Building a tight home has many advantages, but at least one disadvantage—lack of fresh air. Tight, well-insulated homes need a mechanical solution for adequate fresh-air exchange. In the Nichols’ home, a heat-recovery ventilator (HRV) was installed to avoid mildew and mold buildup and ensure good indoor air quality. The Venmar HEPA 4100 recaptures 80% of the heat in the air being expelled from the building, so that incoming air is preheated—not cold and drafty. The system includes a high-efficiency particulate air (HEPA) filter, removing particles as small as pollen from the air entering the house, something Jim appreciates because he has allergies.