I live in an area that is subjected to extreme weather for the majority of the year. We get about six months of winter, with temperatures down below zero and continuous snowfall. During the summer months, the temperature climbs into the high eighties and the humidity is unbearable. Spring and fall are typically wet, chilly and windy. There is rarely an opportunity to shut down the heating and cooling systems and simply open the windows. Because I run either the furnace or the air conditioner most of the time, the majority of my budget goes to paying energy bills. I’ve gone to great lengths to seal up every hole and crack in the house and prevent energy waste. Along with increasing the level of insulation in the walls, ceilings and attic, I’ve caulked, weatherstripped and installed ceiling fans. I’ve invested in a state-of-the-art forced air furnace and central cooling system with adaptable-speed technology and zone control. Every year, I have the furnace and air conditioner professionally cleaned and tuned by a licensed HVAC contractor. Approximately every five years, I hire the HVAC contractor to inspect, clean and seal the duct system. My efforts have resulted in a tightly sealed and energy efficient thermal envelope. My heated and cooled air is contained within the house, and no outside air is allowed in. While this saves me money and improves comfort, it’s bad for indoor air quality. The same stale, stuffy air is trapped inside and continually circulated by the heating/cooling system. The air is actually a health threat. To combat this problem, I’ve installed a ventilation system which brings in fresh, outside air without energy losses.