Foam panels can turn old homes into energy-efficient homes of the future

GOLDEN, Colo. — Snow crunches underfoot as I walk around what was once a humble shipping container. Researchers have now turned its facade into that of a tiny house, complete with two windows and a door. The interior? Unfurnished. With this model home, it’s not what’s on the inside that counts, but what’s on the outside: light beige panels of energy-saving insulation.

On a recent January morn, Chioke Harris, senior research engineer at the U.S. National Renewable Energy Laboratory, shows me these prefabricated foam panels, their faces textured like stucco. They’re made by manufacturer Dryvit from expanded polystyrene — a hard foam that doesn’t yield at all under my curious fingers — which can insulate a building like a tea cozy or an ice cooler.

The building sector, including construction and day-to-day energy consumption, accounts for more than a third of annual U.S. greenhouse gas emissions, according to the U.S. Department of Energy. To reduce their carbon pollution, we need to get buildings off gas and electrify them, as well as reduce the amount of energy they use.

Energy retrofits that combine both of these decarbonizing strategies, especially by replacing inefficient fossil-fuel HVAC systems and insulating buildings, can slash the energy required to heat and cool them by 75 percent or more, the DOE estimates.

Energy codes first began to take effect across the U.S. in the early 1980s, according to Harris. Many buildings constructed before that time weren’t built with sufficient insulation, especially in their exterior walls.

It can be relatively easy and inexpensive to add insulation to the exterior walls of buildings with wood frames — one common method blows the insulation material into holes drilled into the wall cavities between the wood studs. But that doesn’t work with masonry buildings made of brick, stone or concrete. Of those, about 20 million pre-1980 units exist, Harris estimates.