WHOLE-LIFE CARBON | HEATING EQUIPMENT The meaning of life Whole-life carbon in the selection of heat-generation equipment As electricity generation reduces its carbon intensity, embodied carbon represents a higher proportion of whole-life carbon. Clara Bagenal Georges study, summarised at last months CIBSE Technical Symposium, considers the implications for building services S ince the early 2000s, Building Regulations and local, national and EU policy has shifted our attention away from energy cost to operational carbon emissions. These continue to fall because of measures to reduce demand, increase efficiency and optimise operation. Transitional technologies, such as combined heat and power (CHP), have been central to our industrys efforts to reduce the climatechange impacts of heating systems. As the UKs electricity Grid continues to decarbonise, however, CHP units no longer deliver operational carbon reductions and, in fact,pose a threat to urban air quality. Building Regulations and energy policies in our cities are poised to promote the large-scale adoption of all-electric systems, most notably heat pumps. This significant shift deserves scrutiny and requires new tools if we are to avoid repeating the well-intentioned mistakes of the past and future-proof our decision-making today. Whole-life carbon (WLC) offers a powerful way to understand and compare climate-change impacts of building systems, which includes embodied-carbon impacts from manufacture to installation and operation. Our study provides a starting point for investigation into the WLC of building services. It investigates the WLC of four types of heat-generation equipment: natural gas boiler, natural gas-fired CHP, air source heat pump (ASHP), and variable refrigerant flow systems (VRF). As part of the study, primary data was collected from manufacturers of 27 heat-generation units. Operational energy is the largest contributing component of WLC across a 20-year horizon for the majority of the scenarios investigated. Irrespective of systems selection, effective passive design-efficiency measures, to reduce heat demand, and appropriate plant sizing, remain key. For ASHP and VRF systems, carbon emissions from refrigerant leakage can make up a large proportion of WLC. This is because of the global warming potential (GWP) of the most commonly used refrigerants. In some scenarios, refrigerant leakage could have a higher impact than operational carbon emissions, and the Whole-lifecarbon offers a powerful way to compare climate-change impacts of buildingsystems Figure 1: The three stages of embodied carbon product, in-use, and end of life 12 May 2019 www.cibsejournal.com CIBSE May19 pp12-14 Life cycle heat Supp.indd 12 26/04/2019 15:25