Paying attention to the various layers in a building envelope is critically important for ensuring air tightness and moisture management—and can be attractive, too.
Ducting for our HRV, electrical wiring, recessed lights, and plumbing fit into this access ceiling. Click to enlarge.Photo Credit: Alex Wilson
Air leakage and the integrity of insulation in energy-efficient houses is a huge issue—more significant than many people realize. We can have the best of intentions with lots of insulation, but if we leave it leaky or include details that compromise the integrity of that insulation the home’s energy performance can be severely affected.
Take recessed ceiling lights, for example. From a design standpoint, they’re great, since the light source is roughly flush with the ceiling and all of the mechanism is hidden in the ceiling above (in recessed cans).
In a house with an unheated attic (insulation in the attic floor—which is the ceiling of the floor below) or with an insulated, sloped cathedral ceiling (roof), if we install recessed cans into that ceiling we’ve created a significant pathway for air flow and compromised the insulation. This is the case even with recessed lights rated for “insulation contact,” those IC-rated fixtures are far better than older models that required a significant air space surrounding the lights, but they still result in significant air leakage.