Enhanced Energy Performance Modelling for Log Structures
License New Log Wall Insulation Values
As the National Building Code of Canada (NBCC) and other energy codes move toward net zero energy buildings, the BCLTBIA has recognized the need for updated results to assist log homes in meeting these energy performance targets. Within Canada, BC is leading the with the BC Energy Step Code implementation so the need within our province is extremely important.
Over the past couple of years, the BCLTBIA has conducted ASTM C1363 – Guarded Hot Box testing with the National Research Council Canada (NRC) in Ottawa on five log wall assemblies. C1363 measures a real assembly insulation value based on our Canadian northern freezing temperatures. Our results on Western Red Cedar and Douglas Fir log walls are extremely positive and show log walls can be built to exceed insulation targets.
The current NBCC (184.108.40.206) values for log walls are based on ICC 400 published results. These values are based on average log wall diameter, minimum wall thickness, species properties and several other material properties. For example, a log wall built with 16” logs, is turned into a 13.25” thick timber wall. Results for ICC 400 on Western Red Cedar would give this wall an R-value of 19.2. A 16” average Douglas Fir log wall, shows an R-value of 13.4.
New Testing Results
Results from C1363 testing have proven the 16” Western Red Cedar wall, the 16” Douglas Fir wall and the smaller log sizes 8-12”, have results that are 20-40% better than ICC 400.
Using the C1363 results shows a 2-6% point overall home model energy savings in several log home types; the percentage changes based on the design, climatic zone and other home properties.
Essentially, this means even with the same log walls you build, you can show an improvement in the building envelope without further cost of construction. Using these results, it may save your home-owner the cost of upgrading to triple glazed windows, adding external board insulation to gable walls and/or additional roof insulation. In areas that have moved to BC Energy Step Code Level 3 or higher, it may be needed to still use traditional solid logs.
Licensing the New R-Value Results
In order to use the new C1363 NRC results in energy modelling, as a BCLTBIA member you can license the results to use in your projects. You will need to sign the testing Licensing Agreement and your chosen Certified Energy Advisor needs to sign a Non-Disclosure Agreement. The cost of using the C1363
NRC results is based on the following fee schedule:
- Lifetime Membership/Founding Member - $5000
- One year access to report - $1500
- Per project use of report - $500
Funds collected will be used to recoup the cost of initial testing and to provide future testing of additional species. If you’d like to participate directly in the testing (providing sample walls, funding, etc), please contact our office.
Email: [email protected] or call the office toll-free 1-888-720-9212