The framework definition of ‘Net Zero Carbon Buildings’
20 May 2019
We don’t know who deals with the ‘Building Regulations Ideas’ in-tray at Westminster, but they’ve got a lot of bedtime reading to get through. Recently added to the ‘must read’ pile will be the framework definition of ‘Net Zero Carbon Buildings’, which was published in May by the UK Green Building Council (GBC).
This industry-funded study looks at what needs to change if the Government wants to push us towards completely sustainable homes and workspaces, and it’s keen to point out how building regs aren’t looking at the big picture…
“More than 1/2 of a dwelling’s carbon footprint is created before the first occupants move in”
Under our current process, new buildings are required to have a SAP or SBEM calculation completed, which predicts the annual carbon emissions from heating, hot water, ventilation and lighting. Although the maths has changed in the last 20 years this basic definition has remained the same. However, the GBC’s report suggests this only accounts for a quarter of the total CO2 produced by a building over its lifetime.
Their figures show more than half of a dwelling’s carbon footprint is created before the first occupants move in. This includes pollution caused by quarry extraction, transporting aggregates and producing insulation materials.
A proposed form of Life Cycle Assessment
These pre-occupancy figures are completely ignored by current Building Regulations so to remedy this, GBC is proposing some form of Life Carbon Assessment (LCA) is included into a future release of building regs. This calculation already exists in BREEAM (as a Life Cycle Assessment).
The pollutants produced by all building materials are tallied up. This includes the creation of the material, how far around the world it travels, typical waste figures, and how easy it is to recycle at end of life. The LCA isn’t just looking at key construction materials, but also includes kitchen worktops and varnishes to name a few. Developers can score well in the LCA by using materials that are produced using sustainable methods, and by using factories that are close to the building site.
The Net Zero Carbon Buildings also goes on to define – as the name would suggest – a definition for a zero carbon building. This has been a contentious topic over the last decade with the now defunct Zero Carbon Hub unable to agree with the Government on what a ‘Zero Carbon Home’ was. The Hub was shut down in 2016; the same year the UK was supposed to have adopted a zero carbon homes standard.
The GBC suggests defining a zero carbon home in three stages.
“When the amount of carbon emissions associated with a building’s product and construction stages up to practical completion is zero or negative, through the use of offsets or the net export of on-site renewable energy.”
Secondly, lived in:
“…A net zero carbon building is highly energy efficient and powered from… renewable sources with any remaining carbon balance offset”
And finally, how zero carbon can be achieved during renovation work, general maintenance and end-of-life recycling of the building.
GBC admit they haven’t worked this bit out yet, but they intend to publish this in a later release.
To reach these zero carbon levels, they suggest adopting a step-by-step plan that covers the LCA, fabric first design, adding on site renewable technology, and offsetting any remaining CO2. This is a similar approach to that used in The London Plan, just with a couple of extra bits.
Given this document was funded by private construction companies, it shows there is a will within the industry to push towards producing more sustainable buildings.
We must now wait to see how/if the UK’s Governments react to these findings through future building regulation releases.