Homes burn through a staggering 21% of the energy used in the United States. Much of that energy is spent heating and cooling your home, and unfortunately, it's also spent heating and cooling your backyard and front porch through leaks and holes in your building envelope.
Although some of the air leaks in your home are visible to the untrained eye — around old and untreated doors and windows, for example — much of the average home's air leakage takes place in areas you don't see. Stack Effect, or Chimney Effect, is the process by which cold air infiltrates the basement through leaks and cracks in the foundation and walls, and begins rising. Through structural defects, holes in the ceiling, recessed lighting, leaky duct work, the plumbing stack, the furnace flue, or a poorly sealed attic floor, the warm air makes it to the attic despite possible existing insulation. If attic ventilation is insufficient, the end result could be the formation of mold. Utilizing the whole-house approach, our home performance upgrades almost always include air sealing work and we generally focus on the basement and the attic floor in order to minimize the stack effect, and thus minimize unwanted air movement throughout your home.
Perhaps equally important, air sealing is crucial for maximizing the performance of insulation, the other major component of your home's building envelope. The R-Value of insulation is determined under the assumption that there will be no air infiltration throughout the insulation — it assumes that there will be adequate air sealing around the insulation. Once insulation is left exposed to air movement (air moving up through your attic floor, for example), R-Value decreases.
Air sealing often yields the greatest return on your investment in terms of energy savings.