The Passive House

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Village home expected to be first in state to receive top energy-efficiency designation

By Heather Lusk 

The walls are 12 inches thick, the windows are triple pane glass and the concrete foundation has eight inches of under-slab insulation. What is expected to be the first Passive House in Indiana is a one-of-a-kind structure for an Indiana environment that can fluctuate more than 100 degrees in temperature in the course of a year.

The Passive House designation is a rigorous energy standard that is the pinnacle of home energy efficiency. The house, in Zionsville’s village area among historic and unique homes, would be among 92 in the U.S. to meet this criteria.

The house has been a labor of love for the builder and owner, Dan Porzel, and his wife, Ann, who have spent countless hours reading, researching and learning in order to create this original Indiana structure.

“This is the application of a lot of theory,” Ann Porzel said. “We’ve read about it a ton but had never done it.”

The house has passed its final hurdle – in mid-June a blower door test showed that the house measured .38 air changes per hour at 50 Pascal building pressure, with 7.0 being “to code” in Indiana. In layman’s terms this pressurizes and depressurizes the home to check for the amount of air leakage, and showed that the house was incredibly airtight.

Now the Porzel family is awaiting the final review of paperwork before the official Passive House Institute U.S. designation. These test results have been a relief to Dan Porzel, whose company Cedar Street Builders focuses on high performance homes.

“We always kind of felt we were doing everything right,” he said.

The Passive House movement began in Germany, where temperatures don’t fluctuate as much as in certain areas of the United States. That fluctuation makes it challenging to ensure a constant temperature in the home in the most energy efficient way.

To achieve energy efficiency, a key to building a Passive House is insulation – ensuring that no air comes in or escapes through nooks and crannies. The other key is the indoor ventilation system. The home will be consistently supplied with fresh air while stale air is exhausted. As the incoming air passes the outgoing air through a duct system, the new air is heated in the winter by the stale air leaving the home. This helps reduce the cost of heating the fresh air. This is reversed in the summer, with sunshades providing protection for the south facing windows that help to heat the home in the winter.

Porzel estimates that it will cost roughly $140 annually to heat his home and less than $50 a year for cooling. While he estimates that it costs roughly 15 percent more to build a Passive House, the higher building costs are offset by the decreased utility bills in the future.

“It’s also where you choose to spend your money,” said Ann Porzel. “Some people spend on cabinets and fixtures, we spent our money on structure.”

“The whole thing is built on setting the construction numbers,” said Cara Weber, architect for the building. She emphasized that the sizing of the house is also important, considering the minimum number of square feet needed.

“People building today probably don’t realize they can do this,” Dan Porzel said.

The architect and builder are neighbors who met while walking children home from school. They soon discovered that their backgrounds and architectural goals of focusing on sustainability were surprisingly similar.

Weber had been involved in sustainable building projects in healthcare before leaving to create her own architecture firm, DELV Design. She had been doing LEED projects for a number of years, but this was her first opportunity to be part of a Passive House.

“Our thoughts just kind of matched up,” said Dan Porzel. “Cara just nailed it – she showed us her initial thoughts and we said ‘keep going.’”

The high efficiency windows were custom built and imported from Poland. The walls, constructed with 10” of foam with plywood on each side with an additional 2.5” of foam on top of that, were specifically designed, cut and manufactured off-site.

Weber and Porzel would like to continue to build these types of homes. “We’ll just continue to try to get the word out and letting people know it’s possible,” said Dan Porzel, whose company has heard some interest from homeowners.

“Let’s build things better, let’s make them sustainable,” said Weber. “We hope it incites good conversations.”

Project 580 by the numbers

140 – projected dollars spent annually to heat the house

92 – number of fully certified Passive Houses in the U.S.*

50 – projected dollars spent annually to cool the house (or less)

12 – inches of thickness of walls

8 – inches of thickness of under slab insulation

5 – number of energy efficiency certifications (PHIUS, Energy Star, airPlus, Zero Energy Ready, LEED for Homes)

2 – solar shades

1 – rooftop garden

*according to PHIUS

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