RESNET® Proposes Standard Addenda: Draft PDS-01 of proposed Addendum 41f: “Tropical Climate Zone” and “Living Space” Definitions; Time-limited Leakage Test Exception of Puerto Rico and the US Virgin Islands

April 15th, 2019 - Posted by under RESNET News

This addendum establishes definitions for “Tropical Climate Zone” and “Living Space” and provides a temporary exemption from infiltration testing for homes in Puerto Rico and the US Virgin Islands.

While the definitions of Conditioned Floor Area and Conditioned Space Volume intentionally exclude portions of a home that are not conditioned, these definitions did not anticipate an entire home that lacks both space heating and cooling. Such homes are rare in the US mainland, but are common in tropical regions, where there is no heating load, cooling is often achieved through passive strategies, and occupants have an expectation of higher space temperatures. Because ANSI/RESNET/ICC Standard 301 uses the Conditioned Floor Area to determine several characteristics of the reference and/or rated home, such as window area, ventilation rates, residual MELs, interior/exterior lighting, and hot water pipe length, inaccurate values will be produced for these parameters in a home with no Conditioned Floor Area. To address this issue, the addendum modifies Standard 301 as it applies to the RESNET HERS® to allow occupiable space of such a home be modeled as its Conditioned Floor Area and the volume of the occupiable space to be modeled as its Conditioned Space Volume.

HUD is tying hurricane recovery funds on the US Virgin Islands and Puerto Rico to efficiency programs, which creates an opportunity for RESNET to increase HERS ratings on these islands. However, because the rating infrastructure on the islands is in its infancy, blower doors are an expensive investment. Also, due to the extremely temperate weather in these locations, the infiltration rate has a negligible impact on the HERS rating. For example, in one home in Puerto Rico, the HERS impact of increasing infiltration from 3 to 10 ACH50 was 1 HERS point. Consequently, testing each home for leakage outweighs its value in many cases. The addendum adds an exception to the MINHERS standard allowing Raters doing HERS ratings in Puerto Rico and the US Virgin Islands to use a very high default infiltration rate of 10 ACH50 in lieu of testing for a limited period of time corresponding to the hurricane recovery period.

                                  Public comments will be accepted from April 15, 2019, through May 14, 2019.

The draft addendum, comment form, and comments posted to date are posted at Draft PDS-01 MINHERS Addendum 41f.

After the comment period, the RESNET Standard Development Committee 300 will consider and document each of the comments submitted and make appropriate changes. Substantive changes will be submitted for public comment.

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