Rating System

LEED BD+C: New Construction, LEED ID+C: Commercial Interiors, LEED BD+C: Core and Shell, LEED BD+C: Schools

Rating System Version

v3 - LEED 2009, v2 - Schools 2007, v2 - LEED 2.2

Inquiry

We are pursuing LEED NC for a high end high rise residence in Tokyo, Japan. We are showing compliance for EA-P2 and energy cost reduction for EA-C1 using the Performance Rating Method (Appendix G - PRM). ASHRAE 90.1 requires that the ratings for fenestration U-values, SHGC, and VLT are determined in accordance with NFRC 100 and 200. We will be using double paned and double paned Low E flat glass produced by AGC (Asahi Glass Co) here in Japan. AGC is one of the largest flat glass manufacturers and the parent company of AGC Flat Glass North America (formerly AFG - American Flat Glass). As this is a very high end residential project, with large glazed surfaces, a great deal of attention was paid to specifying glass in the design. Our issue is that AGC Japan products are rated using the Japanese Industrial Standards (JIS) and not NFRC as required. Although not explicitly stated in Appendix G - PRM, it is our understanding that if products are not NFRC rated, the poor default values provided in Normative Appendix A (Tables A8.1 and A8.2) of ASHRAE 90.1 are required to be used in place of manufacturer provided data for modeling purposes. NFRC rated products are not available in the in Japanese market. We have contacted AGC Japan to inquire if they have knowledge of NFRC rating procedures. Their response was that they do not, and only rate to JIS standards as required in Japan. The Japanese Industrial Standards (JIS) used for determining the solar optical and thermal properties of windows are JIS R 3106 and JIS R 3107. These two standards are stated by the Japanese Standards Association as being equivalent to ISO 9050 (Glass in building - Determination of light transmittance, solar direct transmittance, total solar energy transmittance, ultraviolet transmittance and related glazing factors) and ISO 10292 (Glass in building - Calculation of steady-state U values of multiple glazing). We understand that ISO 9050 and ISO 10292 form the referenced technical basis for ISO 15099 (Thermal performance of windows, doors and shading devices - Detailed calculations) which is the technical standard for determining optical and thermal properties of fenestration assemblies. ISO 15099 in turn defines the technical basis of NFRC 100 and NFRC 200. Other than the requirement for fenestration products being tested in a NFRC approved laboratory, which do not exist in Japan, we believe the JIS rated properties provided by AGC are in compliance with the technical requirements of NFRC standards and thus ASHRAE 90.1. Given this we have the following questions: 1) Can we use optical and thermal properties provided by AGC for Japanese domestically produced flat glass to model performance compliance in eQuest/DOE-2 using the performance rating method? 2) If 1) above is unacceptable, can we substitute optical and thermal properties of similar AGC NA (AFG) glass products for the eQuest/DOE-2 simulations? If the above is unacceptable, we have not identified any other way around this issue other than to import glass or have glass tested in the U.S. Both of these options are costly and not practical, and would deter this and any future LEED NC projects from being undertaken in Japan. In addition, we believe importing from abroad is not environmentally preferable in terms of CO2 impacts associated with transport.