Passive House Design: Mild Temperate

Renovation Collaborative

How do you design a Passive House in a mild temperate climate like Melbourne?

In today's episode, I continue to investigate the design specifics for each of the four climate zones around Australia where most of our population lives. I talk to very experienced Passive House designer Andy Marlow, a director of the award winning environmental practice Envirotecture in Victoria and New South Wales.

In this episode, Andy explains the Passive House design specifics for Mild Temperate. Plus we talk more about Enerfit, the renovation and retrofit tool, and he shares heaps of other information and insights from his years of experience to help you better understand Passive House.

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 POINT SUMMARY

1. In terms of the five Passive House design components, mild temperate is very similar to cool temperate.

• Windows are double or sometimes triple glazed depending on the design.
• The fresh air circulation system is an HRV
• Stud framed wall thicknesses are typically 140mm to allow for more insulation, and insulation is required to separate a concrete floor slab from the cool earth temperature below.
• An internal wrap for air tightness and moisture control is usually required in addition to the exterior weather tight wrap, and
• Removing thermal bridges is always important.

2. The colour of the roof and walls is considered in the PHPP modelling and affects the design's performance. In cooler climates, dark coloured buildings perform slightly better than light coloured buildings. Dark coloured roof and walls will dry out faster which can be beneficial to reduce any moisture in the wall and roof structure. However, Andy noted that as a nation going forward into climate change and increasing temperatures, generally speaking, lighter coloured buildings are the best solution.

3. Passive House is a performance standard so buildings can be constructed from any material as long as they deliver the required results through the PHPP modelling. Andy references a Passive House that Envirotecture have completed made from straw bale.

4. Passive House certification costs around 3 to 8% extra, however the value it adds far outweighs the extra cost. Envirotecture prefer to build certified Passive Houses over uncertified high performance because of the rigorous testing on site. The quality assurance.

5. When renovating, the whole building must be upgraded to achieve Enerfit certification. Improvements must be made to the existing building where possible, but the new work will carry the existing. This is very different to the Australian National Construction Code in many parts of Australia which only requires the new work to be constructed to the current code requirements.

However, building is expensive and if you can't afford to upgrade the whole house, please don't let this put you off building your new extension to the Passive House standard. The new work needs to have an airtight door that separates it from the existing house and it won't be able to be formally certified. But if it's living areas where you spend most of your time, it will be well worthwhile and add substantial comfort and value.

And finally,

6. Enerfit Heritage renovations are definitely the most challenging. Most of the renovation work is done on the interior to retain the exterior character. Andy notes that you don't always need to replace the windows, particularly if they're beautiful character windows such as lead light stained glass. There are other solutions available.

INTERVIEW QUESTIONS

00:00 Introduction

01:01 How did you get started designing Passive Houses?

05:44 Who are your clients – what are the themes? And has that changed?

09:57 What is the mild temperate Melbourne climate like?

11:50 What are the mild temperate window design requirements?

12:50 What is the mild temperate fresh air system?

16:35 What are the mild temperate air tightness / building wrapping requirements?

18:38 Are building colours considered in the PHPP modelling?

21:14 Information about Enerfit – for renovations and retrofits

28:57 What are the barriers and misconceptions you are aware of?

31:32 How much does Passive House add to cost in your experience?

33:03 Are your projects predominantly un-certified high performance or certified Passive House?

34:47 Do you find that certification adds much more to cost?

38:11 Are there any problems after completion with Passive House that you are aware of?

41:17 Key Points Summary

IN THE NEXT EPISODE

Next week, you'll find out how to design a Passive House in warm temperate climates like Perth, Adelaide and Sydney.

I talk to very experienced Passive House designer Ben Caine, the director of the award winning practice Leanhaus Architecture in Perth.

Ben's architectural mission is to find solutions to reduce the additional costs of Passive House and make it more accessible for clients on all budgets.

Ben shares the climate design specifics plus heaps of other insights to help you better understand Passive House design.

RESOURCE LINKS

Andy Marlow – Envirotecture www.envirotecture.com.au

Envirotecture Project – Thornleigh www.envirotecture.com.au/thornleigh-passivhaus/

Envirotecture Project – Straw bale house www.envirotecture.com.au/huffnpuffhaus/

Envirotecture – Passive House: What’s it worth? www.envirotecture.com.au/passivhaus-whats-it-worth/

Envirotecture – Little Pot of Gold www.envirotecture.com.au/little-pot-of-gold/

Australian Passivhaus Association www.passivhausassociation.com.au/

GET IN TOUCH

If you've got any comments or questions or there's any topic you'd like to know more about, please send me an email at [e-mail].

www.renovationcollaborative.com.au