Rating System

LEED BD+C: New Construction

Rating System Version

v2 - LEED 2.1

Inquiry

Our intention is to design, construct, and commission this building with an emphasis on its superior building envelope, including a tight seal at all building elements to minimize infiltration. Aggressive measures to limit infiltration of air through the building envelope have a significant impact on building performance. We propose to demonstrate the effect of a sealed building envelope by modeling a reduction in the infiltration rate between the proposed building and the budget building in the energy cost budget calculations. For the budget building, we propose the standard established in ASHRAE Fundamentals 2001, Chapter 26. ASHRAE sets the average building infiltration at .30 cfm/ft2 based on a pressure difference of 1.6 lbf/sf. The design case we will use is from the specification for our exterior wall system; this specification permits air leakage of not more than .06 cfm/sf of wall area when tested according to ASTM E 283 at a static air pressure difference of 6.24 lbf/sf. The envelope will be tested in the field with blower door tests to verify infiltration rates. We believe that reducing infiltration is consistent with the goals of the LEED program and promotes the benefits of careful building practices. As such, we request that infiltration rate be permitted as a variable in the energy cost budget calculation for optimizing energy efficiency.