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Ventilation Controller for Improved Indoor Air Quality




Iain Walker and colleagues at Berkeley Lab have developed a dynamic control system for whole-house ventilation fans that provides maximal air quality while reducing by 18-44% the energy spent on ventilation. The system, the Residential Integrated Ventilation Energy Controller (RIVEC), coordinates the operation of a whole-house exhaust fan in response to other exhaust and supply fans in the house and to extremes of indoor-outdoor temperature difference. The system can be used in various climates and programmed according to the size and number of people in a home.

As newer homes have become more airtight to reduce heating and air-conditioning use, they have required more mechanical ventilation to maintain a standard of indoor air quality. These ventilation needs are met by whole-house fans that, in most cases, are operated 24 hours a day and not optimized for energy efficiency.

The RIVEC receives input from exhaust fans other than the whole-house fan, such as those in bathrooms, kitchens, and clothing dryers. When these fans are on, the RIVEC turns down, or off, the whole-house fan because it is temporarily unneeded. An algorithm in the system also slows or stops the whole-house fan at the times of day with the greatest discrepancy between indoor and outdoor temperatures (peak hours for heating or air-conditioning). This further reduces energy waste while maintaining air quality. The algorithm can adjust for the operation of heat recovery ventilators (HRVs) and economizers—devices that, respectively, exchange heat between incoming and outgoing air and draw cool air indoors during the night in hot climates. The RIVEC can be adjusted to decrease ventilation when outdoor pollutant levels are high.

The scientists tested the system in a warm climate (Central Valley, California) in a home with three bathroom fans, a kitchen fan, a dryer exhaust, and an economizer. This field test, reported to the California Energy Commission, demonstrated that the air quality was maintained above the industry recognized standard of the American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE; Standard 62.2, updated in 2007), which has been adopted in several states.

  A schematic of the Residential Integrated Ventilation Energy Controller (RIVEC). The long, green, dotted lines show that each exhaust fan in the home communicates with the controller, which appropriately adjusts the operation of the whole-house exhaust fan.  


DEVELOPMENT STAGE: Bench scale demonstration performed.

STATUS: Published patent application US 2011/0151766 A1 available at Available for licensing or collaborative research.


Inventor Iain Walker and other Berkeley Lab researchers discuss the energy efficient home of the future here.


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