HOUSE FEATU RE
Spreading the Word A family home demonstrates the benefits of passive structure. By Timothy Malcolm
S
teven Bluestone is on a mission. It wasn’t enough for him to build a home for himself and his family to enjoy; he also built it to educate Americans about autoclaved aerated concrete. This building material, most commonly known as AAC, is a soft type of concrete that’s up to 75 percent lighter in weight than traditional concrete. Perfected in Sweden in the 1920s, AAC is primarily used in Asia and Europe, which produces around 15 million cubic meters of AAC per year, according to the European Autoclaved Aerated Concrete Association. Comparatively, there’s only one American AAC plant, located in Florida. Residential builder Bluestone, who mostly works for New York City clients, has used the material to construct a passive structure on an overlook in North Hillsdale, at the tip of Columbia County, not far from the Massachusetts border. Though Bluestone’s new house doesn’t announce its importance to passersby, it essentially signals a whole new era in energy-efficient homes.
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A passive structure achieves energy efficiency through five principles: continuous insulation without thermal bridging, a tight building envelope to keep air in, high-performance windows and doors, balanced heat- and moisture-recovery ventilation, and solar energy implementation. Bluestone’s interest in energy conservation started in the late 1970s, and he discovered AAC around 12 years ago when he and his wife, Kathy, a marketing consultant at Disney, sought property north of their home in Westchester County. The couple had two requirements: a view, and a south-facing house to absorb as much sun as possible for lighting and to create and store solar energy. Their broker found land in North Hillsdale on a 20-acre slope with an unhindered view of the south, including the Taconic Mountains. “We came in with the broker, and we saw this, and said, ‘Yeah. This is it,’” he recalls.