Air Infiltration - A Major Contributor to Residential Energy Loss

Many people are led to believe that when energy bills get out of control, the root cause is lack of insulation.  Lack of insulation is, in fact, a major contributor to high energy bills but a more accurate conclusion to high home energy bills is that the home is leaking - conditioned air is leaving the home from the inside or unconditioned air is invading the home from the outside.  Air infiltration, not just lack of insulation, is a leading cause of wasted residential energy.  A common misconception is that air leaks are most common around windows and doors. But a recent study from Michigan Technical University sheds more light on the sources of household air leaks. 

Floors, ceilings, and walls are the most common areas for air leaks (accounting for 31% of all air leaks) greatly surpassing other areas of the home. These areas, which make up the majority of what is referred to as the "building envelope", are where most air leaks  occur usually due to poor application of insulation. Gaps and voids in insulation installation reduce the effective R-value of insulation.  Remember the “R” in R-Value stands for resistance to heat flow and the laws of physics say that heat moves to cold AND that it will follow the path of least resistance. So it’s not enough that you have the right amount of insulation – there can be no gaps or voids - or heat will find the easiest way into (or out of) your living area. In fact, a properly insulated 1,000 square foot attic with a 10 square foot gap in its insulation (think attic stairs or whole house fan) reduces an R-30 insulation level to R-23!!  

The next leading area of air leaks is the HVAC duct system (15%). Very few duct systems are tested after installation and air leaks at duct connections to grills/registers and the central HVAC unit are common.  Such leaks are invisible to the naked eye.  The first priority to control air leaks in the duct system is to seal leaks that are in unconditioned attics or other unconditioned areas such as unfinished basements or crawl spaces.  Duct leakage in conditioned space (ie interior walls), although not optimum, is not considered an "energy penalty".  

Fireplaces come in as the number three area for air leakage (14%) as most fireplace dampers don’t fit tight and heat/cold either comes in or out - once again following the path of least resistance.

Plumbing is next (13%) - but plumbing as a source of air leakage?  A bit misleading but they’re talking about holes made to accommodate plumbing pipework including chases and holes in the building structure (usually from attic to basement) to make room for the plumbing which create another void in the insulation. 

Air leaks around windows (10%) and doors (11%) are pretty self-explanatory- they’ve got to fit tight in order to prevent air leaks.

Lastly, fans (venting-type fans), dryer vents and electrical outlets contribute a small (6%) yet surprising amount of air leakage. 

The good news is there are solutions for all these air leak sources. But the first step is to get an energy audit of your home by a certified inspector.  They can find and explain the causes of your high energy bills.  Don't be duped by salesreps trying to sell the latest energy efficient HVAC systems or next generation window.  There's usually a more logical explanation as to why your energy bills are rising.  Finding and sealing air leaks is the best (and often cheapest) way to reduce wasted energy and control your energy bills.