Measurement and simulation of the thermal environment in the built space under a membrane structure

This paper presents a study to clarify characteristics of the summer thermal environment in an actual membrane structure with a semi-closed space underneath by using field measurements and simulations. The first part of this paper describes the following findings from the field measurements conducted during a summer period: (1) the solar transmission through the membrane had a greatest impact on the thermal environment in the living space under the membrane structure during the daytime; (2) the mean radiant temperature (MRT) at the central part of the living space went higher than the air temperature due to heat storage in the ground and walls of surrounding buildings where radiation cooling to the sky was obstructed by the membrane. In the second part of the paper, a 3D CAD-based simulation tool (called the thermal environment simulator) developed by the authors' group was used to simulate the thermal environment in the test membrane structure. A comparison between the measured and simulated surface temperature of the membrane was carried out. As a result, it was found that the simulated results agreed well with the measurement data. In addition, the following subjects were discussed using the simulation tool: how the thermal environment under the membrane is influenced by changing the solar transmittance and absorptance of the membrane or changing the ground surface materials. Simulation results show that the simulation tool is able to provide a quantitative prediction and evaluation of the thermal environment in the living space under the membrane structure in terms of the surface temperature and mean radiant temperature distribution.     

校园行道树对夏季室外行人热舒适的 影响研究

道路绿地作为城市绿地的重要组成部分,在缓解城市热岛和改善行人热舒适等方面起着重要作用。通过监测大学校园内7种典型行道树树荫和阳光下的空气温度(T_a)、相对湿度(RH)、风速(V_a)、黑球温度(T_g)和太阳辐射(G)等气象参数以及行道树的叶表面温度(T_(1s),运用通用热气候指数(Universal Thermal Climate Index,UTCI)分析不同行道树对道路空间热环境的影响和行人热舒适的改善效果。结论如下:1)行道树改善道路空间行人热舒适作用明显,对T_a和平均辐射温度(Mean Radiant Temperature,T_(mrt)降低能力最强的树种分别为悬铃木和银杏;2)天空可视因子(Sky View Factor,SVF)是影响道路空间行人热舒适的主要因素;3)T_(1s)与UTCI呈强线性正相关(R~2=0.8083),夏季T_(1s)越高,道路空间行人热舒适度越差。研究结果从室外热舒适评价的角度为行道树设计提供了理论基础和量化指导。     

Thermal environment characterisation of a glass-covered semi-outdoor space subjected to natural climate mitigation

The human thermal sensation inside a semi-outdoor space enclosed by a semi-transparent pitched roof, located in Parma, north of Italy, is compared with the outdoor sensation under the same climate conditions. The assessment of the semi-outdoor setting was performed using the Physiological Effective Temperature (PET) thermal sensation index. With the aim of mitigating the semi-outdoor climate, some natural means were considered at the design stage, namely, the solar radiation absorptivity of the glass sheet roof, natural airflow, space thermal capacity and roof evaporative cooling. The dynamic thermal simulation of the semi-outdoor space was performed for three representative weeks of the months of January, March and July by accounting for the actual climate of the location. The results show that the semi-transparent roof can improve the human thermal sensation inside the semi-outdoor space with respect to that of the outdoor space. The results also demonstrate the effect of each design parameter on the PET index.     

从生态视角看“架空空间”在闽南幼儿园建筑中气候适应性

研究闽南幼儿因的架空空间所具有的适应地域气候和生态节能作用.以幼儿园使用与地域气候之间的矛盾入手,结合闽南幼儿园的四个实例分析架空空间的布局特点的方法.结果显示,在阴雨、烈日、台风天气中,架空空间能避雨、遮阳、防坠物等功能来替代户外的活动场地;在夏热气候中能承担儿童部分室内活动从而降低空调能耗且增加舒适性和生态性,总结...     

夏热冬冷气候城市公共空间热环境季节特征

城市公共空间热环境是影响人们热舒适程度的重要因素。夏热冬冷气候城市公共空间的热环境在一年内会发生很大变化。在长沙市内选择3个典型公共空间(街道、公园和广场)进行长期热环境参数实测实验。通过对不同季节3个实测点的空气温度、相对湿度、黑球温度和风速4个重要热环境参数进行分析,获得夏热冬冷气候城市公共空间的全年热环境特征。研究结果表明:自然气候决定了城市热环境的基本特征,而城市物理结构是引起室外局部热环境发生改变的重要因素;受植物(乔木)和水体(湘江)的影响,沿江街道在全年大部分时间中空气温度显著较低,相对湿度较高,太阳辐射较弱;广场温度较高,太阳辐射较强。     

Assessing thermal comfort of active people in transitional spaces in presence of air movement

The aim of this study is to develop a modeling methodology to assess thermal comfort and sensation of active people in transitional spaces and consider how comfort can be achieved by air movement while changing upper body clothing properties. The modeling is based on a bioheat model, capable of predicting segmental skin and core temperature from locally ventilated clothed body parts. The bioheat model is integrated with thermal comfort and sensation models to predict comfort in presence of air movement.The model accuracy in predicting comfort was validated by and agreed with the results of a survey administered to subjects wearing typical clothing at different activity levels to record their overall and local thermal sensation and comfort in a transitional space at Beirut summer climate. The transitional space temperature monitored during the experiments ranged between 27 °C and 30 °C.A parametric study is performed to assess thermal comfort in transitional spaces for different air movement levels and for three clothing designs. The high permeable clothing at 1.5 m/s and indoor temperature of 30 °C improved the Predicted Mean Vote to values less than 0.5 compared to 1.01 attained with typical low permeable clothing.     

Thermal comfort assessment in semi-outdoor environments: Application to comfort study in stadia

The present study addresses thermal comfort assessment of outdoor and semi-outdoor environments. Two stadium case studies are used to demonstrate the potentiality of the approach that combines wind tunnel data and the calculation of human heat balance due to particular climatic environments. The thermal index PET (physiological equivalent temperature) is used to evaluate the thermal comfort in such complex environments. The specificities of stadium semi-outdoor spaces are summarised and the necessary assumptions made to apply the computation procedure are described. The approach includes assumptions on the thermo-physical phenomena as well as geometric computations. This work benefited from the development of an interactive design tool of built environments (outdoor urban surroundings): EVE (enriched virtual environments). It is a virtual reality platform developed at CSTB to help designers, architects and urban planners to evaluate the various options in competition regarding acoustic, visual, thermal and wind comfort of pedestrian in a particular urban environment.     

On the use of bioclimatic architecture principles in order to improve thermal comfort conditions in outdoor spaces

The present paper describes a process for designing and applying several techniques based on bioclimatic architecture criteria and on passive cooling and energy conservation principles in order to improve the thermal comfort conditions in an outdoor space location located in the Great Athens area. For that reason, the thermal comfort conditions in 12 different outdoor space points in the experimented location have been calculated using two different thermal comfort bioclimatic indices developed to be used for outdoor spaces. The used indices were the following: (a) “Comfa”, which is based on estimating the energy budget of a person in an outdoor environment and (b) “thermal sensation”, based on the satisfaction or dissatisfaction sensation under the prevailing climatic conditions of the outdoor spaces. Calculations were performed during the summer period and two different scenarios of the constructed space parameters have been considered. The first scenario consists of a conventionally constructed space, while the second one includes various architectural improvements according to the bioclimatic design principles. The two bioclimatic indicators were used for calculating the outdoor thermal comfort conditions in the above-mentioned outdoor space locations for both scenarios and the effect of the bioclimatic design architectural improvements on the human thermal comfort sensation was presented and analysed.     

Thermal effect of temperature gradient in a field environment chamber served by displacement ventilation system in the tropics

The effect of vertical air temperature gradient on overall and local thermal comfort at different overall thermal sensations and room air temperatures (at 0.6 m height) was investigated in a room served by displacement ventilation system. Sixty tropically acclimatized subjects performed sedentary office work for a period of 3 h during each session of the experiment. Nominal vertical air temperature gradients between 0.1 and 1.1 m heights were 1, 3 and 5 K/m while nominal room air temperatures at 0.6 m height were 20, 23 and 26 °C. Air velocity in the space near the subjects was kept at below 0.2 m/s. Relative humidity at 0.6 m height was maintained at 50%. It was found that temperature gradient had different influences on thermal comfort at different overall thermal sensations. At overall thermal sensation close to neutral, only when room air temperature was substantially low, such as 20 °C, percentage dissatisfied of overall body increased with the increase of temperature gradient. At overall cold and slightly warm sensations, percentage dissatisfied of overall body was non-significantly affected by temperature gradient. Overall thermal sensation had significant impact on overall thermal comfort. Local thermal comfort of body segment was affected by both overall and local thermal sensations.     

Evaluation of enhanced conduction-corrected modified effective temperature ETFe as the outdoor thermal environment evaluation index

The purpose of this paper is made to clarify that the relationship between the human physiological and psychological responses and the enhanced conduction-corrected modified effective temperature ETFe as the outdoor thermal environment evaluation index upon the human body. Environmental factors and human physiological and psychological responses were measured. It was made clear that the variables by which summer outdoor environmental factors influence the thermal sensation vote are heat conduction, humidity and short-wave solar radiation. The variables that affect the thermal comfort vote are air velocity, heat conduction and humidity. ETFe, into which the environmental factors that are the variables for human response are incorporated, showed good correspondence with the thermal sensation vote. Similarly, ETFe has a good correspondence with thermal comfort vote. The usage of ETFe as a thermal environment evaluation index for summer outdoor spaces is valid. The threshold for the human body with regards to thermal environment stimuli in an outdoor space is higher than the thermal environment stimuli in a summer indoor space.     

Research on seasonal indoor thermal environment and residents' control behavior of cooling and heating systems in Korea

Indoor thermal environments and residents' control behavior of cooling and heating systems were investigated in Seoul, Korea and compared with the results of previous studies. Twenty-four houses in summer, six houses in autumn and 36 houses in winter were used in this study. The measurement of temperature, humidity and air conditioner usage behavior was carried out. The clo-value, thermal comfort, sensation and basic data of the houses were also investigated. The indoor thermal environment in the summer had a high temperature and a high humidity ratio compare to standard comfort zone. Most of the indoor thermal environments at the time of starting the air conditioner in the summer were out of the comfort zone. Some of the data recorded while the air conditioner was stopped were in the comfort zone, but in many cases the temperature was relatively higher than comfort zone. Most indoor climate distributions in the winter were in the comfort zone and the indoor climate in autumn coincided well with the criteria of the comfort zone. Compared with results of previous studies in these 25 years, indoor ambient average temperature in winter has increased and the comfort temperature has increased in the heating period and decreased in the cooling period. This result indicates that the development of an HVAC system has created an expectation of comfort for residents and has shifted their thermal comfort zone warmer in winter and cooler in summer.     

Numerical study of the influences of different patterns of the building and green space on micro-scale outdoor thermal comfort and indoor natural ventilation

Citizens could enjoy a healthy and comfortable living environment if outdoor thermal comfort and sufficient natural ventilation are available in their dwellings. In this paper, numerical studies were performed with the Simulation Platform for Outdoor Thermal Environment (SPOTE) to investigate: (1) the thermal environment and pedestrian thermal comfort of the occupants in the open space with different patterns of the building and green space; (2) the wind pressures on the building facades and the natural ventilation rate of these buildings. The conclusions are summarized as follows: (1) it has been observed that the long facades of building and green space, which are parallel to the prevailing wind direction, can accelerate horizontal vortex airflow at the edges where such airflow could strengthen the convective exchange efficiency of hot air in low altitude and cold air in high altitude, and can obtain thermal comfort and sufficient natural ventilation at the pedestrian level; (2) after a series of simulations and comparisons, the configuration in which buildings are grouped in staggered layout with a centralized green space can provide better ventilation conditions and suitable air movement as a result of attenuated revised standard effective temperature (SET*). This configuration is regarded as the optimum pattern of the building and green space.     

感知控制对湿热地区户外庭园空间热舒适性的影响——以华侨大学“世外·花缘”生活实验室为例

户外热舒适对城市景观空间的使用具有显著影响。目前对户外热舒适的研究较少考虑感知控制(Perceived Control)的影响作用。通过在选定实验区域内对志愿者进行问卷调查,分析感知控制对庭园空间热舒适的影响。结果表明：1)感知控制对湿热地区庭园空间的夏季中性温度具有一定影响,但对秋、冬季中性温度影响微弱;2)感知控制受限会导致热感觉的敏感程度增强,热舒适范围变窄;3)在中性温度范围附近,感知控制对热舒适感的影响十分微弱,而在热感觉为“冷”“凉”“暖”“热”的热环境中,感知控制对不适感具有一定缓解作用;4)感知控制在一定程度上扩大了人们对庭园热环境的可接受范围,当感知控制受限时,人们对热环境的接受度会有所下降。     

夏季空调热舒适响应空间及节能潜力研究

在满足人体热舒适要求的前提下,通过对空调热舒适方程的仿真分析,建立了空调系统环境参数的舒适空间,确立各参数对舒适性指标的影响程度;通过对空调建筑房间冷负荷计算分析,验证了空调系统在热舒适环境参数空间内存在一定节能潜力。     

Dynamic thermal simulation of a glass-covered semi-outdoor space with roof evaporative cooling

In the hot season solar radiation impinging on a glass roofing may overheat the underneath space to temperature values which may generate a high stress environment. To moderate the extreme microclimate which may occur in a glass covered semi-outdoor space, evaporative cooling to be applied to the glass roof is suggested. The analysis is performed under both the thermal and the energetic point of view, by accounting for the actual climate of the considered location. The results point out that roof evaporative cooling coupled with glass sheet high solar radiation absorptivity may offer an attractive way for the control of a semi-outdoor environment.     

Effect of MRT variation on the energy consumption in a PMV-controlled office

This paper investigates the energy-saving potential of a thermal comfort-controlled office building. A comparative simulation study between the thermal comfort control and conventional thermostatic control is conducted on a building with glass façades where changes in the outdoor temperature and solar radiation over the course of a day affect radiant temperature and thus thermal comfort. To evaluate the thermal performance in the comfort-controlled space, a PMV-based thermal comfort controller, which adjusts the set-point room temperature of the existing thermostatic controller according to the changes of environmental variables, is assumed. The results demonstrate that thermal comfort competes with energy saving in a conventional thermostatic-controlled space. However, it is suggested that thermal comfort control provides consistent thermal comfort as well as energy-saving effect. The results show that energy consumption in a thermal comfort-controlled space is more affected by a change in the mean radiant temperature than in the conventional thermostatic-controlled space. The energy-saving potential in the thermal comfort-controlled space increases with low mean radiant temperature conditions. Although the energy-saving potential is reduced under high mean radiant temperature conditions, it is suggested that thermal comfort control is still a reasonable strategy to achieve both thermal comfort and energy savings simultaneously.     

Field study of human thermal comfort and thermal adaptability during the summer and winter in Beijing

This study was conducted during the summer and winter in Beijing. Classrooms and offices in a university were used to conduct the survey. The respondents’ thermal sensation and thermal adaptability in both seasons were analyzed. During the study, indoor environmental parameters including air temperature, mean radiant temperature, relative humidity, and air velocity were measured. The respondents’ thermal sensation was determined by questionnaire.A relationship between indoor temperature and thermal sensation was found. In the summer study, the “scissors difference” between TSV and PMV was observed in the air-conditioned environments if the temperature was out of the neutral zone. People had higher tolerance in the hot environment than PMV predicted. During winter, the outdoor temperature had a prominent influence on thermal adaptability. The low outdoor temperature made people adapt to the cold environment. When the indoor temperature was heated to a high temperature by space heating facilities, respondents felt uncomfortable since their adaptability to the cold environment was nullified.Furthermore, the differences in thermal responses between respondents from North and South China showed that the different climates of people's native regions also affected their thermal comfort and adaptability.     

Energy conservative building air conditioning system controlled and optimized using fuzzy-genetic algorithm

In this work, the combined effect of the energy conservative variable refrigerant volume (VRV) system and the variable air volume (VAV) system was experimentally investigated using genetic fuzzy optimization method that yielded better thermal comfort, indoor air quality (IAQ) requirements without compromising on the energy savings potential. The proposed system was tested using the demand controlled ventilation (DCV) combined with the economizer cycle ventilation (ECV) techniques and examined for a year-round building air conditioning (A/C) application. The supply air temperature (SAT) set points were varied under three distinct strategies and the optimal solutions obtained for the fuzzy systems designed resulted in an enhanced energy conservative potential. The test results of the proposed system were compared with the conventional fan coil A/C system. Based on the three strategies of the supply air temperature, the proposed system yielded an improved per day energy savings potential of 54% in summer and 61% in winter design conditions. Furthermore, for the strategies considered the proposed system achieved an annual energy conservative potential of 36% and exhibited more possible ways to achieve thermal comfort, IAQ and energy conservation.     

Indoor thermal conditions and thermal comfort in air-conditioned domestic buildings in the dry-desert climate of Kuwait

The summer season in the state of Kuwait is long with a mean daily maximum temperature of 45 °C. Domestic air conditioning is generally deployed from the beginning of April to the end of October. This accounts for around 75% of Kuwaiti electrical power consumption. In terms of energy conservation, increasing the thermostat temperature by 1 °C could save about 10% of space cooling energy 1 and 2. However, knowledge of indoor domestic temperatures and thermal comfort sensations is important to aid future advice formulation and policy-making related to domestic energy consumption. A field study was therefore conducted during the summers of 2006 and 2007 to investigate the indoor climate and occupants' thermal comfort in 25 air-conditioned domestic buildings in Kuwait. The paper presents statistical data about the indoor environmental conditions in Kuwait domestic residences, together with an analysis of domestic-occupant thermal comfort sensations. With respect to the latter, a total of 111 participants provided 111 sets of physical measurements together with subjective information via questionnaires that were used to collect the data. By using linear regression analysis of responses on the ASHRAE-seven-point thermal sensation scale, the neutral operative temperatures based on Actual Mean Vote (AMV) and Predicted Mean Vote (PMV) were found to be 25.2 °C and 23.3 °C, respectively, in the summer season. Findings from this study provide information about the indoor domestic thermal environment in Kuwait, together with occupant thermal comfort sensations. This knowledge can contribute towards the development of future energy-related design codes for Kuwait.     

对热舒适、空气感觉质量及能耗的模拟研究

室内空调设计温度和新风量对热舒适，室内空气质量及能耗量有重要影响，然而对它们之间相互关系进行研究的文献却较少。通过计算机模拟空调系统在7种室内设计温度和7种新风量条件下的运行情况，得到不同的设计条件组合对热舒适、人体感觉空气质量及建筑能耗量的影响。基于这项分析，提出了此办公建筑合理的室内设计温度和新风量取值。