We’re writing this post with some trepidation. You see, we’re going to put our necks on the line and try to define what we mean by a ‘zero carbon home’. From our own reading on the subject, a clear definition seems elusive. Those that do exist are often open to interpretation. Over the coming months we’ll be blogging about our personal strategy for trying to achieve zero carbon living in the house. This feels exciting but very exposing since we are so intent on trying to reach ‘zero carbon nirvana’.
There’s a good chance you’ll have read about other examples of low energy homes in the UK and abroad. Perhaps they were described as ‘carbon neutral’, ‘zero-net energy’ or ‘energy-plus’ homes. The different terms for this type of home reflect the diversity of building approaches being adopted. There is little consistency around the world (differing societal and geographical influences) and so the language inevitably becomes confusing.
In the simplest terms, approximately 80% of CO2 emissions from standard buildings are produced during operation, compared to low energy/passive houses where the majority of emissions are produced during construction*. That said, as the end user, we’ve found a surprising lack of common knowledge about what a zero carbon home means in real terms. We’re not writing here as experts but as newbies learning a new ‘green’ language. What does a zero carbon home actually look and feel like?
If you want a thorough technical understanding, immerse yourself in the nitty gritty of BREEAM’s Code for Sustainable Homes (CSH) Code Level 6 which requires zero carbon emissions from a building. When we read, however, that one of the CSH criteria stipulates the correct length of washing line for your laundry, this (along with reasons of time and expense) was enough for us to decide that BREEAM was not the path we wanted to follow towards zero carbon.
Personally, we prefer a more common sense approach to sustainability.
Some time ago, we were sitting around a table with two architects, a BREEAM assessor and an energy consultant. We believed, perhaps naively, that we would be on course to hit Code Level 6. First up, we learned that Code 6 is scaled for larger projects. For residential builds, the bureaucracy of BREEAM can increase your build costs by up to 40%, we were told (the CSH guide is a whopping 272 pages long). Our ‘light bulb moment’ came when an architect asked us, “Can you live with a common sense code for zero carbon?” Naturally, we replied with a robust “YES”!
‘Common Sense Code’ has stuck in this household and we aim to show you that zero carbon is entirely obtainable without the added expense.
Our zero carbon objective:
“We are aiming for a Lifetime Zero Carbon home, meaning zero carbon emissions in the use of the house and the embodied carbon in the home being offset by the energy generated over the lifespan of the building, assumed 100+ years”.
As yet, we don’t have all the facts and figures to back up these goals (construction of the house only started 3 weeks ago) but when we do, we’ll be sharing them on this blog. For the time being, our draft SAP report (Standard Assessment Procedure for energy and environmental performance of dwellings) indicates an impressive ’97’ for Predicted Energy Efficiency rating.
In terms of estimated annual CO2 emissions, these are predicted at (minus) -6.08 per square metre i.e. space heating, water heating, ventilation and internal lighting minus any CO2 emissions saved by generation from low or zero carbon technology. This is compared with 16.76 for a notional dwelling of the same size and shape.
Those figures sound like we could be on course for a zero carbon home, don’t you think? Follow our blog for more information about the construction materials and electrical/renewable technologies we are using. We’d love to hear from you if you have experience of building or living in a zero carbon home.
*Source – Zero-carbon homes – A road map by Joanna Williams