Cold Winter Climate Research Articles

Performance Comparison of a Distributed Energy System under Different Control Strategies with a Conventional Energy System

The distributed energy system (DES) has increasingly attracted considerable attention from researchers due to its environmental friendliness and high efficiency. In the hot summer and cold winter areas, DES is an efficient alternative for district cooling and heating. A case study located in Changsha, China, which is a typical hot summer and cold winter area, is analyzed. Four control strategies are proposed in this study. The four cases under different control strategies are compared in terms of energy, economy, environment, solar fraction, and soil annual heat imbalance rate. Results show that the DES can be an energy saving and environmentally friendly alternative. The primary energy saving (PES) is more than 36.70% and can reach up to 48.04%, whereas DES can realize economical operation and reduce the emission of carbon dioxide, sulphur dioxide, and dust. In addition, DES consumes more electricity and less natural gas than the conventional energy system. These features are beneficial to the optimization of China’s energy consumption structure. Moreover, the operation of seasonal thermal storage for the ground soil is effective in maintaining the balance of soil annual heat. The control strategy combining geothermal and solar energies is recommended due to its good performance and high flexibility. This study may provide guidance in the development of DESs in hot summer and cold winter climate zones.

Effect of inhabitant behavioral responses on adaptive thermal comfort under hot summer and cold winter climate in China

The hot summer and cold winter zone is an important area in China, accommodated with huge population and occupying a great amount of the lands. Due to the local climate and long-term economic conditions, the adaptive thermal sensation of local residents and the thermal regulation behaviors have unique characteristics. The thermal regulation behaviors involve complicated dynamic features and many influencing factors. However, due to the limited experimental testing conditions, it is greatly lack of relevant studies on the characteristics of different thermal regulation behaviors and their influences on both indoor thermal environment and the thermal comfort in this zone. Aiming at this, taking the residential buildings in Hangzhou city as the main object, a large-scale questionnaire surveys and measurements were conducted. The characteristics of various types of thermal regulation behaviors and the annual indoor thermal environment are analyzed. The effects of each regulation behavior on the indoor thermal environment and the adaptive thermal comfort are revealed. Rectified adaptive coefficients for the actual situation of Hangzhou residents are proposed and it is proved that the modified values can be used to evaluate the adaptive thermal sensation of the local residents more precise than the original ones used in the National Standard GB/T 50,785–2012. Incorporating the modified adaptive coefficient λ into the APMV model, the potential impact of summer ventilation on thermal comfort is quantified. The research results can provide theoretical support for the energy saving-oriented indoor thermal comfort research in the region.

Comparing the performance of passive and active double and single slope solar stills incorporated with parabolic trough collector via energy, exergy and productivity

An experimental work is presented on comparing the performance of passive and active single slope (SS) and double slope (DS) solar stills without and coupled with parabolic trough collector (PTC). The comparison is based on still freshwater productivity, and energy and exergy efficiencies. This work is performed at hot (summer) and cold (winter) climate conditions under meteorological conditions of upper Egypt. Results illustrate that the freshwater productivity and efficiency of the solar stills with or without PTC in summer is greater than winter. Moreover, DS still has greater freshwater productivity, energy and exergy efficiencies than SS. The maximum freshwater productivity increases by about 6% in case of using DS still with PTC (DS + PTC) instead of SS with PTC (SS + PTC). Coupling PTC with SS still rises its daily yield by 115% and 85% and its average daily energy efficiency by 38.3% and 49.1% in summer and winter, respectively. The maximum average daily energy efficiency of the DS + PTC system is 49.09% and its total efficiency is 22.96% with an increase of 16.5% and 5%, respectively compared to SS + PTC. The average daily exergy efficiency of the DS only and DS + PTC in summer increases by 3.3% and 2.6%, respectively compared to the corresponding SS.

Outdoor thermal comfort and adaptive behaviors in a university campus in China's hot summer-cold winter climate region

Outdoor thermal comfort in the university campus is an important issue for encouraging students' outdoor activities and interactions. This research conducted field measurement and questionnaire survey in a university campus in Mianyang, located in the hot summer and cold winter climate zone according to China's climate classification for building design and the dry-winter subtropical climate according to the Köppen climate classification. The measurements were conducted over six days in winter and four days in summer; meanwhile, the survey collected 523 responses. Respondents preferred “slightly warm” in winter and “slightly cool” in summer. The range of 90% acceptable PET (Physiologically Equivalent Temperature) was higher than 20.2 °C in winter, lower than 35.6 °C in summer, and between 20.5 °C and 35.7 °C in a year. When PET increased by one degree Celsius, the probability of “using umbrella”, “taking off clothes” and “going to a shaded place” increased by 22.6%, 4.9% and 16.6%, respectively; while the probability of “staying under the sun” decreased by 17.5%. Neutral temperatures in different seasons were examined and compared with those from other studies. These findings provide evidence for planning and design strategies to improve the thermal environment of outdoor spaces.

Understanding differences in thermal comfort between urban and rural residents in hot summer and cold winter climate

Rapid urbanization in China resulted in different architectural characteristics between the rural (traditional, more open to external environment) and urban (modern, relatively closed to external environment) residential building stock. Such differences can influence the way residents regulate indoor thermal environment to maintain their comfort, particularly in hot summer and cold winter (HSCW) climate. This study aims to better understand the differences in the perceptions of thermal comfort and related adaptive behaviours between urban and rural residents. Thermal comfort field experiments are conducted in the central region of China that has climatic characteristics of HSCW. A total of 513 and 2171 survey responses have been collected and matched with concurrent environmental measurements in typical residential buildings in Wuhan city (urban) and Luotuoao village (rural), respectively. The majority of survey respondents accept their indoor thermal environments, even though instrumentally measured physical conditions fall well beyond the comfort zone prescribed in the international standards. The differences of indoor thermal comfort between rural and urban residents are attributed to clothing habits, daily activity patterns, housing openness and potential thermal expectation. Results also indicate that rural residents tend to be more tolerant of cold conditions in winter but less tolerant of hot conditions in summer, compared to the urban residents. The findings are helpful in optimizing housing design in HSCW climate region in order to improve indoor thermal conditions.

Building Energy Retrofit Measures in Hot-Summer–Cold-Winter Climates: A Case Study in Shanghai

Building retrofit measures provide a significant means of mitigating the effect of climate change on buildings by enhancing building energy performance at a beneficial cost-effectiveness. An insight into the applicable building retrofit measures within a climate zone will guide the optimisation framework to attaining sustainability in architecture and the built environment. This article presents a brief overview of recent studies on retrofit measures and its application on a variety of buildings in hot-summer–cold-winter climates, with emphasis on Shanghai. Findings show that the major retrofit measures include improvement in the building envelope, heating, ventilation and cooling (HVAC) and lighting, supported by photovoltaic (PV) systems, accordingly. Furthermore, the study identifies key elements and plausible challenges for the evaluation of building retrofit measures in this region. In this regard, financial barriers and lack of standards and regulatory support are the main challenges identified. These insights provide a systematic approach to guide building researchers, practitioners and decision-makers in the design and development of existing and new retrofit measures for the future of rapidly growing cities with a broad climate variation scope.

Annual energy performance simulation of solar chimney in a cold winter and hot summer climate

The paper studies the energy performance of a solar chimney (SC) in a high performance two-story detached house with 220 m2 floor area using EnergyPlus and the climate data of the hot summer and cold winter in China. An 8 m tall and 1.6 m wide solar chimney with a depth of 1 m is attached to the west wall to enhance building ventilation. The house uses a variable refrigerant flow (VRF) system to provide the heating and cooling and a separate ventilation system for outdoor air. The energy simulation results are compared between the house with the SC (SC case) and the same house but without SC (reference case). The results show that the SC produces larger ventilation rates than the minimum required rate most time of the year and therefore it needs to be controlled to avoid excessive outdoor air that leads to increased heating/cooling loads during the heating/cooling seasons. In this paper, a control is assumed so that the total outdoor air (through windows, doors, cracks and SC all together) is no more than one air exchange rate when the VRF system is running. The simulation shows that the SC can reduce the annual ventilation energy by 77.8% and the VRF energy by 2.3%. Overall, the annual energy saving of the SC for the studied house model is 549.0 kWh or 9.0% of the total HVAC energy consumption.

Thermal comfort in urban mountain parks in the hot summer and cold winter climate

Urban mountain parks are different from urban parks in that they form a unique microclimate environment with special topographical advantages and natural ecological environment. The study aims to investigate the thermal comfort condition and its related visitations in urban mountain parks in the hot summer and cold winter climate. Particularly, the research conducted thermal comfort measurement and visitation observation in three urban mountain parks in Mianyang City. The measurement and observation covered three months: August, October and December of 2018, which represents summer, autumn and winter respectively. The study included climate measurement, questionnaire survey and observation of the attendance rate in the selected parks. Results showed that temperature and solar radiation are the two most important factors affecting the use of parks. The neutral PET (Physiologically Equivalent Temperature) value is 27.0 °C in summer, 23.2 °C in autumn, and 17.3 °C in winter. This study can help to better plan and design outdoor environments of urban mountain parks to encourage people’s visits and social interaction.

Preliminary Simulation Investigation of Building Energy Consumption of Solar PV Windows in Hot Summer and Cold Winter climate zone in China

Photovoltaic building integrated windows can provide electric energy, heat energy and lighting for buildings, which will change the way that buildings consume energy. Aiming at the influence of photovoltaic windows on building energy consumption in hot summer and cold winter conditions, a simplified energy consumption simulation model based on light-heat-electricity is studied. The building energy consumption model, daylighting model, and Sandia photovoltaic model are integrated. Based on the tested building thermal performance parameters, the window’s power generation performance and its optical performance parameters, the impact of double-layer crystalline silicon PV windows on building energy consumption is simulated. The test results were used to validated the simulation model. According to simulation results, PV window could take advantages of the positive of blocking solar radiation, and compensate the negative effect. Considered the whole year energy saving, the PV window could save 470.03kWh, and reduce 466.5 kg of CO2.

Numerical Simulation Modeling of a GSHP and WSHP System for an Office Building in the Hot Summer and Cold Winter Region of China: A Case Study in Suzhou

This paper studies the long-term performance of a Ground Source Heat Pump (GSHP) system and a Water Source Heat Pump (WSHP) system for an office building in Suzhou, which is a hot summer and cold winter climate region of China. The hot summer and cold winter region is the most urbanized region of China and has subtropical monsoon climate, therefore, Heating, Ventilation, and Air Conditioning (HVAC) systems are in great demand. Due to the fact that 42.5% of Suzhou’s total area is covered by lakes and rivers, the city has an abundance of surface water resources. Based on Suzhou’s meteorological data and the thermal characteristics of the building envelope, an office building model was created and the dynamic cooling and heating load was calculated using Transient System Simulation (TRNSYS) simulation software. Two numerical HVAC modeling systems were created: a GSHP system for which the data of an in-situ Thermal Response Test (TRT) was used and a WSHP system for which the Tai Lake water temperature was used. Simulating the performance of both systems over a 20-year period, the two systems were analyzed for their Coefficient of Performance (COP), heat source temperature variation, and energy consumption. The results show that the GSHP system causes ground heat accumulation, which reduces the system’s COP and increases energy consumption. The study also revealed that compared with the GSHP system, the WSHP system has a more stable long-term performance for buildings in Suzhou.

Parametric analysis of applying PCM wallboards for energy saving in high-rise lightweight buildings in Shanghai

The lightweight building industry develops dramatically in recent years, however it has worse thermal comfort than traditional buildings due to its light thermal mass. A considerable amount of energy is consumed by the building sector in space heating and cooling. In addition, the building envelop can highly influence the energy consumption of buildings. Innovative technologies such as the phase change material (PCM) can be utilized on the wall to save energy and improve thermal comfort. In this paper, the performance of PCM wallboards in air-conditioned lightweight buildings in Shanghai with a hot summer and cold winter climate has been evaluated using an EnergyPlus single-zone model. Different room locations in the middle floor of high-rise buildings were studied in the modelling. The results show that the PCM wallboards improve the indoor comfort in both cooling season (summer) and heating season (winter) by reducing temperature fluctuations. However, the PCM in winter has higher efficiency than in summer due to different solar effects in each season. The optimal melting temperature for different rooms is ranged in 22–26 °C, which is the comfort temperature for human beings. The economic results show that the PCM integrated into southern wall has the best economic benefit.

Medical tourism in Korea – recent phenomena, emerging markets, potential threats, and challenge factors: a review

ABSTRACTThe primary aim of this study is to provide comprehensive implications for medical tourism in Korea. Through qualitative review analysis, opportunity factors have been revealed including emerging low-cost carriers in the world and Korea; the widely recognized Korean wave; the increasing market for cosmetic surgery; and potential markets in China and the Middle East. Challenges have been indicated including overcharging by clinics and illegal brokers; the collaboration between Western and Korean medicine; a lack of scientific proof for Korean medicine; Korea's cold winter climate; the North Korean threat; unclear market targeting; and the diverse medical market development in Korea.

Effect of seasonal adaptation on outdoor thermal comfort in a hot-summer and cold-winter city

ABSTRACTIn China, little research on outdoor thermal comfort has been conducted in the hot-summer and cold-winter zone where occupants are in the state of thermal discomfort for most time of the year. This paper presents results from both field measurement and questionnaire survey in the city of Wuhan in both summer and winter seasons about seasonal adaptation effect on outdoor thermal comfort. A total of 417 samples were collected in summer and 426 samples were collected in winter. The neutral standard effective temperature (SET*) in winter and summer was found to be 24.7°C and 25.6°C, respectively. Occupants achieved thermal comfort when their thermal sensation was slightly cool in summer and slightly warm in winter. The SET* with 100% thermal acceptance rate in summer and winter was found to be 27.9°C, 23.4°C, respectively. The results reveal large seasonal differences in achieving outdoor thermal comfort for people in hot-summer and cold-winter climate zone. This research can add more database to outdoor thermal comfort research in China and provide more insights into the thermal adaptation of seasonal effect on outdoor thermal comfort. Its findings can also assist urban designers to create thermally comfortable urban spaces in different seasons.

The Effects of Courtyards on the Thermal Performance of a Vernacular House in a Hot-Summer and Cold-Winter Climate

Achieving comfort in hot summer and cold winter (HSCW) climate zones can be challenging, since the climate is characterized by high temperatures in the summer and relatively colder temperatures in the winter. Courtyards, along with other semi-open spaces such as verandas and overhangs, play an important role in mitigating outdoor climate fluctuations. In this research, the effects of courtyards on the thermal performance of vernacular houses in HSCW climate zones were studied via field measurements and computational fluid dynamics (CFD) models. The selected courtyard house was a representative vernacular timber dwelling situated in the southeast of Chongqing, China. The indoor and outdoor air temperature measurements revealed that the courtyard did play an active role as a climatic buffer and significantly reduced the temperature’s peak value in the summer, while during the winter, the courtyard prevented the surrounding rooms from receiving direct solar radiation, and thus to some extent acted as a heat barrier. The contributions of thermal mass are quite limited in this area, due to insufficient solar radiation in winter and general building operations. The natural ventilation mechanism of courtyard houses in HSCW zones was further studied through CFD simulations. The selected opened courtyard was compared to an enclosed structure with similar building configurations. The airflow patterns driven by wind and buoyancy effects were first simulated separately, and then together, to illustrate the ventilation mechanisms. The simulation results show that the courtyard’s natural ventilation behavior benefited from the proper openings on ground level.

Investigation and Analysis of Energy Consumption Level During the Post-occupancy Phase of Green Offices in Hot Summer and Cold Winter Zone

This paper aims at investigation and analysis of green building energy consumption and green measures in hot summer and cold winter climate zone. In this paper, typical green office buildings in Shanghai and Chongqing are discussed, meanwhile, the authors compared with the national standards and point out future research directions

Adaptive thermal comfort in naturally ventilated dormitory buildings in Changsha, China

This research focused on investigating thermal comfort in naturally ventilated (NV) dormitory buildings in hot summer and cold winter (HSCW) climate zone in China. A field study was conducted during the summer of 2016 in Changsha, located in HSCW climate zone. The occupants reported subjective thermal perception using questionnaires and ambient environmental variables were measured simultaneously. A total of 11 NV dormitory buildings were investigated. 467 valid sets of measurement data and subjective questionnaires were obtained. Both Griffiths and linear regression analysis showed that the neutral operative temperature (To) was 26.2 °C. The upper limit for 80% acceptability was determined as 28.5 °C. The most acceptable operative temperature was 26.6 °C. 80% of occupants were comfortable at the temperature range between 25 °C and 28.7 °C. Based on this study, the adaptive model was developed and verified. The adaptive behaviors of clothing adjustment and air velocity adjustment were closely correlated to indoor To. The functions of adaptive thermal behaviors can be used for building simulation. The results can be used to assess indoor thermal comfort in buildings, and help to build a more rigorous database for building designing.

The study on outdoor pedestrian thermal comfort in blocks: A case study of the Dao He Old Block in hot-summer and cold-winter area of southern China

The commercial pedestrian block, famous for its entertainment and commercial vitality, plays an important role in humans’ daily life. The use of this space is determined by outdoor thermal comfort which can directly the commercial value of this region. So far, few studies have been conducted on outdoor thermal comfort in hot-summer and cold–winter area of southern China.The Dao He Old Block locates in Tai Zhou city which belongs to hot-summer and cold-winter climate zone of southern China. In order to develop the local tourism, the local government has provided guidance for the appropriate directions and opportunities for future development of this region. This study investigates the thermal comfort conditions in microclimate of this block and put forward some suggestion for the tourists determine the best time to visit, also help managers choose their business hours. In this region, humans’ thermal acceptability and the thermal comfort sensation votes are assessed based on the Physiologically Equivalent Temperature (PET). About the future redesigning plan of this block is shown in three stages: increasing the building height; adding tree canyon coverage; changing paving material.Along with performing field measurement in this intended block, in addition, a three-dimensional microclimatic modelling tool ENVI-met 4.0 is used to evaluate the outdoor thermal comfort and validate the accuracy of the software through comparing the measured data with the simulated data. The existing scenario shows that almost the whole area is not comfortable for visiting from 8:00 am to 6:00 pm in extreme summer. After putting forward some suggestion for redesigning this area, the result shows that there is a strong improvement in broadening the cooling time, which means the more suitable time for visiting is given, the new result shows that early morning (8:00–11:00 am) and after 6:00 pm are the most comfortable time for visiting.

CONCEPTUAL DEVELOPMENT OF THE EARTH TUBE COOLING SYSTEM FOR A TALL BUILDING

ABSTRACT Earth tubes are earth-to-air heat exchangers that are frequently utilized in energy conscious low-rise buildings, but are scarcely reported for tall buildings. The feasibility of applying earth tube cooling to tall buildings in a hot summer and cold winter climate zone was studied in this paper. Firstly, the designed cooling load of a tall building was obtained from the energy simulation using the baseline and the modified models with applicable energy efficiency measures. Based on the load, the required cooling capacity, the overall section area and the effective length of the earth tube system was deduced from the heat transfer and fluid flow calculation analytically. Then the performance of the earth tube system was crosschecked and verified via the Computational Fluid Dynamics (CFD) simulation. In the CFD simulation, earth tubes with different diameters and lengths, as well as a full-scale earth tube model with surrounding soil above the depth of constant temperature, were investigated. The outlet air temperatures of the full-scale models were computed with the consideration of different axial distances between adjacent tubes. Meanwhile, multiple conceptual design schemes and the tunnel construction method for the earth tube system were proposed from the perspective of performance enhancement, constructability, efficiency and economy. It revealed that earth tube systems are conditionally feasible for some tall buildings if their design guidelines for climate, underground spaces, construction method, friction of tube interior surface, optimization of effective length and axial distance, as well as synergy with other energy efficiency measures are followed. Even the cooling capacity of earth tubes degrade with time due to the accumulated heat underground, but in a hot summer and cold winter climate zone it can still possibly produce cooled air for a tall building with a Floor Area Ratio of less than 7 effectively in summer.

Seasonal Variation in Slipped Capital Femoral Epiphysis: New Findings Using a National Children's Hospital Database.

Slipped capital femoral epiphysis (SCFE) demonstrates seasonal variation in certain latitudes but not others. Is such variation influenced by temperature differences, sunlight exposure and subsequent vitamin D production, or other climate variables? It was the purpose of this study to further investigate the seasonal variation in month of presentation for SCFE. Data for this study originated from the Pediatric Hospital Information System for all children with a diagnosis of SCFE from January 1, 2004 through December 31, 2014. From this database the patient's sex, ethnicity, hospital location, and month of presentation was determined. Only those patients treated primarily for SCFE were included. Geographic and climate data [latitude, average annual temperature, precipitation, climate type (Köppen-Geiger and Liss), horticultural plant zone hardiness, and sunlight exposure] for each of the 49 Pediatric Hospital Information System hospitals was determined. Seasonal variation was analyzed using cosinor analysis. A P<0.05 was considered statistically significant. There were 10,350 cases of SCFE with an overall peak presentation in mid August. For those living at a latitude of >35-degree N there was single peak, a less prominent double peak for those 31- to 35-degree N, and no variation for those <31-degree N. As the average annual temperature increased there was less seasonal variability. Humid, temperate and cold winter climates demonstrated seasonal variation, whereas other climate types did not. Those living in areas having <2500 hours of sunlight per year demonstrated seasonal variation. Further, areas having a photovoltaic solar production potential <5.0 kWh/m/d also demonstrated seasonal variation. We discovered new seasonal variation findings regarding SCFE. These are a double peak pattern for those between 31- and 35-degree N latitude; less variability as the average annual temperature increases; and sunlight exposure correlates with seasonal variability. Potential explanations are a rachitic state due to seasonal variation in vitamin D production, and seasonal variation in physeal growth and strength. These new findings will require further investigation. Level III.

Specialized pollination by honeybees in Cymbidium dayanum, a fall–winter flowering orchid

AbstractFloral biology and pollination mechanisms of Cymbidium dayanum, an endangered epiphytic orchid, were investigated in south Kyushu, Japan. The flowering period spanned approximately 4 months from fall to winter, with the inflorescences often blooming asynchronously on each plant and individual flowers commonly lasting for a month. The nectarless flowers are self‐compatible but cannot autonomously self‐pollinate; the orchid needs to attract pollinators by deceit for capsule production. The field observations showed that the flowers were pollinated exclusively by the Japanese honeybee Apis cerana japonica, despite its long flowering period. The worker bees pollinated flowers and/or received the pollinarium on the thorax, while escaping from the labellum chamber. The natural fruit‐set ratios at the population level, an estimate of pollination success, varied interannually but were generally low, as the result of infrequent flower visits by honeybee workers owing to the cold winter climate and the lack of a nectar reward. Because most flowers that were artificially pollinated in the winter successfully developed into capsules, the coldness was not considered a direct cause of the low fruit‐set ratios. Our results explicitly indicate that the bee pollination niche could be available to temperate plant species even during mid‐winter. We inferred advantages for the winter flowering of C. dayanum.