How do you build a passive house with insulated concrete forms (ICFs)?
Passive buildings are on the rise, just as you can see covered here and here. And this makes sense given that sustainable green construction is growing amid concerns around climate change. A passive building (whether a residential home or a skyscraper) is an extremely energy-efficient building and one that meets the most rigorous level of energy-efficiency that exists in the industry today.
Passive buildings are built in accordance with five building science principles, with a focus on an extremely airtight building envelope that has continuous insulation, high-performance windows, and balanced heat and moisture recovery ventilation.
However, in order to qualify as a “passive”, a building must meet certain quantifiable targets, which we will cover in this article. We’ll also show you why Certified Passive House Consultant Troy Hodas of Spruce Mountain Inc. chose ICFs when building his net-zero home as well as his tips and tricks for building a passive home.
How to Build A Passive House with ICFs
In builders’ quests to achieve net-zero specs or simply just a very airtight building envelope, many make the mistake of building conventionally framed homes and then trying to add technology to it after the fact.
Building with ICFs, however, offers a much easier path to net-zero status (and ultimately passive house certification as well). Indeed, many builders are already using ICFs to construct net-zero homes, as you can see here. And the reason is simple: ICF builds are highly energy-efficient, inherently airtight and eliminate thermal bridging.
Here is more on Troy Hodas’ personal experience with ICFs.
Interviewer: Why do you think ICFs are a great choice for walls in a passive house?
Troy Hodas: “Simple, durable and cost effective. I also like that the Neopor graphite polystyrene bead used in the Logix Platinum Series ICF is GREENGUARD certified for superior and healthy indoor air quality.”
The Technical Criteria for Building A Passive Home
When it comes to the technical criteria required to be considered a passive house in North America, these standards are set by the Passive House Institute US (PHIUS) and by Passive House Canada.
Taking the USA as an example, the main criteria for PHIUS+ certification (as outlined in the PHIUS+ Certification Guidebook) are as follows, however, keep in mind that the specific targets depend upon envelope area in addition to several other factors.
- For buildings of five stories and above that are also of non-combustible construction:
- q50 <= 0.080 CFM50/ft2 or q75<= 0.100 CFM75/ft2 of gross envelope area
(q50 <= 1.46 m3/m2h or q75<= 1.94 m3/m2h of gross envelope area)
- For all other buildings:
- q50 <= 0.060 CFM50/ft2 or q75<= 0.080 CFM75/ft2 of gross envelope area
(q50 <= 1.10 m3/m2h or q75<= 1.46 m3/m2h of gross envelope area)
Before undergoing the certification process, PHIUS has a software called WUFU Passive, which is an energy modeling software tool used to help builders through the process. When building with ICFs, you can import your design into the software. You then have to meet a certain WUFI rating to be considered a passive home.
The full certification process, however, boils down to the following steps:
- Pre-Process Paperwork – This stage involves signing a contract and making your payment.
- Create A Project in The PHIUS Database & Upload Files – This step involves creating a project in the PHIUS+ Project Database and uploading accompanying project documentation.
- Pre-Certification Design Review Process – During this stage, you will await feedback from the PHIUS reviewer. From here, the process proceeds through a series of implementing any changes and awaiting follow-up feedback. It typically includes 3 rounds of design review.
- Final Certification Review – The final stage involves on-site inspection and testing. The final stage then involves a series of feedback and implementation as in the pre-certification design review process.
Certified Passive House Consultant Tips & Tricks for Building with ICFs
We asked Troy Hodas what is tips and tricks are for designing and building a passive house with ICFs. His tips?
“Keep the design simple so the construction process is very straightforward. You just have to read the manual, and get training and support from your local rep. Overall the process is quite straightforward.”
Looking for more information on how to build a passive house? Request a quote, get more information, or talk to a Logix Advisor by contacting us today