Oregon-based developer Hammer & Hand is currently working on the Karuna House, a project which aims to get certified for three of the most important “green” standards – LEED, Passivhaus and Minergie-P-ECO.

Although construction is still in the early stages, the team working on this challenging project has already had to come up with a series of workarounds to keep it in compliance with all the three green standards. For example, Minergie-ECO prohibits site-applied spray foam, a material previously specified in the original plans, so the guys had to use high-density cellulose insulation and fill the gaps with acrylic-impregnated expanding foam tape. The Minenergie-ECO standard also doesn’t allow the use of treated lumber inside the building’s air barrier, so this was replaced with borate-treated sill plate installed over a structural EPDM gasket. Finally, code requires hood exhaust units in kitchens, which didn’t work well with Passivhaus and Minergie-P certifications, so the builders had to  locate the heat recovery ventilator near the kitchen and install a recirculating fan with a grease filter between the kitchen intake and the HRV.

So although, there hasn’t been any real building done on the Karuna House, Hammer & Hand has faced some serious challenges, but managed to abide by the rules of LEED, Passivhaus and Minergie-ECO standards, and avoided any conflicts. Still the team admitted there’s a big chance bigger problems will come up as the building process advances.

The revolutionary three-bedroom Karuna House will have 3,261 square feet of interior space, and will incorporate three foundation strategies: slab on grade, platform framing (decking above a slab), and a full basement. Expanded polystyrene under every element of the foundation will bring its R-value to 56, and the R-48 exterior walls will have 2×6 studs filled with cellulose and 6 inches of exterior polyisocyanurate foam. The roof will have an R value of 92, thanks to the 8 inches of EPS covering the sheathing and the 16-inch-deep I-joist rafters filled with cellulose.

We’ll be following the progress on the Karuna House and how the guys at Hammer & Hand manage the three certifications. I’m holding my fingers crossed, but obtaining LEED, Passivhaus and Minergie certifications will be pretty tough.

Green Building Advisor