Cold Winter Zone Research Articles

Effects of the tree distribution and species on outdoor environment conditions in a hot summer and cold winter zone: A case study in Wuhan residential quarters

Residential district is the important space for people living and outdoor activities. Vegetation is proved to be effectively regulate microclimate. Living in Wuhan, residents have to suffer heat stress in summer and strong cold wind in winter simultaneously. It is necessary to dictate vegetation types and layout in residential area to get comfortable environment both in hot summer and cold winter. This study examined the vegetation influences of residential wind environment in hot and cold seasons by using the ENVI-met model V4. Field measurement validated the performance of ENVI-met model. The simulation was based on multi-story buildings representing the current primary form of residential area in Wuhan. 3 scenarios with three tree arrangements and 8 vegetation species were simulated. Height-to-distance ratio of trees (as “Aspect ratio of trees”, ART) was used to describe the tree distribution. Results showed that the impact of vegetation on both heat environment and ventilation depended on tree arrangement, LAI, crown width and tree height. The comparison of 3 tree distributions revealed that trees with an ART < 2 should be a priority to mitigate hot environments due to the large effects on PET reduction in summer. Evergreen species with an ART < 2 also effectively decreased wind speed in winter as well as blocked direct sunlight, resulting in negative effects on PET. Tall trees with a large LAI and canopy diameter should be a priority to improve the comfort of outdoor environments.

Benchmark analysis of electricity consumption for complex campus buildings in China

Publicising the energy consumption of buildings is an effective way to promote building energy efficiency in colleges and universities. The aim of this study is to propose a method for developing electricity benchmarks for complex campus buildings. This study uses various statistical methods to determine such benchmarks. The determination of new electricity benchmarks includes the following steps: (a) determination of the factors influencing electricity consumption, (b) standardisation of indicators, and (c) calculation and correction of the electricity benchmarks. Thirteen complex buildings from the hot summer and cold winter zone of China were selected as samples to illustrate the standardisation process. The total electricity and subentry electricity benchmarks are determined based on multiple linear regression analyses. Multi-factor analyses of variance were used to identify the categorical factors that have significant influences on electricity consumption and on the correction of benchmarks. Finally, a rating system for the evaluation of electricity consumption was also established that applied the corrected electricity benchmarks.

Effect of Green Roofs Combined with Ventilation on Indoor Cooling and Energy Consumption

With the increase in building energy consumption and the improvement of the thermal environment requirements of the residents, it is very important to find a way to adjust the thermal environment for the residents and to save energy. In this paper, an experimental building in Shanghai, China, was chosen, and used DesignBuilder software to simulate the cooling and energy-saving potential of green roof combined with intermittent ventilation in hot summer and cold winter zone. The results show that the use of intermittent ventilation is more conducive to indoor cooling than the all-day ventilation, and the green roof combined with intermittent ventilation is better. During the entire air-conditioning season, the proportion of the time which under the upper limit of acceptable temperature reduced by 20% compared the insulation roof with all-day ventilation. In the case of intermittent ventilation, the energy consumption of the two roofs is reduced by about 10% compared with that without ventilation, while the energy-saving rate of green roof with ventilation is 26.7%.

Study on Building Energy Consumption Performance of Composite Polystyrene Granule Thermal Insulation Mortar

In order to solve the problem of building energy consumption, the hygroscopicity, thermal conductivity and transfer properties of composite polystyrene particle thermal insulation mortar are analyzed. According to the commonly used external thermal insulation structure and its thermophysical characteristics in hot summer and cold winter zone, the test is carried out. The thermal conductivity function is applied to the simplified model of DeST thermal environment simulation. The variation of heat and moisture transfer to building energy consumption is analyzed. The results show that the energy consumption of simulated buildings can reach 13.25% of the annual electricity consumption of building heating. Therefore, the heat and moisture transfer characteristics of materials affect the thermal conductivity and thermal insulation performance of building envelope. It is an effective way to decrease the building energy consumption by using the thermal conductivity coefficient of various materials as a measure.

The effect of passive measures on thermal comfort and energy conservation. A case study of the hot summer and cold winter climate in the Yangtze River region

The energy consumption for heating and cooling of buildings in the cities located within the boundaries of the Hot Summer and Cold Winter (HSCW) zone in China is rapidly increasing due to the increased comfort expectations from well-resourced occupants. Guidance on how and to what extent it is possible to improve energy efficiency of buildings is thus required by policy makers as well as designers and building managers. The aim of this study is to demonstrate how the use of climate-sensitive passive design solutions can help the improvement of indoor thermal conditions while reducing the energy needs and ultimately carbon emissions. An extensive parametric analysis of several passive strategies such as building orientation, thermal insulation, glazing area, shading devices, air tightness and natural ventilation, is carried out for a typical apartment block located in the cities of Chongqing, Changsha and Shanghai, which lay respectively in the upper, middle and downstream of the Yangtze River. Detailed hourly dynamic simulations show how it is possible to extend the non-heating/cooling period and reduce the peak loads, highlighting the potentialities of each strategy according to different climate constraints. The recommended strategies provides quantitative guidance to either design of new or retrofitting of existing buildings. This research contributes to the building energy conservation knowledge for policy-makers, developers and building designers with insight on the feasibilities of the application of passive measures for residential buildings located in the Yangtze River region with hot summer and cold winter climates.

Thermal performance and energy savings of white and sedum-tray garden roof: A case study in a Chongqing office building

This study presents the experimental measurement of the energy consumption of three top-floor air-conditioned rooms in a typical office building in Chongqing, which is a mountainous city in the hot-summer and cold-winter zone of China, to examine the energy performance of white and sedum-tray garden roofs. The energy consumption of the three rooms was measured from September 2014 to September 2015 by monitoring the energy performance (temperature distributions of the roofs, evaporation, heat fluxes, and energy consumption) and indoor air temperature. The rooms had the same construction and appliances, except that one roof top was black, one was white, and one had a sedum-tray garden roof. This study references the International Performance Measurement and Verification Protocol (IPMVP) to calculate and compare the energy savings of the three kinds of roofs. The results indicate that the energy savings ratios of the rooms with the sedum-tray garden roof and with the white roof were 25.0% and 20.5%, respectively, as compared with the black-roofed room, in the summer; by contrast, the energy savings ratios were −9.9% and −2.7%, respectively, in the winter. Furthermore, Annual conditioning energy savings of white roof (3.9 kWh/m2) were 1.6 times the energy savings for the sedum-tray garden roof. It is evident that white roof is a preferable choice for office buildings in Chongqing. Additionally, The white roof had a reflectance of 0.58 after natural aging owing to the serious air pollution worsened its thermal performance, and the energy savings reduced by 0.033kWh/m2·d. Evaporation was also identified to have a significant effect on the energy savings of the sedum-tray garden roof.

Thermal and energy performance of a steel-bamboo composite wall structure

Heat transfer through external walls plays a significant role in building energy saving. This paper tries to investigate the thermal and energy performance of a novel lightweight steel-bamboo wall structure. A testing residential building was constructed using the prefabricated steel-bamboo composite wall and field measurement was carried out to determine the heat transfer coefficient, time lag and decrement factor of the steel-bamboo wall. Numerical simulation was conducted in order to further evaluate its performance improvement compared to two commonly used wall structures in this climate region. The results show that the steel-bamboo wall has a high thermal performance with an improvement of U value by up to 26.1%–48.4%, indicating a lower heating demand compared to common wall structures in winter. Meanwhile, it has a high resistance to outdoor air temperature fluctuation with a low decrement factor of 0.022. The relatively low time lag (2h) contributes to a lower indoor temperature during summer nighttime and thus reduces cooling energy demand. The improvement of total energy performance reaches 27.1%–40.9%, indicating a great potential of applications of this steel-bamboo wall in residential buildings in hot summer and cold winter zone. However, the main drawback of the steel-bamboo structure is that its indoor thermal performance during the hottest hours in summer is poorer than conventional walls.

Study on the thermal effect of the ground heat exchanger of GSHP in the eastern China area

The two-year operating performance and the variation in the underground thermal environment of a ground source heat pump (GSHP) system are presented in this work; the GSHP has been installed in an office building in Hangzhou. The system consists of two heat-pump units, each with a heating/cooling capacity of 470 kW/465 kW, and 201 boreholes. The flow rates and temperatures of water on the user- and buried-pipes side, the electrical power consumption of the heat-pump units and the water pumps, and the underground temperatures were monitored during this project. The result of the performance monitoring revealed that the average daily COP of the units and the system was approximately 5.0 and 3.0, respectively, during cooling seasons, and 4.5 and 2.7, respectively, during the heating seasons. It was found that the electricity consumption of the water pump accounted for 39.7% of the total electricity consumption, which is high enough to degrade the system performance. It was also found that the heat released by the GSHP system during the cooling season is more than the heat absorbed during the heating season at the hot-summer and cold-winter zone. The underground heat imbalance rate was approximately 24% in the first year, and was approximately 53% in the second year. The result of underground temperature monitoring showed that the underground temperature increased by 1.1 °C after two years of system operation. This reveals that the heat exchange between the GSHPs and the soil is unbalanced, which eventually caused “heat accumulation”. Moreover, the variation in the underground thermal environment was revealed by the changes in underground temperature according to time, depth, and season. Finally, in this work, a simple model is presented, which quantitatively verifies the underground heat imbalance through the underground temperature variation. Reasonable agreement of results verified the underground heat imbalance, and confirmed the reliability of the model. Overall, this study provides a significant amount of experimental data for the analysis of the underground thermal environment variation and the heat balance. The results of this study will contribute toward the development of more creative methods for the mitigation of the impact of “heat accumulation” on the environment at the hot-summer and cold-winter climate zone. In addition, the method used in this work can be applied to other climate zones for the study of the thermal effect of the GSHP ground heat exchanger.

Performance analysis of a self-adaptive building integrated photovoltaic thermoelectric wall system in hot summer and cold winter zone of China

The traditional building integrated photovoltaic (BIPV) systems are meeting with their limitations. By incorporating thermoelectric radiant system with PV module, a prototype of building integrated photovoltaic thermoelectric (BIPVTE) wall system is proposed and numerically investigated. The system model of BIPVTE wall is established and validated by experimental data. The comprehensive system performance evaluation is conducted based on the comparison with the traditional PV wall and massive wall in hot summer and cold winter zone of China. The comparison between BIPVTE and PV wall in steady state can explain the system working mechanism as well as its weakness. Besides, the typical-day, seasonal and annual dynamic performance evaluations are implemented for the application potential analysis of BIPVTE in Changsha city and other four typical modern cities. The results indicate that BIPVTE wall can achieve noticeable reduction of annual heating/cooling load. The highest energy saving ratio of 172% compared with the massive wall is achieved under Shanghai weather condition. This system has the potential to make contribution to zero energy buildings and low exergy buildings.

Thermal performance of building wall materials in villages and towns in hot summer and cold winter zone in China

Based on the current state of building wall materials of rural buildings in China consume large amounts of energy and have poor thermal performances, theoretical calculation and test detection of thermal performances were carried out for concrete block, cavity wall made of sintered Dalun brick, non-clay sintered porous brick wall, rectangular porous block construction, composite ceramic concrete block construction, steam-pressed sand concrete block masonry with gas, and concrete porous brick wall. And the experimental results of heat transfer coefficients were generallyconsistentwith the theoretical calculations. Both test results and theoretical calculation results of the wall heat transfer coefficients are processed using the weighted average method. Among the above-mentioned walls, we found that the heat transfer coefficients for the rectangular porous block construction, composite ceramic concrete block construction and steam-pressed sand concrete block masonry with gas were 1.22W/m2·K, 0.99W/m2·K, and 0.97W/m2·K. All of these materials met the standards such as Design Standard for Energy Efficiency of Rural Residential Buildings. These materials which met the standard were suitable for exterior walls of buildings and could meet the standard requirement of 50% energy saving. Gray theory analysis showed that the influencing factors such as coefficient of thermal conductivity of wall materials, wall thickness and mortar thickness had successively decreasing gray correlation degrees with the wall heat transfer coefficient.

Exploring the factors and motivations influencing heating behavioral patterns and future energy use intentions in the hot summer and cold winter climate zone of China

The hot summer and cold winter zone (HSCW) plays a significant role in residential energy consumption in China because of climate, policy, and social-economic factors. Accordingly, occupant heating behaviors and associated social-psychological factors are essential elements in understanding energy consumption. This study presents a new investigation on the demographic factors, building characteristics, and social-psychological motivations influencing current heating patterns and future heating intentions among 904 residents in the HSCW zone in China. Most residents surveyed selected the city-scale central-heating system as their future heating pattern, which might lead to a high level of energy consumption. Among demographics, family income was the main factor influencing residents’ current heating patterns, followed by number of children and building age. Additionally, thermal comfort was one of the most frequent motivations for adopting specific heating patterns in our sample. Although residents were generally concerned about the environmental impacts of energy use, they could have been unaware that their current and future heating patterns could cause high levels of energy consumption. This study provides multifaceted insight in occupant research by investigating the link among occupant heating patterns, climate zone, and behavioral motivations, which should be considered by building designers, policymakers, engineers, and energy educators.

Numerical study of thermal characteristics of double skin facade system with middle shade

Architectural shade is an effective method for improving building energy efficiency. A new shade combined with the double skin facade (DSF) system, called middle shade (MS), was introduced and developed for buildings. In this paper, a 3D dynamic simulation was conducted to analyze the influence of MS combined with DSF on the indoor thermal characteristics. The research on MS for DSF involves the temperature, the ventilation rate, the velocity distribution of the air flow duct, and the indoor temperature. The results show that the angle and position of the shade in the three seasons are different, and different conditions effectively enhance the indoor thermal characteristics. In summer, the appearance of MS in DSF makes the indoor temperature significantly lower. The indoor temperature is obviously lower than that of the air flow duct, and the temperature of the air flow duct is less affected by MS. The influence of the position of blinds on indoor temperature and ventilation rate is greater than the influence of the angle of blinds. According to the climate characteristics of winter and transition season, in winter, early spring, and late autumn, the indoor temperature decreases with the increase of the position of blinds at daytime, but the opposite is true at night. The results found in this paper can provide reference for the design and use of MS combined with DSF in hot summer and cold winter zone.

Energy Efficiency for Airtightness and Exterior Wall Insulation of Passive Houses in Hot Summer and Cold Winter Zone of China

There exists huge differences in climatic conditions and occupant energy-consuming behavior between Berlin and the “hot summer and cold winter zone of China” (HSCW), which implies that the building energy consumption compositions of two regions are completely different. In this paper, dynamic energy consumption simulation for passive houses with Design Builder software was performed. The results indicated that the improvement of building airtightness and exterior wall insulation can reduce annual heating and cooling load effectively, and more importantly the effect is much stronger on heating load than cooling load. Because of this, the paper proposed that the ratio of heating and cooling electricity consumption (r) should be adopted as an important index in energy efficiency evaluation of passive houses. It would contribute to the reasonable selection of ventilation modes and the exterior wall heat transfer coefficient, and benefit the healthy development of passive houses in HSCW.

Determining a Practically Optimal Overhang Depth for South-Facing Windows in Hot Summer and Cold Winter Zone

This study investigated the building energy, glare and daylight performance of overhang using building simulation software Energyplus in order to identify an optimal depth in hot summer and cold winter zone. A typical building with different window-to-wall ratios (WWR) was modeled and different overhang depths were considered. Results showed that the optimal overhang depths are 0.9m (WWR=0.15), 1.16m (WWR=0.3) and 1.62m (WWR=0.57), respectively. The total energy savings from overhang design can be ranging from about 3% to 24% depending on WWR and overhang depth. Moreover, the regression relationship between optimal overhang depth and WWR is given to help identify the best overhang dimension at the design stage. The potential energy saving performance for different WWRs then can be roughly inferred according to a total energy saving chart without building energy simulation. In conclusion, to be applicable in buildings, an overhang depth of 0.6-0.8m is suitable in this region since it has a balance in energy performance and aesthetic appearance.

A comparative study on thermal performance evaluation of a new double skin façade system integrated with photovoltaic blinds

The glazing façade is embraced by architects, but this configuration may result in huge energy consumption. This research proposed a new double skin façade using photovoltaic (PV) blinds as a shading device (named PVB-DSF), which could realize multi-function of power generation, solar penetration reduction and flexible daylighting control. The purpose of this comparative study is to demonstrate the superb thermal performance of PVB-DSF. Experimental rig was built at hot-summer and cold-winter zone of China. The first stage comparative study was conducted to evaluate system thermal performance under the effects of ventilation modes, PV-blind angle and PV-blind spacing. The second stage study was conducted to compare thermal performance between PVB-DSF and standard DSF. A validated numerical model was used to describe standard DSF. The results suggested the operation of natural ventilation mode and indicated the evident influence of PV-blind spacing on system performance. The comparison study further demonstrated that PVB-DSF can save about 12.16% and 25.57% of energy in summer compared with conventional DSF with and without shading blinds. The insulation performance of PVB-DSF is shown by its daily average heat transfer coefficient which was as low as 2.247.

Energy Consumption Prediction Model of Public Buildings Based on PSO-RBF

By analyzing thechange characteristics of energy consumption of public buildings in hot summer and cold winter zone, a building energy consumption prediction model based on RBF neural network is established. On this basis, particle swarm optimization is used to optimize our model, and the building energy consumption prediction model based on PSO-RBF is established. This paper applies large numbers of data to construct sample set, trains the prediction model before and after optimization by software, and appliesit to a typical energy consumption prediction example of public buildings. The results show that the building energy consumption prediction model based on PSO-RBF occupies preferable learning ability and predication performance, and achieves the energy consumption prediction of public building accurately.

Applicability research on passive design of residential buildings in hot summer and cold winter zone in China

Passive design has long been a concern as an effective way of building energy efficiency. However, different urban climate characteristics determine the time-effectiveness of passive design. According to the climate characteristics of hot summer and cold winter zone in China, this research chose five cities, Shanghai, Wuhan, Chongqing, Nanjing and Changsha, to analyze their residential building energy consumption and thermal environment conditions. Based on Weather Tool calculation and analysis, the purpose of this research is to put forward the concept of Suitable Degree (SD), namely the applicability of the passive design. In addition, five cities’ SD of passive design technology had been analyzed from aspect of ventilation, temperature, solar radiation and envelope, then passive design strategies and methods of five cities’ residential building were discussed.

Energy Consumption and Thermal Performance in Different Residential Building Types in Hot-Summer and Cold-Winter Zone

Energy Consumption and Thermal Performance in Different Residential Building Types in Hot-Summer and Cold-Winter Zone

Research on Energy-Saving Optimization for the Performance Parameters of Rural-Building Shape and Envelope by TRNSYS-GenOpt in Hot Summer and Cold Winter Zone of China

The aim of this paper is to optimize the building shape parameters and envelope parameters influencing the rural building energy consumption in cold winter and hot summer climate. Several typical models are established and optimized by integrated TRNSYS and GenOpt. Single-objective optimization has provided guidance to the multi-dimensional optimization. Building shape and envelope parameters are considered simultaneously by multi-dimensional optimization. Results of the optimization showed significant reduction in terms of EC (energy consumption). When O (building orientation) was SW (south by west) 10°, LWR (length-width ratio) was 1.1, WWRS (window-wall ratio in south) with the range of 0.6–0.8, ITE (insulation thickness of exterior wall) and ITR (insulation thickness of roof) was 0.05 m and 0.08 m respectively, the building had minimal energy consumption. The results also indicated that the optimal EWT (exterior window type) was plastic single-frame Low-E insulating glazing filled with inert gas, and the optimal shape of building is Re (rectangle). An effective method was provided to optimize the design of the rural building for the purpose of reducing building energy consumption in cold winter and hot summer climate.

Thermal adaptive models in the residential buildings in different climate zones of Eastern China

Adaptive comfort standards have become the main stream comfort research and are now considered an optional choice of natural ventilated buildings in the international thermal comfort standards. However, the international adaptive models were not suitable to evaluate the thermal adaptation level of all the climates. To explore thermal adaptive ability and develop thermal comfort models in different climate zones, field studies on thermal comfort in 120 residential buildings in summer and winter have been conducted in 12 cities, representative of four climate zones in eastern China. Those data were gathered using instantaneous subjective questionnaire surveys and objective on–site measurements. The results showed that the predicted neutral temperatures based on MTS in winter in four climate zones were all lower than the predicted neutral temperatures based on PMV, and vice versa in summer. The clothing was mainly affected by the indoor temperature in the severe cold climate; however, it was affected by the outdoor temperature in the warmer climates. Clothing adjustment was more obvious in the warmer climate than in the colder climate. The warmer the climate, the smaller the yearly temperature difference, and the higher a sensitivity of the neutral temperature to outdoor temperature. The adaptive models in the hot summer and cold winter zone (HSCW) and hot summer and warmer winter zone (HSWW) can be used to predict the comfort temperatures of the natural ventilated buildings in the above two climate zones. Different climate zones should develop their own thermal adaptive models. These findings provide support to the climate adaptation theory and can serve as reference for the design of natural ventilated buildings.