According to the Department of Energy, a typical home contains a half-mile of cracks and gaps behind walls and around windows and doors, along with dozens of holes for pipes, vents, ducts, lighting, and wiring.

When these openings do not exist or are sealed, there are reduced drafts, moisture, dust, pollen, pests, and noise.

The energy savings can quickly add up when you think about all the places that hot or cold air can enter or exit your new home.

The air exchange rate is also known as air changes per hour (ACH). The 2012 IECC Building Codes mandates testing and a verified maximum air leakage rate of 5 ACH in Climate Zones 1-2 and 3 ACH in Climate Zones 3-8. All new construction is required to be both visually inspected and pressure tested. This requirement makes new homes much tighter than previous codes.

The Code also calls for a permanently affixed certificate posted on or near the electrical panel showing the results of whole-house pressure tests in addition to the predominant R-values of insulation.

How Air Infiltration is Measured

A blower door test is done to measure the airtightness of a building enclosure. The best time to perform a test is after the building has been enclosed and before the interior is finished. This allows a chance to seal potential openings before the interior and exterior finishes are installed.

A blower door consists of a frame that blocks a door, with a mounted fan, and equipment that can measure air pressure and air flow. A technician sets up the equipment and the fan pushes air out of the house, depressurizing the interior. This causes air to be pulled in through any cracks, gaps or other overlooked areas. The fan is adjusted to create a difference of 50 Pascals between the inside and outside. This allows the leakiness to be measured.

It is important for those considering a new home because:

╡ Reduced energy costs

Energy savings for heating and cooling is the result of reducing the air leakage into and out of the home.

╡Avoiding Moisture Condensation Problems

When air moves, it takes moisture with it. This moisture can gather creating condensation and put the home at risk for mold and decay.

╡ Improved Comfort

Less air leakage means there is a reduction in drafts, noise, moisture and pests.

╡Right-size for HVAC equipment

Understanding the ACH of a new home can create a better understanding for having the right size of HVAC equipment and can reduce peak heating and cooling loads.