We’ve built more than one passive home with a woodstove and share in this post what you need to know if you’re considering a woodstove in a super airtight home.
Heating with wood
There is something very primal about the heat and light from a wood fire. Many of us can’t imagine a home without it.
Heating with wood is also a great path to sustainability. If you live in a place where a wood supply is out your backdoor, it’s a great renewable resource.
It also begins to make a lot of sense when heating a super energy efficient home — you won’t need a lot of wood to stay warm throughout the cold months. In the example shared here, only about a face cord and a half for the whole season.
The owners of the Galetta house plan shown here opted for an old (Findlay) woodstove with no fresh air supply so they simply keep a window tilted slightly open. As far as the owners are concerned it’s the best of both worlds having wood heat and fresh winter air at the same time.
Galetta House Plan
Fresh air supply options
We just installed a woodstove in a Fiddlehead 3 project that is still under construction. The wood stove has a fresh air inlet so the homeowners won’t have to to keep a window open during operation.
An alternative to using a wood stove with no fresh air inlet is to integrate what’s known as a make-up air system into the HVAC design. We share a video here on this concept.
It is important to note with any of these installation options that a little energy efficiency will be sacrificed. Ultimately, there is an open hole in the wall or roof when the stove is not in operation, creating a break in the airtight system of a super energy efficient home.
However, wood as a primary heating source is absolutely possible in an energy efficient passivehouse and for anyone keen to go off-grid, we believe it to be a good inclusion for any project.
Make up air systems
A make up air system is designed to pull in fresh air from outside to make up for air that can’t be recirculated in the home or building. This video from Cambridge Air Solutions is a good introduction (it focuses on an industrial building, but the principles are the same).
Make up air systems are normally separate from the main (HRV/ERV) heat recovery fresh air system as the fresh air system works continuously and is “balanced” (having incoming supply air equal to exhaust air).
The main residential systems do not have positive/negative pressure indicators to compensate for the major exhaust from a woodstove, so having a separate make up air system is integral for effective air management when draft-induced woodstoves are used.