The Passive House Alliance US (PHAUS) has a big goal: to make the Passive House Building Energy Standard the leading mainstream market force.
So what makes a building—and more importantly—a window—“passive?”
According to the Passive House Institute’s website, “a building constructed using passive house principles is a very well-insulated, virtually air-tight building that is primarily heated by passive solar gain and by internal gains from people, electrical equipment, etc. Energy losses are minimized.”
Official PHAUS standards call for windows to have a U-value of less than or equal to .14 Btu/hr-ft2-degrees Fahrenheit. It also requires that windows in mixed/cold climates have a solar heat gain coefficient (SHGC) of greater than 50 percent and hot climates have an SHGC of less than 30 percent. In a recent webinar, Aurimas Sabulis, principal at Intus Windows and a member of PHAUS, talked about ways to achieve that goal.
“If you want to have a high-performance [window], you want to make sure that it is super air tight [and] that at the end of the day it brings you comfort to your home,” he says.
So how do windows become “super air tight?” Sabulis says it breaks down according to the effectiveness of each component.
First, windows should have three lites instead of two and be a triple-glazed insulated glass unit.
While some may be concerned that triple-glazed windows can be costly, Sabulis insists that though this was once true, there is not much difference anymore.
He continues, “One of the benefits besides the energy savings in the building, triple-pane windows actually bring a lot of comfort,” by improving the inner pane temperature, he says.
Secondly, Sabulis recommends using high-performance spacers between the lites, which allows for reduced condensation on the edge of glass. “Because of condensation, mold [can get] inside the window,” he adds.
Next, Sabulis talked hardware.
“Tilt and turn hardware is actually the most energy efficient,” he says. “[It] features multiple locking points … like a refrigerator effect,” which causes it to maintain air-tightness for decades.
Lastly, Sabulis says to pay attention to the windows’ frame performance. He says in order to achieve “high-performance” in PVC, wooden or aluminum frames, one can mostly add insulation into or around the frame.
Capital City Charter School in Washington, D.C., is an example of an organization with strict budget guidelines that chose to make the investment in order to become a more passive building.
The school used triple-paned windows in its most recent renovation and, “space heating went from 52 percent [of the electric budget] to almost 32 percent … There was [also] an actual reduction in the overall cost of running the building,” saving nearly $73,000 over five years, Sabulis says.
At the end of the webinar, Sabulis was optimistic.
“I’m hoping I gave you enough information to understand that nowadays, you can reach high-performance in residential and commercial buildings and not spend so much extra,” he says.