海洋性气候条件下新型特隆布墙被动降温的通风模式研究

针对被动式太阳房普遍存在的夏季室内过热问题，对海洋性气候条件下带有新型特隆布墙的被动式太阳房进行了实验研究，分析了不同被动降温模式的降温效果和室内空气温度分布。给出了适用于该类太阳房被动降温的最佳通风模式。认为内壁面温度是室内气温最显著的影响因素。与内陆地区利用自然通风降温的效果进行了对比。分析表明提高通风量、强化夜间通风可以改善海洋性气候条件下被动降温的效果。     

Options and applications of passive cooling

The paper summarizes the various heat sinks available for passive cooling of buildings; night ambient air for convective and evaporative cooling, the sky for radiant cooling and the earth. Different techniques for utilizing these options are discussed.     

不同厚度多孔砖在被动蒸发冷却技术中的适应性研究

被动蒸发冷却技术作为自然调和理论的一大支柱,它把调节和控制建筑物室内环境由设备调节的"主动式"转R向自然调和的"被动式",从而达到节能效果.分析被动蒸发冷却技术的适用性,实际上也是在寻找建筑环境的后续能源.借助热湿气候风洞实验台,获得含湿多孔砖的热湿特性参数,讨论不同厚度多孔砖的气候适用性,为被动蒸发冷却技术的实际应用提供基础数据.     

Application of radiant cooling as a passive cooling option in hot humid climate

In hot and humid region, air-conditioning is increasingly used to attain thermal comfort. Air-conditioning is highly energy intensive and it is desirable to develop alternative low-energy means to achieve comfort. In a previous experimental investigation using a room equipped with radiant cooling panel, it was found that cooling water kept to 25 °C could be used to attain thermal comfort under some situations, while water at such temperature would not cause condensation of moisture from air on the panel. This paper reports results of a series of whole-year simulations using TRNSYS computer code on applications of radiant cooling to a room model that represents the actual experimental room. Admitting the inability of radiant cooling to accept latent load, chilled water at 10 °C was supplied to cooling coil to precool ventilation air while water cooled by cooling tower was used for radiant cooling in daytime application. For night-time, cooling water from cooling tower supplied for radiant cooling was found to be sufficient to achieve thermal comfort. Such applications are considered to be more amenable to residential houses.     

夏季湿热地区置换通风和冷却顶板复合系统节能潜力研究

根据上海一办公楼置换通风和冷却顶板复合系统的设计及运行特点,应用EnergyPlus软件模拟了采用转轮除湿方式的复合系统的供冷季能耗,并分别模拟了采用冷却除湿方式的复合系统、带热回收装置的混合通风系统和置换通风系统的供冷季能耗以进行对比。结果表明,在湿热地区采用转轮除湿方式可比冷却除湿方式节约制冷机冷量,空调季总能源费用比混合通风系统节约30%左右。     

Correlation between the local climate and the free-cooling potential of latent heat storage

The natural cooling of energy-efficient buildings using latent heat thermal energy storage (LHTES) that is integrated into the building services makes possible energy savings and improved thermal comfort. In this article, studies of the free-cooling potential for different climatic locations are presented. Six cities from around Europe with a wide range of climatic conditions were selected. The size of the LHTES was optimized on the basis of the calculated cooling degree-hours. First, we analysed the influence of the width of the phase change temperature range and determined the optimal melting temperature of the phase change material (PCM). Then, the optimal LHTES was selected, based on the ratio of the mass of the PCM and the volume flow rate of air ventilating the building. We found that the optimum PCM has a melting temperature that is approximately equal to the average ambient air temperature in the hottest month, and that the free-cooling potential is proportional to the average daily amplitude of the ambient air's temperature swings. For all the analysed climatic conditions the PCM with a wider phase change temperature range (12 K) was found to be the most efficient. The optimal size of the LHTES for the free cooling of buildings is between 1 and 1.5 kg of PCM per m³/h of fresh ventilation air.     

Review of modelling approaches for passive ceiling cooling systems

Passive ceiling cooling systems can lead to reduced cooling requirements, less fan energy and downsized ductwork, compared to conventional all-air systems. Additionally, radiant cooling of occupants allows for improved comfort while allowing for higher operating temperature, improving chiller efficiency. This paper presents a comprehensive review of current modelling approaches for passive ceiling cooling systems in order to document the state of the art and identify current research gaps and modelling development needs. Modelling methods are separated in three main categories, based on the domain of interest: component or “passive ceiling cooler” models, “indoor environment” models and “integrated” models. Simplified, detailed and empirical models are presented for each category. Different modelling approaches may be appropriate for different purposes (design vs. control analysis, and system simulation vs. whole building performance). The study summarizes useful findings, modelling limitations and applications, and presents needs for further modelling and simulation research, including passive chilled beams.     

夜间通风在浙江地区的适用性研究

本文基于夜间通风冷却潜力(CCP)评价方法,对浙江南、北气候分区各自的典型城市(温州、杭州)夜间通风的适用性进行定量分析。结果表明,浙江北区有一定的夜间通风冷却潜力,而浙江南区相对来说实施难度较大。探索并分析了浙江地区夜间通风的强化措施,介绍了相变蓄热在夏热冬冷地区夜间通风中的发展前景,总结了当前夜间通风运行技术方面的研究成果,为浙江地区工程实际夜间通风运用提供参考。     

Modelling of enhanced passive and conventional cooling systems

This study modelled a recently completed typical steel-framed speculative office development in the UK. It investigated the comparative performance of the building for various servicing regimes. These included natural and mechanical ventilation, two types of active fabric energy storage (FES) system (AirDeck and AirCore), air-conditioning (a conventional all-air system and chilled ceiling with mechanical ventilation), and mixed-mode solutions combining some of the above approaches. The assessment covered both summer and winter (heating) performance. The main objective was to evaluate overall performance of these systems in terms of thermal comfort and energy use and to compare the findings with more conventional servicing options for the same building. The study demonstrates that active FES can enhance thermal comfort while reducing energy use and emissions. In comparison with conventionally and naturally ventilated systems, the studied FES systems reduced temperature excess hours and peak temperatures, supplied cooler air as a result of overnight cooling, and reduced chiller consumption and boiler ratings as well as emissions. The annual operating costs of these active FES systems increase energy costs by only 13% over that of the naturally ventilated option. The mixed-mode solutions reduce them by over 35% when compared with all-mechanically cooled alternatives.     

The effects of night ventilation technique on indoor thermal environment for residential buildings in hot-humid climate of Malaysia

This study investigates the effectiveness of night ventilation technique for residential buildings in hot-humid climate of Malaysia. This paper firstly presents the results of a survey on usage patterns of windows and air-conditioners in typical Malaysian residential areas. Secondly, the effects of different natural ventilation strategies on indoor thermal environment for Malaysian terraced houses are evaluated based on the results of a full-scale field experiment. The results show that the majority of occupants tend to apply not night ventilation but daytime ventilation in Malaysian residential areas. It can be seen from the field experiment that night ventilation would provide better thermal comfort for occupants in Malaysian terraced houses compared with the other ventilation strategies in terms of operative temperature. However, when the evaporative heat loss of occupants is taken into account by using SET*, the night ventilation would not be the superior technique to the others in providing daytime thermal comfort mainly due to the high humidity conditions. Therefore, the indoor humidity control during the daytime such as by dehumidification would be needed when the night ventilation technique is applied to Malaysian terraced houses. Otherwise, full-day ventilation would be a better option compared with night ventilation.     

多管地道降温的模拟研究

以三维非稳态固体导热模型和一维流体传热模型为基础,采用有限差分法,建立了考虑管间传热影响的多管地道降温传热模型,并通过与实测数据的比较,验证了其正确性.采用修正温度简化了多管地道降温算法.分析了管数、埋管深度和管间距对地道降温效果的影响.     

Application of passive cooling systems in the hot and humid climate: The case study of solar chimney and wetted roof in Thailand

The thermal performance of two passive cooling systems under hot and humid climate condition is experimentally investigated. The experimental results were obtained from a test cell and a controlled cell with identical walls but different roof configurations. The passive cooling systems applied to the test cell are solar chimney and water spraying on roof. The experimental results obtained from the test cell are compared with the closed and no passive cooling controlled cell. In addition, the significant of solar-induced ventilation by using a solar chimney is realized by utilizing a wind shield to reduce the effect of wind-induced ventilation resulting in low measured air velocities to the solar chimney and low computed value of coefficient of discharge. The derived coefficient of discharge of 0.4 is used to compute Air Changes rates per Hour (ACH). The ACHs with application of solar chimney solely are found to be in the range of 0.16–1.98. The studies of air temperature differences between the room and the solar chimney suggest amount of air flow rates for different periods in a year. The derived relationships show that the air flow rate during February–March is higher than during June–October by 16.7–53.7%. The experimental results show that application of the solar chimney in the test cell could maintain the room temperature at 31.0–36.5 °C, accounting for 1.0–3.5 °C lower than the ambient air and 1.0–1.3 °C lower than the controlled cell. However, to make the test cell's room temperature much lower than the ambient temperature and increase the flow rate of air due to the buoyancy, the application of water spraying on roof is recommended together with solar chimney. The application of the two systems in the hot and humid climate are discovered to sustain the room temperature of the test cell to be lower than the ambient air by 2.0–6.2 °C and lower than the controlled cell by 1.4–3.0 °C.     

Effects of climate variations and global warming on the durability of RC structures subjected to carbonation

Carbonation affects the performance, serviceability and safety of reinforced concrete (RC) structures when they are placed in environments with important CO ₂ concentrations. Since the kinetics of carbonation depends on parameters that could be affected by climate change (temperature, atmospheric CO ₂ pressure and relative humidity (RH)), this study aims at quantifying the effect of climate change on the durability of RC structures subjected to carbonation risks. This work couples a carbonation finite element model with a comprehensive reliability approach to consider the uncertainties inherent to the deterioration process. The proposed methodology is applied to the probabilistic assessment of carbonation effects for several cities in France under various climate change scenarios. It was found that climate change and local RH have a significant impact on corrosion initiation risks.     

Modelling of enhanced passive and conventional cooling systems

This study modelled a recently completed typical steel-framed speculative office development in the UK. It investigated the comparative performance of the building for various servicing regimes. These included natural and mechanical ventilation, two types of active fabric energy storage (FES) system (AirDeck and AirCore), air-conditioning (a conventional all-air system and chilled ceiling with mechanical ventilation), and mixed-mode solutions combining some of the above approaches. The assessment covered both summer and winter (heating) performance. The main objective was to evaluate overall performance of these systems in terms of thermal comfort and energy use and to compare the findings with more conventional servicing options for the same building. The study demonstrates that active FES can enhance thermal comfort while reducing energy use and emissions. In comparison with conventionally and naturally ventilated systems, the studied FES systems reduced temperature excess hours and peak temperatures, supplied cooler air as a result of overnight cooling, and reduced chiller consumption and boiler ratings as well as emissions. The annual operating costs of these active FES systems increase energy costs by only 13% over that of the naturally ventilated option. The mixed-mode solutions reduce them by over 35% when compared with all-mechanically cooled alternatives.     

A study on the potential of natural ventilation and cooling for large spaces in subtropical climatic regions

The potential of natural ventilation and cooling due to stack effects was investigated for large spaces with high ceilings. Different opening area ratios with respect to floor area were studied. Parameters of stack effects that consider floor heights were analyzed. Performance of natural ventilation was evaluated with cooling effects and indoor air quality for different months of the year. Three cities in northern, middle and southern Taiwan were used to represent typical subtropical weather types. It was found that opening ratio above 0.9％ is sufficient to provide fresh air to meet IAQ requirement. Two different temperature control strategies, fixed indoor temperature (FIT) and operative indoor temperature (OIT) were proposed and studied. A sensible cooling potential, f_pc, was proposed. Different levels of f_pc, namely, strong, medium, weak and not available were used to evaluate the number of days for which natural cooling, hybrid ventilation, mechanical air conditioning are to be applied to satisfy the cooling requirement. The research results presented can be used in the design of openings for large spaces, and also the air-conditioning control strategies for different seasons of the year.     

汽机房降温通风系统经济性分析

研究了汽机房不同降温通风方式(蒸发冷却、压缩式制冷、吸收式制冷等降温通风方式)的基本原理,结合实际工程案例,对各降温通风方式进行了设备选型,分析了各种方案的节能及经济性,为火电厂汽机房降温通风设计提供参考。     

典型城市居住建筑室内设置温度对供暖供冷能耗的影响

随着社会经济和城镇化进程的推进,人们对室内热环境的改善需求日益提升。室内设置温度对供暖供冷能耗有很大影响,通过选取中国不同气候区的典型城市,运用DeST-h能耗模拟软件,模拟分析了不同使用模式下,不同室内设置温度对建筑供暖供冷能耗的影响。结果表明,通过运行模式的调整,可以带来40%~60%的供暖供冷需求下降;通过适宜的室内温度设置,可以有效的延长非供暖供冷的时间,每降低要求1℃,可以降低能耗7%左右。     

Impact of climate change on residential building envelope cooling loads in subtropical climates

Future trends of cooling load due to heat gain through the building envelopes in the residential sector in subtropical Hong Kong under different emissions scenarios in the 21st century were investigated. Predicted monthly weather data from five general circulation models were gathered and analysed. An increasing trend of building envelope cooling load was observed. The average annual cooling load during the 2009-2100 period would be 6.1% and 9.8% more than that during 1979-2008 for low and medium forcing, respectively. If only the last 30 years (2071-2100) were considered, the percentage increase would be much larger at 12.3% and 21.6%. Four mitigation or energy conservation measures - raising the indoor temperature, thermal insulation, double glazing and tinted glass - were considered. Among them, raising the indoor temperature has the best mitigation potential because there is a growing awareness and recognition of adaptive thermal comfort and it can be readily applied to both existing and new buildings at no extra cost.     

Effectiveness of indirect evaporative cooling and thermal mass in a hot arid climate

In this paper, we compare results of a long-term temperature monitoring in a building with high thermal mass to indoor temperature predictions of a second building that uses an indirect evaporative cooling system as a means of passive cooling (Vivienda Bioclimática Prototipo -VBP-1), for the climatic conditions of Sde Boqer, Negev region of Israel (local latitude 30°52′N, longitude 34°46′E, approximately 480 m above sea level). The high-mass building was monitored from January through September 2006 and belongs to a student dormitory complex located at the Sde Boqer Campus of Ben-Gurion University. VBP-1 was designed and built in Maracaibo, Venezuela (latitude 10°34′N, longitude 71°44′W, elevation 66 m above sea level) and had its indoor air temperatures, below and above a shaded roof pond, as well as the pond temperature monitored from February to September 2006. Formulas were developed for the VBP-1, based on part of the whole monitoring period, which represent the measured daily indoor maximum, average and minimum temperatures. The formulas were then validated against measurements taken independently in different time periods. The developed formulas were here used for estimating the building's thermal and energy performance at the climate of Sde Boqer, allowing a comparison of two different strategies: indirect evaporative cooling and the use of thermal mass.