Passive House Design: Cool Temperate - Michael Tolhurst, Envelope Architecture

Passive House design is different in every climate zone.

Over the next four podcast episodes, I talk to Passive House designers in the four Australian climate zones where most of our population lives, to discover the key differences.

Today I start with Passive House design for cool temperate climates like Canberra and Hobart. I talk to Michael Tolhurst, the director of award winning practice Envelope Architecture in Canberra.

Michael clearly explains the Passive House design specifics for cool temperate. Plus he shares heaps of other information and insights to help you better understand Passive House design

Australian Architects can claim formal CPD hours for these podcasts.

MORE INFORMATION

Find everything you need on the Renovation Collaborative website.

www.renovationcollaborative.com.au

• PODCAST Key points summary, timestamps and resource links
• FREE RESOURCES Transcript edited into clear Q&A.
• CPD Australian architects can find more information on CPD, and
• COURSES Eleven easy to read courses demystifying the entire home design and construction process.

KEY POINTS SUMMARY

1. Passive House design for cool temperate climates has a focus on warming. Of the four Australian climate zones accommodating most of our population, cool temperate is the most extreme. In Canberra, winters regularly go down to less than -5 degrees Celsius and in summer can reach the 40s.

2. Using a compact building form makes the Passive House standard much easier to achieve in more extreme climates like cool temperate. However, if you want a more linear form because of your site or to capture views etc. The PHPP tool can be used to determine building form alternatives and compensate for heat loss in other ways.

3. Windows are generally triple glazed. The window glass area reduces as the climate becomes colder to reduce heat loss. However, it's still critical to have opening windows in all habitable rooms to get cross ventilation when needed. And shading is still very important to prevent too much heat gain.

4. The fresh air circulation system is a HRV, which stands for Heat Recovery Ventilation System. The HRV provides a constant supply of filtered fresh air and incorporates a highly efficient heat exchanger to retain heat from inside the house. Some additional mechanical heating, usually from a reverse cycle air conditioner, is generally required.

As a side note, Michael clearly explains how Passive House heating is generated from three sources:

i) Solar heat gain,

ii) Internal gains from occupants, showering, cooking and equipment, etc.

iii) Mechanical heating.

The air tightness and insulation in a Passive House very efficiently retains the heat inside the house.

5. An internal air barrier is required in a cool temperate climate zone and this is in addition to the vapour permeable external membrane used for weatherproofing. Heat energy