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Passive house standard buildings (PHSBs), characterized by exceptional airtightness, present a promising technology for attaining carbon neutrality by 2060. The level of building airtightness is closely associated with air infiltration, which significantly impacts building energy consumption. However, there has been insufficient analysis of air infiltration in highly airtight buildings across diverse climatic regions. The present study involves the numerical simulation of the air infiltration rate (AIR) in an airtight building under varying design conditions during winter and summer, followed by a comprehensive analysis of the corresponding energy demand associated with air infiltration. The simulation results indicate that the building's AIR ranges from 125 to 423 m3/h, with an average of 189 m3/h under summer design conditions, and from 40 to 344 m3/h, with an average of 198 m3/h under winter design conditions. The statistical findings demonstrate distinct distribution patterns for AIR and energy demand across various climatic regions, exhibiting significant variations in values. The discussion emphasizes the substantial heating load associated with air infiltration, even at a building airtightness level of 0.5 h−1, highlighting the necessity of considering its impact in the design of highly airtight buildings. Furthermore, it is recommended to establish specific airtightness limits for buildings in different climatic regions of China. This study offers theoretical guidance for the airtightness design of highly airtight buildings. [ABSTRACT FROM AUTHOR]

Heating and cooling in buildings accounts for over 20% of total energy consumption in China. Therefore, it is essential to understand the thermal requirements of building occupants when establishing building energy codes that would save energy while maintaining occupants' thermal comfort. This paper introduces the Chinese thermal comfort dataset, established by seven participating institutions under the leadership of Xi'an University of Architecture and Technology. The dataset comprises 41,977 sets of data collected from 49 cities across five climate zones in China over the past two decades. The raw data underwent careful quality control procedure, including systematic organization, to ensure its reliability. Each dataset contains environmental parameters, occupants' subjective responses, building information, and personal information. The dataset has been instrumental in the development of indoor thermal environment evaluation standards and energy codes in China. It can also have broader applications, such as contributing to the international thermal comfort dataset, modeling thermal comfort and adaptive behaviors, investigating regional differences in indoor thermal conditions, and examining occupants' thermal comfort responses. [ABSTRACT FROM AUTHOR]

The Seawater Source Heat Pump (SWHP) system is an energy-saving and environmentally-friendly technology for the cooling and heating of buildings. The SWHP system is based on obtaining “free” heat from the sea by using heat pumps. In this study, field test and analysis were conducted to compare the performances of beach well infiltration intake system and direct intake system for SWHP systems at the Liaodong Peninsula, China. The average unit COP was 2.99 for the direct intake system and 4.66 for the beach well infiltration intake system, with the average seawater temperature being 5.83 °C and 12.85 °C, respectively. The test results indicate that the beach well infiltration intake method effectively improves the stability, reliability and energy efficiency of the SWHP systems in cold climate areas, and the intake seawater temperature is a critical factor influencing the performance of SWHP system. A simulation study was conducted for further illustration that how the intake seawater temperature of the beach well infiltration intake system was increased. The simulation result shows that the intake seawater temperature of beach well infiltration intake system is higher than the direct intake system, and the main reason is that the underground seawater with higher temperature is extracted. The intake seawater temperature is very sensitive to the seepage velocity in a range, and the flow quantity of pump seawater should not be too large under limited engineering conditions. The simulation results are foundations for further successful SWHP system engineering. [ABSTRACT FROM AUTHOR]

The air-tightness performance of residential buildings in China is not fully investigated. This study intends to investigate the air-tightness performance of an ultra-low energy building in a cold area of China. The air-tightness of the building envelope was measured using blower door method and the whole year air infiltration of the building was simulated by a multi-zone network airflow model based on the air-tightness test results. A thermal infrared imager and a smoke pencil were used to find out the typical air leakage places in the building envelope. The leakage areas of the typical air leakage places are found by measuring the whole building and then sealing the corresponding component and determining the reduction in the building effective leakage area. Test results show that the air change rates of the building at the pressure difference of 50 Pa (ACH50) under the depressurization and pressurization modes are 0.5 and 0.49 h−1, respectively. Simulations show that the air change rate of building under the weather conditions of Dalian changes from 0 to 0.12 h−1with an average of 0.05 h−1. The typical air leakage places of the building were the reserved holes in the building envelope, the junctions of the windows with the walls, the deformation parts of the outer windows and doors, and the joints and vents that imprecisely sealed. The exhaust vents were found to be the most significant source of leakage among the tested typical air leakage places. [ABSTRACT FROM PUBLISHER]

Seawater source heat pump district heating system is a renewable energy utilization system as it can utilize the sensible heat energy contained in the seawater. The energy efficiency of the system is always the main concern for the system researchers. So a field measurement with an emphasis on the energy efficiency of an actual seawater source heat pump district heating system was conducted, and the energy efficiency enhancement potential of the heat pump unit was analyzed and evaluated. The measurement showed that the heat pump units consumed the largest part of energy consumption of the whole system, and the coefficient of heating performance (COP) of the seawater source heat pump units was quite low especially during the coldest measurement period which was only 2.43. In the light of the concept of Thermodynamic Perfectibility, the energy efficiency enhancement potential of the heat pump unit was carefully analyzed and calculated. And the results showed that there is about an average of 24.2% energy efficiency enhancement potential of the heat pump units in this project. [ABSTRACT FROM AUTHOR]

As a renewable energy utilization system, seawater source heat pump district heating system can eliminate the local air pollution compared with the direct combustion of fuel in the conventional boiler house district heating system in northern cold climate area. A field measurement with an emphasis on the energy efficiency of an actual seawater source heat pump district heating system was conducted and analyzed. The field measurement showed that the heat pump units consumed the largest part of energy consumption of the whole system (as high as 78.9% in the project). However, the coefficient of heating performance (COP) of the seawater source heat pump unit was as low as 2.43. Then the energy efficiency enhancement potential of the heat pump unit was carefully analyzed and calculated in the light of the index of Thermodynamic Perfectibility for the heat pump unit. And the results showed that there is about an average of 24.2% energy efficiency enhancement potential of the heat pump units in the project. In the end, a verification case study indicated that the COP of the heat pump units in the project will increase 34.6% if they are substituted by the ones made by another manufacturer. [ABSTRACT FROM AUTHOR]

Abstract: This paper examines people’s thermal sensations during step-changes between ambient and workstation environments with a local ventilation device installed to supply-air motion around heads. We conducted human subject tests in a controlled environment chamber for summer and winter conditions. We performed 29 tests. The ambient air temperatures were 28 and 30 °C for summer conditions and 19 °C for winter conditions. The local supply-air temperatures were at 24, 28 and 30 °C for summer and 50 °C for winter. The supply-air velocities of the local ventilation device were at 3, 3.5, and 5 m/s for summer and 3.5 m/s for winter. The air temperatures near heads were 26–30 °C for summer and 32 °C for winter. The velocities along the jet-flow line at a distance of 10 cm from heads were 1.4–2.6 m/s for summer and 1.8 m/s for winter. In total, 23 subjects participated in the tests, and each subject participated in 1∼2 test conditions. Both the dynamic and stable thermal sensations of head and whole body were analyzed. When head is cooled by local ventilation, head thermal sensation has an effect on overall thermal sensation. When subjects moved from the workstation, where local devices were installed, to the ambient environment that was warmer in summer and colder in winter than the workstation, both overshooting and hysteresis were found. These thermal sensation changing trends in non-uniform step-change environments are helpful in personalizing environment control designs and exploring the possibilities of saving energy in buildings. [Copyright &y& Elsevier]

In order to judge whether a seawater -- source heat pump district heating system (SSHPDHS) is really energy-saving than the conventional boiler-house district heating system (BHDHS), the expression of the critical COP value of the heat pump unit for energy-saving in the SSHPDHS is derived in the paper. Three main factors affecting the energy efficiency of the SSHPDHS are concluded by comparing the energy consumption of the two systems. These factors are the boiler house heating efficiency, the heating district radius and the design parameters of the seawater pump, which are discussed in the context of actual projects. The critical COP value of the heat pump unit for energy-saving is effective on the energy efficiency judgement between the two systems. Also a method to improve the energy efficiency of the SSHPDHS for the system designers is presented here. [ABSTRACT FROM AUTHOR]

• The airtightness of three typical zones of public buildings was tested. • Their air infiltration rates for 1800 cases were simulated. • The influence of air infiltration on public buildings was analyzed. Air infiltration of the building is closely related to its indoor thermal environment, indoor air quality and energy consumption. It is known that, there have been only a few studies focusing on the prediction of air infiltration rate in public buildings in the cold area of China. In this paper, the airtightness of three typical zones of public buildings was tested and their air infiltration rates for 1800 cases were simulated based on the test results. Field tests show that the air change rates under the pressure difference of 50 Pa of the three zones are 3.8 h−1, 4.4 h-1, and 5.2 h−1, respectively. The airtightness of the zones built later (2007) is even worse than that built much earlier (1990). Simulations show that the air infiltration rate ranges from 0.01 h−1 to 0.23 h−1 with an average of 0.09 h−1 for zone 1, from 0.03 h−1 to 0.87 h−1 with an average of 0.37 h−1 for zone 2, and from 0.05 h−1 to 1.05 h−1 with an average of 0.50 h−1 for zone 3, respectively. The frequency of the AIR of all the three zones presents a logarithmic normal distribution. Discussion shows that the impact of air infiltration on public buildings should be fully considered when designing the HVAC system. [ABSTRACT FROM AUTHOR]

• The data sets of CCSH are achieved from measurement during real operation rather than a questionnaire survey. • The features influencing the CCSH are ranked by a comprehensive index of the two methods of partial least squares regression and random forest. • Optimal input variables for rural heating model are examined based on the nonlinear method. • The type of heating equipment, heated area and the indoor air temperature are considered in rural heating model. • The best model with the optimal inputs is verified at the individual and district scale. Identification of optimal subsets of input variables is a primary task in data-driven prediction modeling for the coal consumption for space heating (CCSH) of rural residences. However, most related predictive models of CCSH in rural residences ignore the nonlinear relationship between the factors and CCSH, and are short of feature selection process. This paper proposed an enhanced CCSH prediction model with learning-based optimized feature selection based on the measured weekly CCSH during real operation in Chifeng, Inner Mongolia, China. Partial least squares regression and random forest were employed to rank the features, and ten models with various input subsets were established by support vector regression. The prediction accuracy of the ten models was compared and the optimal features were examined based on the coefficient of variation of the root mean square error (CVRMSE), coefficient of determination (R 2) and model generalization ability. Furthermore, the residual errors between predicted and measured CCSH are distributed around zero evenly and extracted from the normal distribution for the optimized model. Particularly, we employed the best model to predict the aggregate CCSH at the district level. The prediction model with the optimal inputs was verified to be reasonable and accurate at the individual and district scales. [ABSTRACT FROM AUTHOR]

Abstract: A traditional Chinese heating system, the Chinese Kang, is used by 175 million people in detached houses in the rural regions of China, especially in Northeast China. This system utilizes biomass such as corn stalks, straw, corncob and energy plants as the heat sources. The objective of this paper is to establish a set of models to simulate the energy performance of the Kang heating system in one Chinese detached house. An experimental field study was carried out to collect practical parameters in a newly constructed Chinese detached house. The dynamic performance of the Kang heating system was simulated by using IDA-ICE 4.0 embedded with an empirical model built in the field study. The results show that the simulation can obtain good overall agreement with the field measurement results. It was confirmed that the Kang model created by IDA-ICE 4.0 is capable of simulating the performance of the Kang system and of calculating energy consumption in the detached house. Moreover, the result reveals that the thermal environment in the present Chinese detached house is still poor during the severe cold season if only the Kang system is used to heat the whole house. [ABSTRACT FROM AUTHOR]