Avoiding toxins is a good first step but adequate ventilation is also important. A balanced high efficiency heat recovery ventilation system is essential in a well sealed high performance house. Healthy air can be maintained with about one complete air change every three hours (An “complete air change” means exhausting the complete air volume of the house and replacing it with fresh outside air). The system must be balance (air in = air out) to assure that no toxins are being drawn in through the walls and to keep moisture from being deposited within the wall structure.

A ventilation system must have at least three levels of operation. The normal setting is when occupants are in the house and there is a nominal level of toxins and moisture being created. A high setting will help to clear higher levels of odours, toxins and moisture. A low setting is also essential to avoid over drying of the house when occupants are away. A sophisticated ventilation system can sense high carbon dioxide and moisture levels.

A ventilation system, like anything mechanical, needs to be monitored and regularly serviced. The system needs to have filters cleaned at least twice a year. The system needs to be checked for balance periodically.