The Lemas found an ideal lot in Chicago and began building their dream house. When completed in 2012, the Lema residence was the first certified Passive House in the Chicago area. Biltmore Insulated Concrete took care of the thermal shell. Evolutionary Home Builders served as the general contractor. Bassett-Dilley designed the home and conducted the calculations that would ensure high performance spatially, structurally, and mechanically.

Seven years later, says Bassett-Dilley, currently a council member of the Passive House Alliance, he's realized that "as building codes keep ratcheting up specifications for building tightness, and as we continue to translate the German Passivhaus standards to U.S. climates, the specifics of the locality are becoming more critical to the successful performance of passive houses in this country." That meant a few changes in the Lemas' home, as well.

Passive House Principles

Homes designed using Passive House principles have the most airtight and highly insulated building envelopes in the industry—resulting in heating and cooling loads way below those racked up by systems in a traditional home. Because of Chicago's climate of extremes—tropical heat and humidity in the summer, and polar vortices of bitter cold and aridity in the winter, the Lemas' home needed some cooling and heating.

The house has insulated concrete form (ICF) foundations and walls, a wood truss roof with plywood barrier and suspended ceiling, and Zola Thermo triple-pane aluminum-clad windows. With the structure in place, Bassett-Dilley could model the home's thermal performance and calculate how much heat and cooling the house would need