Crops for insulation
© Romancito77/Wikipedia
December 2021

Crops for insulation

By Andrea Neumeyer
Effective insulation, good indoor climate, simple production, plus carbon neutrality: new natural building materials using hemp or corn might revolutionize the construction industry.

For decades, huge amounts of expanded polystyrene – aka EPS foam – have been used in house building. It’s cheap, lightweight and has good insulating properties. But EPS foam is not biodegradable and requires complex recycling. Since the construction sector, accounting for 35 percent of energy consumption, is regarded as the number one energy hog worldwide, the building industry is increasingly looking for sustainable, natural construction materials.

Hemp, for example, supplies not just one but two raw materials for house building purposes. The external hemp fiber has been used as an insulating material for years. Hemp fibers are especially well-suited for incorporation in timber construction. With their high insulating properties and ability to absorb and release moisture, they outperform conventional insulating materials by far. Very low energy costs incurred in producing them and good environmental compatibility are additional benefits.

Hempcrete with numerous advantages

In solid-construction projects, the new building material hempcrete – a combination of organic hemp shives and lime as a mineral binding agent – offers numerous advantages. Hempcrete can be used for monolithic types of structures and, due to its strength, single-story buildings do not require a supporting framework. Compared to concrete, the production of hempcrete consumes less energy. When installed, it can absorb moisture and release it again. Another advantage is that hempcrete walls can be rendered directly or lined with timber, which eliminates the need for a multi-layered structure.

Crops for insulation
The production of hempcrete consumes less energy than concrete© Romancito77/Wikipedia
Crops for insulation
Even larger buildings using hempcrete have long become a possibility: in 2016, the Bright Building of the University of Bradford was erected by architects Farrell and Clark as the largest single-leaf hempcrete building at the time© Farrell & Clark Architects
Popcorn as a versatile material

A visit to a movie theater ten years ago inspired Professor Alireza Kharazipour from Georg-August-University in Göttingen with the idea of developing a popcorn-based insulation material. The corn kernels are ground for this purpose, popped open under application of heat and then glued together to form plates. The popcorn foam has better insulating properties than EPS foam but lower flammability as well as good sound insulation characteristics. But popcorn has even more capabilities: initial tests of using the corn product as a substitute for plastics, for instance as chairbacks in the furniture industry, are already in progress.

Crops for insulation
Corn glued together into plates© Bachl GmbH

After its useful life, the corn-based material can be composted, shredded for reuse, utilized to produce biogas or even used as animal feed. Another advantage is the possibility to use corn production waste such as broken cobs in addition to the corn kernels.