How much does it cost to build an energy efficient house, like a Net Zero house?
Last Updated: JULY, 2024
This is an impossible question to answer accurately. It’s like asking: “How much does a fuel efficient car cost?” There’s so much influencing the final outcome of the cost of a project from complexity of design, to level of finishes, to the builder chosen. That said, we get this question a lot so we’ll do our best to get as close to answering it as we can. Just before the pandemic, we were telling clients that if one were building an energy-efficient custom home in southern Maine, to expect to spend a minimum $325 per square foot. In the following years, we’ve seen a remarkable increase in cost because of pent up demand in materials simultaneous with a construction bubble in the housing market, a shortage of labor, chaotic international shipping issues, and significant inflation. As a result, we are now telling clients to expect to spend a minimum of $550 per square foot to even $650 per square foot. There are signs that the market may be easing and that numbers may come back down a little, but for now, if you are filling in your budget spreadsheet for the construction cost for your project, we’d recommend a budget of at least $600 per square foot for a new custom home.
One might ask, what about garages, screen porches, decks, and basements? Are those included in that square foot price? The answer is no… sort of. This is where using a square foot cost is tricky. For example, the square foot cost of a kitchen is WAY more than that of a bedroom, so it’s good to realize that this is an average number that is also just an estimate. Compounding the ‘squishiness’ of this metric is the fact that some builders include these spaces in their calculations and some don’t. So one should keep in mind when using or hearing a square foot price, that one should know what is being included. In our office, it’s a number that we assign to occupiable living space. Other supporting spaces are often factored at different percentages of the base square foot cost. For example, an unfinished garage is factored at about 40%. So if your base ft² price is $550, then a garage would be at $220 per square foot. Below is a list of factors we sometimes use:
- Unfinished Attic Storage: 15%
- Decks: 25%
- Garage: 40%
- Unfinished Basement: 40%
- Covered or Screen Porch: 50%
But it’s worth stating again, that these are estimates. Based on a completely unknown and hypothetical house design. As architects, we help guide the process to tailor the design to fit your budget as much as possible. While we cannot affect the choice of materials and labor, there are some strategies we can employ to affect budgetary change. For example, the simpler the house is, and the more modest the finishes are, then the lower the construction cost will be.
If you want to learn more about strategies in keeping cost down, we recommend listening to our own Chris Briley on a two-part episode of the Green Architects’ Lounge podcast entitled Making Green Affordable. But do remember, that particular episode was recorded in 2013, and while the strategies are still poignant, times and costs have certainly changed!
Another major factor in establishing the construction cost of your home is the builder. Different builders have different delivery methods, overhead, and profit margins. Bringing in a builder during the design process to have him or her generate estimates or at least participate in conversation of cost is good practice.
