How do you design a Passive House?

In today’s podcast episode you'll get a clear understanding of how a Passive House works and the process to put one together.

I talk to architect Alexander Symes, the director of the highly awarded environmental architectural practice Alexander Symes Architects in Sydney.

Alexander's architectural mission is to advance sustainable architecture, and in today's interview, that is absolutely what he does. He openly shares his incredible knowledge to empower everyone to move forward with their passive house project.

If you're an Australian Architect, you can claim your formal CPD hours for these podcasts. Jump on to the Renovation Collaborative website for more information.

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. There are five design components that the passive house standard uses to achieve its outcomes of energy efficiency and indoor air temperature and quality:

• Thermal insulation: This is about keeping the warmth in during winter and the hot out during summer.
• High-performance windows: These are for thermal insulation.
• Air tightness: This is about sealing your building so there are minimal gaps where the heat energy can get in and out.
• Heat recovery ventilation system: This brings filtered, fresh outside air into your home and evenly distributes it without losing the thermal efficiency of everything else you're doing.
• Thermal bridge-free construction: This stops heat energy transfer through materials from outside in, or inside to out.

2. You also need mechanical heating or cooling but only a minimal system. A passive house requires much less energy to cool or heat it than a very leaky house where you will constantly be running the air conditioning.

3. You can open the windows when the external conditions are right and the temperature and the relative humidity outside are pleasant. Opening the windows, feeling the natural breeze, and hearing the birds outside are essential to a healthy home. The heat recovery ventilation system will remain running.

4. What is the difference between a passive house and a passive solar or climate-responsive design?

• Traditional passive solar design (in the southern hemisphere) is about orientating the glazing primarily to the north to enable sun or shade into the house to passively warm or keep it cool, depending on the season. In addition, climate-responsive houses are deliberately open to optimise cross ventilation and don't seal very well.
• In future climate scenarios, there will be extreme heat peak days, day on day on day. Mechanical heating and cooling will be essential. Climate-responsive houses are not well sealed, so they can't run efficiently.
• The advantage of the Passive House standard is that you can seal it all up and run a very efficient air conditioning system to maintain thermal comfort. The passive within passive house means it looks after the temperature for you with minimal input.

5. You can achieve the health, comfort and energy benefits of a passive House without going as far as formal certification. However, it's essential to understand that the certification process is necessary for QA (and we will talk more about this in the next episode). In a non-certified 'High Performance' home, the insulation, windows and heat recovery ventilation system are the same, but the airtightness requirements are lower than the strict passive house standard.

6. How does the airtightness of the passive house standard compare with the typical Australian home?

• 15-20 air changes per hour: The average Australian house. This means that with all the doors and windows shut, all the air in the house could change over or escape to the outside/ come in 15 to 20 times in a single hour.
• 6.0 air changes per hour or less: A heat recovery ventilation system (fresh air circulation system) is required to avoid mould.
• 3.0 air changes per hour: Alexander considers this a 'high performance' building.
• 1.0 air change per hour or less: Enerfit - Passive House renovation/ refurbishment standard.
• 0.6 air changes per hour or less - The Passive House standard.

INTERVIEW QUESTIONS

00:00 Introduction

01:06 How did you get into designing Passive Houses?

03:53 What are the five Passive House design components?

09:08 You also need mechanical heating and /or cooling in a Passive House. How do they work together?

12:53 Can you open the windows in a Passive House?

14:47 What is the difference between Passive House and passive solar / climate responsive design?

22:05 What are the steps to design a Passive House and who is required on your team?

27:26 Is it better to have the builder involved during the design process rather than going to tender?

29:08 Does the builder need to have completed the Passive House training course?

30:28 What input does the Passive House Designer provide on site around airtightness?

33:52 How does the airtightness of a Passive House compare to a typical Australian house?

35:14 Can you explain more about Enerfit (the Passive House tool for renovations and refurbishments)?

36:58 In your experience what are the main concerns clients have about Passive House?

38:02 Are there any potential problems or issues that might occur?

39:41 What would you suggest to any designers who have completed the Designer Course and are trying to get up to speed?

40:25 Do you have any other advice for anyone attempting their first Passive House?

41:55 Key Points Summary

IN THE NEXT EPISODE

Next week, I talk to experienced Passive House Consultant and Passive House certifier, Luc Plowman, the director of Detail Green environmental consultancy in Victoria.

If you are thinking about your first passive house project, you'll find out how a passive house consultant can help you work through the challenges. You'll also learn how to work with a Passive House Certifier and get your project formally certified. Plus, you’ll hear heaps of other insights about residential and commercial Passive House projects based on Luc's years of experience.

RESOURCE LINKS

Alexander Symes Architects

www.alexandersymes.com.au

Other references in the podcast

Australian Passive House Association

www.passivhausassociation.com.au

Jason Quinn, Sustainable Engineering, New Zealand,

www.sustainableengineering.co.nz

Smart Plus Academy

www.smartplusacademy.com

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 [email protected].

www.renovationcollaborative.com.au