As part of the research for their new book, The Natural Building Companion:A Comprehensive Guide to Integrative Design and Construction, Natural Builders Jacob Deva Racusin and Ace McArleton used state-of-the-art technology, including infrared photography and blower door testing, to document the thermal and moisture performance of seven straw bale homes in the northeastern U.S. As NBN helped fund and publicize the project, Deva and Ace have shared with us the results of the study, which NBN members are welcome to download here: http://www.newframeworks.com/wp-content/uploads/2011/12/Research-Paper-2011_Final_Complete.pdf
SPOILER ALERT: What they found was that attention to detail makes a huge difference in building performance. Anywhere timber frames or rafters or other structural members break the insulative envelope is a potential problem spot and requires a greater level of detailing to avoid compromising performance. Hidden checking in timber frame members and unsealed joints within the frame can allow significant air infiltration. Consistently across all test cases, the largest sources of air leakage occured in non-straw-bale-wall components of the assembly, particularly in roof penetrations, roof edge detailing, and window-unit-to-rough-opening sealing.
More of this type of research and documentation needs to be done on natural material building systems, especially in an “as built” situation. The thermal performance of a house, especially in harsher climates, has a profound impact on the ongoing ecological footprint of a building, and the comfort and well-being of the people who live there. Our hats are off to Deva and Ace.
Their book can be found at
Ace and Deva are co-owners of New Frameworks Natural Building, a Vermont-based contracting and consulting business specializing in the integration of natural materials, holistic design principles, an intentional process to create high-performance structures of beauty. They also teach natural building courses through the Yestermorrow Design/Build School in Warren, Vermont.