How to Keep Buildings Cooler With a Wood-based Foam

Summertime is almost here, a time when many people try to beat the heat. But running air conditioners constantly can be expensive and wasteful. Now, researchers reporting in ACS’ Nano Letters have designed a lightweight foam made from wood-based cellulose nanocrystals that reflects sunlight, emits absorbed heat and is thermally insulating. They suggest that the material could reduce buildings’ cooling energy needs by more than a third.

Although scientists have developed cooling materials, they have disadvantages. Some materials that passively release absorbed heat let a lot of heat through to buildings under the direct, midday sun of the summer months. And other materials that reflect sunlight don’t work well in hot, humid or cloudy weather. So, Yu Fu, Kai Zhang and colleagues wanted to develop a robust material that could reflect sunlight, passively release heat and keep wayward heat from passing through.

The team calculated that placing the foam on the roof and exterior walls of a building could reduce its cooling energy needs by an average of 35.4%. Because the wood-based cellulose foam‘s performance can be tuned depending on weather conditions, the researcher say that the technology could be applied in a wide range of environments.