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Retrofitting buildings to achieve improved levels of energy performance is a key strategy in the transition to a low-/net zero carbon future. In China, there has been an enormous growth in residential construction in recent decades in response to the country’s economic development and population growth. However, although these buildings are structurally solid and have long functional life spans, most have very poor thermal performance. Therefore, they would be very suitable for energy retrofitting. Because of the variety of retrofitting options, it is important to review the retrofit measures, regulations and possible outcomes to find effective, long-term solutions that strike a balance between the energy saved, the carbon emitted and the financial costs over a building’s lifetime. This paper reviews suitable retrofit measures for the hot summer–cold winter region of China, because this is an area with huge numbers of residential buildings that are suitable for energy retrofitting. The study explores the current conditions of targeted residential buildings, retrofit schemes, building regulations, and policy gaps towards achieving China’s 2060 carbon neutrality goal. The review indicates that current mandatory building energy regulations in this region are not ambitious enough to achieve a significantly lower carbon future, and one-step deep Passivhaus retrofit schemes are recommended to achieve decarbonization goals.

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Passivhaus EnerPHit is a rigorous retrofit energy standard for buildings, based on high thermal insulation and airtightness levels, which aims to significantly reduce building energy consumption during operation. However, extra retrofit materials are required to achieve this standard, which raises a contradiction between how to balance the environmental impacts of the retrofitting material inputs and extremely low energy consumption after retrofit. This motivated the analysis in this paper, which aimed to evaluate the possibilities of reducing the required retrofitting material inputs when trying to achieve the EnerPHit energy standard using a typical suburban dwelling in China’s hot summer–cold winter climate region as a case study. Firstly, how the insulation performance of each envelope component affected the building’s energy consumption was analysed. Based on this, sensitivity simulations of combinations of different insulation levels with different fabric components were investigated under four scenarios of insulation levels, airtightness and glazing choice. The final proposed retrofitting plans achieved the EnerPHit standard with insulation materials’ savings between 18% to 58% compared to a baseline retrofit plan, and this led, in turn, to 3.9 to 12.6 tonnes of carbon reductions. Moreover, an energy-saving of 87% in heating and 70% in cooling was achieved compared with the pre-retrofit dwelling.

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