降低建筑空调能耗研究

在分析贵阳市气候特点及实例建筑空调负荷特性的基础上,采用建筑环境模拟软件DeST对实例建筑室内基础室温以及全年建筑冷热负荷进行模拟,在分析模拟结果的基础上,结合贵阳市气候特点,提出如下三条贵阳市降低建筑空调能耗建议：1)舒适性空调设计应首先满足冬季采暖,然后考虑夏季制冷;2)自然通风是夏季降温的优先考虑方式,过渡季节调节是降低建筑制冷能耗的重要手段;3)增加围护结构保温和控制窗墙比是降低建筑采暖能耗的首要手段。研究结果不但能对贵阳市的建筑节能提供参考,而且还对广大温和地区建筑节能有参考意义。     

外墙保温对不同地区大型公共建筑冷热负荷的影响分析

随着我国建筑总量的增加,建筑能耗急剧上升,已成为我国的能耗黑洞,随之建筑节能逐渐被广大公民重视.目前建筑节能有很多措施,外墙保温就是其中一项.采用建筑热环境模拟工具DeST对同一大型公共建筑的冷热负行模拟计算,分析了在不同建筑气候分区下外墙的保温层厚度对空调负荷的影响,分析其有无节能效果,可为不同气候分区的大型公共建筑外墙隔热保温提供参考依据.     

高舒适度低能耗健康建筑构造与施工

锋尚国际公寓是我国首例大面积应用高舒适度低能耗健康建筑技术设计与施工的高档公寓建筑。该工程研究开发应用了天棚低温采暖制冷系统＋置换新风系统施工技术,其主要配套技术包括干挂饰面砖幕墙聚苯复合外墙外保温系统、屋面及地下保温系统和外窗及遮阳系统施工技术;辅助配套技术包括防噪声系统、中央吸尘与垃圾处理系统、水处理系统和建筑智能化系统施工技术。上述技术的应用最大限度地降低了能耗,在不使用传统空调暖气的前提下,提供了健康舒适的居住环境。     

Application of latent heat thermal energy storage in buildings: State-of-the-art and outlook

Latent heat thermal energy storage (LHTES) is becoming more and more attractive for space heating and cooling of buildings. The application of LHTES in buildings has the following advantages: (1) the ability to narrow the gap between the peak and off-peak loads of electricity demand; (2) the ability to save operative fees by shifting the electrical consumption from peak periods to off-peak periods since the cost of electricity at night is 1/3–1/5 of that during the day; (3) the ability to utilize solar energy continuously, storing solar energy during the day, and releasing it at night, particularly for space heating in winter by reducing diurnal temperature fluctuation thus improving the degree of thermal comfort; (4) the ability to store the natural cooling by ventilation at night in summer and to release it to decrease the room temperature during the day, thus reducing the cooling load of air conditioning. This paper investigates previous work on thermal energy storage by incorporating phase change materials (PCMs) in the building envelope. The basic principle, candidate PCMs and their thermophysical properties, incorporation methods, thermal analyses of the use of PCMs in walls, floor, ceiling and window etc. and heat transfer enhancement are discussed. We show that with suitable PCMs and a suitable incorporation method with building material, LHTES can be economically efficient for heating and cooling buildings. However, several problems need to be tackled before LHTES can reliably and practically be applied. We conclude with some suggestions for future work.     

Thermal comfort and energy consumption of the radiant ceiling panel system.: Comparison with the conventional all-air system

The purpose of this study is to investigate the various characteristics of a radiant ceiling panel system and their practical application to office buildings. The radiant ceiling panel system and conventional air-conditioning system were compared in terms of thermal comfort, energy consumption, and cost. Thermal environment, along with human response, was tested by using a small meeting room equipped with radiant ceiling panels. The responses were collected by questionnaires given to the male subjects in the room. The experiment for the female subjects was conducted separately. Results show that the radiant ceiling panel system is capable of creating smaller vertical variation of air temperature and a more comfortable environment than conventional systems. When using a cooled ceiling, a small volume of supplied air creates a less draught environment, which reduced the discomfort of feeling cold in the lower part of the body. Numerical simulation of yearly energy consumption and cost estimation were conducted. Typical office rooms located on the 3rd, 4th, and 5th floor of a six-floor building in the Tokyo area were simulated. Since part of the sensible heat load is handled by radiant ceiling panels, the volume of supplied air can be reduced, leading to lower energy consumption for air transport. By using the radiant ceiling panel system in one of the three floors of the simulated building, energy consumption can be reduced by 10%. Estimated pay back time was from 1 to 17 years depending on the market price of the radiant ceiling panel.     

窗墙比对居住建筑的冷热耗量指标及节能率的影响

以高层公寓式居住建筑为对象,利用特征温度法研究了对建筑采取相同改进措施时窗墙面积比对建筑冷热耗量和能耗相对变化率的影响,并分析了当建筑体形系数不同时,窗墙面积比对全年空调与供暖冷热耗量指标以及采取相同节能措施建筑的全年空调与供暖节能量及节能率的影响。     

Development of a radiant heating and cooling model for building energy simulation software

Efficient radiant heating and cooling systems are promising technologies in slashing energy bills and improving occupant thermal comfort in buildings with low-energy demands such as houses and residential buildings. However, the thermal performance of radiant systems in buildings has not been fully understood and accounted for in currently available building energy simulation software. The challenging tasks to improve the applicability of radiant systems are the development of an accurate prediction model and its integration in the energy simulation software. This paper addresses the development of a semi-analytical model for radiant heating and cooling systems for integration in energy simulation software that use the one-dimensional numerical modeling to calculate the heat transfer within the building construction assemblies. The model combines the one-dimensional numerical model of the energy simulation software with a two-dimensional analytical model. The advantage of this model over the one-dimensional one is that it accurately predict the contact surface temperature of the circuit-tubing and the adjacent medium, required to compute the boiler/chiller power, and the minimum and maximum ceiling/floor temperatures, required for moisture condensation (ceiling cooling systems), thermal comfort (heating floor systems) and controls. The model predictions for slab-on-grade heating systems compared very well with the results from a full two-dimensional numerical model.     

夏热冬冷地区办公建筑降低供暖空调能耗的技术路径

以上海地区某办公建筑为例,基于EnergyPlus能耗模拟,探讨了围护结构性能提升和暖通空调系统优化这2条节能技术路径对夏热冬冷地区办公建筑降低供暖空调全年能耗的有效性.结果 表明:围护结构性能提升的节能潜力较小,经济性较差;单纯提高围护结构保温隔热性能并不能保证降低建筑年耗冷量,应综合分析全年供热供冷能耗确定围护结构...     

Influence of building parameters and HVAC systems coupling on building energy performance

The performance of different HVAC systems varies when coupled with different buildings. This paper examines the relationship between building heating and cooling load and subsequent energy consumption with different HVAC systems. Two common HVAC systems in use throughout the UK office building stock, variable air volume (VAV) system and fan coil (FC) with dedicated outside air system, have been coupled with a typical narrow plan office building with and without daylight control and for both cellular and open plan.The results presented in this paper clearly indicate that it is not possible to form a reliable judgment about building energy performance based only on building heating and cooling loads. For the two investigated systems, variable air volume system and fan coil with dedicated outside air system, the difference between system demand and building demand varied from over −40% to almost +30% for cooling and between −20% and +15% for heating. If a heat recovery unit is used, the difference in heating performance is even greater, rising to −70%.     

天津市某酒店式公寓能耗模拟与因素分析

以天津市莱酒店式公寓为例,基于清华大学自主开发的能耗软件DEST,用正交试验的方法,针对该建筑的全年逐时能耗(空调采暖负荷)进行动态模拟计算,分析其围护结构、空调采暖设定温度、照明等因素的能耗特征和建筑能耗的影响程度,从而为此类建筑的节能设计和节能管理提供必要的技术依据.     

An algorithm for calculating convection coefficients for internal building surfaces for the case of mixed flow in rooms

The treatment of convective heat transfer at internal building surfaces has a significant impact on the simulation of heat and air flow. Accurate approaches for the range of flow regimes experienced within buildings (buoyant flow adjacent to walls, buoyant plumes rising from radiators, fan-driven flows, etc.) are required, as is the ability to select an appropriate method for the case at hand and to adapt modelling to changes in the flow.A new approach — drawing upon previously published methods — has been developed for modelling mixed convection within mechanically ventilated rooms. It is applicable for rooms ventilated with ceiling mounted diffusers and is appropriate for both heating and cooling. ESP-r simulations performed with the mixed flow model indicate that the prediction of heating and cooling loads is highly sensitive to the treatment of surface convection and that significant errors can result if an inappropriate model is employed. The results also reveal that the choice of convection algorithm can influence design decisions drawn from a simulation-based analysis.     

基于DeST的夏热冬冷地区居住建筑人行为能耗模拟验证

为验证DeST人行为仿真建筑能耗模拟软件计算结果的准确性,在夏热冬冷地区开展了居民采暖及制冷的空调用能行为实测,将调研得到的居民用能行为参数及建筑围护结构信息代入到DeST人行为模拟软件中进行计算。将计算结果与实测空调能耗进行对比后,结果显示,原始软件制冷能耗平均绝对计算误差为37.9%;制热能耗平均绝对计算误差为128.2%。与原始软件相比,DeST人行为模拟软件制冷能耗计算误差减少了13.8%,采暖能耗计算误差减少了94.1%。人行为能耗模拟软件的计算结果更接近实测值,空调全年运行时长、启停概率与实测结果符合性也较好。嵌入人行为模块后的DeST将为模拟实际运行状况下建筑的能耗提供很好的计算平台。     

用EnergyPlus模拟检验影响节能办公建筑的因素

本文根据《公共建筑节能设计标准》(GB 50189-2005)对办公建筑的相关规定,运用全能耗模拟软件EnergyPlus对北京等城市节能办公建筑的逐时冷热负荷进行了模拟,得出了不同外墙传热系数、不同建筑朝向和过渡季节通风换气次数等对室内进行全年负荷的影响并对其进行了分析,认为从节能角度讲,外墙传热系数存在合适值而不应盲目减小、既定建筑物存在最佳朝向、过渡季通风可消除室内多余的热量但实际应用中应因地而异,从而为节能办公建筑的设计、建造等提供有益的参考。     

Cooling and heating loads in residential buildings in Jordan

Cooling and heating load calculations for air-conditioned and heated buildings have been calculated for three different cities in Jordan, representing three climatic regions; namely, Irbid, Amman and Aqaba. To analyze the insulation effect of buildings, for each region four combinations of wall and ceiling insulation were considered: no insulation; only wall insulated; only ceiling insulated; and both ceiling and wall insulated. The results showed that the average monthly heating load was reduced when only walls were insulated; however, this has a negative impact on the average monthly cooling load. In the case where only the ceiling was insulated, both the monthly cooling and heating loads were reduced. A comparison showed that with both wall and ceiling insulated, the energy requirements could be reduced by more than 40%. In Aqaba, with both walls and ceiling insulated, there would be no need for any heating during the whole year and in both Amman and Irbid there were at least four months in which there would be no need for either heating or cooling.     

Measurement of thermal stratification in large single-cell buildings

This paper describes measured temperature profiles and thermal stratification in eight aircraft hangar buildings during the heating season. Presented also is the predicted impact of thermal stratification on heating energy requirements. The hangar buildings included two main ceiling heights (9.35 and 17.1 m (31 and 56 ft)), two ceiling types (flat and Quonset), two types of heating systems (vertical discharge forced warm air and downdraft convective unit heaters), and various types of large external doors. Measured stratification, expressed by floor-to-ceiling temperature differential, is in the range 4–11 °C (7.2–20 °F). Two air layers existed in the hangar bay area, a warm upper air layer and a cooler lower air layer. The lower air layer (up to 2 m (7 ft) high from the floor) is characterised by a steep vertical temperature gradient in the range 0.8–2.6 °C/m (0.4–1.4 °F/ft). In the upper air layer, above 2 m, the vertical temperature gradient shallows considerably to 0.5 °C/m (0.3 °F/ft). Results indicate that thermal stratification can have a significant impact on the building's heating energy requirements. In the hangar buildings studied, predicted excess heating energy requirements due to 8 °C floor-to-ceiling temperature differential can be as much as 38% as compared to the case with no stratification.     

New concepts and approach for developing energy efficient buildings: Ideal specific heat for building internal thermal mass

The shortcomings or limitations of the traditional approach to developing energy efficient buildings are that they can not determine: (1) the ideal thermophysical properties of building envelope material, where “ideal” means that such material can use ambient air temperature variation and/or solar radiation efficiently to keep the indoor air temperature in the thermal comfort range with no additional space heating or cooling; (2) the best natural ventilation strategy; (3) the minimal additional energy consumption for space heating in winter or air-conditioning in summer. To overcome these problems, some new concepts for developing energy efficient buildings are put forward in this paper. They are the ideal thermophysical properties of the building envelope material, the ideal natural ventilation rate, and a minimal additional space heating or cooling energy consumption. A new approach for determining these properties is also developed. In contrast to the traditional approach (the thermophysical properties of building envelope material are known and constant so that the relating equations describing the indoor air temperature tend to be linear differential equations), the new approach solves the inverse problem (thermophysical properties, etc. of a buildings are unknown), whose solution can be a function instead of a value. As a first step, the ideal specific heat of the building envelope material for internal thermal mass is analyzed for buildings located in various cities in different climatic regions of China, such as Beijing, Shanghai, Harbin, Urumchi, Lhasa, Kunming and Guangzhou. We found that the ideal specific heat is composed of a basic value and an excessive one which is of δ function for the cases studied. Some limitations that would need further study are introduced in the end of the paper.     

Energy savings potential of a desiccant assisted hybrid air source heat pump system for residential building in hot summer and cold winter zone in China

In hot summer and cold winter zone in China, air conditioning system has four running modes yearly including cooling with dehumidification, cooling, dehumidification and heating in residential buildings. The conventional air source heat pump (ASHP) system is not designed to independently control temperature and humidity, and is not very suitable for the dehumidification mode in the view of building energy consumption. A novel ASHP system combining radiant cooling/heating for residential buildings was presented. The main feature of this hybrid ASHP system is that desiccant wheel and cooling coil accomplish dehumidification process together, and the regenerative heat needed by the desiccant wheel is supplied by the condenser dissipated heat. Based on simulation studies and performance analysis, this paper predicts the primary energy consumption of the hybrid ASHP system in comparison with the conventional ASHP system during the cooling and heating seasons. It was found that primary energy requirement can be reduced by more than 8% in cooling with dehumidification mode, by 50% in dehumidification mode, and by more than 14% in heating mode. The study results prove that the hybrid ASHP system can keep great energy saving and running cost saving yearly, especially in the dehumidification process.     

居住建筑围护结构的节能问题

从适宜居住的角度讲,我国绝大部分地区的居住建筑都要采取一定的技术措施来保证冬夏两季的室内热舒适环境。冬夏两季室内维持的温度与室外的温度有很大的差别,这个温差导致能量以热的形式流出或流入室内,采暖,空调设备消耗的能量主要就是用来补充这个能量损失的。在相同的室内外温差条件下,建筑围护结构保温隔热性能的好坏,直接影响到流出或流入室内的热量的多少。建筑围护结构保温隔热性能好,流出或流入室内的热量就少,采暖,空调设备消耗的能量也就少;反之,建筑围护结构保温隔热性能差,流现或流入室内的热量就多,采暖,空调设备消耗的能量也就多。我国现行的居住建筑节能设计标准对建筑围护结构保温隔热性能提出了明确的要求,按照节能设计标准的要求去设计,新建的居住建筑就能比具有传统围护结构的同类建筑节约25％－35％的采暖,空调能耗,而且节能的潜力还十分巨大。     

A combined system of chilled ceiling,displacement ventilation and desiccant dehumidification

Different types of heating, ventilation, and air-conditioning (HVAC) systems consume different amounts of energy yet they deliver similar levels of acceptable indoor air quality (IAQ) and thermal comfort. It is desirable to provide buildings with an optimal HVAC system to create the best IAQ and thermal comfort with minimum energy consumption. In this paper, a combined system of chilled ceiling, displacement ventilation and desiccant dehumidification is designed and applied for space conditioning in a hot and humid climate. IAQ, thermal comfort, and energy saving potential of the combined system are estimated using a mathematical model of the system described in this paper. To confirm the feasibility of the combined system in a hot and humid climate, like China, and to evaluate the system performance, the mathematical model simulates an office building in Beijing and estimates IAQ, thermal comfort and energy consumption. We conclude that in comparison with a conventional all-air system the combined system saves 8.2% of total primary energy consumption in addition to achieving better IAQ and thermal comfort. Chilled ceiling, displacement ventilation and desiccant dehumidification respond consistently to cooling source demand and complement each other on indoor comfort and air quality. It is feasible to combine the three technologies for space conditioning of office building in a hot and humid climate.     

住宅建筑采暖空调能耗模拟方法的研究

住宅建筑的采暖空调能耗受室内居住人员行为方式的影响,在调查研究基础上,确定了两种反映室内居住人员行为方式的计算模式。在两种不同计算模式下,利用建筑热环境模拟工具DeST对上海地区同一住宅建筑能耗进行模拟,并将模拟结果与调研结果进行比较,分析计算模式对上海地区住宅建筑采暖空调能耗大小的影响,从而获得能正确反映上海地区住宅建筑采暖空调能耗大小的模拟计算方法。此方法可用于上海地区住宅建筑采暖空调的能耗分析与评价,并正确指导住宅建筑的节能设计。