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Lichen could eventually cover your home or office. The soft green living organisms would grow on a structure set apart from the wall, preventing mold from forming in the building materials and acting as a humidity buffer that could save energy and promote air quality. At least that’s Brenton Kreiger’s hope.

Kreiger, an architectural engineering PhD student in is researching lichen for its application as a moisture buffer.

Lichen is a symbiotic relationship of fungi and algae – not a plant. While plants offer benefits, they also add lots of humidity to the air and burden air handling systems. Lichen do not add humidity and have significantly lower maintenance costs and time demands around upkeep compared to plants. Best of all, they act as a great moisture buffer said Kreiger.

“In the past people haven’t considered indoor surfaces as a moisture buffer,” Kreiger said. 

A moisture buffer is a material that absorbs excessive moisture or releases moisture when needed, lowering the variation in humidity throughout the day. The proper material can help keep humidity in an ideal zone. Those that absorb a lot of moisture are best. 

“Wood has a decent moisture buffering value,” Kreiger said. “But living materials can absorb up to two thousand percent of their dry weight in moisture.”

Most building materials do not act as efficient moisture buffers, especially when finished with sealants and paints. Currently, humidity control is accomplished through expensive and energy intensive mechanical systems. Lichen offer a cheap alternative to that model.

“When you’re coming up with a building solution it needs to save money,” Kreiger said. “Through saving energy is where you save money.”

There are other benefits to covering the walls with lichen. The organisms can sequester carbon dioxide and pollutants for example and some can act as biological toxicity indicators by changing color.

“You can measure how much pollution there is in your building by measuring how much the lichens are accumulating,” Kreiger said. “Whenever you add a living material to these processes, you’re going to get CO2 and air quality benefits as well.”

Kreiger would eventually like to come up with a practical solution and product that can be utilized on a large scale. For now, he is working on the preliminary questions. How much lichen would you need? What would a structure housing the lichen look like? What ventilation rates are necessary? What room volumes would it work best in?

“We’re at the very beginning,” Kreiger said. “The very beginning.”