As they begin to comply with New York City’s Climate Mobilization Act, many co-op and condo boards are considering retrofits, such as installing LED lights or solar panels or maybe switching the boiler from oil to natural gas in order to cut their buildings’ carbon emissions. Such thinking is exactly backward, according to a new book, The Power of Existing Buildings: Save Money, Improve Health, and Reduce Environmental Impacts (Island Press, 2019).
“This book is a step-by-step strategy on how to achieve zero energy or low-energy consumption through deep energy retrofits,” says co-author Craig Stevenson, a co-author and the president of the Auros Group, a sustainability consultancy. Stevenson and his co-authors, Beth Eckenrode and Robert Sroufe, dismiss LED lights and solar panels as “low-hanging fruit.” Instead, they argue, owners of multifamily buildings should adopt a holistic approach to retrofits similar to the one used in passive houses. Here, the top priority is to improve the entire building envelope so there is no “thermal bridging,” the loss of heat or cool air through gaps in the envelope.
If a building’s envelope – roof, walls, windows, doors – is leaky, then heated or cooled air is pushed through the walls and lost. “In a passive house,” Stevenson says, “you do have cooling and heating elements, but you might never have to turn them on. The ventilation system is cheap and super-efficient with 30 percent greater ventilation than the current requirements, and the air goes through a heat recovery system.”
Most existing buildings can be insulated from the outside, using modular, prefabricated panels created by technology developed in the Netherlands. “With its new ‘outfit,’” say the authors, “the building has enhanced market appeal, lower utility costs, and superior air quality.”
Once the envelope is tight, all the systems in the building can become much smaller and more affordable. Only then is it time to install renewable-energy sources, like solar panels or cogen systems. “If you’re using less energy for the systems because those systems are now smaller, the onsite energy generator is also that much smaller and affordable,” Stevenson says. “Instead of putting solar panels on the entire roof, one can put up a small, affordable array. People who are looking at renewables first will find it’s not really a good financial decision.”
Stevenson urges boards to follow a simple mantra as they set out to cut their building’s carbon emissions: first, seal the envelope, then add the retrofits.