Achieving Zero Carbon in Active Buildings

This week I’ve been looking into the whole life carbon of buildings, what’s involved in assessing whole life carbon and the different tools available to assist with this.  Reducing the carbon emissions from the UK built environment is critical in the fight to prevent global warming and combat the climate emergency. 

Earlier this year, the Committee on Climate Change, in a report entitled “Net Zero – The UK’s contribution to stopping global warming”, recommended the UK Government amend the Climate Change Act 2008 to mandate that the minimum percentage by which the net UK carbon account must be lower than the 1990 baseline by 2050 is increased from 80% to 100%.

Achieving net zero operational carbon is already possible, as proved by our Active Office, which has recently been assessed as having operational carbon emissions approximately 3.5 times less than those of a standard office building of the same size, backing up our Energy Performance Certificate (EPC), which shows a carbon emissions figure of -9 – something we’re keen to prove in practice.

EPC for Active Office

As the amount of carbon emitted from buildings in use (operational carbon) reduces, the proportion of carbon emitted during the manufacture, transport, construction and end of life (embodied carbon) is set to increase.

Embodied carbon is, however, a lot more difficult to achieve and prove.  The intricacies of whole life carbon assessment of buildings were presented and discussed at an excellent event I attended in Bristol recently – Just How Much Carbon are your Buildings Responsible for?, hosted by the Alliance of Sustainable Building Products (ASBP) and the Green Register.  Here, I learnt about some existing tools that have been developed to assist with the process of undertaking Life Cycle Assessments (LCAs) of buildings, most of which are free to download.  These include the Inventory of Carbon and Energy (ICE) database developed by Circular Ecology – the world’s leading source of embodied energy and carbon data, using data taken from Environmental Product Declarations (EPDs).  And another free downloadable tool developed by Hawkins\Brown Architects.  Known as H\B:ERT (or Hawkins\Brown Emissions Reduction Tool), this is a Revit-based tool that enables design teams to quickly analyse and visualise the embodied carbon emissions of different building components and construction materials at any time during the design process.

At the event, I also picked up some interesting and thought-provoking facts, such as that recycled aggregate has more embodied carbon than virgin aggregate. This is mainly because when recycled aggregate is used in concrete, more cement may be needed, due to the reduced quality. Triple glazing can offer less operational carbon savings than the embodied carbon of the third pane, meaning double glazing may be a more viable choice. These examples highlight some of the challenges we are facing as an industry – the often unknown and unintended consequences of decisions we make when specifying products for use in buildings. While we may specify products for what we believe are the right environmental reasons, we may actually be causing more environmental harm.  The best way to mitigate this is perhaps to ensure LCAs are undertaken early in the design process.

Whole Life Carbon and LCAs will be detailed in Part 3 of my Design Guide, along with information on Life Cycle Costing and proving the Business Case for Active Buildings.

Published by jorclarke

I am an Architect, currently working at SPECIFIC Innovation and Knowledge Centre, Swansea University, and studying for a Doctorate in Sustainable Built Environment (D.SBE), which is focused on developing an Active Building Design Guide.

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