Air Leakage Introduction

Air Leakage Introduction

Air Infiltration can account for 5-40% of conditioning costs. Reducing air infiltration can be difficult, but is widely considered to be the first and most important step towards managing your home's energy and comfort. Air infiltration is controlled by what is referred to as the air barrier of the home. The thermal boundary consists of the air barrier and insulation barrier. An energy efficient home has its air barrier and insulation barrier touching and continuous.

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The main goals of reducing air infiltration are:

  • Save energy.
  • Increase comfort.
  • Reduce "wind-washing" of insulation
  • Provide cleaner indoor air
  • Help reduce moisture migration

In the early to mid 1900s, engineers estimated building leakage by measuring cracks between joined building materials. Little did they know, the air infiltration story went much deeper than that. The energy crisis of the 1970s started to pour funding into researching home energy management. Out of that research came a greater understanding of building infiltration and the invention of the blower door (pictured above), a modern, more accurate way of measuring building infiltration. Click here for a 1979 New York Times expose on the "Princeton House Doctors."

Air infiltration is the main mode of fresh air ventilation in existing homes. For that reason, it is important to make sure you don't seal your home too tight for health and safety reasons. In new construction, it is general practice to seal the home as tight as possible and install mechanical ventilation for more precise control of air infiltration and energy savings.

In later posts, we will discuss how to diagnose and measure your air infiltration, common problem sites for air infiltration in your home, methods and materials used for sealing air leaks, and some more of the scientific principles behind air infiltration