[Source: Mother Earth News]
Sealing air leaks and adding insulation are two important ways of conserving energy in your house. But some homes may be so tightly sealed that
they don’t allow in enough fresh air for a healthy environment. To allow adequate fresh air into your house (without using extra energy to heat or cool the fresh air) you might need some type of ventilation system. Energy-recovery ventilators, also known as air heat exchangers, are mechanical ventilation systems that remove stale, polluted air from homes and replace it with fresh outdoor air.