The home's cobalt blue siding sets it apart from older brick houses in its River Forest neighborhood. But the color of the house on Jackson Avenue is the least of its distinguishing factors.
As northern Illinois' first certified passive house, Corinna and Rodrigo Lema's new house is a celebrity in architectural circles. Originated in Germany, a passive house has maximum indoor air quality and is super energy-efficient.
The Lemas' house is the third certified passive house in Illinois, according to the Passive House Institute U.S., which certifies them. The other two are in Urbana and Champaign.
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"If it were a car, it would be getting 300 miles per gallon," said Mark Miller, executive director of the Passive House Alliance United States, which advocates for these homes. "Europe has embraced this for years. In the U.S., we're just catching up. There are only 34 certified in the U.S."
Corinna Lema was vaguely familiar with passive houses before she met their architect, Tom Bassett-Dilley of Oak Park.
"As energy prices went up, we knew we wanted a house that was less dependent on gas and electricity. If not off the grid, at least as much as possible," she said.
After meeting with Bassett-Dilley, Corinna and her husband knew a passive house was the right choice. Bassett-Dilley recruited the house's builder, South Elgin-based Brandon Weiss. Like Bassett-Dilley, Weiss has a green-building track record.
To earn certification, the house had to pass a third-party audit that included a blower-door test to detect air leaks, a visual inspection to make sure specified products were used, and an air-flow test of the ventilation system to ensure that incoming and outgoing air was balanced.
Including the finished basement, the house has 3,800 square feet plus a detached, two-car garage. That includes three upstairs bedrooms, an open living area plus in-law suite for Corinna's parents on the main level and a recreational room on the lower level.
The first thing a visitor notices about the Lemas' house is its 18-inch-thick exterior walls. They contain the key to keeping the house airtight — Logix insulated concrete forms, which are Lego-like panels of concrete and foam. Outside of that is a 2-inch rigid foam layer, an air cavity and SmartSide engineered wood siding.
"It's all about making the house airtight," said Bassett-Dilley. "It's so airtight, in fact, we had to have an air exchanger that changes the air every three hours, and we used the healthiest building products possible."
The health aspect of the house is a bonus, said Corinna. "And, it's quiet. You can't even hear the kids at the school down the street."
To meet their goals, Weiss told his subcontractors to use eco-friendly products where possible. Their supply lists included zero-VOC (volatile organic compounds) paints and adhesives, water-based sealants, formaldehyde-free cabinetry and CertainTeed AirRenew drywall, which captures VOCs from the air.
Weiss recommended SmartSide engineered-wood siding instead of fiber-cement siding, he said, because it is all wood, stronger and lighter, but looks like traditional clapboard. It has a 50-year warranty and will not have to be painted for about 25 years, he said.
The house's walls are framed 24-inch-on-center (24 inches between the centers of studs), which uses less wood and makes more room for insulation than conventional 16-inch framing does. Blown into the cavities is Knauf Jet Stream fiberglass insulation, made of recycled bottles.
"We researched every product for the healthiest and most energy-efficient choice — not just the products but also what goes into them, like the type of adhesive used by the plywood manufacturer," said Weiss. "That meant taking more time and having to run around to a lot of suppliers, but it's worth it."
To take advantage of passive solar heat, Bassett-Dilley put most of the windows on the house's south side. Made by Zola European Windows, they are triple-paned.
"Typically the windows are where you have energy loss," said Bassett-Dilley. "But with these, you gain more than you lose."
Instead of a furnace and air conditioner, a heat pump heats and cools the house by absorbing warm or cool air. Solar panels on the garage roof heat the house's hot water. A high-efficiency water heater is a backup when solar power does not provide enough energy.
The house has no connection to a gas utility. Its electric Bosch Axxis Condensation Dryer clothes dryer requires no vents or ducts because it condenses moisture into water, which is drained. The induction stove is electric also.
