Application of natural ventilation of residential buildings in hot-humid regions

The current ventilation condition of the hot and humid regions was analyzed through on-site investigation. It is found that residents in this region expect to improve indoor thermal environment through natural ventilation as much as possible. Then,it comes to a conclusion by the field test that natural ventilation has certain practical effect on improving indoor thermal environment. CFD simulation software is employed to verify the test result. Based on PMV modified model,and according to norms,geography and climate combined with the measured and simulated results,the application of the time and effectiveness of natural ventilation in hot and humid region were analyzed,to some extent,providing a basis for reducing the air-conditioner's runtime with natural ventilation.

A theoretical study on gaseous pollutant flushing of natural ventilation driven by buoyancy forces in industrial buildings

The acceleration of industrialization worsening indoor environments of industrial buildings has drawn more attention in recent years.Natural ventilation can improve indoor air quality(IAQ)and reduce carbon emissions.To evaluate gaseous pollutant levels in industrial buildings for the development of buoyancy-driven natural ventilation,two theoretical models of pollutant flushing(Model I and Model II)are developed based on the existing thermal stratification theory in combination with the mixing characteristics of lower pollutant.The results show that indoor pollutant flushing is mainly dependent on the pollution source intensity and effective ventilation area.The mixing characteristics of lower pollutant has an important effect on pollutant stratification and evolution during ventilation,but it does not change the prediction results at steady state.When the dimensionless pollution source intensity is larger than 1,the pollution source should be cleaned up or other ventilation methods should be used instead to improve IAQ.In addition,the comparisons between Model I and Model II on instantaneous pollutant concentration are significantly influenced by the pollution source intensity,and the actual pollutant concentration is more likely to be between the predicted values of Model I and Model II.To reduce pollutant concentration to a required level,the pollution source intensity should be in a certain range.The theoretical models as well as the necessary conditions for ventilation effectiveness obtained can be used for the ventilation optimization design of industrial buildings.

Study on the Optimization for Design of Indoor Natural Ventilation and Lighting Based on Passive Design Measurements

Based on the current indoor natural ventilation and lighting in the space of traditional residential buildings,this paper starts from the passive-design optimization of the spatial natural ventilation and lighting,and makes quantitative evaluation on the quality of current interior natural ventilation and lighting for two typical residential buildings by three indexes,including wind speed,static wind area ratio and satisfaction ratio about minimum lighting coefficient. Based on that, this paper conducts the passive design optimization, and establishes the quantitative association and reevaluation among the passive reformation design, natural ventilation,and lighting environmental quality,proposing the general strategy for the existing residential buildings to respond to the passive reformation design of the natural ventilation and lighting. The special reconstruction of core functionary space of integration of "the living room + dining room + partial space"is researched,and the redesign for the optimization and replacement of both indoor and outdoor enclosure parts is explored,which is expected to provide practical exploration on the strategies for passive construction of spatial natural environmental quality within a large number of highly-energy-consumed residential buildings in China,as well as the green design of residential buildings.

Research on the influence of outdoor trees on natural ventilation performance of an academic building

Planting trees around buildings has always been used as one of the most common viable landscaping strategies in schools.However,the impact of trees on natural ventilation inside the building has been neglected without investigation.The emphasis of this study related to the impact of outdoor trees around the academic building on indoor ventilation.Numerical simulations of the indoor wind environment of the academic building affected by trees were performed utilizing the k-εmodel with additional source terms.The numerical model was also validated by measured data.Two kinds of trees were selected,they are camphor and metasequoia.Camphor is a kind of broad-leaved tree and metasequoia is a kind of coniferous tree.26 simulation cases with six different tree canopy spacings were conducted.These results showed that the outdoor trees had great influences on the natural ventilation performance of the academic building.Compared with the case without the trees,the highest decrement in ventilation flow rate could be up to 31.97%in this study.For the cases of classrooms with horizontal distribution,the ages of air of the classrooms became fresher with the increase of the canopy spacing.While for the cases of classrooms with vertical distribution,the canopy spacing had fewer effects on the natural ventilation performances.It was also found that the blocking effects of camphor on indoor ventilation were higher than that of metasequoia.The average ventilation flow rate in cases with metasequoia was increased by 14.89%compared to the cases with camphor.This study could provide guidance for the layout design of trees around the building.

Physics-based,data-driven approach for predicting natural ventilation of residential high-rise buildings

Natural ventilation is particularly important for residential high-rise buildings as it maintains indoor human comfort without incurring the energy demands that air-conditioning does.To improve a building’s natural ventilation,it is essential to develop models to understand the relationship between wind flow characteristics and the building's design.Significantly more effort is still needed for developing such reliable,accurate,and computationally economical models instead of currently the most popular physics-based models such as computational fluid dynamics(CFD)simulation.This paper,therefore,presents a novel model developed based on physics-based modelling and a data-driven approach to evaluate natural ventilation in residential high-rise buildings.The model first uses CFD to simulate wind pressures on the exterior surfaces of a high-rise building.Once the surface pressures have been obtained,multizone modelling is used to predict the air change per hour(ACH)for different flats in various configurations.Data-driven prediction models are then developed using data from the simulation and deep neural networks that are based on mean absolute error,mean absolute percentage error,and a fusion algorithm respectively.These data-driven models are used to predict the ACH of 25 flats.The results from multizone modelling and data-driven modelling are compared.The results imply a high accuracy of the data-driven prediction in comparison with physics-based models.The fusion algorithm-based neural network performs best,achieving 96%accuracy,which is the highest of all models tested.This study contributes a more efficient and robust method for predicting wind-induced natural ventilation.The findings describe the relationship between building design(e.g.,plan layout),distribution of surface pressure,and the resulting ACH,which serve to improve the practical design of sustainable buildings.

Impact of indoor heat load and natural ventilation on thermal comfort of radiant cooling system:An experimental study

Construction and operation of buildings are responsible for about 20%of the global energy consumption.The embodied energy of conventional buildings is high due to the utilization of energy-intensive construction mate-rials and traditional construction methodology.Higher operational energy is attributed to the usage of power-consuming conventional air-conditioning systems.Therefore,moving to an energy-efficient cooling technology and eco-friendly building material can lead to significant energy savings and CO 2 emission reduction.In the present study,an energy-efficient thermally activated building system(TABS)is integrated with glass fiber rein-forced gypsum(GFRG),an eco-friendly building material.The proposed hybrid system is termed the thermally activated glass fiber reinforced gypsum(TAGFRG)system.This system is not only energy-efficient and eco-friendly but also provides better thermal comfort.An experimental room with a TAGFRG roof is constructed on the premises of the Indian Institute of Technology Madras(IITM),Chennai,located in a tropical wet and dry climate zone.The influence of indoor sensible heat load and the impact of natural ventilation on the thermal comfort of the TAGFRG system are investigated.An increase in internal heat load from 400 to 700 W deteriorates the thermal comfort of the indoor space.This is evident from the increases in operative temperatures from 29.8 to 31.5℃ and the predicted percentage of dissatisfaction from 44.5%to 80.9%.Natural ventilation increases the diurnal fluctuation of indoor air temperature by 1.6 and 1.9℃ for with and without cooling cases,respectively.It reduces the maximum indoor CO 2 concentration from 912 to 393 ppm.

Field measurement of the impact of natural ventilation and portable air cleaners on indoor air quality in three occupant states

Natural ventilation(NV)has been considered a simple and effective method of ventilation.However,the intro-duction of NV does not achieve better indoor air quality(IAQ)when the outdoor atmospheric environment is polluted.Therefore,portable air cleaners(PACs)are increasing in use in recent years,but their effectiveness is highly dependent on the residents’habits.A typical residence in Xi’an,China was selected to examine the effects of the use of NV alone and the use of NV and PACs together on IAQ in the three occupant states,i.e.,unoc-cupied,sleeping and leisure.Parameters,such as temperature,relative humidity,CO_(2),and PM_(2.5)concentration were measured when changing the window opening and the position of the PAC.The results showed that in the unoccupied state,opening the inner door can promote a more uniform thermal and humid environment.In the sleeping state,the I/O ratio of the PM_(2.5)concentration was the lowest when the window opening of the bedroom was 1/2 or 3/4,with a mean value of 0.3.In the leisure state,only using NV,when the purification rate reaches 90%,the mean purification time of each window opening in the living room is 87.5 min.The mean purification time was reduced to 25 min when both NV and PAC were used.The on-site purification efficiencies were 91.0%and 94.5%,when the window opening was 1/2(i.e.,the PAC was placed in the center of the room)and 3/4(i.e.,the PAC was placed away from the outer window),respectively.

Natural Ventilation Design:Predicted and Measured Performance of a Hostel Building in Composite Climate of India

Natural ventilation is recognized for improving the thermal comfort of the built environment and indoor air quality.It provides comfortable conditions for building occupants and reduces energy consumption for air-conditioning.Therefore,it is important to study and explore effective means of ventilation to improve the building designs.This study investigates the thermal comfort of a naturally ventilated hostel operational building in the composite climate of Jaipur,India using Computational Fluid Dynamics(CFD)simulation tool‘Cradle scSTREAM’.A 3D building model has been developed to analyze the thermal comfort for different natural ventilation strategies with advanced mesh algorithms which generate fewer mesh elements and maintain good mesh quality.A field study was carried out to collect the actual data and to validate the model which was further used to evaluate the thermal comfort range based on the ASHRAE-55 standard.Several design strategies have been applied to enhance thermal comfort.It was found that an increase in air velocity up to 0.5 m/s was achieved by Cross Ventilation while a drop of 2.0-2.5℃in the air temperature was found using Night Ventilation.It can be stated that cross ventilation increases the air movement while night ventilation gives comparatively higher comfort regarding air temperature and relative humidity.

Discussion on the Application of an Interlayer Ventilation Channel in Buildings

Good natural ventilation is the basic function of residential buildings in hot summer and cold winter areas. The intensive use of urban land makes high-rise residential units adopt a large number of multi-household layouts, and the middle households are often difficult to penetrate from north and south, and the natural ventilation effect is not good. The application of a utility model patent "building interlayer ventilation channel" can improve this situation. This paper mainly introduced the basic form and functional characteristics of the patent, and discussed its advantages in detail.

公共建筑入口形式对室内气溶胶扩散的影响研究

气溶胶是悬浮于空气中的微小颗粒物质,对人体呼吸系统健康具有严重危害。作为室内外空气流通的关键过渡空间,公共建筑入口的不同设计形式对室内空气质量(IAQ,Indoor Air Quality)产生显著影响。通过文献综述和实地调研,选取合肥市36座公共建筑的入口设计形式进行特征提取,归纳出了平入口、有雨棚的平入口和凹入口三类典型入口形式模型;利用计算流体力学(CFD)数值模拟方法建立了空气流场和气溶胶扩散分布模型,对模型的不同精度网格展开模拟结果的网格无关性验证;并在此基础上,利用现场实测数据进行了模拟数据的对比验证;探讨了三类不同入口形式下室内气溶胶的扩散路径和分布特征。结果表明:1)室内气溶胶浓度与空气流动之间存在显著的关联性。空气流动速率越大,气溶胶浓度越低;空气流动速率越小,气溶胶浓度越高;2)转角空间或狭小空间容易形成涡流,涡流会导致空气滞留,阻碍气溶胶扩散,进而导致局部区域的气溶胶浓度增加;3)有雨棚的平入口的气溶胶进入量略小于无雨棚平入口,占比无雨棚平入口的92.8%,但其室内气溶胶残留量为23.6%,高出无雨棚平入口7.3%;4)室内气溶胶残留量占比从高到低排列为:有雨棚的平入口(23.6%)>平入口(16.3%)>凹入口(14.8%),凹入口在自然通风情况下气溶胶的扩散得到了有效抑制,室内气溶胶残留量最低。建议在设计中采用凹型入口,避免采用大体量雨棚,有利于自然通风,提升建筑出入口空间的空气质量。

深凹立面建筑房间自然通风效果及污染物浓度分布

以西安地区某主导风向为侧向来风的深凹立面建筑房间为研究对象,通过过渡场模型对室外场到室内场进行了多尺度CFD模拟,研究了不同开窗方式下的室内空气质量。结果显示:全开窗对于排出室内产生的污染物有较好效果,但是对于室外污染物的抵抗能力不如单开平立面窗;当室内污染物集中于某个单个房间时,开窗形成的对流通风会造成其他无污染源房间内的污染物浓度增大;当污染物分散在各个房间时,对流通风则可以有效降低各房间污染物浓度,降低幅度约为50%;单开平立面窗能有效杜绝室外污染物进入室内,而增大出风口是排出室内污染物的最好方法。

环境温差对中型体育馆自然通风环境的影响

温度分层是大空间建筑的一个普遍存在的现象,近年全尺寸测量的相关研究已经验证了这一现象,并逐渐引起关注。相关研究表明体育馆室内温度与自然通风环境的变化可能是复杂且敏感的,因此以混合通风的视角切入到后续研究当中很有必要。为探讨亚热带地区环境温差对于体育馆自然通风的潜在影响,文中选取了亚热带地区两个中型体育馆作为研究对象,采用全尺寸测量方法,在夏、秋过渡季节对其室内外空气温度与自然风速进行了监测与分析,并运用计算流体力学(CFD)的数值模拟方法评估并还原了环境温差对于亚热带地区中型体育馆自然通风环境的影响。研究结果表明:负温差环境下的运动区域进口气流风速更高,室外新鲜空气能集中在大空间底部,提高运动区域的换气效率,通风环境显著优于正温差环境;较低的室外空气温度更有利于创造体育馆内部良好的自然通风环境,而对进风口气流进行预冷可能是改善体育馆被占用区域热舒适度的有效途径。本研究运用实测数据对数值模拟结果进行了误差分析,证明模拟方法能有效地解释亚热带地区中型体育馆自然通风环境的温度敏感性,并有效反映了室内大空间复杂的自然通风现象,为未来的相关研究提供基础条件。

自然通风、冷屋顶与外遮阳对室内热环境改善效果实验研究

对自然通风、冷屋顶与外遮阳3种被动技术在夏热冬冷地区的综合隔热降温作用及对室内热环境的改善效果进行了测试分析。结果显示:当三者协同作用时,外遮阳可以遮挡太阳辐射,有效降低窗户的得热量,实验房间玻璃外表面温度较对比房间最高降幅达到7.6℃;高反射涂料的应用使屋顶表面降温幅度达到10.3℃,有效减少了屋顶的温差传热;自然通风系统成功诱导了连续并具有周期性波动的气流,并对埋管内空气有着良好的预冷效果;实验房间室内温度稳定在26.8~27.9℃之间,室内热环境得到了明显的改善。

寒冷地区近零能耗建筑参数优化研究

针对寒冷地区近零能耗建筑的围护结构在夏季会增加室内制冷能耗的问题,提出在夏季和过渡季采用空调与自然通风系统相结合的节能方法,运用EnergyPlus软件模拟研究窗墙面积比、外窗太阳得热因数、窗户传热系数、外墙传热系数、外遮阳悬挑梁长度等5个参数对建筑能耗的影响,通过正交试验确定最优因素水平组合.研究结果显示,优化建筑与既有建筑相比,全年供暖制冷综合能耗可节约43.7%.

结合疫情环境滨海高校绿色建筑概念设计——探索风能的利用

随着经济高速发展,环境问题成为我们面临的巨大挑战。研究绿色能源利用,发展绿色建筑技术,是目前建筑行业的发展趋势。滨海城市拥有丰富的风能、潮汐能等绿色清洁能源,使得绿色建筑的建造有更广阔的发挥空间。根据大连市区具体校园环境,利用计算机模拟软件设计一套能够利用这些清洁能源的模式。经过理论推演、建筑形体推敲的方法,营造一个适合利用风能的建筑概念(环境风6 m/s,风道内最大可达12 m/s)。此外,通过其他节能手法,如辅助日照,将幕墙设计成可活动式,以改变阳光入射方向,补充建筑采光;降低风噪,实现无能耗无尘通风;通过形体设计以提高建筑的通风效率,改良“方盒子”形式的建筑的不利因素;利用环境水体制冷,利用水体底部的低于空气温度的环境来调节室内温度等,从多个方面满足建筑的使用要求,降低建筑的能量消耗。为了适应疫情爆发的突发状况,建筑设计概念还加入了“适疫情化”设计逻辑。通过研究探索滨海地区绿色建筑形式与运行模式,在为绿色建筑发展提供新的设计概念的同时,实现了疫情模式下的管理方法改变。

大型铁路客站站房外遮阳节能潜力分析及调控阈值优化

大窗墙比、大天窗比的透明围护结构是大型铁路场站冷负荷大、环控能耗高的重要原因之一,外遮阳设置是缓解该现象的有效手段,但其应用还需合理平衡对自然采光的影响。以某大型铁路客站站房为对象,建立其光热环境数值分析模型并进行验证;在此基础上,以空调照明综合能耗为指标,选取卷帘外遮阳为代表,分析建筑外遮阳在不同气候区铁路客站应用的综合节能潜力,并确定了适宜外遮阳应用的热工气候分区;在保证室内光热环境水平的前提下,分析空调照明综合能耗随外遮阳调控阈值(以太阳辐射投射强度为依据)的变化情况,并总结不同气候区的最佳调控阈值。该研究成果完善了交通基础设施的被动式技术体系,可为外遮阳技术在大型铁路客站站房的设计和调控提供理论依据。

自然通风技术应用于绿色建筑的路径探析

本论文探析了自然通风技术在绿色建筑中的应用路径。首先,介绍了自然通风技术的定义和原理,以及绿色建筑的定义和设计原则。接着,分析了自然通风在绿色建筑中的优势和效益,包括节能、环保和提升室内空气质量等方面的优点。然后,针对自然通风技术应用中的挑战,包括地理和气候条件限制、噪音和污染控制、安全性和保护需求,以及用户接受和舒适性问题,提出了相应的解决方案。最后,在建筑设计阶段、通风系统设计阶段以及运营和维护阶段,对自然通风技术应用的路径进行了探析。该论文通过系统地研究自然通风技术在绿色建筑中的应用,为绿色建筑设计和实施提供了有益的指导和借鉴。

世界卫生组织对医疗建筑自然通风的建议及思考

医疗建筑中的感染预防和控制是阻断传染病传播的重要一环。自然通风作为最为常见的一种通风形式可以降低医疗建筑中医务人员、患者及探视者被感染的风险。本研究梳理了严重急性呼吸综合症(SARS)至新型冠状病毒感染(COVID-19)疫情期间(2003—2022年)世界卫生组织对医疗建筑自然通风的建议,对本国此类问题的现状进行归纳并提出前述建议所带来的启示。世界卫生组织提出的建议较为明确和具体,值得本国相关主管部门及科研单位重视和学习。部分经验可为本国《医院隔离技术规范》《医院空气净化管理规范》《传染病医院建筑设计规范》和《综合医院建筑设计规范》等规范或标准未来的修订工作提供有益的参考。

寒冷地区自然通风型光伏双层皮幕墙全年节能特性研究

针对寒冷地区普通双层中空玻璃幕墙、自然通风型透明双层皮幕墙(CG-DSF)和半透明光伏双层皮幕墙(PV-DSF)进行了全年建筑能耗分析,利用Energyplus软件对建筑供冷、供热、照明能耗及光伏产能情况进行模拟,并分析了新型PV-DSF幕墙结构的节能潜力.首先通过实验测量结果验证了传热模型、通风模型、发电模型和光照模型的可靠性;然后利用双层幕墙自然通风的功能,分别设定合理的通风模式进行全年能耗模拟.结果表明,相比于普通中空玻璃幕墙,CG-DSF及PV-DSF均可以降低建筑全年的空调能耗,其空调能耗分别为普通中空玻璃幕墙的60%和52%左右.耦合碲化镉半透明光伏玻璃的PV-DSF夏季供冷能耗显著降低,其年光伏发电量约为50.68 kW·h/m^(2),虽然其供热和照明能耗有所增加,但其全年总净能耗最低,比普通中空玻璃幕墙降低了46%,表现出优异的建筑节能潜力.

夏季室外环境对展览温室热环境影响的仿真研究

以上海某展览温室为研究对象,利用数值模拟法对上海夏季4种典型工况下(高太阳辐射天气、低太阳辐射天气、阴雨天气、有风天气)的温室室内热环境进行模拟,并依据模拟结果分析室内热环境的形成原因。结果表明:采用遮阳和自然通风均可使夏季温室的室内温度降低;除阴雨天气外(关闭顶部通风窗),在其余工况下均可采用上述2种措施使温室的室内温度达到设计要求;室外空气流动也可使室内温度降低,且会影响室内温度的分布情况。模拟结果可为采用大面积透明围护结构建筑的夏季室内热环境的预测及改良提供参考。