Energy Efficiency Retrofits Can Cut Mold, But Ventilation Is Also Key

September 17th 2020
Workers inside a building open vents in ceiling.

Air sealing and insulation, which are common elements of energy efficiency upgrade packages, come with a bonus: In addition to saving energy, they almost always cut dampness and mold.

This latest research comes from a new publication from the U.S. Department of Energy's Lawrence Berkeley National Lab (Berkeley Lab). However, the paper also found that levels of some indoor air pollutants increased when ventilation was not added.

Researchers led by William Fisk, a senior scientist at the Lab who recently retired, evaluated a variety of impacts on indoor air quality from these residential retrofits by extracting data from 36 studies described in 44 papers, plus two reports. Their findings point to significant benefits that extend beyond the energy savings associated with making homes less leaky, and they also highlight the need to consider ventilation.

Energy efficiency retrofits are desirable because they help lower utility bills and reduce greenhouse gas emissions in buildings. However, they can also affect indoor air.

"We wanted to see whether there were consistent changes in environmental quality inside the home as we improve energy efficiency," said Rengie Chan, a research scientist at Berkeley Lab and paper co-author.

In addition to the decreases in dampness and mold, the study found that occupants reported feeling more comfortable with the indoor temperature after energy efficiency improvements, and they usually felt better in terms of general health and mental health.

However, the researchers caution that these improvements in comfort were subjective, self-reported outcomes rather than objectively verified results. The review also found indoor radon and formaldehyde concentrations tended to increase after retrofits that did not add whole-house mechanical ventilation.

"A more airtight home means less air flow," Chan said. "When these retrofits are performed, proper ventilation is required to make sure pollutants such as formaldehyde are being controlled."

The paper authors pointed to a need for more research. Most of the data came from studies in the U.S. and Europe, so retrofit results for other regions, particularly in warm, humid climates, should be gathered. They also cited a need for newer, better data on indoor pollutant concentrations and objective health outcomes.

The study, "Association of Residential Energy Efficiency Retrofits with Indoor Environmental Quality, Comfort, and Health: A Review of Empirical Data," appears in the journal Building and Environment. Funding for the work came from the Department of Energy, the Environmental Protection Agency and the Electric Power Research Institute.