Passive House Design: Subtropical

Renovation Collaborative

How do you design a Passive House in a Subtropical climate like Brisbane?

Today’s episode is the fourth and final episode focussing on 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 Tiago Guerreiro, a director at the award-winning design and construction company H4 Living based in Brisbane. In this episode, Tiago explains the Passive House design specifics for Subtropical, plus he shares heaps of other information and insights about designing and building 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 POINTS SUMMARY

1. The 5 Passive House design components for a subtropical climate are as follows:

• Windows are typically double-glazed and always operable. Windows should enable cross ventilation, purging of any excess heat build-up, and connection to the outdoors to enjoy comfortable external temperatures over spring and autumn and much of winter.
• The fresh air circulation system for subtropical is an ERV (energy recovery ventilation system) which is different to the HRV systems used in the cooler southern states.
• Wall insulation can fit within a typical 90mm timber stud framed wall thickness. No under-slab insulation is required because connecting to comfortable earth temperatures (usually around 22-23 degrees Centigrade) is beneficial for cooling.
• Only one layer of external wrapping is required; the vapour-permeable weatherproof membrane on the outside of the home is taped, sealed and made airtight. An additional internal membrane may be used to obtain certainty of airtightness, but it can be avoided in most cases to reduce costs.
• Removing thermal bridges is always essential to avoid heat gain.

2. Effective shading to avoid all heat gain is critical - no sun can enter the house. Passive houses retain heat very effectively because they are well-insulated and sealed; therefore, the hotter the climate zone, the more shading is required.

3. Humidity and condensation are major issues in subtropical design. It’s always essential to run a Wufi analysis (which is a moisture study) as well as the PHPP modelling to resolve any moisture issues and prevent unseen mould growth in the building structure over the long term. . If you’d like to hear more about the Wufi analysis you can find more information in Episode 4. Passive House Consultant and Certifier – with Luc Plowman the director of Detail Green.

4. A dehumidification system is usually required in subtropical. The dehumidification system can be added to the ERV system in line or added as a separate system.

5. Active cooling through air-conditioning is usually required. H4 Living use split system or ducted air-conditioning systems depending on their client preferences. If you choose a ducted system, its critical that the ducts are within the insulated building envelope to maintain optimal energy efficiency.

And finally,

6. H4 Living offer passive house consulting advice covering both design and construction. They can work with you on design, help you choose the right builder and also get your chosen builder up to speed on the Passive House construction process.

INTERVIEW QUESTIONS

00:00 Introduction

01:18 How did you get started with Passive Houses at H4 Living?

03:47 Where does H4 Living build Passive Houses?

04:42 Where do you offer Passive House design and build consulting advice?

06:16 What materials do you typically use for your Passive Houses?

08:15 What budget range do you work in?

09:17 What is the difference between Certified Passive House and high performance?

11:01 Is the demand for Passive House growing?

12:29 What is the Subtropical climate like?

14:39 What are the key design considerations when designing a passive house in subtropical?

18:00 What are the requirements for window design?

23:25 What are the cooling system and fresh air circulation system requirements?

26:25 What are the airtightness and wrapping requirements in subtropical?

28:03 How is a dehumidification system integrated?

29:20 Who installs the air-conditioning, ERV and dehumidification system?

30:15 Can you explain about condensation and mould growth?

32:55 Do colours or materials make a difference?

34:17 What makes clients hesitant about passive house?

37:39 What is the additional cost of passive house?

39:35 Have you experienced any problems with Passive House?

43:10 What is your advice on importing windows from overseas?

45:25 Key Points Summary

IN THE NEXT EPISODE

Next week, is the final episode of Season 2 and you’ll learn How to get started with Passive House and where to find more information. I will be joined by two guests:

• Australian Passivhaus Association CEO, Alexia Lidas – who will tell us about all the courses support services and information the Association provides.

and

• The Managing editor of Sanctuary Magazine at Renew, Anna Cumming – who will tell us about Sustainable House Day where you can visit Passive Houses in your area. Plus you’ll findout about all the other information offered by Renew.

RESOURCE LINKS

Tiago Guerreiro – H4 Living www.h4living.com.au

International Passive House Association - Certified Components Database www.database.passivehouse.com/en/components/

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