There is a lot of talk about net zero, and a lot of confusion in the mix about house construction models. Here’s what you need to know!
House construction model comparison
Passive house is a model of home construction, whereas net zero is an energy consumption model. These are not the same thing.
The building code that has dictated and guided house construction for decades has never taken into account energy usage. This is a new concern of the 21st century. It’s high time, too!
The only downside right now is resulting confusion, as “net zero” is thrown around a great deal with very loose definitions. In this post, we’ll actually show what energy consumption means across the main home construction models. This will include a fairly commonly used “net zero ready” model which is contributing to the confusion we’d like to help unpick.
Annual energy demand by house construction type
The real story here is simple: we compare the annual energy demand of a Current Code Built (2024) house against an Energy Star Home, a “Net Zero Ready” Home, and a Passive House. The math is clear: if you’re building new, build passive. The cost to build passive is only incrementally more than any other model shared here. The very small increased cost comes in with the secondary layer of the wall system (a bit more material, a bit more labour).
Code Built Home 2024
Base construction: R22 Walls, R32 Roof
Annual energy demand kWh/m2/yr (heat/cool): 125 (16,250 kWh)
Cost of annual energy demand (heat/cool): $1,625
Annual energy demand (daily living) kWh/m2/yr: 85 (11,050 kWh)
Cost of annual energy demand (daily living): $1,105
Total annual energy demand: 210 (27,300 kWh)
Annual energy demand (TOTAL COST): $2,730
Size of solar array: 21 KW
Cost of solar array: $60,000
Energy Star Home
Base construction: 20% better than Code
Annual energy demand kWh/m2/yr (heat/cool): 100 (13,000 kWh)
Cost of annual energy demand (heat/cool): $1,300
Annual energy demand (daily living) kWh/m2/yr: 85 (11,050 kWh)
Cost of annual energy demand (daily living): $1,105
Total annual energy demand: 185 (24,050 kWh)
Annual energy demand (TOTAL COST): $2,405
Size of solar array: 18.5 KW
Cost of solar array: $52,000
“Net Zero Ready” Home
Base construction: 50% better than Code (similar to R2000 or LEED)
Annual energy demand kWh/m2/yr (heat/cool): 60 (7,800 kWh)
Cost of annual energy demand (heat/cool): $780
Annual energy demand (daily living) kWh/m2/yr: 75 (9,750 kWh)
Cost of annual energy demand (daily living): $975
Total annual energy demand: 135 (17,550 kWh)
Annual energy demand (TOTAL COST): $1,755
Size of solar array: 13.5 KW
Cost of solar array: $38,500
Passive House
Base construction: 90% better than Code
Annual energy demand kWh/m2/yr (heat/cool): 13 (1,560 kWh)
Cost of annual energy demand (heat/cool): $156
Annual energy demand (daily living) kWh/m2/yr: 60 (7,200 kWh)
Cost of annual energy demand (daily living): $720
Total annual energy demand: 73 (8,760 kWh)
Annual energy demand (TOTAL COST): $876
Size of solar array: 7 KW
Cost of solar array: $20,000
Sample house assumptions
We’ve assumed a home of roughly 1,600 square feet for these examples.
The heating and cooling energy demand for the Code Built and Energy Star homes assumes a home built to be heated with natural gas. For anyone choosing to heat with electricity (air source heat pump), the R value of the walls for either of these homes would bump up to R30 (a required minimum).
The heating and cooling energy demand for the “net zero ready” and passive house examples is so reduced thanks to a couple of factors. This includes the greater R (insulation) value of the building envelope and the lesser energy demand of the heating and cooling systems used.
The “daily living” energy demand assumes energy efficient appliances for all household appliances, as well as computers, phones and chargers, etc. It also includes hot water heating and the fresh air machine or ERV/HRV used in the most energy efficient models.
Defining net zero homes
Cutting through the noise of “net zero homes” can be a bit challenging. We’ve seen quite a variation on how a “net zero home” is defined.
It’s important to remember that ANY home or building can be made net zero. A net zero building has the ability to make as much energy as it consumes, usually through a solar array. This is why our chart above includes the size and investment cost of purchasing a solar array.
It’s simply going to cost a lot more to net zero a code built home versus a passive house, as we’ve shown. And it’s not just cost — if you want to net zero a code built home, you have to ask if there will be space enough for the much larger solar array required.
For our purposes, a “net zero ready” home conforms to the definition noted above and is roughly 50 per cent better than current building code. “Net zero ready” means the home can be net zeroed based on its construction, but the solar array or systems aren’t yet in place.
Variations on passive house
It is worth noting, particularly for our US customers, that going passive can involve a range in insulation values. Some of our American neighbors just don’t have to contend with the same cold (or heat) extremes.
In this case, while EkoBuilt’s standard passive house shell includes R75 walls and R110 roof, we adjust this based on the home’s location and requirements. Depending on climate zone, insulation values can range as follows:
Inground basements can range from R30 to R45.
Walkout basements can range from R30 to R45 for inground walls, with the walkout wall ranging from R45 to R75.
Above ground wall insulation can range from R45 to R75.
Roof insulation can range from R60 to R110.
Factors for going net zero
As we noted above, going net zero also means you need to be able to accommodate the solar array required.
Many of us live in urban and suburban neighbourhoods where homes are closer together and trees and other buildings create a lot of shade. Unless you build passive, you simply may not be able to have the solar array needed to go net zero. There won’t be sufficient space or solar exposure.
A passive house has such a small energy demand, even a highly shaded house like the one shown here performs extremely well.
This home is certified passive and net zero and makes use of a small 6 kW solar array. This is possible in spite of the home being shaded on all four sides.
And don’t forget: in going net zero, you also need to factor in things like a heating a pool or hot tub, a garage or workshop space, etc.
Building today? Go passive!
We think we can’t make the case any more strongly than this. If you’re building a home today anywhere in North America, it only makes sense to go passive.
EkoBuilt has the most affordable passive house plans with companion passive house building system anywhere in Canada or the US. We have the volume and the supply chain relationships that make this possible. We ship our kit across both countries, and handle full builds in our local area (Ottawa, Canada). Give us a shout to discuss your project!
