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1、,建筑遮阳和日光照明Building shading and daylighting control,许鹏 教授 博士 博导机械工程学院Peng Xu Professor, PhD, PE, MBACollege of Mechanical Engineering,建筑遮阳和日光照明Building shading an,Contents内容纲要,Importance of shading control and daylighting 遮阳和自然采光的重要性Shading strategies 常见遮阳策略Day lighting and building envelope 日光照明与建筑立
2、面Sample projects and successful stories 成功案例Software 计算软件,Contents内容纲要,3,Windows, architecture love them, occupants love them. They are modern, stylish, provide better view, easy to build, easy to maintain,What is the pain?,Public buildings,Office,Residential,Small commercials,3Windows, architecture
3、 love th,4,But engineers hate them, regulators do not want them, because they are wasting energy,What is the pain?,Building codes all over the world are using description or energy budget method to regulate the window to wall ratio,In summer, direct solar heat gain accounts for more than 50% of cool
4、ing load,In winter, wall insulation value is about 10 times higher than that of conventional windows. Therefore, buildings in cold climate can only have small windows,4But engineers hate them, regu,Windows are more important than any other building components in term of energy impactIn cold climate,
5、 more than 50% heat loss are through windowsIn hot climate, direct solar heat gain is about 1/3 of cooling loadLighting energy consumption is more than heating and cooling combined in commercial buildings,Low-energy intensity design and windows,Windows are more important tha,Low-energy intensity des
6、ign and windows,Air conditioning peak load analysis in summer50% of building envelope load are caused by windowsWindow shading in summer and window insulation in winter are two critical issues,Low-energy intensity design an,Year of Built, Government office building built at different years,Energy su
7、rvey results,Year of Built, Government offi,Worst energy intensity buildings get worse and worse,Energy survey results,Worst energy intensity buildi,Background,Misunderstanding of windowsThe smaller the better, control Window to Wall RatioEast and West facades are sameSmall north facing windowsSize
8、matters, height does notWindow is fixedBlinds are interior design jobs, nothing to do with energy,Low energy intensity buildings,Mis-concept today,BackgroundMisunderstanding of,Contents内容纲要,Importance of shading control and daylighting 遮阳和自然采光的重要性Shading strategies 常见遮阳策略Day lighting and building en
9、velope 日光照明与建筑立面Sample projects and successful stories 成功案例,Contents内容纲要,The major flux is direct solar beam in summerIn winter, heat loss is the biggest problemSecond transfer is importantTint glass is not very useful,Heat flux through the window,The major flux is direct solar,Window and shading de
10、sign principlesUse exterior shading, or shading in between glasses, internal shading is uselessDesign the building to shade itself Use a horizontal form for south windowsMaximizing windows in northRecessed windows, somewhat useful on the eastUse a vertical form on east and west windows.Give west and
11、 south windows shading priority. East is not importantThe shades color modifies light and heat.Movable shading is better than fixed shade. Use movable devices if budget is allowed,Window and shading design prin,West shading is hardest, vertical louvers sometimes not working,Ways to reduce overhang s
12、ize,West shading is hardest, verti,建筑采光和遮阳课件,Reducing the size of overhang furthermore,Allow lighting to come in,Reducing the size of overhang,Design shading for glare relief as well. Useexterior shading to reduce glare by partiallyblocking occupants view of the too-bright sky.,Design shading for gl
13、are relie,Dirt accumulation on blades, negative effects on building appearancePoor reliability. Actuators and mechanical systems are prone to failure due to exposure to wind, sun and rain.Difficult to repair.Visually unattractive.To avoid glare, blades are typically shut off in winter and useful sol
14、ar heat is blocked too,From thermal point of view, exterior shading systems are perhaps one good solution, because direct solar radiation is completely blocked outside of buildings. However, it has the following shortcomings:,Practical problems,Dirt accumulation on blades, n,Interior shading system,
15、Need to be cleaned and maintained regularlyProne to damage. Furniture moving, indoor activities will inevitably damage the shutter.No automatic adjustment. Interior blinds are left open or closed as they were, till someone feels discomfort with the glare.,Interior shading systems overcome the shortc
16、omings of exterior shading systems,but on the thermal side, they are not as effectively as exterior shading. Although solar radiation is blocked, solar heat are retained indoor in summer. Beyond that, other shortcomings include:,Interior shading systemNeed to,Double facades with ventilation,Ventilat
17、ed faade still have dirt problem. Dirt accumulated in-between the faade is hard to clean Interior recycling ventilated double faades are useless thermal dynamically, because all the heat is still trapped indoor.High cost. Need two layers of window systems. Double the building cost.,Ventilated double
18、 facades with shading in between are better than interior and exterior shading system. However, they have several drawbacks:,Double facades with ventilatio,Shading in between the glasses, dynamic facade,Shading in between the glasses,Contents内容纲要,Importance of shading control and daylighting 遮阳和自然采光
19、的重要性Shading strategies 常见遮阳策略Day lighting and building envelope 日光照明与建筑立面Sample projects and successful stories 成功案例,Contents内容纲要,Day lighting is untapped energy source in buildings,Natural lighting is freeNatural lighting release less heat than artificial lighting, even with ventilated fixturesLigh
20、ting is on all four seasons,Day lighting is untapped energ,Day lighting saving potentials,Adding photo-controls 0.62 kWh/sf-yr of office SF 14.6% of 4.24 kWh/sf-yr (average interior lighting energy use) 2.11 kWh/sf-yr in primary daylit zone 53.5% of 4.24 kWh/sf-yr (average interior lighting energy u
21、se） 35% of office space sf in daylit area,Market size Office spaces with windows, 67%- 3,578 day lit office spaces Net window-to-wall ratios, 38% average for office buildings,Day lighting saving potentials,Day lighting and building envelope,Day lighting and building enve,Day lighting and building en
22、velope,Adding a light shelf increase savings About 5% increase in savingsReducing furniture partition heights increase savingsAbout 10-14% depending on partition heightsIncrease interior reflectanceAbout 15% depending on interior reflectance,Day lighting and building enve,Day lighting and building e
23、nvelope,Day lighting and building enve,Day lighting and building envelope,Day lighting and building enve,Day lighting and building envelope,Day lighting and building enve,Day lighting and building envelope,Day lighting and building enve,Day lighting and building envelope,Building Form and Skin Incre
24、ase exposure to daylight. High skin-to-volume-ratio, the greater percentage of floor space available for daylighting Shape building for self-shading Take a deep facade approach Balance daylight admittance Keep private offices somewhat shallow,Day lighting and building enve,Day lighting and building
25、envelope,Windows The higher the window, the deeper the daylighting zone. The practical depth of a daylighted zone is typically limited to 1.5 times the window head height. With a reflective light shelf, this zone may be extended up to 2.5 times the head height Strip windows provide more uniform dayl
26、ight. Large windows require more control. Size the windows and select glazing at the same time. Keep occupants away from large areas of single-pane glass. Use separate apertures for view and daylight. Position windows to direct light onto the ceiling. Introduce more light-colored surfaces for good d
27、istribution.,Day lighting and building enve,Window design to maximize daylighting,Incorporate shading elements with windows Use horizontal window shapes Place view windows wisely. Locate windows near room surfaces (beams, walls) for good distributionthese surfaces help reflect and redistribute dayli
28、ght. Windows on every orientation - North: High quality consistent daylight with minimalheat gains, but thermal loss during heatingconditions and associated comfort problems. - South: Good access to strong illumination (theoriginal source), although varies through the day.Shading is “easy”.- East an
29、d West: Shading is difficult. Shading iscritical for comfort on both sides and heat gain too,especially on the west. Windows facing generallynorth and south create the fewest problems. Dont waste glazing area where it cant be seen,Window design to maximize dayl,Blinds matters!,90% of buildings have
30、operable fenestration controls, blinds, shades, louvers, curtains,Blinds matters!90% of building,Daylighting simulation examples,Daylighting simulation example,Blinds day lighting simulation,Blinds day lighting simulation,Automated blinds control,Raised for hours when there is no direct sun, lowered
31、 for hours when there is direct sunBlinds are at 45 deg angle to block direct sunRepresentative of a fully automated system,Automated blinds control,Blinds control is an energy saving gold mine,Blinds retrofitsThey are easy to improveScope of design and product improvementDaylighting optimized blind
32、sBlinds manufacturers dont know the potential of their product for daylighting savingsEveryone is focus on HVAC savingsJust like glass/windows forget they are making a daylighting productsLow cost retrofit item,Blinds control is an energy sa,Split blinds, no cost ideas,Split blinds, no cost ideas,Se
33、parate the window functions with different operation schedulesDaylight windows provide:Seasonal adjustment for solar redirectionView windows provide:Occupant daily or hourly control for glare,Separate the window functions,Reflective louvers acts as light shelf,Reflective louvers acts as lig,Automate
34、d blinds retrofit options,Automated blinds retrofit opti,Successful examples,Genzyme BuildingAutomated reflective blindsAll facades operated to produce uniform daylightingArchiving persistent savings,Successful examplesGenzyme Bui,Time,% savings,方位：东,Real picture of daylighting control,Time9:3012%10:3017%11:3026%12:,建筑采光和遮阳课件,
