Build A Super Energy Efficient Ecolog Log Home?
I have a passion for building with wood - I love the smell and look of it and it creates warm and inviting living spaces. That's why I started designing and building Ecolog log homes in 2009. At the same time, I am passionate about environmental aspects, and I worry a lot about climate change. Over the last years, I took several trainings about energy efficiency in construction, including a Passivehouse training.
Log homes can have many environmental benefits. For our Ecolog homes we use second growth Hemlock harvested and milled on Vancouver Island. The trees sequester a lot of carbon for the lifetime of the homes. The harvested areas are replanted and grow new trees - taking more CO2 out of the atmosphere. Therefore, wood as a building material is a natural and sustainable choice.
But wood is not the best insulator. Many modern materials like mineral wool or various foam products have way higher insulation values.
Initially, I wanted to use our Ecolog concept as a basis for our new home, and add additional insulation to the log walls (a double wall on the inside of the log wall) to achieve higher energy efficiency. While this may sound simple in the beginning, when I tried to figure out all the nitty gritty details on how to construct such a building envelope, I found lots of potential risks. The key issues result from the fact that log walls shrink and move, while the added "double wall" with insulation would not. One important aspect for energy efficient buildings is that the building is as air tight as possible, and ventilation is provided by energy efficient mechanical systems. Creating an air tight structure, while having a shrinking and moving log wall, would be very challenging to say the least.
Our "standard" Ecolog homes can achieve the energy efficiency required by the Building Code (at least in the moderate and warmer areas in Canada) without using a double wall with extra insulation. We can achieve this by adding more insulation in the "non-log wall areas" (roof, basement, gable walls), thereby offsetting the reduced insulation of the log walls.
After lots of research and discussions with building envelope specialists, I decided against using a log home as a basis for our new home. Energy efficiency was more important for us than the "look-and-feel" of a log home.
Once that decision was made, I did some more research to find the "right" approach for our home, and settled on SIPs (structurally insulated panels) for the main level walls and the roof, and ICF (insulated concrete forms) for the basement walls. To accommodate my love for wood, I added lots of timberframe and wood cladding to the overall design, which is detailed in the Design section of this article.