Thermal Environment In Summer Research Articles

Coupling mechanism of water and greenery on summer thermal environment of waterfront space in China's cold regions

Water and greenery space is an essential part of the urban ecosystem and plays a vital role in alleviating the urban heat island effect. Water and greenery differently affect the urban microclimate. After coupling the two factors, the quantitative human thermal environmental experience analysis needs to be revealed. This study investigated the thermal environment of the waterfront space with the greenery of Tianjin in the cold regions of China. Different types of microscale water were analyzed to evaluate their thermal environment in summer using subjective and objective analysis and model simulation. We concluded the coupling mechanism of waterfront greenery and thermal evaluation standard. The results show that water and greenery's coupling effect peaked at 14:00 and waterfront at 4–8 m. Conversely, the cooling effect was more significant at 3–6 m from the water's edge, where the location was suitable for construction as verified by the optimization model. The prerequisite of coupling mechanism was suitable green coverage rate and vegetation type, based on the comprehensive analysis of four cases. The objective effects of different waterfront distances on the thermal comfort of Heat Index (HI) and the subjective evaluation of Universal Thermal Climate Index (UTCI) for people were quantified. This research provides a theoretical basis and data support for urban waterfront renewal in cold regions.

Environmental Effects from Pocket Park Design According to District Planning Patterns—Cases from Xi’an, China

Rapid urban expansion leads to the continuous deterioration of the urban thermal environment, which endangers the sustainable development of the city; meanwhile, countries all over the world are becoming increasingly interested in the mitigating effects of urban green spaces on heat islands. In this context, many studies show that pocket parks play an important role in optimizing the thermal environment of urban blocks, especially with the high-intensity development of urban blocks. Moreover, many cities in China have become mature, and it is difficult to open up large green areas. Therefore, to improve the urban thermal environment in summer, it is necessary to adapt to an efficient pocket-park design strategy in blocks. To consider the impact of block development intensity on the design strategy of pocket parks, three pocket parks in blocks with different floor-area ratios in the central area of Xi’an were selected as examples. This research compares the effects of tree density and green-space layout on the thermal environment in different floor-area ratio districts on a summer day using environmental simulation (ENVI-met). The results show that the design strategies of pocket parks in urban blocks with different development intensities are different. High tree density performs better from the perspective of improving the urban thermal environment. For the low and medium development intensity blocks, the effects of the open green space and closed green space are similar, while the open green space layout can significantly improve thermal comfort in high-intensity development blocks.

Operation performance evaluation of green public buildings with AHP-fuzzy synthetic assessment method based on cloud model

At present, there always is a significant gap between the design and the actual operation performance. This study presents the application of AHP (Analytic Hierarchy Process) and fuzzy synthetic evaluation method based on cloud model theory to evaluate the overall operation performance of the green public buildings, considering indoor environment quality (IEQ) and energy consumption. The evaluation method contains three criteria as objective IEQ, subjective IEQ and annual energy consumption. Criteria of objective and subjective IEQ includes the same six sub-criteria of thermal environment in summer, in winter and in transition season, luminous environment, air quality and acoustic environment. The criteria annual energy consumption includes four sub-criteria of air conditioning electricity, lighting and socket electricity, power electricity and special electricity. Two cases of green and non-green library building are applied to be evaluated by this method, which is also validated with other method. Building managers can judge if the building performs efficiently or not with the evaluation method, and can also find which criteria or sub-criteria has poor operation performance. Furthermore, the evaluation method can reflect the relationship between sub-item of energy consumption and corresponding sub-criteria of IEQ, it can provide a direction for optimizing energy consumption. This evaluation method can not only be applied to evaluate the operation performance of different similar buildings, but also can be applied to evaluate the same building in different years. This study can provide a certain guiding significance for the development of evaluation the comprehensive operation performance of green buildings.

The projected effects of urbanization and climate change on summer thermal environment in Guangdong-Hong Kong-Macao Greater Bay Area of China

The individual and combined impacts of near-future urbanization and climate change on thermal environment in July over the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) are projected. Results indicate that both the urbanization and climate change lead to near-future temperature rise, with comparable daily mean urban-warming of ~0.51 °C and ~ 0.70 °C respectively. In which, the two factors also enhance the probability of extreme heat events, especially the role from climate change. However, the relative contributions of two factors on human thermal comfort are very different. Urbanization leads to drier daytime but warmer nighttime, resulting in more comfortable daytime but uncomfortable nighttime. Under the changing climate, significant and uniform increase of Humidex (HI) can be found in whole day, suggesting future climate change intensifies human discomfort thoroughly. Climate change takes up ~93.33% of the total increased HI, attributing to both the caused temperature rise and humidity increase. Contrarily, urbanization only contributes ~7.41%, because the urban-reduced humidity offsets the effect of urbanized warming. It is further revealed that exposure duration of dangerous discomfort (HI ≥ 45) for the GBA residents will increase at least 8.87% in 2030 under the effects of climate change and urbanization, suggesting necessity of mitigating climate change in future megalopolis.

Use of the Comprehensive Climate Index to estimate heat stress response of grazing dairy cows in a temperate climate region.

The aim of the study was to assess the effect of the summer thermal environment on physiological responses, behaviour, milk production and its composition on grazing dairy cows in a temperate climate region, according to the stage of lactation. Twenty-nine Holstein Friesian multiparous cows were randomly selected and divided into two groups, according to the days in milk, as mid-lactation (99 to 170 d in milk, n = 15) and late lactation (225 to 311 d in milk, n = 14). The comprehensive climate index (CCI) was used to classify the hour of each day as thermoneutral or heat stress, considering a threshold value of CCI of 20°C. Data were collected for 16 d (summer 2017) and analysed as a completely randomized 2 × 2 factorial arrangement with repeated measurements over time. Vaginal temperature increased with CCI ≥ 20°C. Respiration rates were dependent on the thermal condition, regardless of days in milk. There was an interaction between the time of day and the CCI category for activity and rumination. Grazing activity decreased by 17.6% but lying down, standing, and shaded animals increased by 1.6, 9.8, and 6.3% respectively when CCI ≥ 20°C. Over 80% of cows presented a panting score ≥1. However, milk production and composition (fat, protein, and lactose concentrations as well as somatic cell count) were not affected by the thermal condition, although there was a numerical (non-significant) decrease in afternoon milk protein concentration on days with CCI ≥ 20°C, while urea in milk increased. In conclusion, thermal condition challenged grazing dairy cows' behaviour and physiology independent of the stage of lactation but had little or no effect on milk production.

The impact of building height on urban thermal environment in summer: A case study of Chinese megacities.

The quantitative relationship between the spatial variation of building’s height and the associated land surface temperature (LST) change in six Chinese megacities is investigated in this paper. The six cities involved are Beijing, Shanghai, Tianjin, Chongqing, Guangzhou, and Shenzhen. Based on both remote sensing and building footprint data, we retrieved the LST using a single-channel (SC) algorithm and evaluate the heating/cooling effect caused by building-height difference via correlation analysis. The results show that the spatial distribution of high-rise buildings is mainly concentrated in the center business districts, riverside zones, and newly built-up areas of the six megacities. In the urban area, the number and the floor-area ratio of high to super high-rise buildings (>24m) account for over 5% and 4.74%, respectively. Being highly urbanized cities, most of urban areas in the six megacities are associated with high LST. Ninety-nine percent of the city areas of Shanghai, Beijing, Chongqing, Guangzhou, Shenzhen, and Tianjin are covered by the LST in the range of 30.2~67.8°C, 34.8~50.4°C, 25.3~48.3°C, 29.9~47.2°C, 27.4~43.4°C, and 33.0~48.0°C, respectively. Building’s height and LST have a negative logarithmic correlation with the correlation coefficients ranging from -0.701 to -0.853. In the building’s height within range of 0~66m, the LST will decrease significantly with the increase of building’s height. This indicates that the increase of building’s height will bring a significant cooling effect in this height range. When the building’s height exceeds 66m, its effect on LST will be greatly weakened. This is due to the influence of building shadows, local wind disturbances, and the layout of buildings.

Influences of atrium geometry on the lighting and thermal environments in summer: CFD simulation based on-site measurements for validation

Atriums have recently been applied with increasing frequency for natural illumination, though they produce a harsh indoor thermal environment. Cooling energy consumption is extremely huge in atriums due to the hot summer in certain regions of China. Accordingly, this paper mainly focused on the ratio of skylight to atrium to optimize the thermal environment without compromising the natural lighting. The study quantitatively analyzed the impacts of two geometric parameters, the area ratio (AR) and section aspect ratio (SAR) of the skylight to the roof, on the lighting and thermal environments of atriums by simulation. These models are calibrated with the data measured in a library in Guangzhou, China, to obtain the most appropriate models and boundary conditions. The SAR range of models was set in SAR<4 to be universal through the investigation of buildings. From the results revealed, the AR is the critical factor affecting the diffuse skylight in atriums, whereas the SAR is not. It was when the AR≥1/5.5 that atriums with square plane can meet the natural lighting requirements. The atrium thermal environment was assessed comprehensively from the aspects of air temperature, surface temperature, and vertical temperature difference. It generally became better as the AR decreases and the SAR increases until to AR<1/5. Thus, the optimal nondimensional combination of the atrium configuration was AR = 1/5 and SAR = 4. The temperature distribution characteristics were explained by the theories of heat pressure and air flow, extending the application scope and prospects of this research.

Influence of grass lawns on the summer thermal environment and microclimate of heritage sites: a case study of Fuling mausoleum, China

The thermal environment and microclimate of heritage sites has been severely impacted by rapid urbanization. This study collected various meteorological measurement data as a reference for computational fluid dynamics (CFD) simulation settings. Then CFD was applied to simulate the impact of lawns on the thermal environment and microclimate of Fuling Mausoleum. We found that lawns and soil can cool the air through evaporation, and thus have a specific cooling effect on the bricked ground. Simulations with the lawns, the bricked ground temperature decreased by 1.56–17.54 °C than that simulations without the lawns at 14:00, a decrease of 2.68%–24.20%. Under normal circumstances, when the wind speed or relative humidity increased, the ground temperature dropped. Greenbelt vegetation can adjust the microclimate and human thermal comfort indicators. The consistency of the difference between the actual measurement and the CFD simulation results shows that CFD simulation can thus accurately reflect the internal temperature field distribution if the selection of simulation parameters is reasonable. Theoretical calculation and analysis, experimental measurement research, and modern computer simulation analysis methods applied together constitute a complete system for studying modern physical environmental problems and can provide reliable and economic results.

Field experiments on the effects of an earth-to-air heat exchanger on the indoor thermal environment in summer and winter for a typical hot-summer and cold-winter region

An earth-to-air heat exchanger (EAHE) is a shallow geothermal energy utilization technology, which can significantly reduce the building energy consumption. This study aims to investigate the effects of an EAHE on the indoor thermal environment in hot-summer and cold-winter regions. A full-scale experiment was conducted for a continuous 24 h period using two identical buildings (with and without an EAHE) exposed to the same outdoor conditions on typical summer and winter days. Experimental results show that the EAHE provides an average outdoor air temperature reduction of 9.12 °C under cooling conditions and increase of 5.53 °C under heating conditions. Moreover, the average outdoor air relative humidity increases by 46.89% and decreases by 27.41% in the cooling and heating conditions, respectively; the corresponding average EAHE coefficients of performance (COP) are 7.03 and 4.26, respectively. Compared to that of the building without EAHE, the average indoor air temperature of the building with EAHE decreases by 5.9 °C in summer and increases by 4.29 °C in winter, and the average walls’ internal surface temperature decreases by approximately 6 °C and increases by approximately 5.8 °C. Moreover, the EAHE system reduces the average building cooling and heating loads by 55.4 and 40.43 W/m2, respectively.

Environmental impact assessment of introducing compact city models by downscaling simulations

In this study, first, three compact city models with different degrees of compactness for a prefecture in a large metropolitan area of Japan were designed. Based on the urban classifications “population-induced area,” “population-unchanged area,” and “withdrawal area,” we constructed the compact city models. Next, the impact of introducing the designed compact city models on the summer thermal environment in the 2050s was quantitatively assessed by downscaling simulations from a global scale to an urban scale. Moreover, we examined the effect of a land use change in the withdrawal area on the future thermal environment in the urban area (the population-induced and population-unchanged areas). As expected, a temperature increase in the urban area occurred due to urban densification in the compact city models. On the other hand, the temperature decrease in the urban area as a result of changing the land use of the withdrawal area, i.e., by replacing the withdrawal area with grassland, approximately offset the above-mentioned temperature increase. This implies that, in compact city planning, it is necessary to properly plan not only for the concentrated urban area but also for treatment of the withdrawal area from the viewpoint of environmental impact.

The SPA-TOPSIS-Based Evaluating Approach on Thermal Sensation Model at Different Vane Angles in UFAD–DV System

Under floor air distribution system and displacement ventilation (UFAD–DV) system is used to provide comfortable indoor thermal environment in summer, which largely satisfies overall and local thermal sensation. In UFAD–DV system, the selection of supply vane angle is particularly important to achieve the best thermal comfort. This paper studied thermal sensation of a manikin in sedentary state through the AIRPAK simulations. Firstly, in order to analyze the influence of the local thermal sensation on overall thermal sensation (OTS), the manikin model consisting of five local body parts was constructed. Then, the set pair analysis technique for order preferences by similarity to an ideal solution (SPA-TOPSIS) method was proposed to analyze the overall thermal sensation model and the combination model of overall and local thermal sensation at different supply vane angles. Finally, according to the SPA-TOPSIS analysis, the combination model of overall thermal sensation and local thermal sensation was determined and the best supply vane angle was 10° downward. The PMV and PPD values of each part of the body and overall body were 0.1932, 0.3413, 0.2287, 0.0503, − 0.0992, 0.173 and 5.9721, 7.5005, 6.377, 5.2632, 5.2579, 6.79, respectively. The weight coefficient method was used for the validation of SPA-TOPSIS-based evaluating results with p < 0.05. In addition, the thermal sensation of foot has important impact on thermal sensation, and the ideal integrated thermal sensation of five local body parts and overall body was achieved. The proposed SPA-TOPSIS-based evaluation approach can determine the best supply vane angle, which optimizes the OTS on the premise of satisfying the local thermal sensation.

Evaluating the influence of traditional land allotment in the historical district of Japanese regional urban center upon outdoor summer thermal environment

AbstractIn Japan, hot summer nights caused by urban heat island phenomena are affecting the health of the elderly population in many regional urban centers. Kumamoto city is one of the major regional urban centers in Japan, and urban heat island phenomena have serious implications especially in summer. Furumachi district is located in the center of Kumamoto city, and regarded as a historical district where many early modern houses have existed. The land allotment of city blocks in this district has not changed since the end of the early modern period in Japan (around 1868), and all new developments are performed as per this traditional land allotment. In the present study, for the effective utilization of the traditional land allotment in the historical district, summer thermal environment in Furumachi district has been analyzed and evaluated both from field measurements and numerical simulations. As a result, it has been demonstrated that the ground cover and spatial structure in and around vacant lands in the district, which have performed under the preserved traditional land allotment, have a significant influence on the sensible heat flux in building scale, and outdoor thermal comfort in living area scale.

Architectural spatial design strategies for summer microclimate control in buildings: a comparative case study of Chinese vernacular and modern houses

The objective of this paper is to clarify the spatial design strategies used to control the microclimate of a Chinese vernacular house in summer by comparing the building with modern Chinese rural houses and presenting ideas for contemporary architectural design practice. For this goal the spatial configuration, the spatial boundary conditions, the vegetation in the space and the human activity in the space were analysed for the vernacular house and for modern rural houses. Also, field measurements were conducted to evaluate the summer thermal environment in the vernacular and a modern house. The results show that the vernacular house has a diverse spatial design and a better building microclimate, making it easier to obtain thermal comfort than the modern houses. Therefore, spatial design strategies of Chinese vernacular houses are still of great value to modern house design, especially when the free-running thermal comfort theory is applied.

Architectural spatial design strategies for summer microclimate control in buildings

The objective of this paper is to clarify the spatial design strategies used to control the microclimate of a Chinese vernacular house in summer by comparing the building with modern Chinese rural houses and presenting ideas for contemporary architectural design practice. For this goal the spatial configuration, the spatial boundary conditions, the vegetation in the space and the human activity in the space were analysed for the vernacular house and for modern rural houses. Also, field measurements were conducted to evaluate the summer thermal environment in the vernacular and a modern house. The results show that the vernacular house has a diverse spatial design and a better building microclimate, making it easier to obtain thermal comfort than the modern houses. Therefore, spatial design strategies of Chinese vernacular houses are still of great value to modern house design, especially when the free-running thermal comfort theory is applied.

여름철 열환경을 고려한 도시생태공원 리노베이션 방안 융합 연구 : 길동생태공원을 사례로

본 연구는 최근 기후변화로 인한 도시 열환경 변화로 도시 열섬현상, 폭염, 가뭄 등 다양한 문제를 발생하고 있으며, 이러한 실정에도 도시민은 삶의 질에 대한 인식과 기대는 더욱 높아져 외부활동에 대한 욕구가 증가하고 있다. 이에, 본 논문은 열환경과 생태공원의 융합연구로 많은 도시민이 이용하는 도시생태공원을 중심으로 열환경 실증분석을 실시하였으며, 이를 통하여 열환경을 고려한 도시생태공원 리노베이션 방안을 제시하였다. 연구결과 및 내용은 다음과 같다. 연구대상지는 다양한 공간구성 및 생태적으로 양호한 길동생태공원으로 선정하였다. 측정항목은 열환경 및 열쾌적 지표로 나누어 측정 및 분석을 실시하였다. 공원 공간유형별 분석결과 산림지구에서 가장 양호한 결과가 도출되었다. 이를 통하여 열환경을 고려한 도시생태공원 리노베이션 방안을 3가지 제시하였다. 이러한 본 연구의 결과는 열환경을 고려한 생태공원 조성 방안의 기초자료로 활용될 수 있다는 점에서 의의가 있다.

An experimental study on applying PCMs to disaster-relief prefabricated temporary houses for improving internal thermal environment in summer

During disaster relief reconstructions, prefabricated temporary houses (PTHs) have been extensively used for resettling disaster victims. However, due to the nature of disaster relief, PTHs are normally light-weighted, without an electrical thermal environmental control systems installed. Hence, the thermal environments inside these PTHs can become intolerably hot in summer. Therefore, simple and low cost measures should be applied to disaster-relief PTHs for improving their indoor thermal environments. In this paper, an experimental study on applying PCMs to disaster-relief PTHs is reported. Two different designs of applying PCMs were examined. In Design 1, PCMs were fixed to the internal surfaces of a model PTH and the related experimental results demonstrated that both indoor air temperature and internal surface temperature of the model PTH can be reduced at daytime. However, in Design 2, a movable PCM based energy storage system (PESS) was used and the related experimental results suggested the use of the mobile PESS with a total charge of 148.8 kg PCM helped reduce the average indoor air temperature by 3.2–3.6 °C. The experimental results from both Designs suggested that, due to the nature of disaster relief and since outdoor air at a lower temperature may be the only cooling energy source for charging the PCM, a movable PESS system was preferred, so that it can be moved to outdoor at nighttime for being charged with more cooling energy using lower temperature outdoor air not adversely increasing the air temperature inside PTHs.

CFD 시뮬레이션을 이용한 시설원예단지 여름철 외부 열환경 특성 및 개선방안

CFD 시뮬레이션을 이용한 시설원예단지 여름철 외부 열환경 특성 및 개선방안

通気層とアルミ反射材の複合工法による熱負荷低減効果の検証（その8） 夏期温熱環境調査及び排熱特性の評価

通気層とアルミ反射材の複合工法による熱負荷低減効果の検証（その8） 夏期温熱環境調査及び排熱特性の評価

置換換気方式を導入した食品工場における室内温熱環境の調査研究 : 第1報-夏期・中間期の室内温熱環境の実態調査と省エネルギー効果の試算

置換換気方式を導入した食品工場における室内温熱環境の調査研究 : 第1報-夏期・中間期の室内温熱環境の実態調査と省エネルギー効果の試算

A-21 非空調の大空間作業室の改修による熱環境改善効果に関する研究 : (その1)改修概要及び夏期の熱環境改善効果

A-21 非空調の大空間作業室の改修による熱環境改善効果に関する研究 : (その1)改修概要及び夏期の熱環境改善効果