WHOLE LIFE CARBON | HEAT AND COOLING 170 kWhe.m-2 PAPER C A CEPTED CIBSE Technicalm Symposiu 679 kWhe.m-2 .org/ www.cibse m symposiu 298 150 kWhe.m-2 kWhe.m -2 COUNTING WHOLE LIFE CARBON To minimise carbon emissions from heating and cooling, the whole life of a system must be taken into account. Hoare Leas Will Belfield and Mathew Stark compare three common cooling and heating systems to see which has the lowest impact over a 60-year lifetime F ocus on whole life carbon (WLC) has increased significantly in recent years, with the aim of reducing the environmental impact of the built environment and driving towards net zero carbon. WLC encompasses the emissions from the operation of the building and the embodied carbon of the materials. Operational energy is generally considered to be well understood and, in recent years, there has been a growing focus on the embodied carbon of a building. Initially, a lot of this was targeted at structural elements, such as the concrete or steel frame, as this typically contributes the largest proportion of embodied carbon emissions. In a net zero carbon future, however, the industry will move away from new builds and towards major refurbishments, so the internal fit-out of a project becomes a significant proportion of the embodied carbon. As an item that is replaced regularly during a buildings life, and that is directly linked to operational energy consumption and fugitive emissions (refrigerant leaks and irregular releases), building services can have a major impact on the WLC of a development. The recently released Greater London Authority (GLA) WLC benchmarks for a typical office clearly demonstrate this, with the services accounting for 21% of the total. Recently, CIBSE published TM65, which made the task of estimating embodied carbon in building services much more accessible. In an effort to contribute to this field, this study quantifies the WLC of three options for typical office heating and cooling systems: air source heat External works 2% Substructure 13% Superstructure 26% Faade 18% Internal nishes 16% FFE 4% Services/MEP 21% Figure 1: GLA WLC benchmark for typical UK ofce pump (ASHP) four-pipe fan coil unit (FCU); variable refrigerant flow (VRF); and hybrid-variable refrigerant flow (HVRF) (see panel, Systems in the study). The study is based on an eight-storey office block comprising two tenancy splits per floor, providing about 12,500m2 of commercial office space. For each system, the following items have been included in the scope of 64 May 2022 www.cibsejournal.com CIBSE May 22 pp64-66, 68 Whole life carbon cooling and heating.indd 64 22/04/2022 18:12