自然通风环境下办公建筑中庭空间热舒适性模糊优化研究

：随着绿色建筑设计理念深入人心,办 公建筑的中庭空间因其特有空间特质受到越来 越多的关注。通常办公中庭空间中的节能性与热 舒适性是一对矛盾体,而自然通风作为被动节能 技术之一,不仅能够促进中庭空间的内外空气 循环,改善室内空气质量,而且降低能耗和提升 热舒适性,较好地解决这一矛盾。以江雅园办公 楼中庭空间为案例进行研究,从中庭屋顶形态、 中庭高度及进风口开启方式三个变量因素出发, 引用模糊评估方法寻找出中庭空间自然通风热 舒适性最佳方案,结论显示在多个组合方案中 斜屋顶形态+进风口全部开启的方案热舒适性最 佳,同时也证明屋顶形态与通风方式的变化对自 然通风舒适性的影响较大,而中庭空间高度的变化对自然通风舒适性影响较小。本研究希望建立一套以风速和温度为评价指标的模糊体系,为自 然通风的热舒适性的评价提供一种客观的评估手段,从而为方案阶段的中庭空间设计提供一种 有效的优化方法。     

某报告厅空调系统的设计及其能耗分析

介绍了西安某办公楼报告厅空调系统的设计。分别应用置换通风与混合通风两种通风方式，在室外和室内设计参数相同的情况下，充分比较了它们在送风量、新风量、能耗以及室内空气品质的不同。结果表明在某些应用场合，置换通风在空气品质提高和能耗降低上有明显的优势，同时这种优势不以牺牲热舒适性为代价，因此建议使用置换通风系统。     

An investigation of naturally ventilated teaching spaces with windcathers in secondary school where site is constrained by noise and air pollution

Built environment consumes the bulk of the UK’s fossil fuel. Schools account for 15% of the public sector’s carbon emissions. Energy efficient building design can play a vital role in achieving the national carbon emission reduction target of 80% by 2050. Natural and mixed mode ventilation is at the forefront of suggested energy efficient strategies for reducing carbon emissions from schools while maintaining good indoor air quality and thermal comfort. However, it is challenging to naturally ventilate many urban school buildings through side openings because of high noise and particulate air pollution. An alternative strategy, such as multi floor operation of windcatchers was assessed in this research as a sole source of fresh air in teaching spaces. Dynamic thermal simulation (DTS) and computational fluid dynamics (CFD) simulations assessed the performance of the adopted natural ventilation (NV) strategy in meeting the approved requirements for fresh air, indoor air quality (IAQ) and summertime overheating. Simulation results show that it is challenging to meet approved guidelines on air quality and thermal comfort, only when windcatchers are employed for ventilation purpose. However, fan assisted ventilation in conjunction with windcatchers provided satisfactory results. Detailed performance assessments using CFD seem desirable to validate DTS based findings.     

Will future low-carbon schools in the UK have an overheating problem?

Meeting thermal comfort and internal air quality standards for schools can be difficult for buildings that, traditionally in the UK, have not used mechanical ventilation and air-conditioning. With a trend towards increased internal gains, and climate change predicted to cause a significant rise in temperatures, this issue becomes more problematic. Considering this within the context of low-carbon buildings creates an added hurdle—can low-carbon schools be produced that will provide a comfortable teaching environment in the future? Through a series of simulations on template school buildings, this study highlights the effect that future small power and lighting energy use could have on reducing the overheating of school teaching areas. The effect of a warming climate is also estimated, and the impact that has on the internal temperatures of a school quantified. Introducing external shading and increasing ventilation in classrooms can reduce overheating significantly but, for many cases, the risk that the school building cannot cope with the overheating problem might still remain.     

Selection of window sizes for optimizing occupational comfort and hygiene based on computational fluid dynamics and neural networks

The present paper presents a novel computational method to optimize window sizes for thermal comfort and indoor air quality in naturally ventilated buildings. The methodology is demonstrated by means of a prototype case, which corresponds to a single-sided naturally ventilated apartment. Initially, the airflow in and around the building is simulated using a Computational Fluid Dynamics model. Local prevailing weather conditions are imposed in the CFD model as inlet boundary conditions. The produced airflow patterns are utilized to predict thermal comfort indices, i.e. the PMV and its modifications for non-air-conditioned buildings, as well as indoor air quality indices, such as ventilation effectiveness based on carbon dioxide and volatile organic compounds removal. Mean values of these indices (output/objective variables) within the occupied zone are calculated for different window sizes (input/design variables), to generate a database of input–output data pairs. The database is then used to train and validate Radial Basis Function Artificial Neural Network input–output “meta-models”. The produced meta-models are used to formulate an optimization problem, which takes into account special constraints recommended by design guidelines. It is concluded that the proposed methodology determines appropriate windows architectural designs for pleasant and healthy indoor environments.     

Building signatures: A holistic approach to the evaluation of heating and cooling concepts

A sustainable and environmentally responsible building concept aims at a high workplace comfort, a significantly reduced heating and cooling demand, a high-efficient plant system, and the use of renewable energy sources to condition the built environment. This paper presents a comprehensive analysis of the heating and cooling concepts of 11 low-energy buildings in terms of energy use, efficiency and occupant thermal comfort. All buildings investigated employ environmental energy sources and sinks – such as the ground, ground water, rainwater and the ambient air – in combination with thermo-active building systems. A limited primary energy use of about 100 kWh_prim/(m²_neta) as a target for the complete building service technology (HVAC and lighting) was postulated for all buildings presented. With respect to this premise, a comprehensive long-term monitoring in high time resolution was carried out for two to five years, with an accompanying commissioning of the building performance. Measurements include the useful heating and cooling energy use, auxiliary energy use for the hydraulic system, as well as end and primary energy use, occupant thermal comfort and local meteorological conditions. A new methodology is proposed for a holistic approach to the evaluation of heating and cooling concepts, which not only considers the occupants thermal comfort, but also the useful energy consumption and the efficiency of the generation, distribution and delivery of heating and cooling energy.     

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.     

Addressing climate change in comfort standards

According to the Buildings Energy Data Book published by the U.S. Department of Energy, in 2006 the building sector consumed 38.9% of the total primary energy used in the United States. Of this energy, 34.8% is used by buildings for space heating, ventilation, and air conditioning. This energy often involves the combustion of fossil fuels, contributing to carbon dioxide emissions and climate change. Even if greenhouse gas concentrations are stabilized in the atmosphere, extreme climate events and sea level rise will continue for several centuries due to inertia of the atmosphere. Therefore, adaptation will be a necessary compliment to carbon dioxide mitigation efforts. This paper argues that both mitigation of greenhouse gases and adaptation to climate change should be added to our building codes and standards. Since space heating, ventilation, and air-conditioning utilize a large amount of energy in buildings, we should begin by redefining our thermal comfort standards and add strategies that mitigate carbon dioxide emissions and adapt to predicted climate variability.     

我国北方地区居住建筑节能率再提高的瓶颈问题分析

对比我国北方地区不同时期的居住建筑节能标准与发达国家相关标准,发现我国建筑节能设计标准尚有待提高。以某多层住宅为例,按照我国建筑节能率的计算方法,计算出芬兰2008年与2010年节能设计标准可以达到的节能率水平;并对实现不同节能率的建筑围护结构保温方案进行了分析,找出我国北方地区居住建筑节能设计标准再提高的瓶颈问题,包括高性能围护结构保温产品匮乏、现有产品的成本过高以及新风耗热量比例过大。建议在引进和吸收国外先进产品与技术的同时,加强国内产品和施工工艺的研发,采用有组织通风换气的热回收,以及加大可再生能源在建筑供能系统中的应用比例等应对策略。探讨了我国建筑节能标准再提高的技术路线。     

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.     

The impact of zoning regulations on thermal comfort in non-conditioned housing in hot,humid climates: findings from Dhaka,Bangladesh

In parts of the developing world where densities are high but the availability of air conditioning is limited, building massing and height regulations can influence interior comfort levels. Dhaka, Bangladesh, is characterized by high population densities, a lack of open spaces, and high poverty levels, combining to produce living conditions which are not only uncomfortable, but may lead to the spread of disease. A recent change in zoning regulations provides an opportunity to assess the success of building heights and setbacks in improving indoor thermal comfort conditions. We assess the impact on thermal comfort within Dhaka’s non-conditioned apartment buildings of four zoning schemes which differ in their specifications for setbacks, maximum buildable area, and building heights; but that maintains the current density. Computer simulation techniques model the buildings to test solar, daylight, and ventilation inside the central building to calculate resultant indoor temperature, mean radiant temperature, relative humidity and air velocity. Comparison between these values helps to determine which zoning schemes produce the most favorable thermal conditions. Findings suggest that zoning schemes that provide better solar protection and better natural ventilation are able to reduce indoor temperature and increase indoor air velocity over that provided by current zoning regulations. Recommendations for revising current zoning regulations are given along with general recommendations for how buildings in hot, humid climates can maximize passive cooling, encouraging energy savings and environmental sustainability.     

The effects of roof covering on the thermal performance of highly insulated roofs in Mediterranean climates

While the EU Directive 2002/91/CE on the Energy Performance of Buildings (EPBD) clearly establishes regulations for the thermal insulation of buildings for saving energy in winter, the summer strategy is described by a little more than qualitative provisions. As a consequence, in the national requirements, the high insulation of the building envelope is considered as the principal strategy to control energy consumption even in summer, regardless of the different climates. This approach leads to a homologation of the building trade, and imposes construction technology and materials which do not adhere to the traditional way of making buildings, like in Southern Europe. Here, the “over insulation” of buildings runs the risk of reducing the effectiveness of traditional passive cooling strategies (thermal mass, air permeability of the roof covering, roof ventilation) and could have adverse effects on internal comfort. In this paper, we focus on the effects of over insulation on the thermal performance of roofs in summer, by analyzing experimental data from monitoring a full-scale mock-up in Italy. Results show how an increase in insulation thickness reduces the effectiveness of traditional passive cooling strategies, as an effect of the thermal decoupling between the interior and the upper layers of the roofs.     

Estimating natural-ventilation potential considering both thermal comfort and IAQ issues

Natural-ventilation potential (NVP) value can provide the designers significant information to properly design and arrange natural ventilation strategy at the preliminary or conceptual stage of ventilation and building design. Based on the previous study by Yang et al. [Investigation potential of natural driving forces for ventillation in four major cities in China. Building and Environment 2005;40:739–46], we developed a revised model to estimate the potential for natural ventilation considering both thermal comfort and IAQ issues for buildings in China. It differs from the previous one by Yang et al. in two predominant aspects: (1) indoor air temperature varies synchronously with the outdoor air temperature rather than staying at a constant value as assumed by Yang et al. This would recover the real characteristic of natural ventilation, (2) thermal comfort evaluation index is integrated into the model and thus the NVP can be more reasonably predicted. By adopting the same input parameters, the NVP values are obtained and compared with the early work of Yang et al. for a single building in four representative cities which are located in different climates, i.e., Urumqi in severe cold regions, Beijing in cold regions, Shanghai in hot summer and cold winter regions and Guangzhou in hot summer and warm winter regions of China. Our outcome shows that Guangzhou has the highest and best yearly natural-ventilation potential, followed by Shanghai, Beijing and Urumqi, which is quite distinct from that of Yang et al. From the analysis, it is clear that our model evaluates the NVP values more consistently with the outdoor climate data and thus reveals the true value of NVP.     

Energy consumption and potential energy savings in old school buildings

Energy and indoor environmental audits of energy consumption and indoor air quality were taken in 24 school buildings in Slovenia. The audits show that these buildings are high energy consumers and have poor indoor air quality, as expressed by 60% of the surveyed pupils. This article deals with energy consumption in the analysed schools. The nominal heating power of boilers, and heat exchangers, which are used in district heating, show a 57% overcapacity. The heat losses of the school buildings are 89% higher than the recommended values. According to our analysis of the possible measures to improve the situation in the school buildings, it will not be possible to ensure rational energy use and good indoor air quality with low investment costs. Should we change from hot-water heating systems and natural ventilation to energy efficient blown air systems with which one device provides the comfort of both heating and air conditioning?     

Field experiments on natural energy utilization in a residential house with a double skin façade system

Energy consumption in the residential and commercial sector accounts for over 25% of the total in Japan. With the information technology revolution and the improving requirement for indoor air environment, energy consumption for household air conditioning is increasing. In this research, a double skin facade is proposed for a two-story house in Kitakyushu of Japan. The stack effect in the double skin space during the summer, the green house effect during the winter and the availability for free air-conditioning during the autumn have been studied. The temperature distribution, thermal performance in the double skin space and its impact on air-conditioning load in rooms have been measured. Results show that the double skin façade leads to about 10–15% energy saving for cooling in the peak of summer because of heat exhausted by natural ventilation, 20–30% energy for heating in winter because of the green house effect, and the temperature adjustment is quite large with the different operation mode of the double skin system during the intermediate seasons. Therefore the double skin system is proved to be effective in energy conservation in residential buildings.     

Energy modeling of two office buildings with data center for green building design

Energy simulation models are developed with EnergyPlus for two office buildings in a R&D center in Shanghai, China to evaluate the energy cost savings of green building design options compared with the baseline building. As a R&D center of an international IT corporation, there are data centers in the two buildings, which make them different from typical office buildings. The data centers house high energy consuming IT equipments and need 24 h air-conditioning every day all year round. In order to achieve energy cost savings, multiple energy efficiency strategies are employed for design proposed building, encompassing high performance building envelope, lighting system, and HVAC system. Through energy modeling, the design proposed options are compared to an ASHRAE 90.1-2004 compliant budget model to highlight energy cost savings versus “standard practice” and show the potential LEED™ Credit EA1—Optimize Energy Performance. Meanwhile, they are also compared to China Code model to figure out the energy cost savings versus the most popular practice conforming to China Public Building Energy Saving Design Standard. The whole building energy simulation results show that the yearly energy cost saving of the proposed design will be approximately 27% from China Code building and 21% from ASHRAE budget building, which can achieve 4 points for LEED credit due to energy performance optimization.     

Microclimate and ventilation in Estonian and Finnish dairy buildings

A series of ventilation, thermal and indoor air quality measurements were performed in 14 different dairy buildings in Estonia and Finland. The number of animals in the buildings varied from 30 to 600. Measurements were made all year round with ambient temperatures ranging between −40 °C and +30 °C. The results showed that microclimatic conditions in the dairy buildings were affected by the design of the building, outside temperature, wind, ventilation and manure handling method. The average inside air concentration of carbon dioxide was 950 ppm, ammonia 5 ppm, methane 48 ppm, relative humidity 70% and inside air velocity was 0.2 m/s. Although occasionally exceeded, the ventilation and average indoor air quality in the dairy buildings were mainly within the recommended limits.     

Simulation of energy use, human thermal comfort and office work performance in buildings with moderately drifting operative temperatures

Annual primary energy use in a central module of an office building consisting of two offices separated with a corridor was estimated by means of dynamic computer simulations. The simulations were conducted for conventional all-air VAV ventilation system and thermo active building system (TABS) supplemented with CAV ventilation. Simulations comprised moderate, hot–dry and hot–humid climate. Heavy and light wall construction and two orientations of the building (east–west and north–south) were considered. Besides the energy use, also capability of examined systems to keep a certain level of thermal comfort was examined. The results showed that with the moderate climate, the TABS decreased the primary energy use by about 16% as compared with the VAV. With hot–humid climate, the portion of the primary energy saved by TABS was ca. 50% even with the supply air dehumidification taken into account. The TABS working in a moderate climate kept the predicted percentage of dissatisfied (PPD) <10% during 60–80% of the working hours per year. Optimization of the TABS's control strategy (circulation pump dead-band, water supply temperature) resulted in significant reduction of the annual working hours with PPD > 10%; 1.4% in comparison to 17.5% h/yr. The highest estimated loss of occupants’ productivity related to their thermal sensation hasn’t exceeded 1% in whole year average.     

Passive climate control in Spanish office buildings for long periods of time

Recent studies have shown that the effect of the internal wall coating on an indoor thermal environment can be seen for short periods of time [Hameury S. Moisture buffering capacity of heavy timber structures directly exposed to an indoor climate: a numerical study. Building and Environment 2005;40(10):1400–12]. However, for long periods of time this effect is hidden by the air renovation and vapour release. These passive methods are gaining popularity because they are energy conscious and environmentally friendly. However, there is little published data on mass transfer between building envelopes and indoor air [Simonson CJ, Salonvaara MH. Mass transfer between indoor air and a porous building envelope: part I—field measurements. In: Proceedings of healthy buildings, vol. 3, 2000; Simonson CJ, Tuomo O. Moisture performance of buildings envelopes with no plastic vapour retarders in cold climates. In: Proceedings of healthy buildings, vol. 3, 2000]. The main objective of this study is to show the internal wall coating effect on indoor air conditions by means of the indoor air parameters. These measurements were taken in 25 office buildings during different seasons. Our results will allow us to understand the internal coating effect for long and short periods of time and, therefore, the thermal comfort and indoor air quality conditions.     

Facade design optimization for naturally ventilated residential buildings in Singapore

Parametric studies of facade designs for naturally ventilated residential buildings in Singapore were carried out to optimize facade designs for better indoor thermal comfort and energy saving. Two criteria regarding indoor thermal comfort for naturally ventilated residential buildings are used in this study. To avoid the perception of thermal asymmetry, temperature difference between mean radiant temperature and indoor ambient air temperature should be less than 2 °C [F.A. Chrenko, Heated ceilings and comfort. J. Inst. Heat. Ventilating Eng. 20 (1953) 375–396; F.A. Chrenko, Heated ceilings and comfort. J. Inst. Heat. Ventilating Eng. 21 (1953) 145–154]. Thermal comfort regression model for naturally ventilated residential buildings in Singapore was used to evaluate various facade designs either. Facade design parameters: U-values, orientations, WWR (window to wall ratio) and shading device lengths are considered in the investigation. The building simulation results for a typical residential building in Singapore indicated that the U-value of facade materials for north and south orientations should be less than 2.5 W/m² K and the U-value of facade materials for north and south orientations should be less than 2 W/m² K. From the coupled simulation results, it was found that the optimum window to wall ratio is equal to 0.24. Optimum facade designs and thermal comfort indexes are summarized for naturally ventilated residential buildings in Singapore.