Advanced Energy Technology Group
Center for Energy Research

Thermal Sciences

Energy Efficiency Research

The current emphasis of the Energy Efficiency program is to develop improved energy recovery ventilators. The program is funded by the California Energy Commission, Energy Innovations Small Grant Program. Our progress reports are located here.


Modern, energy efficient homes and office buildings are well-insulated from the environment to prevent heat loss or gain. Such well-sealed buildings also prevent air exchange. Poor air quality in well-insulated buildings can result in "Sick Building Syndrome". If windows are opened to provide air exchange with the outdoors, the building may lose or gain a considerable amount of heat depending on the outside conditions.

To prevent heat loss (or gain), heat recovery ventilators (HRV) or energy recovery ventilators (ERV) use air-to-air heat exchangers to retain building heat (or cold). HRV's only transfer sensible energy (heat) while ERV's are total heat devices which transfer sensible energy and moisture.


According to the American Society of Heating, Refrigeration, and Air Conditioning Engineers (ASHRAE), the current guideline for fresh air ventilation is 0.35 air changes per hour (ACH). This works out to 8.4 air changes over a 24 hour period.

The R-2000 program in Canada certifies homes to meet efficiency and health criteria. All R-2000 homes use an HRV or ERV to provide a minimum of approximately 8 air exchanges per day. Some states in the U.S. are beginning to adopt the Canadian R-2000 standards.


Current HRV/ERV costs for home use (approx 200 CFM) are in the $900 to $1600 price range and use 100 to 200 Watts of power to operate. A typical 2000 sq ft home needs about 120 CFM of flow to provide 8.4 air changes per day.

Click here to see: How an ERV works in a home


We seek to improve the heat exchanger effectiveness in an HRV by using a high conductivity porous media. See the advantages of using porous media in heat exchanger applications here: --Link to Porous Media section of this site--

By using a porous media to enhance heat transfer, we hope to show that:

  1. porous media can be engineered at the microstructural level to optimize heat transfer
  2. porous media heat exchangers improve on current technology
  3. porous media can reduce the cost of current technology devices


The simple process loop has an easily removable test article section for flexibility in testing different types of porous media.

Click to view a larger image:

Sources of porous media: