The system combining double-layer pipe-embedded wall with air source heat pump has been proposed for low-temperature heating. However, such system still requires relatively high temperature water in buildings with large window-to-wall ratios (WWRs). Therefore, a system integrating double-layer pipe-embedded wall and fan-coil window with shallow geothermal energy and air source heat pump is proposed in this study for ultra-low-temperature heating. Taking a residential building as an example, the models of traditional system, reference system combining double-layer pipe-embedded wall and air source heat pump, and the proposed system are established. The heating performances of the three systems are analyzed under various WWRs and ambient temperatures in Beijing. Additionally, seasonal performance as well as economic and environmental assessments are conducted in Harbin and Beijing. The results show that compared with reference system, (1) the proposed system maintains low-temperature heating when WWR exceeds 0.35; (2) as WWR increases to 0.5–0.65, the proposed system reduces the water temperature by 5.6–10.1 ℃; (3) when WWR is 0.35, 0.5, and 0.65, the COP of the proposed system is improved by 7.9%, 10.1%, and 15.0%, with corresponding energy-saving rates of 17.4%, 23.0%, and 25.9%, respectively; (4) in Harbin and Beijing, under a WWR of 0.6, the proposed system achieves cumulative seasonal heating load reductions of 46.7 kWh/m² and 24.1 kWh/m² as well as reducing annual carbon emission reductions of 20.9 kg/m² and 7.5 kg/m² with payback periods of 0.2 and 3.6 years, respectively. Besides, compared with traditional system, under a WWR of 0.6, the proposed system reduces annual carbon emissions by 18.0 kg/m² in Harbin, and 5.6 kg/m² in Beijing. In conclusion, the proposed system demonstrates substantial potential for advancing low-carbon heating technologies.

A high-quality indoor environment is essential for ensuring occupant comfort and health. Conventional heating, ventilation, and air conditioning (HVAC) systems, which are designed under the most unfavorable conditions with lumped parameter approaches, often lead to energy waste. To address this problem, an occupant-oriented indoor environment-creation framework is presented. The system identifies occupant distribution and usage scenarios through an occupant positioning system. Based on the occupant distribution, the system switches air distribution patterns and adjusts air supply parameters to supply air to occupied zones efficiently. This perspective paper presents the key technologies involved and outlines future research directions in this field. The key technologies and the future roadmap are introduced. This perspective will help address research gaps and inspire ideas to create occupant-oriented environments for more healthy, comfortable, energy-saving, and low-carbon indoor environments.

The indoor parameters are generally non-uniform distributed. Consequently, it is important to study the space cooling/heating load oriented to local requirements. Though the influence of indoor set point, heat sources, and ambient temperature of convective thermal boundary on cooling/heating load has been investigated in the uniform environment in previous research, the influence of these factors, particularly the convective heat gain/loss through a building envelope, on cooling/heating load of non-uniform environment has not yet been investigated. Therefore, based on the explicit expression of indoor temperature under the convective boundary condition, the expression of space cooling/heating load with convective heat transfer from the building envelope is derived and compared through case studies. The results can be summarized as follows. (1) The convective heat transferred through the building envelope is significantly related to the airflow patterns: the heating load in the case with ceiling supply air, where the supply air has a smaller contribution to the local zone, is 24% higher than that in the case with bottom supply air. (2) The degree of influence from each thermal boundary to the local zone of space cooling cases is close to that of a uniform environment, while the influence of each factor, particularly that of supply air, is non-uniformly distributed in space heating. (3) It is possible to enhance the influence of supply air and heat source with a reasonable airflow pattern to reduce the space heating load. In general, the findings of this study can be used to guide the energy savings of rooms with non-uniform environments for space cooling/heating.

Ground heat exchanger (GHE) is an important component of ground-coupled heat pump system. The soil temperature distribution and heat exchange capacity of GHE will largely determine the overall performance of the system. Consequently, it is very important for system design and its further performance improvement to seek a proper method of calculating the soil temperature field around GHE and the corresponding heat exchange rate. To break the limits of the existing calculating solutions and to improve the calculation accuracy and speed simultaneously, a fast distributed parameter model based on response factor (RF model) was proposed in this paper. The response factor refers to the contribution of a heat source to the excess temperature variation of a certain soil point. In a case study, the response factors and the temperature distribution of the soil heat container around one borehole were calculated using the RF model. Compared with results of numerical simulations, it can be known that the RF model equaled numerical solution in terms of accuracy, but enjoyed faster speed over numerical solution. In addition, the RF model was validated against the experiment data, with deviations less than 1.2%. In conclusion, the proposed RF model was a potential solution to predict the transient soil temperature distribution fast and accurately.