Is Cordwood Masonry Construction Energy Efficient?

High Thermal Mass

Cordwood masonry walls are built using a combination of wood and organic materials, which provides high thermal mass. This means the walls absorb and release heat slowly, reducing temperature fluctuations and maintaining a relatively consistent indoor temperature. According to the Cordwood Construction Guild, a well-insulated cordwood masonry wall can achieve R-values of up to 20-30, comparable to or even exceeding those of insulated concrete forms (ICFs). This high thermal mass also allows cordwood masonry structures to be used as a thermal battery, absorbing excess heat during the day and releasing it at night.

Insulation and Air-Tightness

While cordwood masonry walls have high thermal mass, they often require additional insulation to achieve optimal energy efficiency. This can be achieved through the use of insulation materials such as fiberglass, spray foam, or recycled denim. It’s also essential to ensure the wall is air-tight to prevent heat loss. This can be achieved through the use of a continuous air barrier, such as a layer of plastic sheeting or a liquid-applied membrane. The Cordwood Construction Guild recommends a minimum of R-10 insulation in the walls and R-20 in the ceiling to achieve optimal energy efficiency.

Building Orientation and Design

Building orientation and design also play a crucial role in the energy efficiency of a cordwood masonry structure. The building should be oriented to maximize passive solar gain during the winter months and minimize heat gain during the summer months. This can be achieved through the use of overhangs, awnings, and carefully placed windows. The design should also take into account the natural ventilation of the building, providing opportunities for cross-ventilation and natural cooling during the summer months.