百叶型外遮阳对建筑光热能耗影响的优化探讨

为探究水平百叶外遮阳装置对室内全年照明、制冷、采暖能耗的影响，以确定装置的最优调节策略和对应节能效率，文章以上海地区某建筑为例，通过Ladybug和Honeybee分析软件，结合Energy Plus、Radiance、Daysim等模拟引擎，对无遮阳与不同百叶遮阳条件下，室内全年的制冷、采暖、照明能耗进行对比，得出三部分能耗的增减情况。然后以全年为周期，对百叶倾角进行人工调整，当全年频率为0次、2次、4次、6次、12次时，对应的室内最低光热综合能耗降幅分别为3.17%、4.16%、4.99%、4.96%、5.54%。研究从定量的角度证明水平百叶外遮阳装置可降低室内夏季制冷能耗，但也会显著增加全年照明和采暖能耗，可作为百叶遮阳装置节能调控的参考依据。     

不同光区大进深办公室室内采光与节能研究

基于ECOTECT软件,以不同光气候区大进深办公室为研究对象,在南向外窗设置水平百叶遮阳对室内光环境进行模拟,分析了不同的百叶间距对室内照度分布、照度均匀度的影响,并分析了基于天然采光的人工照明节能性。模拟结果表明:水平百叶外遮阳能改善室内的照度均匀度,提高室内光照舒适度。百叶间距增大,照度均匀度有所降低。不同光气候区天然采光结合人工照明电能节省率在30.1%~55.7%之间。     

基于综合能耗下外遮阳百叶控制策略

针对目前建筑能耗增长过快的现状,结合空调采暖能耗与照明能耗在能耗组成中占比大的事实,提出了基于综合能耗下的外遮阳百叶控制策略,深入挖掘建筑节能潜力。使用建筑设计软件Ecotect,建立郑州地区某遮阳建筑的仿真模型,分别导入采光分析软件Daysim和能耗模拟软件EnergyPlus中,模拟11种百叶倾角(15°～165°)下全年逐时照明能耗和空调采暖能耗,整理出各时刻下11种百叶倾角对应的综合能耗,取各时刻综合能耗最小值对应的百叶倾角作为动态百叶开启角度,分析得到动态遮阳下的全年综合能耗。结果表明,与常规外遮阳控制策略相比,基于综合能耗下的外遮阳优化控制策略可大幅提高建筑节能率。     

广州某典型办公楼垂直百叶遮阳的综合节能分析

在夏热冬暖地区,降低窗和玻璃幕墙的外遮阳系数是降低空调能耗的有效方法之一,然而降低窗的外遮阳系数的同时也减少了对自然光的利用,从而增加了照明能耗.因此,需要对空调能耗和照明能耗进行权衡判断.本文对某办公楼的全年空调能耗和照明能耗进行了模拟,以建筑全年空调能耗和照明能耗的总和为控制指标,对建筑垂直外百叶遮阳结构(百叶出挑长度、百叶数和百叶倾角)进行了优化设计分析.结果表明,增加百叶出挑长度或增加百叶数,空调耗电量降低,照明耗电量增大,总能耗降低.但是,改变百叶偏角,空调和照明的总耗电量先是增大,而后减少,当百叶偏角为-15°时,总耗电量出现最大值.     

建筑遮阳对建筑室内照明能耗的影响分析

建筑遮阳可以降低室内局部区域过高的照度水平,但会降低室内整体照度水平,在室外照度不高的情况下,遮阳还会影响室内照度,增加照明能耗。针对建筑遮阳对建筑室内照明能耗的影响问题,选取具有代表性的建筑南向水平遮阳进行研究,利用光环境模拟软件Ecotect和Radiance对五个气候区的典型城市进行模拟,分析了不同气候区的不同窗墙比、不同窗户类型、不同遮阳板长度对建筑室内照明能耗的影响,得到建筑遮阳对室内光环境的影响规律。     

基于隔热采光性能的建筑百叶综合节能效果研究

本文兼顾隔热以及采光性能,研究了建筑百叶对室内制冷能耗和照明能耗的综合影响,并提出光热综合能耗来全面评估其节能性。依据软件模拟无遮阳、45°以及90°开启百叶三类模型在夏季典型日的制冷负荷与所需光通量,计算出建筑窗体引起的光热综合能耗。结果表明：夏季在使用光效较低的灯具时,90°开启百叶比无遮阳情况节能13%,而使用光效高的灯具时,90°开启百叶比无遮阳情况节能29%,但45°开启百叶的节能效果与其相差不大。当根据室外光热环境对百叶进行合理控制时,光热综合能耗将会更小,节能率高达40%。     

外遮阳百叶隔热性能与采光分析

外遮阳百叶能合理控制太阳光线进人室内,减少建筑空调能耗和人工照明用电,改善室内光环境,已成为当前追求"绿色建筑"目标的一项具体措施.该文通过理论分析和模拟,借助EnergyPlus、Radiance等软件,结合光和热两方面综合考虑,对空调时期上海地区布置不同角度和活动的外遮阳百叶办公房间的空调能耗、照明能耗及室内光环境进行了模拟、分析与比较.算例结果表明:外遮阳对照明能耗和建筑光环境的影响不容忽视;夏热冬冷地区固定式遮阳百叶的不同角度设置对建筑能耗的影响较大,其中实施活动式外遮阳措施能大幅度降低建筑能耗,有效改善室内光环境.     

基于采光和能耗分析的某图书馆内遮阳节能研究

以夏热冬冷地区某高校图书馆为模拟案例,利用DeST软件对有无内遮阳以及不同深浅颜色的内遮阳模型进行室温和能耗模拟计算,结果表明:内遮阳可以有效改善室内热环境,缩减了全年17.5%的35℃以上高温小时数,中庭室温平均下降0.83℃。浅色内遮阳引入更少的照明能耗,深色内遮阳阻隔更多的太阳得热量,从而降低空调能耗,但浅色内遮阳的综合能耗更少。利用Ecotect和Radiance软件对中庭和边庭进行自然采光和室内眩光模拟分析,研究结果表明:内遮阳可以有效改善顶部采光质量,降低中庭较高的采光系数,减少眩光,采光均匀度U1可以提高40%。内遮阳百叶有利于边庭光环境的调节,在典型夏季日(7月1日),调节遮阳百叶角度为60°,边庭红色易眩光区域大面积减少,全天室内光照度可以控制在2 000 lux以内,室内采光均匀度大幅度提升。     

基于隔热采光性能的建筑百叶综合节能效果研究

本文从隔热和采光性能出发,研究了建筑百叶对室内制冷能耗和照明能耗的综合影响,并提出以光热综合能耗来全面评估其节能性。依据软件模拟无遮阳、45°以及90°开启百叶三类模型在夏季典型目的制冷负荷与所需光通量．计算出建筑窗体引起的光热综合能耗。结果表明：在使用光效较低的灯具时,90°开启百叶比无遮阳情况节能13％．而使用光效...     

基于能耗对教室南向窗口外遮阳形式的研究

窗户对于建筑的光环境质量、夏季空调能耗和冬季供暖能耗有着非常重要的影响。以青岛地区高校教室南向窗口为例,运用Ecotect软件对设置了不同遮阳设施的教室进行了采光系数与照度水平的模拟,分析了不同遮阳形式冬夏季及全年的太阳能辐射得热问题。通过对模拟结果的分析与比较,得出了百叶式遮阳对室内采光更为有利的结论,为学校营造良好的教室光环境和降低教室能耗提供了参考。     

Field study on indoor thermal environment in an atrium in tropical climates

Solar penetration through the transparent envelope can severely deteriorate indoor thermal environment inside an atrium building particularly in tropical climates. This paper reports the application of two low-cost measures, namely high level internal solar blinds and water spray, to minimise overheating problems on the three levels inside the atrium of a guesthouse in Southern China, where summer is hot and humid. The blinds reduce direct solar penetration at the top of the atrium whilst the evaporative spray system cools down the glazed surfaces of the atrium envelope. A site test was undertaken over 10 consecutive days covering both overcast days and clear days in July 2004. Measurement of indoor thermal environmental parameters was conducted on three levels in the atrium and the recorded data represent the internal conditions: with and without internal blinds protection from solar, and with and without water spray. This study has shown that on hot and clear summer days, with water spray and without blinds the average air temperature difference from 1200 to 1800 h between both first floor and second floor, and second floor and external were 5.7 and 1.7 K, respectively; whilst with blinds and without water spray the average air temperature differences were 8.7 and 4.8 K, respectively.     

Convection at the indoor side of complex fenestration systems: the ASHWAT model revisited

This paper examines the three-temperature problem of convection at the indoor side of a complex fenestration system (CFS) based on recent theoretical developments, namely the extended Newton formulation and the dQdT technique. CFD solutions were obtained for natural convection at the indoor side of various CFS configurations. The dQdT technique was then implemented numerically to obtain the paired heat transfer coefficients of each configuration. The results were used to assess the approximate relations used in the ASHRAE Window ATachment (ASHWAT) tool. The comparison shows that while there is remarkable agreement between the ASHWAT estimates and dQdT results for roller blinds, discrepancies exist between results for venetian blinds. Furthermore, although use of a delta resistor network to model convection at the indoor side is valid and relatively accurate for roller blinds, the application of this model to CFSs with venetian blinds requires additional levels of approximation. Nevertheless, the heat transfer rates calculated based on the approximate resistor-network model are in close agreement with the CFD results.     

南京地区活动式建筑外遮阳设施对室内热环境影响

针对活动式铝合金的外遮阳百叶帘和卷帘,对夏季和过渡季节南京地区建筑室内的热环境的影响进行了计算和分析研究,指出在该地区两种活动式建筑外遮阳设施在夏季能有效改善空调房间室内热环境,但对过渡季节自然通风房间室内热环境的影响正相反。     

Indoor thermal environmental conditions near glazed facades with shading devices – Part I: Experiments and building thermal model

This paper presents an experimental study of indoor thermal environment near a full-scale glass facade with different types of shading devices under varying climatic conditions in winter. Interior glazing and shading temperature, operative temperature and radiant temperature asymmetry were measured for façade sections with roller shades and venetian blinds at different positions. Interior glass surface temperatures can be high during sunny days with low outdoor temperature. Shading systems significantly improved operative temperature and radiant temperature asymmetry during cold sunny days, depending on their properties and tilt angle. During cloudy days the impact was smaller, however the shading layers could still decrease the amount of heat loss through the façade. A transient building thermal model, which also calculates indoor environmental indices under the presence of solar radiation, was developed and compared with the experimental measurements. Part II of this paper uses this validated model with a transient, two-node thermal comfort model (including transmitted solar radiation) for assessment of indoor environmental conditions with different building envelope and shading properties, façade location and orientation.     

Illuminance-based slat angle selection model for automated control of split blinds

Venetian blinds play an important role in controlling daylight in buildings. Automated blinds overcome some limitations of manual blinds; however, the existing automated systems mainly control the direct solar radiation and glare and cannot be used for controlling innovative blind systems such as split blinds. This research developed an Illuminance-based Slat Angle Selection (ISAS) model that predicts the optimum slat angles of split blinds to achieve the designed indoor illuminance. The model was constructed based on a series of multi-layer feed-forward artificial neural networks (ANNs). The illuminance values at the sensor points used to develop the ANNs were obtained by the software EnergyPlus™. The weather determinants (such as horizontal illuminance and sun angles) were used as the input variables for the ANNs. The illuminance level at a sensor point was the output variable for the ANNs. The ISAS model was validated by evaluating the errors in the calculation of the: 1) illuminance and 2) optimum slat angles. The validation results showed that the power of the ISAS model to predict illuminance was 94.7% while its power to calculate the optimum slat angles was 98.5%. For about 90% of time in the year, the illuminance percentage errors were less than 10%, and the percentage errors in calculating the optimum slat angles were less than 5%. This research offers a new approach for the automated control of split blinds and a guide for future research to utilize the adaptive nature of ANNs to develop a more practical and applicable blind control system.     

Adding advanced behavioural models in whole building energy simulation: A study on the total energy impact of manual and automated lighting control

Behavioural models derived from on-going field studies can provide the basis for predicting personal action taken to adjust lighting levels, remedy direct glare, and save energy in response to physical conditions. Enabling these behavioural models in advanced lighting simulation programs, such as DAYSIM and the Lightswitch Wizard, allows for a more realistic estimate of lighting use under dynamic conditions. The current downside of these approaches is that the whole building energy impact of manual changes in blind settings and lighting use, including its effect on heating and cooling requirements, is not considered. A sub-hourly occupancy-based control model (SHOCC), which enables advanced behavioural models within whole building energy simulation, is presented. The considered behavioural models are the Lightswitch2002 algorithms for manual and automated light and blind control, while the investigated whole building energy simulation program is ESP-r.The enhanced functionality is demonstrated through annual energy simulations aiming at quantifying the total energy impact of manual control over lights and window blinds. Results show that building occupants that actively seek daylighting rather than systematically relying on artificial lighting can reduce overall primary energy expenditure by more than 40%, when compared to occupants who rely on constant artificial lighting. This underlines the importance of defining suitable reference cases for benchmarking the performance of automated lighting controls. Results also show that, depending on the proportion of buildings occupants that actively seek out daylighting, reduced lighting use through automated control may not always produce anticipated savings in primary energy for indoor climate control. In some cases, reduced lighting use is shown to even increase primary energy expenditure for indoor climate control, trimming down initial primary energy savings in lighting alone. This reveals the superiority of integrated design approaches over simpler daylighting guidelines or rules of thumb.     

Factors affecting wavelength-resolved ultraviolet irradiance indoors and their impacts on indoor photochemistry

We measured wavelength-resolved ultraviolet (UV) irradiance in multiple indoor environments and quantified the effects of variables such as light source, solar angles, cloud cover, window type, and electric light color temperature on indoor photon fluxes. The majority of the 77 windows and window samples investigated completely attenuated sunlight at wavelengths shorter than 320 nm; despite variations among individual windows leading to differences in indoor HONO photolysis rate constants (J_HONO) and local hydroxyl radical (OH) concentrations of up to a factor of 50, wavelength-resolved transmittance was similar between windows in residential and non-residential buildings. We report mathematical relationships that predict indoor solar UV irradiance as a function of solar zenith angle, incident angle of sunlight on windows, and distance from windows and surfaces for direct and diffuse sunlight. Using these relationships, we predict elevated indoor steady-state OH concentrations (0.80–7.4 × 10⁶ molec cm⁻³) under illumination by direct and diffuse sunlight and fluorescent tubes near windows or light sources. However, elevated OH concentrations at 1 m from the source are only predicted under direct sunlight. We predict that reflections from indoor surfaces will have minor contributions to room-averaged indoor UV irradiance. These results may improve parameterization of indoor chemistry models.