ENVIRONMENTAL AWARENESS
Retrofitting will reduce whole life carbon in buildings and help the UK reach Net Zero
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The UK remains committed to its target of reaching Net Zero by 2050, and decarbonising the country is a vital part of this goal. With buildings currently accounting for around 40% of carbon emissions in the UK, Mitsubishi Electric’s Graham Temple explores how finding ways to reduce their impact on the environment will play a central role in reaching these targets
s concern around the environmental impact of our buildings continues to grow, the importance of whole life carbon (WLC) is increasingly being
considered. This is defined as the carbon emissions associated with a building over its entire life cycle, including both the operational carbon resulting from the energy used during a building’s occupation and embodied carbon, the emissions resulting from the materials and construction of a building. This focus on WLC is also being driven by client demand. Construction professionals, building designers and installers all need to help clients meet increasingly stringent standards around carbon measurement and abatement. Right now, guidance on calculating WLC is limited, but it’s important that designers, installers and contractors understand the role that mapping and reducing WLC plays in decarbonising UK buildings – starting with finding ways to balance embodied and operational carbon in these spaces.
Our existing building stock presents a challenge
There are currently around 30 million buildings in the UK, and the majority of them will still be around in 2050. This means that we can’t just focus on ensuring new buildings are built sustainably – we need to reduce the whole life carbon of our existing building stock in order to achieve Net Zero. If we fail to reduce the carbon impact of the existing building stock, they may even become unusable – or ‘stranded assets’. This is because organisations looking to lease or purchase building space will need it to meet certain efficiency and sustainability credentials, and if older buildings don’t meet them they will lose their commercial value and fall into disuse. This also means that taking steps to reduce WLC must be a focus now. Only by ensuring buildings are retrofitted with low-carbon technologies will spaces be future-proofed and continue to be attractive investments for years to come.
Instead of demolishing and rebuilding spaces,
re-using and retrofitting existing buildings can be a lower carbon option, and keep embodied carbon (the carbon used in building
construction and demolition) down. But there is also operational carbon to consider (the carbon impact of the building being used – like heating and cooling systems), and the two must be balanced to help buildings operate as efficiently as possible.
Balancing operational and embodied carbon is crucial
Taking one course of action in a building could cause operational carbon to be higher and embodied carbon to be lower, and vice versa. At the same time, finding information about operational carbon – for example, through the energy performance of HVAC products – is much easier to access than information on embodied carbon. To address this gap CIBSE has developed TM65, a basic and mid-level calculation methodology for measuring the amount of embodied carbon in a building, and we are able to provide mid-level calculations for embodied carbon in our heating, ventilating and cooling products.
Upgrading building service systems can be a good option to reduce operational emissions at the same time as improving the indoor environment for occupants. But it might not be as simple as just opting for a highly efficient and sustainable heat pump over a gas boiler. Instead, building designers may need to ask some important questions to determine what type of equipment to use:
• At what point does the equipment’s operational efficiency outweigh higher embodied carbon?
• How long does a high-efficiency product with high embodied carbon have to operate before its WLC levels are more favourable against a lower-efficiency product with lower embodied carbon?
Deciding on the best HVAC equipment to invest in can take some analysis as we try to give more consideration to WLC.
One important factor to consider is the impact of rating systems or targets for building performance on WLC. For example, an Energy Performance Certificate (EPC) would focus
14 BUILDING SERVICES & ENVIRONMENTAL ENGINEER DECEMBER 2023
on the delivery of low energy usage intensity measured as kWh/m2, so a potential solution for buildings meeting these criteria would be a variable refrigerant flow (VRF) system. This is because these systems are designed to only provide heating and cooling to a space when it is required, meaning they operate at full capacity less frequently and use significantly less energy overall. Another alternative is installing a renewable heating system such as a modular air source heat pump, which are around 300% more efficient than a traditional gas boiler and use a lower amount of energy as a result.
The time to act is now
As attention turns towards reducing the environmental impact of the built environment, construction professionals will also increasingly have to comply with stricter regulations for emissions reporting. This includes the proposed Carbon Emissions (Buildings) Bill, which will require the WLC emissions of buildings to be reported while also setting limits on the amount of embodied carbon in the construction phase. Furthermore, the UK Net Zero Carbon Buildings Standard, developed by a group of leading industry organisations, including CIBSE, RICs and RIBA, is also likely to include performance targets for energy use, embodied carbon and lifecycle embodied carbon in the existing building stock. With the government increasingly focused on
introducing legislation designed to reduce the amount of embodied carbon in our buildings, construction professionals must act now and consider how they will reduce WLC within building services.
Final thoughts
The UK firmly set on reaching Net Zero by 2050, so assessing the WLC of every building must become standard practice. With legislation continuing to change, it is imperative specifiers, contractors, and installers familiarise themselves with discussions around embodied carbon. Incorporating ‘carbon thinking’ into emissions calculations while learning to balance embodied and operational carbon in building systems will help this become a reality.
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