One thorny issue faced by passive house retrofitters is whether or not to have their buildings passive house certified. In this post, we’re going to look briefly at the certification process and break down the pros and cons of getting certified.
To begin, what is passive house certification?
There are two main standards for certification. While they’re pretty similar, it’s good to understand the differences. The two primary organizations that provide certification are the International Passive House Institute (PHI) and the Passive House Institute US (PHIUS). The histories of these organizations are deeply intertwined, as PHIUS grew up as a branch of the international body and the groups worked closely together for many years.
The big difference between the groups lies in their separate standards. PHIUS made its first changes to the international standard in 2015 and has since pursued a set of differing standards based on building types, location and the local climate, while PHI has continued to offer a one-size-fits-all standard.
Here is the original PHI standard:
• an infiltration rate no greater than 0.60 air changes per hour at 50 Pascals,
• a maximum annual heating energy use of 15 kWh per square meter (4,755 BTU per square foot),
• a maximum annual cooling energy use of 15 kWh per square meter (1.39 kWh per square foot), and
• a maximum source energy use for all purposes of 120 kWh per square meter (11.1 kWh per square foot).
The PHIUS standards, alternatively, vary quite a bit. If you’re building in a warmer location, for example, there is an added allowance on annual cooling energy usage (and a corresponding decrease in the allowance for heating).
Some people say that the PHIUS standards are easier to meet, and this would make sense, at least in areas with more extreme climates. The original PHI standards were developed for buildings in the temperate region of Central Europe. However, when we average out the additional strictures and allowances in the PHIUS standards, we usually see that the numbers are about in-line with international standards.
So which standard is right for you, if any? It’s worth digging deeper into the more nuanced variations between the organizations. PHI and PHIUS offer different subsidy programs, advice, and even use different software to calculate energy usage. We recommend checking out this article from Ecohome for more info on the difference between PHI and PHIUS.
We also recommend seeking qualified advice from professional consultants and designers, which may include members of your build team.
Understanding goals
We’ve touched on the two largest organizations that offer passive house certification, but other groups carry out similar functions. There may be organizations that act as accreditors at the local level and there are many knowledgeable builders and designers who, while not performing accreditation, can nonetheless personally certify your construction, methods and materials.
In recent years, for example, PHI has created the EnerPHit renovation certification, specifically designed for retrofits that may never meet the rigorous standards placed on new passive homes. This certification follows the EnerPHit renovation plan, which ensures that older structures increase energy efficiency, some by as much as 93 percent!
Learn more about the EnerPHit plan: https://passipedia.org/
Pros and cons
Let’s look at the pros and cons of passive house certification. Getting your build certified will mean the structure conforms to international standards, but it can add to the time and cost of a project.
Pros:
• The building will meet a set of stringent and internationally held standards.
• This means, additionally, that the construction, methods and materials will be of the highest quality and will conform to strict expectations.
• This also usually means an increase in the efficiency and longevity of the structure.
• Sometimes this can mean a reduction of costs, as starting the accreditation process early means all the different building partners will be planning together, eliminating waste and reducing mistakes down the road.
• This can also contribute to the value of the structure, as long as energy efficiency is marketable in your area.
Cons:
• While certification can sometimes reduce costs, it can also add to costs, as it is one more component that needs to be attended to during planning and construction. If it requires outside help, for example from a building certifier, this often adds to the total cost.
• Similarly, the process of planning for and then carrying out the certification can add undue time to the project.
• The certification process isn’t undertaken by laypersons, so there is often the added complication of finding and hiring a building certifier.
• If there is no economic benefit to certification, your consultant or designer may recommend that you work to meet the international requirements, even if you don’t have the structure formally certified.
Getting certified
If you do decide to pursue passive house certification, your building will undergo a series of tests after construction is complete. These tests are carried out by recognized building certifiers and are used to ensure that the structure meets international standards. The blower door test, one of the most common, measures the airtightness of the building. After successfully completing the tests, a building owner needs only to fill out some required paperwork and submit it to the certifying body. If the submission is accepted, the owner will be presented with the certification.
There is a lot to consider when thinking about passive house certification. We’ve tried to simplify the concept here, but we recommend you speak to a professional who can assess your specific situation and offer guidance on accreditation. There’s plenty more info and resources to be found online too. Check out the links below!
Helpful links:
Information on certification from PHI: https://passivehouse-
Certifications requirements from PHI: https://passivehouse-
Resources on certification from PHIUS: https://www.phius.org/phius-
List of global building certifiers from PHI: https://passivehouse.com/03_