The New York chapter of the United States Green Building Council released a study about preventing heat loss in city buildings.
The study finds that the biggest source of roof air leakage comes from the open vents at the top of elevator shafts in tall buildings.
Apartment building owners in New York City spend an average of $3,400 each year to heat air that escapes through the roof. For taller buildings, the cost can be well over $20,000 each year, according to the report.
Fixing the leaks is relatively inexpensive – about $500 to $15,000 per building, and a 15-story building could achieve $3,000 to $6,500 a year in energy savings just by sealing the vents in elevator shafts, reports The New York Times.
These vents come in a range of sizes and shapes, from simple openings to more complicated systems. They can be found in the walls or ceiling of elevator rooms and are typically at least three square feet in area. Building maintenance staff can assess the vents, estimate the energy losses and savings, and perform the retrofit either in-house or with the help of a consultant.
There are two main options for retrofits, according to the report:
- Cover two-thirds of the vent with annealed glass, and leave the rest open.
- Install a motorized set of louvers that will remain completely closed until there’s a fire, when the alarm system or a smoke detector will open them.
The first option is best for smaller, simpler buildings, and can be installed inexpensively in-house by building maintenance staff. The cost ranges from $500 to $2,000 per vent, depending on the in-house capabilities of building staff, with a simple payback period of less than one year, depending on the details of installation.
The second option, installing motorized louvers, is now a possible retrofit solution thanks to a recent change to the NYC building code. The total vent area can be covered as long as the louvers will open upon detection of smoke, loss of power, or manual override. This solution is best for larger, more sophisticated buildings. The cost can range between $5,000–$15,000 per vent, depending on access to the various systems and other site-specific concerns. Although it’s a pricier solution, the payback period is similarly short (one to five years depending on the details of the installation) and will save significant money in the long term.