Section 12-B908. R908 - COOL ROOF REQUIREMENTS

 

Insert new Section R908 in the Residential Code to read as follows:

 

R908.1 General.  Roof coverings for roof slopes less than or equal to two units vertical in 12 units horizontal (17 percent slope or less) for buildings and covered parking shall conform to this section.  A minimum of 75 percent of the entire roof surface not used for roof penetrations, renewable energy power systems (e.g., photovoltaics or solar thermal collectors), harvesting systems for rainwater to be used on-site, or green roofing systems shall be covered with products that comply with one or more of the following:

 

1.Have a minimum three-year-aged Solar Reflective Index (SRI) of 64.

 

2.Comply with the criteria for roof products as defined in “ENERGY STAR® Program Requirements, Product Specification for Roof Products, Eligibility Criteria.”

 

Exceptions:

 

1.Building projects where an annual energy analysis simulation demonstrates that the total annual building energy consumption with the proposed roof is 2 percent less than it would be with a roof having a three-year-aged SRI of 64.

 

2.Roofs used to shade or cover parking and roofs over semi-heated spaces or used as outdoor recreation space by the occupants of the building shall be permitted to be either landscaped or have a minimum initial SRI of 29.  A default SRI value of 35 for new concrete without added color pigment is allowed to be used in lieu of measurements.

 

3.Terraces on setbacks comprising less than 25 percent of the area of the largest floor plate in the building.

 

4.Green roofs shall be permitted to comprise part or all of the 75 percent required area coverage.

 

R908.2 Solar Reflective Index.  Initial and aged values of the SRI shall be calculated in accordance with ASTM E1980 for medium-speed wind conditions, using a convection coefficient of [2.1 BTU/(h ∙ ft2 ∙ °F)] or the metric equivalent [12 W/(m2 ∙ K)].  The SRI shall be based upon solar reflectance as measured in accordance with ASTM E1918 or ASTM C1549, and the thermal emittance as measured in accordance with ASTM E408 or ASTM C1371.  For roofing products, the values for solar reflectance and thermal emittance shall be determined by a laboratory accredited by a nationally recognized accreditation organization, such as the Cool Roof Rating Council CRRC-1 Product Rating Program, and shall be labeled and certified by the manufacturer.

 

 

authority

Section 10 of the Construction Codes Approval and Amendments Act of 1986 (Act), effective March 21, 1987 (D.C. Law 6-216; D.C. Official Code § 6-1409 (2012 Repl.)) and Mayor’s Order 2009-22, dated February 25, 2009, as amended.

source

Final Rulemaking published at 61 DCR 3063 (March 28, 2014 – Part 2).

EditorNote

The District of Columbia Residential Code (2013), referred to as the “Residential Code,” consists of the 2012 edition of the International Residential Code for One- and Two-Family Dwellings, published by the International Code Council (ICC), as amended by the District of Columbia Residential Code Supplement (2013) (12 DCMR B). The International Residential Code is copyrighted by the ICC and therefore is not republished here. However, a copy of the text may be obtained at:http://publicecodes.cyberregs.com/icod/irc/2012/index.htm?bu=IC-P-2012-000002&bu2=IC-P-2012-000019.