Being green and sustainable is such a trend thing at the moment. Everyone and every company or product claims to be sustainable or green. But how do you know if they are really interested and invested in designing and building a sustainable home? And if they really care about the environment and have knowledge about sustainanable and energy efficient construction?

If you start having discussion with a designer/ architect or with a potential builder for your renovation, extension or new build, here are 3 questions you should ask before making a decision on who to engage.


  1. Have you build or worked on a highly energy efficient/sustainable home before?

Obviously, if the answer is NO, they are not the right fit.

Assuming the answer is yes. Try question 2.


  1. What star rating did the house achieve?

    If the answer is something like: we did this really energy efficient 6 star home….

Okay. 6 stars is the absolute legal minimum requirement. Think about it. If you would put in a tiny bit less insulation. Or if they would have used windows with a bit of a lesser performance the house would not have gotten a building permit. Or to put it more bluntly or extreme: if they would have done anything less the house would not have passed, it would be illegal. Mh. So that means a 6 star home isn’t really an energy efficient home, is it?

So, move on and find someone else.

If the answer is something like: yes, we did this amazing energy efficient and sustainable 7, 8 or 9 star home… Amazing. Great stuff! Proceed with the next question.


  1. What did you do to make sure the house actually did perform as a 7 / 8/ or 9 star home?

If the answer is something like: well, we did install all the insulation and windows etc like they were specified….

Keep digging deeper.

But how did you make sure that there were no thermal bridges or air-leakage?

If they can’t really give you an answer to that it sadly probably means that although the house they worked on was designed to be highly energy efficient, the actual end product might have quite some air-leakage and will most likely not perform as per the energy rating assessment.

But: If they really know how to design and build an air-tight well performing home. They should be talking about how the insulation needs to be snug fit with no gaps. That any penetrations are sealed. That vapour barriers are used. That the house is taped well. Or if they start talking about the ventilation system they have put in place, or the heat recovery system or heat exchanger. In that case you know you have found the right person. Keep them tight and don’t let them go.