Energy-Efficient Wood Wall panels
Design professionals face many decisions and options when choosing design approaches and materials that meet today’s more stringent energy codes for light commercial and multifamily construction. The variety of primary construction materials that can be specified differ between regions and cities based on climate zone, product availability, and historical preferences. As the energy codes have become more stringent, the insulation requirements for different climate zones can also influence changes in how exterior walls are constructed. Because construction materials can vary greatly in terms of energy performance, it is increasingly important to recognize the thermal performance characteristics of the specified products in project design.
Wood naturally has a higher thermal resistivity compared to steel or masonry, making it a superior product for improving energy efficiency when used in wall assemblies. Wood studs have nearly four times the thermal resistance of steel studs or masonry blocks: A nominal 2×4 stud has an R-value of 4.38, whereas a 3-1/2” cold rolled steel stud has an R-value of 1.34, and an 8-inch nominal concrete masonry unit (CMU) has an R-value of 1.11. The 2015 International Energy Conservation Code (IECC) recognizes this difference and requires continuous insulation on steel and CMU wall assemblies.
Some erroneously assume that the use of steel and concrete masonry wall systems with continuous insulation (c.i.) provides a wall superior in energy efficiency to wood framed construction without continuous insulation. This assumption is based on a misconception that continuous insulation mitigates the insulating deficiencies of steel framing and CMU walls by neutralizing the significant thermal bridging in non-wood structures.
Wood construction consumes minimal energy. Wood is light and easy to put together on site. Foundations are minimized. Transport and construction require less energy.
Buildings with wooden panels are more energy-efficient
Wood is a natural thermal insulator. Using wood helps to save energy over the life of a building, as its cellular structure provides outstanding thermal insulation: 15 times better than concrete, 400 times better than steel and 1 770 times better than aluminum. A 2.5cm timber board has better thermal resistance than an 11.4cm brick wall. Wood’s low thermal conductivity means 90% of the insulation value can be realized, with only 10% lost to thermal bridging. Timber structures from frame walls to CLT panels provide cavities for additional insulation materials to meet energy regulations. This means thicker walls and more insulation materials are required for steel, concrete, or masonry structures to achieve the same level of thermal resistance.
Unlike solid concrete or masonry structures, wooden walls, floor joists, and roof joists inherently provide space for fibrous insulation, the most economical way to achieve better insulation. Application of mineral insulation is a standard element of any wood construction project. It is conducted with minimal additional labor or material expense and provides significant returns. Wood’s low thermal conductivity means 90 per cent of the insulation value can be realized, with only 10 per cent lost to thermal bridging. Wood structures can also be readily insulated on the exterior or interior if additional energy savings are desired.