Understand thermal implications of underfloor heating

Embedded under-floor heating is a luxurious way of keeping a house warm. You may encounter clients who hate heat pumps and who aren’t deterred by the cost of under-floor heating. But there’s some implications for a high-performance design that architects/designers must be aware of. Passive House buildings by definition have a very low heating demand. Heating the slab is an …

Growth in multi-family Passive House buildings in North America

The PHI-aligned Passive House Network has released a detailed and inspiring guide to the costs and benefits of multi-family Passive House buildings. It draws on data from New York and Massachusetts, two US states that have been early adopters. It’s a free download and worth your time. It contains detailed information about the minimal cost premium required to build to …

A logical staircase to build PH design skills

Seaward House, a newly certified Passive House on Auckland’s waterfront, is a fantastic example of how architects can build their skills in high-performance design in effective, methodical ways. The architect entrusted with this ambitious project was Marc Lithgow from Space Division. First, he chose to bring in Passive House experts to do the PH design, doubtless learning a whole lot …

Thermal bridge calc error rate is way too high

I estimate nearly half the thermal bridge calculations we see during pre-construction review are wrong. Newly minted Passive House designers and consultants are not wholly responsible. The Sustainable Engineering Ltd team is finding errors in the maths provided by experienced designers too. Lifting skills and confidence in thermal bridge modelling—and slashing that error percentage—is our motivation for organising an online …

Glazing percentage: handy rule of thumb to prevent overheating

Prevent overheating by keeping the window area to 20% of the floor area. That’s a very old passive solar rule-of-thumb from New England (Eastern USA) where I grew up.  So I was interested to discover that Mark Siddall has researched this same metric for homes in the UK and found it holds true there. He details this in a brief …

Q&A: Is spray foam insulation a good idea?

Q. What’s your opinion about spray foam insulation for New Zealand homes? A. Spray foam can be used with good results if properly designed and installed well—but a successful outcome requires both of these or a lot of luck. In the UK, there have been enough problems with bad installations of spray foam in retrofitted roof insulation that it impacts …

MBIE releases technical guidance on operational carbon

I welcome the release of technical guidance for operational carbon calculations by MBIE, as part of its Building for Climate Change programme. There is lots of work ahead of us but it’s an important step to have a document to argue about now. In short, the methodology calculates energy use by predictive energy modelling and uses a badness factor (annual …

Kids suffer when schools are poorly designed

Some solid work has been done in Aotearoa New Zealand by very capable architects and Passive House designers to design classrooms to Passive House performance levels. The fact none have yet been built is a sad reflection on prevailing attitudes in the Ministry of Education. Mechanical ventilation for consistent fresh air is getting stripped out at the so-called value engineering …

New thermal bridge requirements in US will influence NZ

There are new thermal bridging requirements being rolled out in the US, of which ASHRAE has just summarised. ASHRAE standard 90.1 is for all new buildings excepting low rise housing and the 20220 version introducees many changes to improve energy efficiency.  Fun (?) fact: there are many thousands of different Building Codes across the US. However, 90.1-2022 is a core …