1. Has a reasonable and substantial connection with the health, safety, and welfare of the general public: This proposal has a reasonable and substantial connection with the health, safety Official Form 9B-3.047-2004 565339566 and welfare of the general public because it will ensure that windows with excessive solar gain are not used extensively throughout the home. As a result, this modification will increase occupant comfort, reduce HVAC sizes, reduce electrical peak demand and potentially save energy, which benefits are all discussed in more detail above. 2. Strengthens or improves the code, and provides equivalent or better products, methods, or systems of construction: This proposal strengthens and improves the code, and provides equivalent or better products, methods, or systems of construction. Low solar gain windows are nationally recognized as the best measure to address high solar gain in southern, cooling-dominated climates. This is reflected by the adoption of this same requirement in the 2004 IECC. The existing Florida code also recognizes the appropriateness of this technology by setting the baseline SHGC for windows at 0.40 (well below this weighted-average maximum). By ensuring that windows with excessive solar gain are not used extensively throughout the home, this proposal will increase occupant comfort, reduce HVAC sizes, reduce electrical peak demand and potentially save energy, which benefits are all discussed in more detail above. . 3. Does not discriminate against materials, products, methods, or systems of construction of demonstrated capabilities: This proposal does not discriminate against materials, products, methods, or systems of construction of demonstrated capabilities. This proposal is no different in concept from the existing prescriptive requirement that windows meet maximum air infiltration requirements. This proposal will permit substantial room for use of alternative windows and glazing products by use of a weighted average and a maximum value 25% above the existing 0.40 SHGC baseline in the code. All window manufacturers, regardless of frame type, can manufacture windows that will meet this requirement. By using an objective SHGC standard, this provision does not require a specific window or glass material type. 4. Does not degrade the effectiveness of the code: This proposal will not degrade the effectiveness of the code, but will enhance the effectiveness of the code. By ensuring that windows with excessive solar gain are not used extensively throughout the home, this modification will increase occupant comfort, reduce HVAC sizes, reduce electrical peak demand and potentially save energy, which benefits are all discussed in more detail above. Moreover, this provision will make the code more consistent with the national model code. This provision is included in the 2004 IECC and will be included in the 2006 IECC. Official Form 9B-3.047-2004 565339566 Section for DCA Only Committee Action: Committee Reason: Commission Action: Commission Reason: Official Form 9B-3.047-2004 565339566