Welcome to Project: Tighthouse. No, this is not another James Bond 007 sequel, but the incredible story of how a Brooklyn row house built in 1899 became NYC's first Passive House-certified home. The journey from dilapidated brownstone to a model for residential retrofits was not an easy one. Last week, green building professionals and enthusiasts gathered to meet the Tighthouse’s architect, builder, and PH consultant and learn how they did it at Deep Energy Retrofit: Row House.
Both designer Julie Torres Moskovitz (Fete Nature Architecture) and builder Jordan Goldman (Zero Energy Design) took on the project without much experience or guidance. When the project started six years ago, even the supplies needed for this type of retrofit—rigid insulation materials, industrial strength adhesive tapes—were hard to find on the market, resulting in a lot of trial-and-error to reach Passive standards.
Much of what makes a Passive House ‘passive’ is airtightness, measured by a blower door test. “Think of a balloon needing to be inflated to reach a certain amount of pressurization,” Goldman said, explaining how the test locates air leakage in the building. The tester closes all the windows and doors of the structure, then uses the blower door fan to fill the volume of the building with an amount of pressurized air. The less air required to fill the building, the fewer the holes in your balloon, so to speak.
Passive House calls for a tested air infiltration rate of 0.6 ACH (air changes per hour) or less. Moskovitz proudly recalled the blower door test pizza party she hosted in the house during construction to celebrate meeting 0.6 ACH even before completion. The final measurement came out to 0.4 ACH, after completing five separate tests for accuracy.
Much effort and many steps added up to this impressive ACH score. The entire back wall of the house was torn down and rebuilt with a steel frame, concrete slabs, rain screens and other insulation methods. The fireplace and chimney had to be removed; Goldman stated that, “Chimneys are large holes in the building envelope. Open fires have no place in passive house.” Fear not, the chimney brick was not trucked to a landfill, but creatively reused in other areas of the house, such as an exposed brick wall in the living room and in the foundation for the backyard patio.
Water can be another trouble-maker for retrofits. Protecting the Tighthouse from precipitation and freezing and thawing required multiple layers of insulation on both the interior and exterior walls. Potential flooding from Park Slope’s underground rivers meant first lowering the basement floor a foot, and then padding the flooring with rigid insulation to prevent heat loss and water gain.
Today, the 113-year-old Tighthouse might be considered to be in better-than-mint condition. The specialized tape used to seal multiple layers in the house has only become stronger with age, making the house even more airtight now than at completion. With no boiler or gas bill, plus solar panels and a high-efficiency ventilation system in place, the Tighthouse spends 60 to 65 percent less on energy than a standard row house. Most notable is the awareness raised throughout the neighborhood thanks to the living example provided by this retrofit. Six years later, the block where the Tighthouse sits is now home to four certified Passive House row houses. If a house can change a neighborhood, perhaps a neighborhood can change New York City.