HVI's Fresh Ideas Home Ventilation & Indoor Air Quality Guide Articles

Whole-House Comfort Ventilators

Simple cooling for the entire home.

Whole-house comfort ventilators can provide an effective way to improve comfort in the entire house without air conditioning. If the home has air conditioning, whole-house comfort ventilators may help reduce energy costs because the air conditioner doesn't have to operate as frequently.

Available in various models to fit any home, whole house comfort ventilators allow the house to breathe freely when summer breezes are not strong enough to cool the house. A properly located whole house comfort ventilator draws cooler outside air through screened windows and doors, pulls it up through the house and exhausts it, usually through static vents in the attic.

With traditional, high-volume whole-house comfort ventilators, the result is a cooling breeze throughout the house that can lower skin temperature by two to eight degrees – a significant cooling effect. In the evening, the fan provides relief from the day’s heat by flushing the house with cool night air as the outdoor temperature drops.

How they work:

  • In the early evening, or when the temperature outside is less than the inside temperature, the homeowner opens the windows and turns on the fan.
  • Later in the evening, the homeowner closes the windows and doors in unoccupied areas and opens the bedroom windows so the air flows only through the bedroom areas.
  • In the morning, the homeowner opens the windows and lets the fan draw in cool air until the outside temperature rises, at which time they turn off the fan and close the windows and doors to store the cool air indoors. Closing the drapes, especially on the sunny side, also helps keep the house cool.

Large, traditional whole-house comfort ventilators generate enough airflow through the house to create a perceivable "breeze" that cools both the house and its occupants. As houses have become more energy-efficient with smaller heating and cooling loads, smaller whole-house comfort ventilators can effectively cool the mass of the house quietly with low energy cost. These efficient units usually have motorized and insulated doors and can be used to meet cooling loads and the requirements of many energy-efficiency programs.

A whole-house comfort ventilator can reduce air conditioning operating costs and help prolong compressor life by ridding a house of hot air before the air conditioner is turned on.

Mounting configurations
Whole-house comfort ventilators are mounted in one of three ways:

  • Horizontally – Suspended on joists over a ceiling opening in a central location and concealed by a ceiling grille or a shutter with automatically opening louvers.
  • Vertically – Usually installed in a gable end with a motor-operated ceiling grille in a central location. You can install smaller fans in a wall of the living space.
  • Through the wall or roof in houses that have no attic.

Note: For these systems to work properly, there must be adequate openings from the attic to the outside. Openings should be provided equal in "clear" area to the airflow in CFM of the fan divided by 750. For example, a whole-house comfort ventilator with a 3,000 CFM capacity should have openings from the attic to the outside equal to a clear four square feet.

Whole-house comfort ventilators are modular, requiring only minimal on-site assembly; manufacturers usually provide templates for cutting ceiling, gable or wall openings.

Control options
Timers and thermostats are available for starting and shutting off fans automatically. Two-speed and infinite-speed controls are available on some models, and other models include remote or "smart house" controls.

Note: To prevent negative pressure and back drafting of combustion appliances, automatic controls must not be used when windows are closed.


Bookmark and Share