Seattle Passive House – Draftless in Seattle with a .41ACH!

David Vollan of Home Performance, Inc. came out to do Dan’s 2nd blower door test today.  It was a resounding success.  The house registered a .41 ACH @ 50 pascals.  The Tectite Building Airtightness software v 3.2 projected a 121cfm for anyone wanting to know the PH Nerd Numbers.  Way to go Dan!

Dan has had some other accomplishments this past week – he passed his electrical, plumbing, and framing inspections!  He said that he noticed the draft from the positive pressure in the sewer line was blowing a continual stream of cool air through the plumbing ventilation stack and was concerned that with all the sealing he was doing, that this is a leak he could not prevent.  In Seattle homes are required to have a plumbing vent that exits the building envelope and allows the sewer gas to escape.  This is for health reasons.  AAV’s or Air Admittance Valves are another way to deal with this issue in a way that would not affect the building envelope.  Dan was told that he would not be able to do that on this project.  Another Certified Passive House Consultant, Tad Everhart has been successful in getting a code alternative allowed for his project in Oregon and he is using a combination of solutions for the negative and positive pressures that need to be addressed.  Tad used Studor AAV’s for the negative pressures and installed a 2 way valve for the positive pressure instead of the traditional plumbing stack vent.  You can see more of what Tad did regarding his PH project here.

Next up is drywall and painting while Dan works on the landscaping.  Time to make this Passive House look more like a home!


3 responses to “Seattle Passive House – Draftless in Seattle with a .41ACH!

  1. any thoughts on why AAVs weren’t feasible?

  2. Our arbiter of plumbing code applications here in Seattle is the King County Health Department and they were adamant about the necessity of continuous venting. (This allows an established, accepted and easy, non-mechanical path to relieve both positive-pressure – sewer gasses coming from the sewer main – and negative pressure – less clogging, free-flowing & gurgle-free drains.) In the maze of code creation and enforcement, every jurisdiction has a lot of authority as far as adapting as they see fit. Unlike some other locations, King County Health (though responsive and friendly) was not flexible as far as using only AAV’s and eliminating the continuous venting. Moreover, their code mandates this vent to be of the same diameter as the waste pipe leaving the building. SO… I’ve got a 4″ pipe leaving the building. No, this is not a 4″ hole in the air-barrier, but it is a avenue for a continuous flow of cool air through the walls of the building, starting from the (50deg F?) sewer in the street. In opening one of the cleanout plugs inside the house, one can readily feel this flow. It’s not simply a matter of cold air falling into the roof vent (I insulated the last 10+ feet of this vent) I’m guessing the heat-loss issue is more a matter of the flow of cool air flowing up. As such it could potentially be important to insulate the entire length of the plumbing system which would be a major, expensive headache. A significant reason to lobby heartily for integration of AAV-only installations. Clear as sewage sludge?

  3. So is the vent stack essentially a mini-refrigerator running through the entire height of the house? Any way to make it an effective cooling system for hot weather, and at least benefit from it for the ~2 weeks of hot weather in Seattle in any given summer?!

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