Acorn Glade: Chicago Area’s Third Passive House
Last Updated: Apr 11, 2025After working with architect Tom Bassett-Dilley on several renovations, Jennifer Talarico and Tom Smith were about to embark on their home's final and most expensive overhaul. The couple has always been sensitive to environmental concerns and their impact. "Jen was in an environmental club in college," says Smith, "and I grew up during the oil embargo in the 1970s, so conserving energy is in my DNA."
Then, the couple discovered Passive House design. Passive House building, Smith says, "is about using conventional construction more effectively. That's very appealing. Certainly, the energy efficiency is the cornerstone of process, and ultimately your energy costs are low."
So, the couple asked Bassett-Dilley, principal of Tom Bassett-Dilley Architects in Oak Park, IL, about Passive House design. "Tom got super excited," Talarico recalls. "Knowing what we'd put into the house and what we'd still needed to do, we wondered if Tom could design a new Passive House for us. It quickly became clear that we'd be spending the same amount of money, whether we renovated our old house or built a new home. With new, we'd have a house designed just for us with cutting-edge environmental sensitivity and energy efficiency."
Table of Contents
- What Is The Acorn Glade Passive House?
- What Technologies Were Incorporated Into The Acorn Glade Passive House?
- Lessons Learned
- Healthy Home Initiative
- Adding Solar
- Costs and Returns
What Is The Acorn Glade Passive House?
The Acorn Glade Passive House is a new, modern 1,800-square-foot home, located in Downers Grove, IL. It was completed in 2017. You can read about the homeowner's process on their blog. The house has received PHIUS and PHIUS+ Source Zero certifications.
Homeowners earn Source Zero after achieving PHIUS+ targets by integrating additional air-tightness, space-conditioning, and source-energy-limit building-science principles. Reaching PHIUS+ Source Zero, according to the PHIUS website, is "a holistic view" that "pursues both radical load reduction and clean energy production, allowing faster convergence toward the goal of eliminating carbon emissions from building energy."
Bassett-Dilley founded his firm in 2006 to meld sustainability with contemporary design, grounding his work in region, climate, and context. The firm designed the first certified Passive House project in the Chicago region. Talarico and Smith's home is the third Passive House in the area. The team designed the house, called Acorn Glade, "using the metaphor of the acorn," explains Bassett-Dilley, "so it harmonizes with its site, which includes views to mature oak trees, via a two-level structure that peels back."
What Technologies Were Incorporated Into The Acorn Glade Passive House?
Evolutionary Home Builders constructed Acorn Glade's walls with mineral wool batts, an air-tight layer of plywood with a fluid-applied air barrier, 6 inches of EPS cladding, and a vented rain screen with fiberboard cladding, prefinished wood siding by LP SmartSide, and corrugated metal siding, achieving R-45. The floors, which are R-21, include:
- 5-inches of EPS below the 4-inch slab.
- An air-tight layer of 15 mil poly above EPS vapor control.
- 15 mil poly above the EPS.
The roof includes trusses with loose-fill cellulose insulation and interior taped plywood to reach R-87.
Zola windows and doors add to the home's air-tightness. A CERV smart ventilation system ensures healthy indoor air quality. Two ductless Mitsubishi mini-splits (one upstairs and one downstairs) provide additional heating or cooling.
Adding Solar
Initially, says Smith, "solar wasn't part of the equation. It's not required to meet Passive House certification." Having an all-electric house, however, is required. "So, solar was a dream of mine because we also wanted to achieve net-zero."
The home's 36 roof panels produce approximately 1,300 kWh per year and power the house and the family's Tesla. The home has a grid-tied array "because Illinois doesn't allow you to be off-grid," Smith explains. "We do feed energy back into the grid, which is required. I'd like to get battery storage at some point, to keep more of what we generate."
As a PHIUS Source Zero house, monitored results show Acorn Glade uses 86 percent less energy overall, including all household energy use and electric car charging.
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Costs and Returns
Talarico is pleased with her "right-size home. There's very little I would have done differently." Her husband, however, isn't happy about the internal heat pump hot-water heater, as it makes a noise that filters into the family's tv and music room. "I would rather have had an external compressor," Smith says.
He also wishes they would have included solar from the start, "as we would have shifted the exterior and the shed roof to accommodate the solar panels better."
Still, the family is happy with their choice to build a Passive House with solar providing all the energy they need for their electric home. "The cost was about 10 percent more than traditional construction," Smith says, "but part of the idea of Passive House is you're investing in the environment upfront, so you're not paying much in energy costs down the line."
There's isn't any good reason not to do it.
Camille LeFevre
Camille LeFevre is an architecture and design writer based in the Twin Cities.