ENERGY MANAGEMENT, OPTIMISATION AND SUSTAINABILITY
We must reduce whole life carbon in the built environment
Chris Newman, zero carbon design manager at Mitsubishi Electric argues that it is essential to reduce whole life carbon in buildings in order to meet the government’s carbon emissions targets
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n 2019, the government committed to achieving a 78% reduction in greenhouse gas emissions by 2035 and Net Zero by 2050. Buildings are responsible for 25% of these emissions once their construction, operation, maintenance and demolition are accounted for - meaning they are a crucial area to consider when working towards this goal. These emissions, otherwise known as Whole Life Carbon (WLC), are the carbon emissions associated with a building over its entire life cycle. This includes the operational carbon resulting from energy usage during a building’s occupation, alongside the amount of embodied carbon - the emissions resulting from the materials and construction of a building. Awareness around the importance of WLC
is already being driven by growing client demand. Installers, designers and specifiers must increasingly demonstrate that their buildings meet embodied and operational carbon standards. So can building professionals lower the amount of WLC in these spaces and ensure these targets are met?
Reducing the amount of embodied and operational carbon in the early construction stages is key. Opting for energy-efficient systems to heat, cool and ventilate these spaces can also lower operational carbon emissions, helping to reduce the amount of WLC in the future built environment.
Significant progress is already being made
In recent years, both the government and the wider building industry have been working to establish a framework for measuring WLC in the built environment.
For example, WLC is currently being considered within local planning legislation, with regulations such as the London Plan outlining how to prepare a WLC assessment. A proposed Carbon Emissions Bill is also currently under parliamentary review, which if successful, will require the WLC emissions of buildings to be reported - while also setting limits on embodied carbon emissions during the construction phase. Our recently published whitepaper also highlights the growing importance of WLC in the commercial sector, with clients increasingly turning to local assessment schemes such as BREEAM to assess the amount of embodied and operational carbon in these spaces. A group of leading organisations in the
construction industry are also working towards developing a Net Zero Carbon Buildings Standard, which, if successful, will allow building professionals to demonstrate their built assets are Net Zero Carbon. With WLC becoming an increasingly important consideration for both the industry and government alike, it’s crucial that specifiers, designers and installers have a good understanding of WLC and how it can be reduced. However, it can be difficult to know where to start.
Assessing embodied and operational carbon is a priority
Achieving a low WLC building starts with assessing the amount of embodied and operational carbon in your building systems. There are two main approaches to measuring embodied carbon. The first is an Environmental Product Declaration (EPD), which offers a standardised framework for measuring embodied carbon throughout the product lifecycle. Another option is using the
TM65 methodology, which offers guidance on calculating embodied carbon in mechanical, electrical and public health (MEP) products. The Global Warming Potential of refrigerants (GWP) can also impact the amount of embodied carbon in a building, so it should be an important consideration when selecting equipment during the early construction phase. Opting for a product with a lower GWP, such as R32, can help reduce the amount of overall refrigerant. Measuring energy usage is vital when assessing operational carbon because an energy-efficient system can reduce carbon emissions during a building’s operation. Energy Usage Intensity (EUI) is one way of measuring energy use and is recommended by organisations such as CIBSE and the UK Green Building Council (UKGBC).
Adopt a whole-building approach
Installing energy-efficient heating, ventilating and cooling (HVAC) systems can also reduce the amount of operational carbon in a building. However, this requires a ‘whole building’ approach rather than opting for individual equipment such as heat pumps or chillers. Re-using heat through energy recovery can save energy and reduce a building’s operational carbon footprint while lowering running costs. One potential solution is mechanical ventilation with heat recovery (MHVR), which can recover up to 90% of the heat energy lost and provide localised ventilation.
Ambient heat networks that operate at lower temperatures of 10 to 30 degrees Celsius are another option. These work by pumping water around a loop that is used as a heat source by nearby water source heat pumps, while also re-using the rejected heat elsewhere. This makes them ideal for mixed-use buildings where apartment blocks, retail outlets or offices are located alongside each other, where rejected heat can heat nearby buildings. With awareness around the environmental impact of the built environment continuing to grow, reducing WLC in these spaces is fast becoming a priority for government and industry alike. By measuring embodied and operational carbon and opting for energy-efficient HVAC systems, building professionals can help create low-WLC buildings and contribute to a greener future for all.
18 BUILDING SERVICES & ENVIRONMENTAL ENGINEER APRIL 2024
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