Sealing in the benefits of energy efficiency

When asked for advice on heat pump instal­la­tions, energy effi­ciency expert Tom Sahagian doesn’t hesi­tate — he recom­mends air sealing before anything else. 

“Even if they have no plans to convert to a heat pump, they should do air sealing,” he says. 

In older build­ings espe­cially, air can surrep­ti­tiously leak from all types of places, from a gap between a window frame and the wall to a base­board that isn’t caulked along the bottom edge. Air sealing is the process of finding and closing those gaps. This not only improves living condi­tions for resi­dents, but also lowers the heat load — the amount of heat neces­sary to make a space comfortable. 

“You don’t want the air sneaking around,” said Sahagian.

Sahagian decided well before the heat pump instal­la­tion at the UWS building that partic­i­pated in the Taitem Engineering pilot project that air sealing was essen­tial to its overall success. 

This process started with what’s known as a ​“blower door” test: A machine that can be fitted to a door frame pres­sur­izes or depres­sur­izes a building, revealing gaps that air can seep through. It’s a method more commonly used in single-family build­ings, but can also work for multi­family buildings.

“Exaggerating leaks makes them easier to find, and then you can do the work of plug­ging them up,” Sahagian said.

Taitem Engineering performed two rounds of these tests: One in June 2020, pre-retrofit, and then another in February 2022, post-retrofit. Once the leaks were iden­ti­fied, Sahagian and a handyman hired by the building did air sealing on the front door, the roof door, the base­ment doors, and a selec­tion of apart­ment doors for resi­dents who opted in. This involved adding weather-strip­ping tape made of synthetic rubber and aluminum around the door frame and door sweeps to close the gap between the door and the floor, a process known as compart­men­tal­iza­tion.

Sahagian and the handyman also sealed a defunct dumb­waiter shaft, which had been acting as a pipeline for warm air, and two windows in the basement. 

The cost of the air sealing, which came in at about $12,000, was subsi­dized by Daikin, the heat pump company behind the pilot project. 

The process worked so well for resi­dent Lisa Harrison that it not only blocked cold air but also kept out unpleasant odors, like the strong-scented floor cleaner used in the hall­ways. ​“Even a smell didn’t come in,” she said.

While the co-op waited until after the Daikin heat pumps were installed to perform air sealing, Jon Hacker, Daikin’s former Energy Efficiency Business Development Manager, said that best prac­tice is gener­ally to do it in the reverse order: ​“If you reduce the load of the building, we can now appro­pri­ately size a heat pump for that load,” he said. 

Along with air sealing, the building also added insu­la­tion to apart­ment walls, the base­ment, and the roof grad­u­ally over the years. They hired Brooklyn Insulation & Soundproofing, a company that special­izes in cellu­lose insu­la­tion in older build­ings, to do the job. For their projects, the company uses cellu­lose made of shredded recy­cled news­pa­pers and magazines.

The pilot study by Taitem Engineering that the building partic­i­pated in found that forti­fying the build­ing’s enve­lope went a long way in increasing thermal comfort for resi­dents. Umit Sirt, an engi­neer at Taitem, also said that apart­ment temper­a­tures remained more consis­tent throughout the building, and more even across different floors. As a result, the study suggested that peak demand for elec­tricity was ​“lowered consid­er­ably” due to enve­lope upgrades.

Amalia Peña, a resi­dent on the top floor who has lived in the building since 1987, said she’s noticed a big differ­ence since the insu­la­tion was added. Sometimes it’s so warm, she doesn’t need to turn on the heat pumps at all. ​“It was a very good invest­ment,” she said.