Reducing Energy Consumption and Improving Comfort by Retrofitting Residential Buildings in the Hot Summer and Cold Winter Zone of China

Abstract

China's Hot Summer and Cold Winter zone with a 550 million population, accounts for 45% of China's building energy consumption; as such, building retrofits could offer substantial energy savings. This paper presents results from a dynamic thermal modelling study of a typical urban multi-storey residential building under three types of A/C operating schedules. Seven energy saving retrofit measures (external wall insulation, roof insulation, double-glazing, air infiltration control, window shading, communal staircase design and energy-efficient A/C) were evaluated, and the retrofit strategy with the highest annual energy savings and lowest thermal discomfort was identified. This retrofit strategy was subsequently evaluated for other flats (apartments) with different orientations and positions in the typical building. The annual space-conditioning energy could be reduced by 59 to 68%, depending on the flat location, orientation, and A/C operating schedule. The findings were then scaled up to estimate the potential energy savings in the city of Chongqing. Over 320 multi-storey residential buildings were represented by twelve archetypes. Space-conditioning energy consumption was reduced by up to 58% (18.8 TWh). This work provides evidence of the potential energy savings of city-scale retrofit that could aid China in reducing building energy consumption and achieving net-zero carbon emissions by 2050. Practical applicationsUsing dynamic thermal models, it was possible to explore a wide range of refurbishment options for China's highly energy-consuming HSCW zone with hot, humid summers and mild, chilly winters. The simulation models developed in this paper revealed that double-glazing with air infiltration control is the most effective retrofit measure for middle-floor flats, but for top-floor flats, roof insulation is the most effective; south-facing flats consume more high energy consumption than north-facing flats.Furthermore, high-rise buildings consumed less energy than low-rise buildings per square meter, and one-bedroom flats consume more energy than three-bedroom flats per square meter. This study also demonstrated the procedure to develop thermal comfort evaluation methods, A/C operating schedules and construction parameters from literature in this climate zone, when there were no standards or databases available. Findings offer a tangible, clear retrofit strategy which considers different A/C operating schedules, flat locations, and building archetypes. It can assist decision making by practitioners and homeowners aiming to upgrade the building stock of this climate zone which covers 3.4billion m 2 with 550million population, so as to reduce energy consumption and improve occupant comfort.

Reviewing the contribution of retrofitting for climate resilience in residential buildings

“…Thus, it is moderately applicable for assuring the robustness in these climate zones. For instance, roof insulation with a 50 mm thickness facilitated the most significant decline in thermal discomfort (up to 320 h) for Chinese multi-family houses (MFHs) (Tsang et al , 2022). Moreover, thermal insulation assists in ensuring robustness in tropical and arid regions when using mechanical cooling and does not support passive cooling.…”

“…Glasses with lower u values increase the robustness of houses next to insulation, mainly in heating-dominated regions and also support in cooling-dominated regions coupled with a mechanical HVAC system. For example, double glazing has reduced 140 h of summer thermal discomfort in a temperate region (Tsang et al , 2022).…”

Calculating the optimum window-to-wall ratio according to daylight factor and thermal performance in Mediterranean climate

“…This part concentrates on the theoretical background and historical development of available literature about the subject of this research. Generally, in the field of saving energy and reducing greenhouse gasses (GHG) emission, a big amount of current knowledge and studies focuses on developing existing buildings' performance through energy retrofits [14,15]. In other words, to improve building energy performance and reduce greenhouse gas (GHG) emissions, numerous studies have concentrated on assessing and enhancing the performance of existing buildings through energy retrofits.…”

Retrofit Analysis of City-Scale Residential Buildings in the Hot Summer and Cold Winter Climate Zone

“…The system can increase thermal comfort time by 12.8% and reduce energy consumption by 14%. Tsang et al [29] predicted the energy consumption for space heating and cooling and the thermal comfort of individual flats, single buildings, and a city in Chongqing. They examined the energy consumption of seven energy-saving measures and three air conditioning operation modes.…”