Party Walls

Welcome to part three of the air sealing blog post series! In previous posts, we have reviewed the substantive changes in 2016 New York Residential and Commercial Energy Code, focusing specifically on the new blower door testing requirements. In this blog post, we’ll examine how these requirements stack up in comparison to green building certifications that we are already familiar with: LEED for Homes, LEED BD+C, ENERGY STAR® Certified Homes, ENERGY STAR® Multifamily High-Rise (ES MFHR) and Passive House (PH).

To make this easier to digest, we’ve divided this comparison into two parts – compartmentalization and building envelope. If you need a refresher on the difference between these two types of blower door tests, we recommend referring to the article “Testing Air Leakage in Multifamily Buildings” by SWA alumnus Sean Maxwell.

Compartmentalization

Testing a dwelling unit’s air infiltration

Testing the air infiltration of individual dwelling unit

Let’s start by comparing New York Energy Code with certification programs that reference compartmentalization: LEED for Homes Midrise, LEED BD+C NC and ES MFHR. Note that for NYC buildings, ES MFHR is referenced by NYC-specific programs such as NYSERDA Multifamily Programs and Enterprise Green Communities. New York Residential Energy Code requires blower door testing in all residential buildings and allows compartmentalization in buildings with more than one apartment. Code requires a maximum air leakage in each dwelling unit to be 0.30 CFM50/SF (CFM tested at 50 Pascals per square foot of enclosure). If you’re thinking that number looks familiar, that’s because both LEED for Homes Midrise and ES MFHR require the same testing threshold! New York Residential Energy Code is catching up with the standards of better performing buildings, however with the advent of v4, USGBC has upped the ante and reduced the maximum leakage threshold by 25% to 0.23 CFM50/SF for LEED for Homes Midrise. LEED BD+C NC, on the other hand, utilizes a different testing metric for compartmentalization. This program requires a maximum leakage rate of 1.25 ELA/100SF (effective leakage area per 100 square feet of enclosure), however under v4, USGBC has also adopted compartmentalization testing threshold of 0.23 CFM50/SF.

Summary: How does Energy Code’s compartmentalization testing requirement weigh up against some familiar certification programs?
It has already approached the compartmentalization requirements of ES MFHR and is approaching LEED v4 compartmentalization testing requirements for mid and high-rise buildings.

Building Envelope Testing

Testing the air infiltration of the building envelope

Testing the air infiltration of a building’s envelope

Now let’s compare New York Energy Code’s building envelope blower door testing requirements with ENERGY STAR® Certified Homes, LEED for Homes, and Passive House. New York Residential Energy Code requires a maximum air leakage rate of 3 ACH50 (air changes per hour at 50 Pascals) for single family homes. LEED for Homes for detached single-family buildings requires 6 ACH50* under prescriptive path (and performance path projects will have a tough time achieving their HERS rating with higher blower door results). Under v4, USGBC drops the requirement to 3.5 ACH50* for prescriptive buildings. ENERGY STAR® Certified Homes references a maximum leakage rate of 5 ACH50*. Passive House blows all of these requirements out of the water with a maximum leakage requirement of 0.6 ACH50, according to International PH Standards.

If you recall part two of this blog series, New York City’s Commercial Energy Code now requires blower door testing on buildings between 25,000 and 50,000 square feet and 75 feet in height or less. These buildings have to perform blower door testing with a maximum leakage threshold of 0.40 CFM75/SF (CFM tested at 75 pascals per square foot of envelope area). This requirement is not as stringent as LEED for Homes v4, which requires 0.125 CFM50/SF*. Passive House (US Standards) on the other hand, requires 0.05 CFM50/SF! In this case, Commercial Energy Code has a ways to go to approach the performance standards of LEED and Passive House.

Summary: Do New York Energy Code’s building envelope blower door requirements rival those of high performance certification programs?
Residential Energy Code has made better strides to surpass LEED and ENERGY STAR® than Commercial Energy Code. However, both have a long way to go to catch up with Passive House standards.

* Climate Zone 4 was assumed for air leakage requirements.

Written by Sunitha Sarveswaran, Energy Engineer