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The energy crisis and environmental pollution pose great challenges to human development. Traditional vapor-compression cooling consumes abundant energy and leads to a series of environmental problems. Radiative cooling without energy consumption and environmental pollution holds great promise as the next generation cooling technology, applied in buildings mostly in indirect way. In this work, a temperature-regulating module was introduced for direct summer cooling and winter heating. Firstly, the summer experiments were conduct to investigate the radiative cooling performance of the module. And the results indicated that the maximum indoor temperature reached only 27.5 °C with the ambient temperature of 34 °C in low latitude areas and the air conditioning system was on for only about a quarter of the day. Subsequently, the winter experiments were performed to explore the performance of the module in cooling and heating modes. The results indicated that indoor temperature can reach 25 °C in the daytime without additional heat supply and about a quarter of the day didn’t require heating in winter. Additionally, the transient model of the module and the building revealed that the electricity saving of 42.4% (963.5 kWh) can be achieved in cooling season with the module, and that was 63.7% (1449.1 kWh) when coupling with energy storage system. Lastly, further discussion about the challenges and feasible solutions for radiative cooling to directly combine with the buildings were provided to advance the application of radiative cooling. Furthermore, with an acceptable payback period of 8 years, the maximum acceptable incremental cost reached 26.2 $/m2. The work opens up a new avenue for the application mode of the daytime radiative cooling technology.

In-duct pulsed xenon lamp can destroy the bioaerosols in the flowing airstream as it passes through. Current researches mostly focus on the food sterilization and surface sterilization. In this work, an in-duct pulsed xenon lamp sterilization experimental system was developed with stainless steel duct to model use in the HVAC (Heating, Ventilation and Air Conditioning) system. To study the effect of power supply parameters on the inactivation efficacy, 42 experimental conditions were conducted with the variation of input voltage, capacitance capacity, flash frequency and airstream velocity. The results indicate that the one-pass inactivation efficiency ranges from 63.12% to 88.87%. Inactivation efficiency has positive correlation with input voltage, capacitor capacity and flash frequency of the device, and negative correlation with airstream velocity. The factors affecting the inactivation efficiency in descending order are input voltage, capacitor capacity, flash frequency and airstream velocity. As the power consumption indicator P/G (input power per airflow volume) increases, the inactivation efficiency shows a near linear increase. This study developed a comprehensive evaluation method on the inactivation efficacy by selecting higher ratio of efficiency to input power under the premise of ensuring inactivation efficiency. Optimal combinations of parameters could be obtained with the method in the applications.

In building energy conservation , HVAC systems have great potential, and load prediction plays an important role in optimizing system control and improving system energy efficiency. Therefore, improving the accuracy of load prediction is of great significance. This paper aims to improve the prediction accuracy of the data-driven model of load prediction through optimizing the input variable selection. Factors such as outdoor temperature, wind speed, solar radiation, indoor temperature and user behavior have different mechanisms of action to influence the heating load, and there exists difference among the influence degree of each factor on the heating load at each moment. Therefore, the optimal input variable used by the heating load prediction models at different moments will be different. Based on this, this paper proposes to establish an input variable selection method based on hourly correlation analysis. Taking an office building as the case building, this paper uses the back propagation neural network (BPNN) model and the support vector regression (SVR) model to compare the selection methods of hourly correlation analysis and non-hourly correlation analysis. The results show that the influence degree of solar radiation intensity and the historical load at the moment of 24 h ahead on the load at each moment have great difference. Compared with non-hourly correlation analysis, hourly correlation analysis can reduce the root mean square error (RMSE) of the prediction results of the BPNN model and the SVR model by an average of 10.4% and 12.9%, respectively, and increase the coefficient of determination ( R2) by an average of 11.7% and 7.9%, respectively, while all the calculation time is about 0.4 s. This shows that the heating load prediction method based on hourly correlation analysis can improve the prediction accuracy of model while keeping the prediction rate unchanged.

Chitosan is considered as one of the eco-friendly absorbents for HCHO removal, and its fibrous material possesses great application value in the domain of indoor air treatment. Herein, chitosan nonwoven (CSNW) and prepared chitosan-coated polypropylene nonwoven (CS-PPNW) were used to investigate the performance on dynamic HCHO purification in a one-pass air duct system. The impacts of exterior environmental parameters containing relative humidity and initial concentration on purification efficiency were assessed by CSNW at dynamic condition, while the other two interior factors including raw material and acid-pretreatment pH were both at dynamic and static condition for validation. Results indicated that the snow crab chitosan outperformed red crab in HCHO purification due to the higher amino content in molecule. The protonation of amino groups was found the reason for the deterioration of adsorptive capacity at low pH situation. And the optimum pH value was approximately 6, where the purification efficiency reached to 89.6% in static adsorption while 34.8% at dynamic condition. As the relative humidity and HCHO concentration ascends, the one-pass purification efficiency exhibits a near quadratic and exponential increase, respectively. The prepared CS-PPNW was characterized by SEM and FTIR analysis, which ascertained the adhesion of chitosan on the PP substrate. Despite lower utilization of chitosan, CS-PPNW revealed prominent capacity of HCHO removal at a loading amount of 292 g/m2 or higher. Additionally, the robust resistance properties of CSNW and CS-PPNW at filtration velocities ranging from 0.05 to 0.2 m/s also suggested the potential applicability of chitosan-based nonwoven in air purification applications.

Considering the fact that customers of large commercial buildings have the characteristics of the higher density and randomness, this paper presented an airconditioning cooling load prediction method based on weather forecast and internal occupancy density. The multiple linear feedback regression model was applied to predict, with precision, the air conditioning cooling load. Case analysis showed that the largest mean relative error of hourly and the daily predicting cooling load maximum were 18.1% and 5.14%, respectively.

Air-source heat pump (ASHP) has been widely applied in heating systems of school buildings. In order to achieve building energy efficiency while ensuring indoor thermal comfort, the paper compared the effects of different operation strategies including intermittent heating mode in non-working hours and setpoint of return water temperature in working hours. A middle school building in Tianjin, China is chosen as a case study and its physical model is developed by using the EnergyPlus tool. After verifying the validity of the model, the article simulated 64 different operation conditions produced by combining 8 start-up times with 8 return water temperature setpoints to find a better operation mode of the intermittent heating. Results indicate that running at a lower water temperature with an earlier start-up time is more energy efficient compared with running at a higher water temperature with a later start-up time while meeting the thermal comfort requirement. In addition, by changing the return water temperature setpoints hourly based on the outdoor air temperatures, the situation of overheating and undercooling during working hours has been well improved and the energy saving rate is about 17% during the entire heating season.

With the advance of light and heat management in photovoltaic field, the photovoltaic efficiency has been significantly improved. In this work, the hybrid photovoltaic-thermoelectric systems with different glass cover coatings are developed to investigate the performance improvement with light and heat management. The results indicate that selective coating can improve the power generation of the system by about 14%, while the values for self-assembled SiO2 coating and antireflection coating are 0.8% and 1.3%, respectively. Additionally, the impact factor analysis reveals that atmospheric humidity has little impact on the performance of the system, while ambient temperature, wind speed and concentration ratio play the critical role on the power generation. And the results of the operation modeling in clear and cloud days highlight that selective coating can help achieve a significantly greater power generation than that with ordinary glass. Furthermore, antireflection coating and self-assembled SiO2 coating can still improve the power generation of the hybrid system slightly. Additionally, self-assembled SiO2 coating achieves a payback period less than three years, while the values of antireflection coating and selective coating are less than four years and about five years, respectively. Our work provides a novel avenue to improve the performance of the hybrid system.

Heating and cooling sources occupy a large proportion of the total energy consumption of office buildings and hence the related environmental impacts cannot be underestimated. In this paper, a localized life cycle impact assessment (LCIA) method was established based on local environmental policies and energy regulations according to the framework of life cycle assessment (LCA). It is used to analyze the heating and cooling sources for office buildings in northern China. The environmental impact inventory was classified, characterized, standardized and weighted based on local energy resources. The exergy exhaustion (EE) factor was adopted to analyze the importance of local primary energy. Cost analysis was conducted to increase the practical value and significance of the research results. Questionnaires were used to determine the weight of environmental impact, EE, and cost analysis (CA) for combination scheme selection. Different heating and cooling sources and 7 combination schemes for office buildings in the cold regions of northern China were comprehensively evaluated. Results showed that gas-fired cogeneration + conventional electric refrigeration air conditioners and ground source heat pump (GSHP) for both heating and cooling were two recommended schemes which had the least comprehensive environmental impact index. These investigations can guide decision-makers and designers to choose environment-friendly and economical heating and cooling sources, and help government departments to formulate appropriate incentive policies to encourage the use of suitable,sustainable, and economical energy sources. Refereed/Peer-reviewed

With the development of building energy saving technology, low-temperature two-phase closed thermosyphon (TPCT) will be widely used in building energy supply and storage. However, the non-condensable gas (NCG) can affect the performance of TPCT. In this paper, experiment, theoretical heat transfer model and CFD simulation model have been established to comprehensive analyze the operation performance of the TPCT with NCG (NTPCT). The research contents include the variation of TPCT wall temperature, heat transfer efficiency ( η ), thermal resistance ( R ) and NCG phase distribution. Experimental results showed that the temperature difference between the evaporator and condenser sections of the NTPCT was greater than that of the TPCT in the steady state, resulting in R exp NTPCT being higher than R exp TPCT , and the difference was widening with the decrease of input temperature ( T b ), leading to serious adverse impact on heat transfer. When T b was higher than 60 °C, the η theory difference with different mass of NCG ( X NCG =0.0418%~0.0746%) was small, but when T b was low, the difference became larger, and even when T b = 27 °C, the η theory = 44.02% for X NCG = 0.0418%, and η theory = 0.04% for X NCG = 0.0746%, i.e., the heat pipe failed to work. In addition, with the decrease of inclination angle, NCG diffused downward and occupied more and more length of the condenser section, resulting in worse and worse heat transfer performance.

This paper discussed the influence of apartment location on household space heating energy demand per floor area in multi-apartment buildings. According to the actual data, apartment location has a significant impact on space heating consumption per floor area in multi-apartment buildings. Based on average data of each location, a corner unit on the top floor has a space heating consumption per floor area 26.1% higher than a center unit on the middle floor. For multi-apartment buildings, a correction should be made to reflect the effect of apartment location when billing is calculated from space heating consumption instead of floor area. Location correction factors (LCFs) of seven typical cities based on building type and building age were analyzed by calibrated simulation method. The study finds that LCFs for older buildings are smaller than those of younger buildings, varying from 0.8% to 15.3% for seven typical cities. As for different regions, the greater the heating degree day is, the larger the location correction factor (LCF) is, with the deviation among 5.7–14.4%. LCFs can provide a billing-tool to make a fair allocation of heating costs, which may promote the reform of heat metering and billing in China.

With the rapid development of education cause, the increasing energy consumption of school buildings is gradually causing widespread concern in recent years in China. This paper presented an analysis of energy consumption of 270 schools located in the city of Tianjin, China. The analysis focused specifically on calculating the space heating energy consumption indexes and non-heating energy consumption indexes of different types of schools, aiming at providing reliable and precise data for the government to elaborate policies and measures. The space heating energy consumption of schools adopting district heating and gas boiler were 92.04 kWh/(m2·a) and 64.25 kWh/(m2·a), respectively. Comparing to the schools without a canteen, the non-heating energy consumption index of schools with a canteen can increase by 8%–37%. Furthermore, clustering of different energy sources, the total primary energy consumption indexes were also presented. Space heating energy consumption accounted for approximately 64%–79% of the total primary energy consumption. When using time-sharing control and self-contained gas boiler instead of district heating, an amount of almost 27.8 kWh/(m2·a) and 77.5 kWh/(m2·a) can be saved respectively. Through extensive statistical analysis of the data collected, this paper demonstrated that gross floor area, heating energy source and canteen had a close relationship with the total primary energy consumption regarding complete schools. Eventually, a linear regression equation was established to make a simple prediction about the total energy consumption of existing complete schools and to estimate the energy consumption of complete schools to be built.

Hotel buildings generally consume more energy than other types of public buildings, so measures should be adopted to reduce their energy demands. Energy retrofit measures (ERMs) were explored by eQuest software, using the example of an existing four-star hotel in Tianjin, China. The study investigates predictive accuracy for the major factors in the energy consumption of hotel buildings. The results indicate that the schedules of internal loads have the most significant impact on the accuracy of the model for hotel buildings, followed by occupancy rate and coefficient of performance (COP) of the chillers. A retrofit scheme was formulated and its energy-saving potential was evaluated by the calibrated model. Post-implementation monitoring was carried out, and the similarity between model predictions and the actual outcomes of the retrofits confirms that the calibrated model provides a highly accurate forecast of the energy-saving effects of the building energy efficiency retrofit (BEER) scheme.

To promote energy efficiency and emission reduction, the Chinese government has invested large amounts of resources in heat-metering reform over the past decade. However, heat-metering, which can reduce energy consumption by 15% at least in developed countries, is still not well known in China. This paper quantitatively analyzed the arousal effect of heat-metering policy on occupancy behavior regarding energy saving utilizing statistics method based on measured data of heating energy consumption of approximately 20000 users from 2008 to 2012 in Tianjin. The statistical data showed significant difference on energy consumption between users based on metering and based on area. The energy-saving rate in the heating season increased significantly from 4.11% in 2008–2009 to 10.27% in 2011–2012 as the implement of the heat-metering policy. The difference in energy-saving according to various outdoor temperatures showed that the energy-saving of occupancy behavior was more significant in a warm season than in a cold season. It also showed that the impact of heat-metering policy would be more pronounced in generally insulated buildings (15.55%) than in better insulated units (6.45%). Besides, this paper proposed some feasible suggestions for the formulation and implementation of heat-metering policy in northern heating areas of China.

To analyze the effect of energy conservation policies on energy consumption of residential buildings, the characteristics of energy consumption and indoor thermal comfort were investigated in detail in Tianjin, China, based on official statistical yearbook and field survey data. A comprehensive survey of 305 households indicates that the mean electricity consumption per household is 3215 kWh/a, in which annual cooling electricity consumption is 344 kWh/a, and the mean natural gas consumption for cooking is 103.2 m3/a. Analysis of 3966 households data shows that space heating average intensity of residential buildings designed before 1996 is 133.7 kWh/(m2·a), that of buildings designed between 1996 and 2004 is 117.2 kWh/(m2·a), and that of buildings designed after 2004 is 105.0 kWh/(m2·a). Apparently, enhancing the performance of envelops is effective in reducing space heating intensity. Furthermore, the results of questionnaires show that 18% of the residents feel slightly warm and hot respectively, while 3% feel slightly cold in winter. Therefore, the electricity consumption in summer will rise for meeting indoor thermal comfort.

This paper discussed a comparative study of several state-of-art methods for determining building energy consumption benchmark. A new approach, which combined the idea of “building benchmark” and “operational benchmark” in its rating system, was proposed. A case study was conducted which applied the proposed approach to benchmarking an existing office building in Tianjin. Besides, the calculation of benchmarks of the reference building model and real building model using the rating method in eQUEST was also considered. Furthermore, the simulation results of the reference building model were taken as the baseline to divide real office buildings into different energy performance grades.

Based on the opening baffle mode for natural ventilation of city road tunnels, this paper studies the impacts of opening baffle on natural ventilation performance by verifying numerical simulation through model tests. By analyzing the impacts of installation angle, dimension, location, and quantity of opening baffle on ventilation performance, the paper reached the conclusions as follows: 1) When installation angle is larger than 45° and tunnel ventilation is well operated, the baffle exhaust could increase by at least 30% compared to when there is no baffle. 2) The baffle reaches its optimal performance when the length of the baffle is equal to the width of the city road tunnels. 3) Baffle exhaust could increase by 30% when it is installed in the downstream of openings. 4) The performance of a single baffle is better than that of multiple baffles.

An energy audit of 22 tertiary hospitals was conducted in Tianjin. The detailed content included design data, basic information, energy bills and equipment lists. It was shown that during the study, the energy intensity of hospitals in Tianjin was approximately stable and the average level of energy consumption was 348 kW·h/(m2·a). From the date collected, it was calculated that the energy intensity of general hospitals was 380 kW·h/(m2·a), and the average carbon emissions was 157 kgCO2/(m2·a); While the energy intensity of specialized hospitals was 309 kW·h/(m2·a), and the average carbon emissions was 131 kgCO2/(m2·a). By breaking the energy consumption down into several items, it was found that the heating system consumed the highest amount of energy (42.12%), followed by the cooling system (6.78%), the medical equipment (4.98%) and the lighting system (3.63%). The main factors that affect the hospital energy consumption were determined, and some feasible technology and management measures to save energy and reduce carbon emissions were proposed.

The widely use of cooled storage technology in our country will be an irreversible trend with the development and improvement of the TOU price policy. Naturally stratified Chilled water-storage is a very important cool storage technology. In this paper, the effect of using uniform flow orifice in naturally stratified water-storage with slotted pipe diffuser is studied by contrast experiments firstly. Then the cases with uniform flow orifice are simulated. Through the comparison of experimental data and simulation data, the correctness of the mathematical model is verified. Finally, the effect of water-storage is studied by simulation when the uniform flow orifice is set with different voltage drop. Conclusions can be obtained as follows: the layered effect is greatly improved by setting the uniform flow orifice; it is when the voltage drop of uniform flow orifice is in an appropriate range which is about ten to tens Pa that the improvement is obvious.

For the problem of reasonable longitudinal and horizontal spacing of inducing fan in ventilation system in underground garages, the test of single inducing fan was carried out. Comparing the results of the test and of the numerical simulation, boundary conditions of numerical simulation were determined. By using fluent software, appropriate longitudinal spacing of inducing fan was gotten. Thinking of the polytrope of volume capacity ratio and parking utilization factor, the concept of garage utilization coefficient was defined. On this basis, CO concentration is taken as control standard in this paper and numerical simulation is performed for kinds of small space models. As a result, we get the recommended values of reasonable horizontal spacing for inducing fans' arrangement. Reference data are given for the design of no-duct inducing fan system of underground parking garages in future.

The power consumption of air conditioner is the major reason for load peak and off-peak difference in power system, and the cooling storage technology used in air conditioner can improve the power supply and demand. The most popular cooling storage technology in air conditioner is the water stratification method. In this paper, a cuboid water pool is employed to analyze the influence of Reynolds Number (Re), Froude Number (Fr) and water distributor type for the efficiency and improvement of water pool. Experiment data show that: the smaller Fr and the higher water height, the better performance of storage is got under the same Re and water supply temperature. However, the influence of Fr change is less when Re is lower than 200. At the same time, the water pool efficiency is improved for the density increase of the supply and return water under the same water temperature difference. It can be obtained that the increase of temperature difference will enhance the effect of cooling storage in air conditioner.

Now, the standard about urban tunnel with roof openings is blank. The study establish the model of urban tunnel with roof openings, make the basic experiment research about ventilation effect of natural ventilation openings, which in two condition, piston wind and the coupling effect of piston wind and jet fan. The result of experiment indicate that as the increase of traffic flow, speed of vehicle, and as the decrease of distance with tunnel exit and roof openings, the air volume through roof openings is increasing. With the effect of fan between roof openings, all openings would become steady air-inlet or air-outlet.