Modelling mould growth in domestic environments using relative humidity and temperature is a useful technical paper, as it seeks to modify the VTT model of mould growth on surfaces to make it easier to use in built homes. The research also suggested the existing VTT model underestimates the risk of mould in domestic settings. The authors surveyed a large number …
Bader Ventura is a certified Passive House project

Oddly, this write-up about Kainga Ora’s Bader Ventura project doesn’t make it explicit that the building did achieve Passive House certification. You can read a detailed case study by Sustainable Engineering here—our team certified this project and provided lots of technical support. The result is all the more impressive because Passive House performance wasn’t a focus from the very beginning …
Fine particulate pollution is terrible for human health

Today I learned that lymph nodes are heavily impacted by air pollution. This photo shows lymph nodes specifically associated with the lungs and how they are affected by air pollution as we age. It’s gruesome. I already knew fine particulates were bad, but this image has visceral impact and I’ll strengthen the advice I give to clients about how to …
Design Passive House for your individual client

Should Passive House designers be doing more to design buildings that avoid summer overheating? This article from mainstream business magazine Forbes considers Bahnstadt, a Passive House district in Heidelberg, Germany. The story quotes residents who were struggling to stay comfortable as summer temps soared in 2023. The two residents have different motivations for living there and different experiences of their …
Lee home in Cockle Bay is outstanding but it’s not a certified Passive House yet

The Lee family home in Auckland—all 660m2 of it—is indeed newsworthy but it is unfortunate that Stuff has twice jumped the gun (here and here) by describing it as a certified Passive House building. It isn’t, yet. Sustainable Engineering Ltd is the Passive House certifier on this project and we’re not aware of any road blocks to it achieving its …
Morning Report: why are NZ homes so damn hot right now?

Morning Report rang me this week for comment about overheating homes, in the face of record temperature spikes. You can listen to the short segment here, or there’s a print version also. For the physics geeks, here is how I worked out the numbers I provided about emissions. I used an average grid emissions factor of 0.12 kgCO2e per kWh …
New free tool for exploring climate files

I’ve discovered a climate file exploration tool that will be really useful for Passive House designers. Best, it’s open source, so free to use. This is particularly timely given the promised update to the climate files we currently use for Passive House design in Aotearoa. What we currently access contains 30 years of climate data—but NIWA compiled those files 20 …
Replacement cycles should inform climate change mitigation policy

It’s curious there is so much public discussion about electric vehicles and why and how we should ‘flip the fleet’ … and so little about buildings. Yes, we need to move people and goods in far less polluting, carbon-intensive ways. But decarbonising buildings is even more urgent and the graph below shows why, in a compelling and easy-to-grasp way. Replacement …
Choose the right heat pump

Source: Coming in from the cold: Heat pump efficiency at low temperatures, Duncan Gibb et al. 2023 This graph from a recent European academic paper shows air-source heat pump performance in mild cold climates in Canada, China, Germany, Switzerland, the United States and the UK. The red dashed line showing average COP is not the important takeaway from this graph. …