Integration of LCA and LCCA through BIM for optimized decision-making when switching from gas to electricity services in dwellings
Nao Shibata, Francisco Sierra, Ahmed E. Hagras
Abstract
This study aims to assess electric heating system retrofit options and identify the optimal solution by applying a combined LCA and LCCA approach using BIM for existing UK homes. Exemplary case study illustrating an LCA and LCCA calculation using a BIM model of a house in Bristol (UK), to assess: (baseline) gas boiler; (i) electric boiler; (ii) air source heat pump; (iii) electric boiler + PV; and (iv) ASHP + PV. The optimal option overall is (iv) ASHP + PV, which reduces the kgCO2e emitted by 77% while increasing lifetime cost by 2.1%, compared to the classic gas boiler. This research also finds that embodied carbon still has a low impact on the decision, since the main impact of heating systems like ASHP (SCOP = 3.4) is to reduce kgCO2e by improving the efficiency of old gas boilers (COP = 0.76). Electric boilers are not the optimal alternative; they reduce kgCO2e by 47% but increase the lifetime cost of the system by 105% compared to gas boilers. The change in the “carbon factor” of electricity from 0.519 kgCO2/kWh to 0.136 kgCO2/kWh means that now dwellings using electrical systems emit 35% less kgCO2 than those that use gas (0.210 kgCO2/kWh).