Integration of LCA and LCCA through BIM for optimized decision-making when switching from gas to electricity services in dwellings

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).