Sharing another best practice, Pruban has found that blocking the cold, north winds from the home’s primary living spaces to be an effective technique. Essentially, the idea is to site spaces where comfort and temperature isn’t as crucial on the north side—such as the laundry room, storage area and closets—so that these rooms can act as a buffer, thereby reducing heating needs in the winter.
Touching briefly on heat/energy recovery ventilation, Cobblestone’s Wahl states, “balanced ventilation systems that incorporate heat recovery are a must in a tight, energy-efficient home” (For more on HRVs, see “Mechanical Ventilation Update,” on pg. 33.).
Adding It All Up
With such a high level of sophistication and detail required to design a successfully operating passive house, builders are encouraged to use other readily available tools, such as energy modeling software to sort through different approaches, “The energy modeling is essential in determining which strategies are the most effective for each climate, site and building layout,” asserts Jovanović.
Similarly, Wahl relates, “we do a lot of ‘what if’ scenarios involving changing window performance, insulation systems, HVAC efficiencies, lighting and appliance consumption. It’s essential.”
One good program for building a super shell is the Passive House Planning Package from the Passive House Institute (
www.passivehouse.us/passiveHouse/DesignTools.html), known for its accurate level of information. In addition, THERM from Lawrence Berkeley National Laboratory calculates thermal bridges, and Oak Ridge National Laboratory’s WUFI software provides a detailed moisture analysis of the enclosure.
Ultimately, such software will provide lots of good ideas, calculations and values— but it takes a committed builder to truly follow through to the level of detail necessary to build a super shell.
PANASONIC WHISPERCOMFORT SPOT ENERGY RECOVERY VENTILATOR
This easy to install, ceiling mounted energy recovery ventilator from Panasonic Home & Environment Company requires just two, 4” ducts—one to exhaust stale air and the other to supply fresh outdoor air, thereby providing balanced ventilation. The unit operates continuously at a low rate for enhanced indoor air quality, and can be used for spot ventilation or for the whole house.
www.panasonic.com/ventfans.
MILGARD ESSENCE SERIES WINDOWS
Combining the beauty of natural wood for the interior with the durability of a fiberglass exterior, Milgard’s Essence Series Windows also features a rain management system which drains water away from the wood in the rare event that rain penetrates the sash system. An Energy Star-rated product, the windows are available in 15 finishes.
www.milgard.com
NCFI INSULSTAR SPRAY FOAM INSULATION
InsulStar spray-in-place polyurethane insulation from NCFI offers a high R-value, blocks air movement and has a low permience, thereby eliminating water condensation. Once the foam is sprayed, it expands rapidly to fill in gaps and voids within the floors, walls, ceilings, roofs and crawl spaces. Once cured, the SPF forms a fully adhered, solid and monolithic layer of insulation.
www.insulstar.com
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