Natural vs. Mechanical and Building Efficiency

Traditionally, building ventilation was achieved through the various crevices and gaps existing in the building envelope. These points of leakage provided natural pathways by which air could freely flow in and out of the building. Combined with other forms of natural ventilation such as doors and windows, limited ventilation was achieved. However, such natural ventilation could not adequately account for occupant comfort and was not the most energy efficient method for air circulation considering widespread use of central air and heating systems. With recent green building programs and more stringent code compliance measures, homes and buildings are built to higher energy efficiency standards. Achieving this requires homes and buildings to be “tighter” to reduce air leakage or infiltration.

To obtain this airtight design, house wraps, differently designed windows and doors, caulks, and other insulating materials are used to create tighter seals for improved energy efficiency. However, these homes and buildings now trap particles and pollutants inside and increase the need to provide mechanical ventilation to replace stale, moist, and polluted air with fresh outside air. In some building code currently written and adopted, mechanical ventilation has moved from just a smart building practice to one that is required to ensure acceptable indoor air quality.