Pleasantly Tight Times in a MF Passive House

So you’d think that blower door testing on a four-story multifamily passive house project with 60 studio apartments would be one long afternoon (or at least a series of them). Well, that’s quite a different story (and shorter one, I might thankfully add) when you’re dealing with PHIUS+/Passive House design.

Madison Supportive HousingLast week, Eco Achievers ventured to the capital of our cheese-loving state to the north for the first round of mid-construction air leakage testing. Madison Supportive Housing (MSH), a 60-unit affordable housing development for homeless and those on the brink of it, is a joint effort between the Wisconsin Housing and Economic Development Authority and Heartland Alliance, an international anti-poverty organization. MSH was developed as part of The City’s Response to Homelessness in 2015. It broke ground last summer with plans to open it’s doors to residents in early 2017.

Centrally located ERV

Centrally located ERV

The afternoon started with a full building envelope review, taking note of wall/ceiling joints, exterior wall penetrations, and any areas that lacked (or succeeded) in air sealing. We were joined by Heartland’s Enterprise Rose Fellow and Passive House Consultant, James Lewis, who has been instrumental in the development and application of its sustainable features and energy efficient design. Some of the project highlights include:

  • 4” of continuous exterior wall and roof insulation
  • Fluid applied air barrier
  • Detailed air sealing to meet Passive House airtightness
  • Multiple ERV fresh air ventilation systems centrally located
  • High performance, thermally broken windows
  • Advanced wood framing
  • White/reflective roofing materials to lower solar heat gain, and
  • A chicken coop, beehives, and rooftop vegetable gardens.

Img 20160224 162647305After a walk through inside and out of the entire building, it was finally time to start setting up for the blower door. Buildings of this size and volume necessitate multiple fans, so we came prepared with a double-fan shroud and extra equipment just in case. We determined this by calculating the volume and ensuring we had enough blower door capacity to get below 1 Air Changes per Hour (ACH) @50 pascals. Today’s testing was going to be a first for many of the team members, including the Passive House consultant, so suspense and anticipation was growing.

Once the fans were in place, baseline was pressed and the countdown began. (Building Scientist Extra: Baselining manometers (i.e. fancy pressure gauges) is one of the first steps to an accurate test so that we know that our readings are coming solely from building infiltration and not extraneous sources.) In dual-fan set-ups, one fan is brought to it’s maximum and the other is then adjusted to reach 50 pascals. Before we knew it though, our first fan had already reached 75!

Blower Door Results

Wait… what? 75? That’s right - this meant that the 500,000 cubic foot enclosure was so effective that it only needed one fan! Our PHIUS+ Passive House target threshold of .050 cfm50 of airflow per sf of shell enclosure was beat with a total of 0.46 cfm50/ sf of shell. For those accustomed to volume-based blower door measurements, that comes out to 0.35 ACH@50pa. Less than 10% of Eco Achievers' projects are able to reach this level of quality and airtightness.
Needless to say, the team was ecstatic.

So what’s next in this venture? What about ducts? Insulation? And did we say fresh air ERVs? Stay tuned tuned for more details! Eco Achievers is performing the LEED verification and all Passive House performance testing for MSH. Curious about what that entails or if that can apply to your home or project? Give us a shout! We’re certified for nearly all green building programs and are one of the only Passive House certified-raters in the state of Illinois. Our staff is currently the only with multifamily PHIUS+ MF certified raters operating in Illinois, Wisconsin, and Minnesota.

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