How Do I Know I’m Getting an Energy Efficient Home?
‘Eco-homes DOUBLED our energy bills: Resident rocked by £1,600 charge after just six months‘
This morning this headline caught my eye. It's a story about a family that bought a house, thinking that its eco credentials would be a guarantee of lower energy bills when in fact the reverse ended up being the case. We could speculate where it all went wrong but I wondered whether with the knowledge I have now, I could have avoided making a similar mistake? Hopefully the answer is yes!
So I thought I'd share some of my thoughts on this topic.
An Eco-Home Badge Means Nothing
At any given time there will be different buzzwords that sum up opinions and desires. Right now, the biggest pain point is rising fuel bills and people perceive ‘eco-homes' to hold the answer. If I buy an eco-home, then my bills will be cheaper, some might think. While that could be true, unfortunately it depends on what you're buying. If the local builder realises that he can't sell houses anymore unless they carry the buzzword of the day, then guess what, he's going to jump on the band wagon. So we have to be really careful we are buying the genuine article.
Gadgets Don't Make a Building Energy Efficient
Annoyingly there is no way you can tell if a house is energy efficient from its appearance. Solar panels and other renewable sources might have their place in generating energy, but have nothing to do with energy efficiency. Think of them as the eco-bling! You want evidence of how the building performs.
Although I could look at the Energy Performance Certificate (in the UK) of a house, I would prefer to see a history of bills. This is a lot more telling and although the previous occupants of a house may be very careful energy users it's likely to give me a good feel of what to expect. If the house is energy-efficient then the current owners will probably be eager to share this information.
Self Building Will Allow You to Know How Your House is Built
If you want to buy a new build, then clearly you won't have data from the previous occupant. This is what makes me wonder whether self building (or custom building) has come of age. So much of creating an energy efficient home depends on attention to detail and when you buy from a volume house builder you have no idea what you are getting. If you could instigate the construction of your house, you are far more likely to get things right (assuming you've done your research!).
Understand How Energy Savings Are Made
Energy efficient homes don't come about by magic, they work because of building physics. If you can grasp the basics of this then you're more likely to invest wisely. Here's an overview and then there are some links to help you continue your research.
Space heating (or space cooling in a hot climate) is where the largest energy savings can be made. That's why we often hear about a fabric first approach, because by investing in the fabric of the building we can reduce these energy losses. Very high levels of insulation and air tightness are needed for this. And of course, if your house has an airtight seal then it becomes equally important to get proper ventilation (with MVHR – mechanical ventilation and heat recovery). All this requires components (windows and doors, etc.) that perform very well.
Clearly this is just scratching the surface. I suggest visiting the International Passive House Association to get more information and also a link to an affiliate association where you live. Episode 4 of our podcast also includes an interview with one of the founders of the Passivhaus standard, Professor Wolfgang Feist.
‘As-Built' Standards Are The Future
For a long time there's been a big difference between what's on the plans and what you actually get when it's built. This is another strength of the Passivhaus standard. As part of its mandatory technical requirements, an air tightness test is required after construction. It would be very difficult to cheat this test if you'd cut corners during the build and so certification is like a guarantee of the build quality.
What other research will you do to make sure your next house is more energy efficient?