Zola European Windows
Perhaps the most engineered product in Passive House is the window with plenty of manufacturers keen to strut their triple and quadruple panes. Big news was the end of Serious Windows, a unique window company which used film in the center instead of a sheet of glass and the only US window that came close to passive house specs. They are reborn as Alpen Windows, a Boulder, Colorado company which founded the technology. Another Boulder window company which is making inroads in the super efficient window market is Zola Windows, which imports custom units that meet the exacting passive house standards and does R&D for the many US climates. Intus Windows, a low cost passive house window, comes in at a much lower price than many other European companies using German components based on uPVC, but fabricates the windows in Lithuania to be more cost-competitive.
The high tech and high performance device in every passive house is a heat or energy recovery ventilator. Passive House not only takes into account the efficiency of the heat exchanger as the home is constantly flushed with fresh air but also the electricity required to do so. The US company UltimateAir has a high efficiency ERV and fully programmable unit which hit the sweet spot of performance and cost using a rotary core heat exchanger. A step up in efficiency is Zehndar which also sells engineered air distribution systems that maximize performance. Air Pohoda, the most efficient unit at the conference, made its debut from Czechoslovakia. While enormous compared to the others, it has nearly half the energy consumption, a big deal for a device that runs 24/7. Brooklyn-based material supplier 475, named after the famous energy threshold for passive house, was touting their micro Luno ERV. A 5-inch round tube that contains a super efficient reversible fan and ceramic core that captures the heat in the outgoing stale air also reverses to heat the incoming fresh air.
The latest talk in the green building world is that air sealing is as important as insulation. Swiss based Siga Tapes and membranes are an entire air sealing system which rely on two air barriers. Here is what is so extraordinary about them: not only do their tapes stick to just about anything to keep the chill out but are made with 100% organic non-voc materials that easily outperform the petroleum-based stuff made in the US. What about a foam tape that expands from 1/4 inch to nearly 2” in a couple of hours? The Termco EXOAir window tape is a unique replacement for expanding can foam, which is not only messy but hard to get where you want it.
Another way to air seal is to use R-Guard Cat5 by Prosoco, a sort of gasket-in-a-can, was tested to a simulated category 5 hurricane and let in zero water through the window. The simplicity of using the product is double bonus for providing high efficiency results when it comes to making a wall system air tight.
Insulation is also a big, big deal. Joe Lstiburek said to the audience in the opening plenary, “insulating good, solar bad,” referring not only to failed passive solar homes but the over-reliance on slapping technology on a roof and calling it a green building. His method of choice has been foam but more earth friendly, energy sipping products were on display. Cork Insulation has found its way across the Atlantic and while it comes at a premium price, it is a uniquely healthy choice. More mainstream was German made Agepan fiberboards which clad buildings in an air tight water resistant coat that is still vapor open to reduce chances for rot.
Roxul Drainboard image by Rocky Mountain Passive House
For a stateside low impact insulation which performs even better when it comes to rot prevention, look no further than Roxul DrainBoard, a dense board made from mineral wool – a compressed mixture of rock and slag. Priced similarly to XPS foam but without the environmental impact, DrainBoard is vapor open and can be used underground.
The most exciting aspect of future high performance homes may be the recent innovation of Phase Change BioPCmat, a bio based waxy material in a plastic blister pack which when placed inside a wall can retain and release heat at prescribed values. As the wax melts at say 78 degrees it can store the equivalent heat as 12 inches of concrete in just half an inch. By absorbing heat in the day and releasing it at night buildings can use much smaller HVAC equipment, thereby saving money and energy while keeping interiors comfortable. It doesn’t get more passive than that.
+ 2012 North American Passive House Conference
Lead Photo VolksHouse by Mosa