If you took an infrared camera and looked at your father’s house on a cold or hot day you would probably see it had many leaks to the outside. When your father’s house was built, due to the low energy costs, leaking, un-insulated walls were not considered a problem. Leakage and lack of insulation in pre-1975 housing resulted in the need forlarger heating ventilation and air conditioning (HVAC) equipment. In the 80’s, higher energy prices resulted in many homes having their insulation, doors, and windows upgraded. That is when the problems with toxic air in homes started becoming widely noticed. Newspapers sensationalized the worst cases and the HVAC industry began looking for solutions applicable to the residential housing market. Today we have some recommended solutions that seem to resolve the air quality problems related to tight home construction.