Regulated Air Sealing
Air sealing measures such as foaming or caulking around penetrations within a building assembly is one of the simplest and cost effective ways to save energy and increase comfort. Combined with the use of a blower door test and an infrared scan we are able to air seal to a specific target or CFM (cubic feet of air). In new construction this is best done before insulation after all windows and doors have been installed and all electrical and plumbing work "roughed in".
In existing houses without a fresh air ventilation system, this target number depends on a number of factors including occupants, combustion devices, smokers present etc. People generally have an idea of whether their house is "too tight" or "too drafty" because they notice the condensation on windows or feel that draft near the front door. Without a blower door test it's all best guess work. Typically in existing houses when we are insulating an attic we always start with air sealing any penetrations between the outside and the living area. It's these gaps around chimneys or interior partitions for example that contribute to your comfort and money flowing out of your house.
I often refer to air sealing as "low hanging fruit" since it can make a dramatic difference in energy use and comfort and it usually doesn't take an exorbitant amount of time or costly materials. One of the most important forces involved in a heating climate is what is referred to as the stack effect or chimney effect. Hot air rises, eveyone knows this right? Actually it's a bit more complicated as one of the drivers of this stack effect is cold air sinking and creating currents of air that can make a dramatic difference as warm, heated air leaves the thermal envelope up high and cold air replaces it down low. For every cubic foot of warm air that escapes it will be replaced by the same amount of cold air. Occasionally very small air leaks can lead to expensive repairs if they cause a pipe to burst for example but usually air leakage in New England makes it much harder to stay warm in the winter and cool in the summer and therefore continually costs you over the life of your home with decreased comfort. Air seal first and THEN add insulation.