Part #3 - Net Zero Energy, The Next Generation of New Homes
Last month I posted the second installment in our series on Net Zero Energy homes, Part 2 - Net Zero Energy, The Next Generation of New Homes. In that post I gave 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.
Today, I am going to focus on the wall systems and insulation we will be using to achieve the insulation values required to build a home that can produce (with the use of solar photo voltaic panels) as much energy as it uses.
When considering building a home that is designed and modeled to produce as much energy as it might use it is very important to reduce energy use as much as possible; the biggest energy demand in a Canadian home is for heating and cooling, so it is important that we design and build a home that is air tight with very good insulation.
The wall system that you choose therefore has a big impact on your energy consumption. When RDC looked at the new BASF HP+ wall System we knew we had found the right formula for exceptional insulation performance and building air tightness.
The BASF HP+ advanced high-performance wall system uses the following products:
- WALLTITE® - a spray foam insulation and air/vapor barrier material sprayed on the inside of the exterior walls and roof
- Neopor® - a graphite-enhanced rigid thermal foam insulation applied to the exterior of the framed walls
- MasterSeal® NP1™ - a polyurethane sealant used to seal all the exterior framing pieces where they connect
How does HP+ help make a home better? In addition to energy reduction, a high performance wall system will also provide the following benefits:
#1 - More Comfortable - helps prevent air leaks from outside, improving overall comfort.
#2 - Improved Indoor Air Quality - A tighter home envelope contributes to lower levels of humidity, dust and pollen inside the home.
#3 - Durability - Reduced air leakage improves moisture control and increases the homes durability.
#4 - Strong - Walls with increased load resistance.
The HP+ wall, at 1st glance, looks much like a conventional framed wall, Until you look closely! Rather than a typical 2X6 stud this system uses a 2X4 on a 2X6 top and bottom plate with a 2" horizontal strapping (to make up the difference between the 2X4 stud and 2X6 plates). This significantly reduces the thermal bridging typical of a conventional stud wall, as we now only have a thermal bridge where the strapping connects to the 2x4's. We use 2.5" of Waltite spray foam on the inside of the assembly to seal between the strapping and the 2x4 studs.
The NP1 is used to seal all the framing connections, studs to plates, plates to floor etc. These 2 elements combine to give us our air tight seal for the walls.
So you might be thinking that 2.5" of spray foam does not give us very much insulation and you would be right. We would now have an effective R value of about 12 - a long way off of where we need to be. This is where the Neopor ridged insulation comes in. We will use 4.5" on the exterior of the home giving us an additional R20 for a total R32. This is right where we need to be for our climate zone to achieve or energy reduction standard to achieve a Net Zero Ready energy footprint.
If you are interested to learn more we will be having an open house at 38580 High Creek Dr. in Squamish April 29 & 30 and May 6 & 7. Come on by and learn more about building a high performance home.
Mike Holmes will be on site on April 29th!!!!
Bob Deeks & The RDC Team,
Posted: Sunday, April 02, 2017