For the last decade or so, the trend has been to build tighter and tighter houses in an effort to reduce air and moisture infiltration. The idea here was to make homes more energy efficient. The problem, as everyone knows, is that sealing houses has resulted in poor ventilation. When a house can’t “breathe,” there is more of an opportunity for mold to grow, moisture can condense on windows, people may become sick more often, and a musty smell may be noticed.
The State of Minnesota recently responded to this issue by mandating mechanical ventilation in every new residential building. Its hope is that a constant flow of fresh air will alleviate many of the problems associated with tight houses. Meanwhile, ASHRAE Standard 62.2, while not final, is expected to require some form of mechanical ventilation in new homes.