Friday, 29 September 2017

PragSust HQ going Passivhaus

At a recent institutional sustainability committee meeting I attended there was some discussion about the effectiveness of Passivhaus construction techniques. My  opinion is that broader adoption of building to Passivhaus certification would make a relatively simple but substantial contribution to cost-effective GHG emission reductions around the planet. On a personal note, I've recently done the offgrid energy system concept design for a green resort in regional Victoria that at this stage is aimed at Passivhaus certification. It was a lot easier and cheaper designing an offgrid solution for the minimal energy required. And in terms of walking the talk Mrs PragSust and I have just started the process of designing and building a Passivhaus extension to our house. This is something we have been working towards since I visited various certified Passivhaus buildings in Europe in 2012. I thought it would be worthwhile to list some points about how we will approach this project.

a/ We will require the extension to achieve Passivhaus certification; probably under EnerPHit. (

This is an objective standard that defines various energy metrics including:

  1. blower air change results
  2. post-occupation measurement and verification of the energy consumed at the site.

b/ We will treat this as a systems engineering project.

IMO any project with any more than minimal engineering component needs to be conducted in this fashion. Projects go astray when contractors are not familiar with working in a team, don't understand or won't commit to the level of quality required, there's poor project management and so on. Having a systems engineering approach with well defined requirements, design, a project plan and timeline and well-organised project management combined with the right architects/designers/builders/contractors drastically reduces the possibility that the project will fail.

c/ That's all very well but how does this relate to architects?

Architects/builders should have a reasonable degree of project management experience or they are unlikely to succeed in whatever construction technique used. One nice feature about aiming at Passivhaus certification is the extensive guidance on what's required to design and deliver the project and the objective metrics mentioned above representing very well-defined requirements. This helps architects/designers/builders/contractors faced with their first project requiring Passivhaus certification (and subsequent projects if they're successful)  to understand what's required. In particular, it gives the architect as the project manager a framework to work within.

d/ But what about the general population wanting to do a Passivhaus project?

Obviously there's a good whack of buyer beware in that regard as there is with any project. I've been asking candidate architects:
These are all questions that could be asked and checks that could be made by someone in the general population. We'll want more detail about certifiers and so on but the above is a good start. I've had affirmative answers to this list from architects.

e/ But isn't Passivhaus more expensive?

This was definitely an issue initially with Passivhaus as tends to be the case with initial deployments of any new technology. However, now that there's a lot more experience with what works and what doesn't, architects/designers/builders/contractors with experience in delivering certified projects, a good range of certified components and so on, much of the risk has been removed. And certified Passivhaus buildings need minimal HVAC kit which reduces their price. One architect with several successful certified projects told me that he will now only do Passivhaus buildings as they're comparable in price to good quality conventional construction but much cheaper to live in, excellent sustainability credentials etc Comparing Passivhaus costs to cheap construction is apples and oranges. Cheap construction is a poor outcome on many criteria not just energy efficiency.

f/ Does it work in hotter climates like Australia?

Again, this was relevant when Passivhaus was first deployed in cold climates in the northern hemisphere. The standards now have provision for warmer climates.

g/ The architect says that he can deliver an energy efficient building project without using Passivhaus certification?

Maybe. Australia generally has very poor commercial and residential building energy performance. The 6 star residential rating is of some use but this is a design standard with no requirement for followup monitoring and verification that operational performance meets design estimates. A CSIRO study several years ago found that houses designed as 6 star frequently have operational performance below 6 star. 9+ star would be acceptable but only if this was a measured operational post-construction result - not a design estimate - and there were terms in the contract that final payments would not be made until the building met agreed requirements. What we want is results not nice drawings. One (uncertified) architect told me that he didn't think certification was required. He went into blather mode when I asked him what post-delivery energy requirements he would sign up to. Over the years I've had a number of conversations with architects along these lines. They'll talk a big game but are very reluctant to commit to an outcome. That's all neatly bypassed by requiring Passivhaus certification.

We might blog this project as per:

1 comment:

  1. Did you know that there is a house at Redesdale that is open for inspection on Passivhaus weekend in November? Interested in going??