Jessica Eyers was the architectural designer and Passive House designer for this month’s featured case study, a groundbreaking prefab straw home. Jessica ran her own architectural design company from 2012 to 2023, when she wound up the practice and we welcomed her to the Sustainable Engineering Ltd team.
The independence and impartiality of Passive House certifiers is absolutely vital. The design work and pre-construction review of this project was carried out before Jessica joined Sustainable Engineering Ltd. Sara Wareing did the final review and Jessica was not involved. To avoid even the perception of a conflict of interest, PHI reviewed the submission (a second time) and confirmed the certification outcome.
The Passive House community in New Zealand is small and overlapping. Our small, highly-qualified team has deep expertise that is extremely useful. We will act only as either Passive House designer or certifier on any one project. There is scope to provide support services on a separate contract and when we do this, we discuss it early with PHI. For instance, as detailed in this case study, colleague Aleksandar Kotevski carried out some specialist 3D thermal bridge modelling for Āhuru, a stunning certified Passive House Plus home in Raglan, while I served as certifier.
Similarly, on another project in a warmer climate, we supported the Passive House designer with advice about how to best regulate temperature in a 8m2 storage room designed for long-term storage of fresh and dry food. Passively cooling such a small space is tricky—it’s too small for modelling to be accurate. We’re aware of some approaches going very wrong, because we were consulted on how to fix them. Toby Brooke, then with Sustainable Engineering Ltd, certified the project and I provided advice on the store room. It sits outside of the thermal envelope so is anyway out of scope for Passive House certification.
The secret cool storeroom in a certified Passive House project. Photo © 2024 Andy Spain, AS Visual, used with permission.
I’m probably labouring the point but I want to be very, very clear that as Passive House certifiers, we take our independence and integrity very seriously. We also want to be as useful as possible for our clients and the Passive House community and we can accomplish the latter while upholding the former.
PS I have one of the first blower doors that arrived in New Zealand and still sometimes do the occasional blower door test. (Below, I am discovering this very tall entrance door is too big to fit my test rig.) PHI’s guidance is there is no issue with acting as certifier and doing blower door tests on the same project. Best practice is to have someone independent of your construction team undertake this very important check on build quality. The number of airtightness testers is growing steadily—see this list of registered practitioners.
Too big for my blower door!