Why Airflow Matters

When air moves into, out-of, and through your house, in transports "hitch hikers" - heat, moisture, and particulates. A primary goal of building performance is to have control over this airflow, thus having control over the hitch hikers.

Leaky buildings allow air to randomly flow into and out of the walls, floors, and ceilings.

This random airflow can deposit its hitch hikers within the structure, often leading to mold growth, wood rot, and deteriorating air quality.

By tightening up the building envelope and eliminating this random, uncontrolled air leakage, greater control over the quality of the living environment can be achieved.

This also creates a more efficient home, that no longer heats the neighborhood.

Air Leakage Affects Performance

The "stack effect" refers to the concept of warm air rising through the house, much like a chimney. Air comes in the bottom (negative pressure), rises through the house, and then leaves through the top (positive pressure).

As the warm air rises, it wants to push out of any hole it can find in the top of the house. Here is an example of a can light acting like a chimney - letting the warm air escape from the house directly into the attic.

As air leaves the house through the top, replacement air enters through holes in the bottom of the house. Typcially these holes are connected to spaces that have a negative affect on air quality. Here is a common hole around a plumbing pipe over a crawlsapce. This hole allows moisture and contaminants to enter the house.