Assessment and optimisation of life cycle environment, economy and energy for building retrofitting

Abstract

Building retrofitting plays a vital role in realising net-zero carbon ambition. Conventional retrofitting solutions are generally based upon decreasing operating energy usage or corresponding costs. However, many of these would increase the embodied carbon and energy. The innovation of this paper is to develop a building retrofitting assessment and optimisation approach to select the optimal combination of retrofitting options to minimise its carbon emissions, economic costs and energy usage over its life cycle. A real-life three-floor real-world office building is implemented to exhibit the behaviour of the newly developed retrofitting assessment and optimisation approach. This paper mainly focuses on passive options, including improving envelope thermal properties (e.g. wall insulations, roof insulations and triple-glazed windows) and installing renewable energy devices (e.g. photovoltaic panel, solar heater and wind turbine). The effects of varying embodied carbon, investment cost, embodied energy, annual salvage ratio, and material recycle ratio on the life cycle behaviour of the retrofitted building is investigated. For cost optimisation, the selection priority is sheep wool for roof insulation, insulation board for wall insulation, solar heater and wind turbine. The selection priority for energy or carbon optimisation would be insulation board for wall insulation, sheep wool for roof insulation, solar heater, triple-glazed window, and wind turbine. The largest achievable reduction in life cycle carbon, cost and energy are 3.9 × 106 kg, £3.6 × 105 and 7.8 × 107 MJ, respectively. The research outcome will benefit the government for policymaking on approach-based net-zero retrofitting guidance and building engineers for designing sustainable retrofitting measures.