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• Build the load uncertainty model of incorporating the annual load growth rate. • Integrate the grid integration level into multi-objective optimization. • Propose the multi-objective two-stage adaptive robust planning method. • Implement the planning method into an industrial park. • Analyze the influence of quantitative parameters on the evaluation indicator. An integrated energy system (IES) is considered as an effective approach to reduce carbon emissions, lower energy supply costs and increase system flexibility. As numerous energy conversion and storage devices with various features have been developed, determining their types and capacity size and optimizing the synergic action of all selected energy devices under load uncertainty have become challenging issues during the planning and designing of a new IES. To address these issues, a load uncertainty model is constructed by integrating the regional equivalent standard building-integrated load prediction method, the robust uncertainty set method and the fuzzy C-means clustering algorithm. Based on this uncertainty model, this paper proposes a planning method that incorporates the fuzzy multi-objective decision and two-stage adaptive robust optimization methods for handling these challenging issues. The multi-objective decision method enables comprehensive optimization based on the system's economic performance, carbon emissions and grid integration level. The two-stage adaptive robust optimization method aims to optimize the single-objective problem transformed by the multi-objective decision method. The planning method is implemented in an industrial park in the Baoding City of China. The influence of load budget uncertainty, annual load growth rate and energy purchase price is then investigated. The results show that the load budget uncertainty and annual load growth rate only affect the optimal capacity size of the selected devices, whereas the energy purchase price influences both the optimal device types and their capacity size. The optimal capacity size remains constant when the load budget uncertainty exceeds 3. This study provides a methodology to select the suitable device types and determine their capacity size for IES under load uncertainty, which will benefit the design of a new IES. [ABSTRACT FROM AUTHOR]

• Three adjusting methods suitable for district heating using ASHPs are proposed. • Energy loss corrections of frosting and on–off are adopted in the simulation model. • Power consumption increment caused by the correction of frosting reaches 3.85–17.41%. • Energy loss ratio of on–off declines from 3.19% to 0.68% with heating area increase. • Energy-saving potential of pump reaches 80.97–86.46% in different adjusting methods. Air source heat pump (ASHP) has been used in Northern China for district heating. However, few investigations on its regulating methods have been conducted till now. To increase the energy-saving effect of AHSPs, a simulation model, which considered the energy loss caused by frosting and on–off, was developed in this paper. Based on this model, three combination regulating modes suitable for district heating using ASHPs as heating source were proposed. Then the heating performance of ASHPs used for district heating in seven cities was investigated using this model. Results showed that both the energy loss corrections of frosting and on–off have evident impacts on the power consumption and seasonal coefficient of performance (SCOP). Owing to the energy loss correction of frosting, the power consumption of ASHP unit is increased by 3.85%–17.41%, and meanwhile SCOP is decreased by 3.72%–14.83%. The influence of the energy loss of on–off decreases gradually with the increase of heating area. In the three regulating modes, the power consumption of ASHP unit changes slightly, while the energy saving rate of water pump can reach 80.97%–86.46%. When the pitch of buried pipe was 300 mm, ASHP can meet the heating demand in all the three regulating modes. [ABSTRACT FROM AUTHOR]

• Cooling operation of the multi-energy system (SAAC and GSHP) was discussed, three different operation configurations and their best working condition in a NZEB was analyzed. • Real energy consumption of three working modes wad analyzed and discussed. A 4025 m2 office building was built in Beijing, China, in 2014 as a living laboratory and prototype to explore the technical energy systems of nearly zero energy buildings (NZEBs) in China. Not only the building itself but also the heating, ventilation and air conditioning (HVAC) systems were designed with flexibility to explore their performance. Solar-assisted air conditioning (SAAC) and ground source heat pump (GSHP) systems with different terminal units were designed as HVAC systems for either experimental, comparison, or measurement purposes. In this paper, the cooling operation of multienergy systems is discussed on the basis of actual measurement data. HVAC systems have three possible types of operation configuration types, namely, SAAC priority, GSHP only and multimode. Operation scenarios for these configurations are presented first, and the small-scale simulation was carried out to analyze the performance of SAAC priority and GSHP#1 only mode. It indicates that SAAC could save about 47% of energy than that of GSHP#1. Then, the actual operation performance in 2018 was analyzed by reference to the operation data. Through this study, it is found that 1) multienergy systems of SAAC and GSHP operated well in this NZEBs during the summer season; 2) a 10 RT absorption chiller can work well for an NZEB building of approximately 1000 m2 when outdoor enthalpy is low and the solar radiation is stronger than 400 W/m2 as a result of high building thermal performance and air tightness; 3) SAAC can save about 40 to 50% of energy compared to that of GSHP system when providing services for the same terminal system under the same outdoor weather conditions and 4) The GSHP system is a good complement to the SAAC system which works well in June, September and early July when outdoor enthalpy is low. This study indicates that a combination of GSHP and SAAC systems is highly promising for NZEBs in cold climate zones such as Beijing, where the solar radiation is sound. [ABSTRACT FROM AUTHOR]

Over the past decade, there has been an unprecedented growth in the development of green building projects in China. Using a unique cross-sectional database compiled from multiple sources, this study employs a Negative Binomial regression model to analyze the determinants of local green building development in 282 municipalities, with a focus on local policy and design standards. We present evidence that geographical location, local fiscal revenue, and real estate investment are strong predictors of green building counts. In terms of policy effectiveness, the results indicate that both mandatory regulations and incentive-based policies contribute to increasing the adoption of green buildings; nevertheless, mandatory regulations have a stronger effect on green building development than incentive policies. This paper also suggests that, when controlling for local green building policies, local design standards may negatively affect green building development. [ABSTRACT FROM AUTHOR]

This paper considers the potential heating and cooling energy savings from retrofitting to the Passivhaus EnerPHit standard a low-rise suburban dwelling in the southern Chinese town of Huilong, which has a hot summer/cold winter climate. An existing residential building in Huilong was chosen as a case study and a baseline digital model was created with the dynamic thermal simulation software DesignBuilder. The model was validated using 12 months of air temperature and relative humidity measurements from the building. The virtual retrofitting process of the baseline model involved insulating the envelope, improving the airtightness and adopting a high efficiency mechanical ventilation heat recovery system. It was more difficult to reach the EnerPHit cooling energy demand criterion than the heating target, and so additional passive cooling from shading and natural ventilation were adopted to finally achieve the EnerPHit standard. The final simulation results suggest that the EnerPHit standard for energy was successfully achieved, with a 90% heating energy demand reduction (down to 14.9 kWh/m2a), and a 70% cooling energy demand (down to 12.6 kWh/m2a), compared to the dwelling's baseline values. [ABSTRACT FROM AUTHOR]

• China has abundant SGE resources but the utilization of which remains still low. • SGE is mainly used for building heating and cooling via GSHP technology. • Energy efficiencies of GSHP systems are generally not high in China. • Some measures can be considered to enhance the utilization efficiency of SGE. • AI technology will be a significant measure for SGE resource evaluation. This paper summarized the shallow geothermal resources within a depth of 200 m in China. This geothermal resource is divided into five regions based on the geological structures, geomorphology, geology, and hydrogeology. The recoverable amount of shallow geothermal energy (SGE) is equivalent to 7 × 1012 kg of standard coal in a survey area of 1.69 × 105 km2, 60% of which is distributed in the mid-eastern region of China. SGE is mainly used for building heating and cooling via ground source heat pump (GSHP) technology since 1990s. The coefficient of performance (COPs) of the GSHP system exhibits large regional differences, and the energy utilizing efficiencies of GSHP systems are not high. The utilization rate of SGE is still low compared with those of other forms of renewable energy. Some measures, including a standardized and simplified management system, a feasible evaluation and utilization plan, modified technology and standards, an intelligence environmental impact assessment, and intelligence monitoring, can be considered to enhance the utilization efficiency of SGE. [ABSTRACT FROM AUTHOR]

• Halocarbon emissions in the building sector is increasing. • Non-Annex parties become bigger emitter instead of Annex parties. • Building sector accounts for more than half of global HFCs emissions. • Data sufficiency is key barrier for policy making. • Building cooling demand increase will push further halocarbon emissions. Estimates of the non-CO 2 greenhouse gas (GHG) emissions contributed by the buildings sector are necessary to evaluate this sector's potential for climate change mitigation. As data is lacking on fluorinated gases (F-gases) and hydrofluorocarbon (HFC) emissions from the buildings sector, this study aimed to estimate these emissions. First, the share of total global GHG emissions represented by buildings-sector emissions was estimated. Then, the HFC emissions of the buildings sectors in several countries (USA, EU, Japan, and China) are compiled. Next, based on necessary assumptions, global buildings-sector HFC emissions were estimated. Finally, this paper discusses implications for policy-makers. [ABSTRACT FROM AUTHOR]

• Solar hot air heating systems are more suitable for application in plateau areas. • Embedding PCM optimizes solar heating systems using air-medium ETC. • Performance of several solar heating systems in plateau areas is compared. • Solar heating systems have low energy efficiency under poor building envelopes. • Parameter study results provide reference for solar hot air systems' design. Rich solar energy resources in plateau areas of Western China are suitable for local heating. However, common solar heating systems face the potential hazard and maintenance difficulties caused by climatic conditions. In this paper, the solar hot air heating system using the air medium evacuated tube collectors (ETCs) with embedding phase change materials (PCM) was discussed, which can be a good solution in plateau areas. The whole system model was built in TRNSYS software and validated with practical data. Then the comparative study was conducted to evaluate the energy-efficiency performance and feasibility of six kinds of solar heating systems, which also involved the fully electric heating, based on the three thermal types of buildings in Lhasa. It was concluded that the solar hot air heating system is the most suitable application in plateau areas, which shifts more solar energy to night time heating and requires less maintenance. Furthermore, the influence of parameters on the system performance was also investigated, such as collector area, buffer tank volume and electric power. This study will help the design and application of solar hot air heating system with PCM in plateau areas for winter heating. [ABSTRACT FROM AUTHOR]

• The energy consumption of 38 Chinese district heating systems was investigated and compared. • Method to break down the consumption and evaluate the operational problems was presented. • Field measurements were conducted to evaluate problems leading to high energy consumption. • Overheating was responsible for 23% of total heat consumption. • Resistance, operation flow, and pump efficiency were three major problems in distribution networks. Worldwide, China has the largest district heating (DH) area and is also the fastest growing country. This paper presents field measurement results for operational energy consumption from 38 DHSs to fill in the gaps in understanding of the current operational issues of the district heating system (DHS). The average heat consumption during the heating period was 98.6 kWh/m2 and the monthly average electricity consumption for circulating pumps in the primary and secondary networks was 0.27 kWh/(m2 × month) and 0.29 kWh/(m2 × month), respectively. Thereafter, a systematic method for breaking down the energy consumption and quantitatively evaluating the underlying problems is presented. Based on several detailed measurements conducted in typical heat-exchange substations (HESs), it was found that overheating was the most prominent problem in energy-efficient buildings, constituting 23% of the total heat consumption. Another problem encountered was heat loss through pipes, which constituted approximately 5%–10% of the total heat consumption and was highly dependent on the actual conditions. In distribution networks, problems such as high resistance, high operational flow, and low pump efficiency were also identified and analyzed. Finally, practical energy-efficiency suggestions and future potential targets for the Chinese DHS are discussed from both a design and operational perspective. [ABSTRACT FROM AUTHOR]

• A novel design method for ASHPs was developed. • It considered both output heating capacity and frosting suppression. • A prototype ASHP air heater was designed using the novel design method. • Applicability of the method was verified by laboratory and field tests. Currently, the conventional design method for ASHPs is only to ensure that the required output heating capacity at specific rated conditions can be provided, without considering the impacts of frosting on the operating performances including the output heating capacity of ASHPs when operating at different regions with different climate conditions. Therefore, in this paper, a novel design method for ASHPs considering both the required output heating capacity and frosting suppression has been proposed, and its development is reported. A prototype ASHP air heater for use in the cold and frosting regions in China was designed using the proposed design method, and tested in both laboratory and field. The laboratory test results showed that the prototype ASHP air heater could both provide the required output heating capacity of 3 kW at its rated condition of -12 °C DB / -13.5 °C WB, and achieve the desired level of mild frosting at the standard 2 oC DB / 1 oC WB frosting condition. Furthermore, the field results indicated that the prototype ASHP air heater could maintain a better operating performance due to better frosting suppression than a conventional ASHP air heater with the same rated capacity of 3 kW. The COP values of the prototype ASHP air heater were 21% ~ 37% higher than those of the conventional ASHP air heater. The test results suggested that the novel design method could be used to help design ASHPs that can not only provide the required output heating capacity at rated condition, but also achieve a desired level of frosting when operated at different frosting regions. [ABSTRACT FROM AUTHOR]

• The replacing of a coal-fired boiler by a GWHP system is investigated. • The operation of each system has been monitored over one-year period. • The boiler has lower investments and covers lower thermal load than the GWHP. • GWHP shows higher economic performance considering Average Energy Price. • GWHP system may be cost effective over traditional boilers for applications. Currently in China, the replacement of coal-fired boilers by clean and renewable energy sources is considered as an essential measure to alleviate air pollution. This paper investigates the thermo-economic performance of replacing a coal-fired boiler by a Groundwater Heat Pump (GWHP) system for a greenhouse, where the GWHP system was constructed to reduce emission and also to provide cooling. The operation of this system has been monitored over a one–year period. The results show that the thermal efficiency factor of the boiler varies in the range of 0.53–0.68 and the Coefficient of Performance (COP) of the GWHP system averages at 4.1 for cooling and at 3.3 for heating. Although the boiler has both lower capital costs and lower operating costs, the analysis of Average Energy Price (AEP) shows that the GWHP system has a higher economic performance, since it has a lower AEP of 0.040 USD /kWh in heating and 0.023 USD/kWh in cooling over an expecting lifetime of 20 years, in comparison to the boiler at 0.052 USD/kWh over a lifetime of 10 years. This indicates that GWHP system may be considered as an alternative over traditional boilers in terms of thermo-economic performance for applications in other places of the world with similar climate condition. [ABSTRACT FROM AUTHOR]

• Traditional Chinese kang systems are reviewed and compared. • Improved kang systems are summarized and compared. • Possible directions for further study of Chinese kang are suggested. Chinese kang, which serves as the main space heating equipment in rural residences of cold regions of China, has received increasing attention due to people's increasing requirements of thermal comfort and concerns about indoor air environment in recent years. Most of the existing studies focused on one specific type of Chinese kang by using experimental or numerical methods to investigate the system's energy performance and its effect on the indoor environment. Therefore, there is a lack of comprehensive review of all the existing types of Chinese kangs. This paper firstly classifies the traditional Chinese kangs into three categories according to their culture and ethnic background. Secondly, the detailed construction, flue modality and thermal performance of the three kang systems are reviewed and compared. Thirdly, some recently proposed improved kang systems are introduced and analyzed. Finally, based on the review results, several possible research opportunities are suggested to guide future research on Chinese kangs. [ABSTRACT FROM AUTHOR]

Thermal comfort evaluations in the built environment are essential to occupant's satisfaction and also building energy consumption. Traditionally, thermal comfort has been assessed by Fanger's PMV model that was developed based on extensive laboratory tests. However, it's been found that PMV predictions are not good in field studies, especially in buildings with natural ventilation. In this paper, machine learning (ML) algorithms were used to predicted occupants' thermal comfort votes (TCV) and thermal sensation votes (TSV), using 5512 sets of thermal comfort data collected in naturally ventilated residential buildings in fourteen cities in China. Environmental parameters, personal parameters, climatic types, and adaptive control measures were considered and used as input parameters for the ML model. It was found that environmental parameters (both outdoors and indoors), personal parameters (metabolic rate and clothing insulation), and climatic types all significant affect both TCV and TSV, while adaptive control measures only affect TSV but not TCV. Comparing with established models (PMV, ePMV and aPMV), the ML models had smaller errors in predicting TSV and TCV. Based on these results, we suggest that the ML, especially ANNs model was reliable in predicting occupants' TCV and TSV in naturally ventilated residential buildings, and performed better than traditional thermal balance based models. Moreover, using the new model, we found that acceptable temperature ranges in naturally ventilated buildings were far wider than the ASHRAE adaptive comfort zone, suggesting that appropriate models should be established based on local data. [ABSTRACT FROM AUTHOR]

• Thermochromic coatings with five different colors were prepared. • Spectral reflectivity and color-changing properties of the samples were measured. • A three-step control method is used to simulate energy performance for an office building model. • Thermochromic coatings are most favorable in areas with uniformly distributed cooling and heating demands. Thermochromic coatings are promising in lowering air conditioning energy consumption of buildings. In this paper, thermochromic coatings with five different colors are prepared and their optical properties are measured. A two-story office building model is established and simulation is conducted to evaluate the energy performance of thermochromic coatings by using a three-step control method based on their dynamic color-changing properties. A comparative analysis is carried out for thermochromic coatings, cool coating and common coating. It is observed that when the building is located in Shanghai, average daily surface temperature of thermochromic coatings is lower than the common coating during cooling period and higher than the cool coating during heating period. Annual energy consumption results indicate that thermochromic coatings can avoid the penalty of increasing heating load for cool coatings. In particular, the annual energy consumption of the office building using thermochromic coatings can be reduced by 4.28–5.02 kWh/m2 compared to the common coating, and 0.73–1.47 kWh/ m2 compared to the cool coating. Simulation of other cities in different climate zones in China reveals that thermochromic coatings have better energy saving effects especially for the areas with hot summers and cold winters, and relatively uniform distribution of cooling and heating demands. [ABSTRACT FROM AUTHOR]

Recently, the structural insulated panels (SIPs) with the wood-based surfacing materials are developed in housing industry to increase the thermal efficiency of the wall system. In order to integrate the waterproof feature into SIPs, a newly designed GFRP reinforced squared tube sandwich panel (GSTPs) is introduced, where the Glass fibre reinforced polymers (GFRP) is utilized as surface material and the core is reinforced by the GFRP square tube. This paper focused on the thermal insulation performance of GSTPs. Both experimental, theoretical and numerical methods are employed to study their thermal insulation performance as roof panels. More specifically, the thermal conductivity of GFPR with three different core materials, including glass wool, Extruded polystyrene (XPS) and Polyurethane (PU) in the SIP, was first measured by hot plate apparatus (HPA) in the steady-state heat transfer tests. Then, the heat transfer coefficients of three type of GSTPs with above mentioned core materials are measured by guarding heat box (GHB) test. The theoretical and finite element (FE) method based numerical studies applied to conduct the heat transfer analyses on those SIPs. The accuracies of the theoretical and numerical studies are verified by comparing the obtained heat transfer coefficients with those from the experimental tests. The results from the present study could provide a good reference to the selection of the suitable panel thickness and core materials for different thermal regions in China. [ABSTRACT FROM AUTHOR]

In the context of residential energy consumption, the top-down approach and bottom-up approach have been developed to model and predict residential energy demand, and the bottom-up engineering model is a promising choice and an effective tool for urban planners and policymakers. However, unlike the existing building stock databases in some developed countries or regions, China's Pearl River Delta (PRD) region lacks such building databases. Thus, the study established a database of 120 residential districts in the PRD region, and developed typical models through the data of the collection, quantification and classification. In this paper, three typical residential district models have been defined, which was a supplement to previously develop seven typical residential building models. Moreover, four common family patterns in the PRD region were determined by literature research, the corresponding schedules and basic settings were developed subsequently for them. Finally, the simulations of the energy consumption of the three residential districts were conducted, whose energy consumption intensities were 28.43 kWh/m2a, 28.41 kWh/m2a and 28.24 kWh/m2a, respectively. The results of the simulation are similar to the results of the actual energy audit, which is considered that the typical residential buildings are representative yet simple-to-use energy model. [ABSTRACT FROM AUTHOR]

• We selected three benchmarking methods to establish building energy benchmarking models based on a sample of 45 hotel buildings in China. • We compared the three benchmarking methods in terms of consistency, robustness and explanatory ability. • The energy efficiency performance obtained from the three methods were found to be inconsistent. • We came up with suggestions based on comparative analysis for policy-makers to develop building energy benchmarking programs. A reasonable building energy efficiency benchmarking program plays an important role in energy consumption control and supervision. Previous studies have focused on the process of establishing a single benchmarking method, but few have compared the performances and outcomes of different methods. To fill this gap, this paper selects three benchmarking methods—multiple linear regression (MLR) based on Energy Star, stochastic frontier analysis (SFA) and the descriptive statistics method (DSM) based on the national energy consumption standard in China—to develop benchmarking models. We demonstrate each method using data on the energy and building characteristics of 45 four- and five-star hotel buildings located in Chongqing, China. To compare the consistency, robustness and explanatory ability of the three methods, we first utilize the Spearman rank correlation analysis to test whether these methods have consistent energy efficiency ranks and then present Sankey diagrams to further reveal the interactions of the estimated energy efficiency grades obtained from the three methods. It is found that the results of DSM and SFA are most consistent, while MLR vs. SFA and MLR vs. DSM present significant differences in evaluating building energy performance. In addition, DSM is more robust for evaluating the ranks of sampled buildings, while SFA is more robust for evaluating energy efficiency grades. Furthermore, we discuss the explanatory ability of each method. In addition to the building characteristics, the design and operational characteristics of the HVAC system have great effects on building energy consumption. Finally, we present suggestions for policy-makers regarding the development and implementation of the building energy benchmarking program in Chongqing and for the management of buildings with different energy performances to further improve the energy efficiency. [ABSTRACT FROM AUTHOR]

Groundwater heat pump (GWHP) systems are central heating and cooling systems that utilize groundwater heat. With the rapid development of this technology in China, it has become imperative to study the changes in the ground environment, including the flow features, heat transfer characteristics and clogging caused by long-term recharge, during the operation of GWHP systems. In this paper, a mathematical model considering the effect of particle deposition was proposed to describe a GWHP system based on the typical geological and hydrogeological conditions (i.e., a dual-structure strata) in Wuhan, China. During research on a GWHP engineering project in the Baibuting Garden community, four groundwater flow conditions (including no flow, forward flow, reverse flow and cross flow) and two typical flow modes (continuous and flushing modes) were considered. The groundwater temperature and flow rate were measured through measuring wells, and a comparison between theoretical and actual values shows that this model can provide an easy yet effective way to describe GWHP engineering. The seepage and temperature fields both display periodic trends under the continuous flow mode and can be significantly affected by well flushing. The central area is marginally influenced by groundwater flow when compared with the surrounding areas; for instance, the temperature fluctuation at MW3 can reach 8.2 °C, while the fluctuation reaches 2.9 °C at MW1. Particle deposition can affect the parameters of the ground environment; we find considerable correspondence between the concentration of deposited particles and the porosity. Moreover, both the concentration of deposited particles and the porosity change by a large margin after flushing, especially in regions around pumping wells (the concentration of deposited particles can fluctuate by 108 g/L, and the porosity can change by 0.055). [ABSTRACT FROM AUTHOR]

• A series of typical residential building models were defined through statistic method. • The envelope's size, shape, thermal properties and opaque feature were determined. • The indoor space partition and function area distribution were also identified. • The models could serve as a standard platform for building energy simulation research. • The method can be applied to other regions and building types with sufficient data. With the rapid growth of urban population in the Pearl River Delta (PRD) region, the research on residential energy saving has attracted increasing attention. Typical buildings are useful tools for building performance simulation of residential district, which is of great significance for local green building-related research, policy formulation as well as market orientation. In this paper, the spatial information (building size, shape, area and amount of dwelling unit area) and the thermal properties of the envelope (such as window-to-wall ratios, shading coefficient, and the heat transfer coefficient) of about 120 residential districts were collected and statistically analyzed. Meanwhile, 120 residential districts are the actual data in the PRD region since 2010. The analysis method involved K-means, histogram and bubble diagram, box plot - bin mean method and slope method, which aims to remove outlier points and find representative value for each parameter, and define a series of typical residential building models. From the analysis result of 120 residential districts, which involved around 350 types of 1300 residential buildings and over 900 types of dwelling units, 7 typical residential building models were determined to be used in other research. [ABSTRACT FROM AUTHOR]

• Two thermal comfort investigations were conducted in severe cold area. • The thermal neutral temperatures derived from the linear regression model and logistic model were compared. • The relationship between probability of opening windows and temperature difference was developed. In recent years, the indoor air temperature in residential buildings for space heating rose gradually in the severe cold area of China. Would people feel comfortable in a warmer environment? This paper focuses on the appropriate indoor air temperature in winter. Two field investigations were conducted on the indoor thermal environment and human adaptation in residential buildings with district heating in Harbin during two winter seasons from 2011 to 2014. Ten apartments and their residents were chosen as samples in each investigation. The investigations included measurements of physical environmental parameters as well as subjective questionnaires. The results show that when the indoor air temperature was higher than 24 °C, people would have a sensitive response and preferred a lower temperature. An ordinal logistic regression model was used to examine the result of the linear regression model. The neutral temperature derived from the logistic model is 0.5 °C higher than that from the linear model and the adjusted neutral temperature is 0.8 °C higher than the linear model. Detecting whether people felt "cool" or not and "warm" or not is relatively accurate with the logistic model. It is not sensitive to judge whether people felt "neutral" in low air temperatures. Thermal neutral temperature is not a suitable set-point of indoor air temperature. In the severe cold area of China, the indoor air temperature of 20 °C is suggested as the standard for space heating in residential buildings in terms of comfort and energy saving. [ABSTRACT FROM AUTHOR]

• A novel evaluation method is developed for evaluation of energy saving potential of HVAC system. • The evaluation method considers measurement uncertainties of operation data. • The evaluation benchmark is the probability distributions of real ideal exergy efficiency. • The evaluation method is accurate and credible under uncertainties. Measurement uncertainties exist widely in the operation of HVAC system. If they are not taken into account, the evaluation results may be inaccurate. Therefore, the paper proposes a novel evaluation method based on exergy analysis, which considers measurement uncertainties of operation data. The evaluation method quantifies the uncertainties of the real exergy efficiency and the real ideal exergy efficiency of HVAC system by Latin hypercube sampling (LHS) and particle swarm optimization (PSO) algorithm, and set up an evaluation benchmark and an evaluation index I prop to evaluate the energy saving potential of HVAC system. The evaluation benchmark is the probability distributions of real ideal exergy efficiency, and the evaluation index I prop is defined as the ratio of the expectation of the real exergy efficiency to the expectation of the real ideal exergy efficiency. An airport HVAC system which is located in the south of China is used for validation. The proposed evaluation method is compared with a conventional evaluation method on the simulation model under two levels of uncertainties. Results show that the proposed evaluation method is more accurate and credible than the conventional evaluation method under uncertainties. [ABSTRACT FROM AUTHOR]

• PMV overestimated the thermal sensation of students. • Students preferred cooler thermal environment. • A higher percentage of students felt local thermal discomfort. • The lower limit for 80% acceptability determined by TAV could be 19 ℃. • If indoor design temperature is 19 ℃, 3.46% of annual heating load can be saved. A classroom thermal environment directly not only influences students' thermal comfort but also energy-saving. Numerous studies indicate that students' actual thermal comfort is different from the PMV and adaptive model predictions, and the current thermal comfort standards could not be applicable for the classroom thermal environment design and evaluation. This paper aims to study the university students' general and local thermal comfort by a field survey conducted in a classroom during the heating season in Taiyuan, China. The results indicated that PMV overestimated the thermal sensation of students. Thermal acceptance vote (TAV) defined the widest acceptable temperature range, and the lower limit for 80% acceptability could be 19 ℃ in Taiyuan. Students preferred a cooler than a neutral environment. The indoor design temperature determined by the heating load duration curve (LDC) was about 21.85 ℃. If the indoor design temperature could decrease from 21.85 ℃ to 19 ℃, 3.46% of the annual heating load could be saved. Moreover, although a majority of students found the environment general thermal acceptable, a higher percentage of students felt local thermal discomfort. Local thermal comfort should be a critical issue for the classrooms' thermal environment improvement. [ABSTRACT FROM AUTHOR]

A ceiling-sidewall composite air carrying energy radiant air-conditioning system (ACERS) is presented, and the heating performance of the ceiling-sidewall composite ACERS combined with air source heat pump is investigated by field experiment. The results show that the combined system can meet the heating requirement for office buildings in south-central China, and also have the energy-saving potential. Moreover, the indoor thermal environment under three different installation types, namely the ceiling, the sidewall, and the ceiling-sidewall composite type, is analyzed by using computational fluid dynamic (CFD) simulation. The comparisons of three types indicate that all of them can meet the temperature requirement, but the temperature is more uniform and higher in the composite ACERS. Meanwhile, the temperature gradient in the ceiling ACERS is smaller than that of the sidewall ACERS due to the further heat transfer caused by air penetration. Both the experimental and CFD simulated temperature distribution demonstrates that the shelter of furniture has an impact on the indoor thermal environment, and it should not be ignored in practical engineering. This research shows the feasibility of winter heating by using the ACERS in office buildings, and is helpful for HVAC engineers to design and apply different ACERS types and realize the integration of air conditioning in winter and summer in this area. [ABSTRACT FROM AUTHOR]