Part #2 - Net Zero Energy: The Next Generation of New Homes
In my post, Next Generation of New Homes a few weeks ago, I gave an overview of a series of changes in the building code for the construction of new homes in Canada regarding Energy Efficiency.
The goal of these progressive building code changes will be to achieve a Net Zero energy standard for new homes (and all buildings) in BC by 2032.
RDC agrees with and is excited about these changes and is working in partnership with a number of key industry partners to build a demonstration home highlighting how a Net Zero Home (a home that produces as much energy as it uses) can be built. This project is not without its challenges in that the home design and orientation is not optimal for a Net Zero outcome; the design was not optimized for solar orientation, rather the home was designed to take advantage of the lot topography and the view corridors.
As you can see from the EnerGuide Home Owner Information label shown at the top, the home as modeled by the energy software Hot 2000, with the solar panels on the roof would produce as much energy as it uses. This satisfies the goal of designing a home that would be considered Net Zero. In our case we are not planning on installing the solar panels right away and so would achieve a Net Zero READY status.
While most of the emphasis on these type of super energy efficient homes is placed on energy saved there are numerous other benefits - From improved thermal comfort to better indoor air quality an energy efficient home will give back in so many more ways.
In today's post I will give an overview of the steps we are using at the foundation stage to improve thermal comfort and indoor air quality at the same time as we make sure we can reduce our energy use to meet the Net Zero standard.
But first, here are some details about our Net Zero ready home:
- 2850 sq. ft. 3 storey south facing home in the Valleycliffe area of Squamish
- R24 Insulated Concrete Forms foundation with R10 additional insulation layer for a total effective R value of 34;
- HP+™ walls, XR series with a combination of 2.5" BASF Waltite Eco spray foam and 4" of Plastifab Neopor graphite EPS exterior insulation for an effective R 35 air tight wall;
- Air tightness target under 1 ACH;
- BASF Waltite spray foam for the roof insulation effective R48 installed by Greer Spray Foam
- Window U value +/- 1.0 metric U
- Dettson Chinook Gas furnace with Alize cold climate heat pump and Venmar HRV
- Solar Panel modeling and design by Panasonic
- Total energy consumption 51 GJ
- Total energy production over 12 months 52 GJ
Foundation Stage Steps - Our approach to basements:
Up until recently basements required very minimal insulation and crawlspaces had no requirement for insulation at all: additionally, traditional concrete foundations only require minimal waterproofing strategies. Unfortunately this can lead to damp moldy smelling below ground spaces that often are turned into living space. I am sure all of us have lived in a home (or suite) that was cold damp and smelly. This condition can not only be uncomfortable but also can make the occupants much more susceptible to colds and flus. This is what we recommend:
Steps #1 - Keep it warm
Here you can see the various layers applied to the foundation wall. The foundation itself is poured using an Insulated Concrete Form and then to bump up our insulation values and improve our air tightness and waterproofing we have added 2" of Halo Subterra provided by Standard Building Supplies, a graphite impregnated expanded polystyrene foam. The ICF foundation blocks have an effective insulation value of R 24, the Subterra will add R10 giving us a total effective R value of 34.
Step #2 - Keep it dry
Concrete is like a sponge and if exposed to water will very quickly wick moisture that can then transfer to interior framing and insulation. The high moisture/ humidity levels then begin to promote mold and mildew and that bad musty basement smell we all know so well!
In the photo on the right, if you look closely, you can see that the base of the foundation/footing itself is wrapped in plastic. This plastic is wrapped under the footing and will be sealed to the interior under slab insulation ensuring that the entire foundation is protected from moisture. The plastic is connected on the exterior with a layer of peel and stick membrane (Nudura) and the whole assembly will be protected by a plastic dimpled membrane designed to eliminate any hydrostatic pressure. Of course, we will have the required perforated pipe as a perimeter drain.
Foundation forming will be complete this week and framing of the revolutionary HP+™ walls, XR series system will begin March 13. Stay tuned for Part 3 - An in-depth look at this new high performance wall system used in the framing stage.
If you are interested in learning more about the benefits of a home like this, or just like to talk high performance housing, please connect with me at firstname.lastname@example.org
Bob Deeks & The RDC Team
Posted: Wednesday, February 22, 2017