WHOLE-LIFE CARBON | HEATING EQUIPMENT PAPER ACCEPTED Technicalm Symposiu Whole-life carbon at different carbon factors osium .org/symp www.cibse 2019 Figure 3: How the WLC of the heat-generation equipment changes with varying carbonfactors THE RESEARCH Goal: The goal of this study was to calculate and understand the carbonemission equivalent (referred to as Global Warming Potential in LifeCycle assessments) of heat-generation equipment, to inform selection of building service equipment with the lowest WLC. Variables of whole-life carbon (WLC) scenarios Elements of building life-cycle Systems assessed: The study considered the WLC of four types of heatgeneration equipment: gas boiler, gas CHP, ASHP and VRF. Application to building types: The study is relevant for multi-residential, schools, hotels and office developments, as these have a similar kWh heating and hot-water demand per kW of installed capacity. Although data was collected for a range of heat-pump capacities, the calculations are carried out based on a 100kW heat pump. 40% lower than the medium scenario A1: Extraction and processing of rawmaterial Boundaries: The study includes all elements of the building life-cycle, A1-C4, as defined by BS EN 15978:2011, excluding B7 operational water use, and B2 maintenance. It is assumed that the maintenance is carried out by in-house facilities management. Time horizon: A service life of 20 years has been applied to all equipment and the reference period of the study is 20 years. Method: Very little data is available on embodied carbon or WLC of heat-generation equipment in published data sources. So WLC calculation models are based on primary data collected from manufacturers of 27 heat-generation units for this study. The WLC calculation methodology is based on the RICS guidance, as this is seen as industry standard. The methodology deviates from the RICS methodology for the end-of-life stages (C1-C4). When carrying out these calculations, assumptions on carbon emissions in the extraction and processing of raw materials (A1) were taken from the ICE database. Assumptions for transport, disposal and disassembly were used from the RICS guidance. See table opposite for details. Carbon factors: A 20-year projected average carbon factor of 0.12kgCO2e/kWh was used for grid electricity; the carbon factor for natural gas used was 0.21 kgCO2e/kWh. This value is then further multiplied by 0.25, to account for 75% reused components Adjusted as per published databases A4: Transport from factory to site B6: Operational energy Scenarios: For each of the four heat-generation equipment types, a low, medium and high WLC scenario was established. These were based on the WLC calculations from the primary data collected. Manufacturer refrigerant-leakage rates were amended using published information. The scenarios were sense checked against published data, using the Oekobaudat database and Environmental Product Declarations (EPDs) of similar products. The scenarios considered the following factors: Operational efficiency % reused materials Weight and embodied carbon of materials Transport type and distance Refrigerant leakage and global warming potential. Scenario Low B1/C3R: Refrigerant leakage Scenario Medium Scenario High Average A1 for products with capacity close to 100kW 25% more than the medium scenario Adjusted as per published databases Adjusted as per published databases Locally manufactured (50km by HGV) European manufactured (300kmby HGV) Global manufactured (1500km by sea and 200km by HGV) Boiler: 98% Boiler: 95% Boiler: 91% CHP: 56%Th 34% El CHP: 52%Th 37% El CHP:47%Th 38% El ASHP: COP 5 ASHP: COP 3 ASHP: COP 1.8 VRF: COP 6 VRF: COP 4.5 VRF: COP 3 Boiler: 0 Boiler: 0 Boiler: 0 CHP: 0 CHP: 0 CHP: 0 ASHP: 1% annual, 99% end of life ASHP: 3.8% annual, 98% end of life ASHP: 6% annual, 90% end of life GWP 1 GWP 150 GWP 2088 VRF: 1% annual, 99% end of life VRF: 6% annual, 90% end of life VRF: 10% annual, 85% end of life GWP 1 GWP 150 GWP 2088 Carbon-emission equivalent of heat-generation equipment 14 May 2019 www.cibsejournal.com CIBSE May19 pp12-14 Life cycle heat Supp.indd 14 26/04/2019 15:25