Up to 25% of heating energy escapes from multi-residential buildings
Most multi-residential buildings are very leaky (not airtight), with 20 to 25% of heating energy simply seeping away. As a result, air leakage has a significant impact on annual space heating and cooling costs as well as peak energy demand. Furthermore, leakage is greatest during the coldest periods of the year. In fact, during the winter, air leakage can account for 40% of a building’s overall heating bill.
Air leakage can also have a significant impact on a building’s envelope. Moisture migration due to air leakage can lead to the corrosion of fasteners, steel studs and other structural assemblies. Moisture carried by leaking air can also damage interior drywall or exterior materials and finishes.
Air tends to move with relative ease into, through and out of high-rise buildings. Wind, mechanical systems and the stack effect — in which cool air enters, heats, rises, then exits above — all contribute. Leaks can happen anywhere, from the underground garage and elevator doors to the exterior walls and roof.
Finding and fixing leaks can therefore result in big rewards. With less energy waste, heating and cooling costs go down. Fewer leaks also means less moisture, which translates to a more durable building envelope, less mould and lower long-term maintenance costs. Additionally, less air transfer increases residents’ comfort, since they will deal with fewer drafts, pests, invasive cooking odours and less noise.
This manual gives information on where, how and why buildings leak. It offers practical advice on how to identify and properly seal the most common types of air leaks. It also provides guidance on prioritizing tasks, selecting materials and performing required work. Property managers, owners and contractors will also find, in this manual, steps for developing air leakage control plans.