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Dynamic Shading of Skylight Improves Indoor Office Environment Abstract Experiment Set up Howard Wu, Chen Hu, Angela Kolosky Advisors: Erica Cochran, Flore Marion Vivian Loſtness, Azizan Aziz, Bertrand Lasternas Glare Analysis Surface Temp. Analysis Dynamic skylights and shading devices provide mulple energy and occupant benefits. To document the benefits, a field experiment was conducted in the Intelligent Workplace (IW) on CMU’s campus. The team installed mulple shading devices on skylights in the IW Living laboratory. Skylights were separated with a 1” thick material to idenfy the performance benefits of each skylight bay. To document and analyze the benefits, the team measured radiant temperature, ambient temperature, lighng intensity, relave humidity, outdoor air temperature, weather condions, glare, and occupant level temperature and lighng intensity. The results show that skylights can provide passive solar heat gain and daylight, and shadings can provide night insulaon and reduce excessive heat gain. Performance Analysis We analyzed the measured data in MS excel in order to compare and idenfy the best soluon for skylight shading. First, we classified the data according to weather condion, dayme & nighme. Next, we developed a metric to develop an opmal strategy to promote building performance. The skylights evaluated are all southwest-oriented. In northern hemisphere, the south-facing windows will receive most sunlight and passive heat gain, comparing to other orientaons. Generally, if the skylight is designed for both daylighng and passive heat gain, it will be oriented to the South. The RETROSolar venean blinds is a W-shaped louvers which reflect the summer sunlight out and winter sunlight into the building, which protect the building from overheang but provide passive solar in winter at the same me. www.koester-lichtplanung.de The Lutron Tensioned Shade is specifically designed for skylights and lted windows, the shade remains parallel to windows with minimal sag in various angles, there are also remote control that makes the adjustments more convenient. Model Developed by Russell Harmon Computer Simulaon A computer simulaon based on the field test is conducted using the soſtwares Ecotect and Radiance to quanfy impacts of shading devices on light levels and glare. The evaluaon on indoor visual performance is based on output illuminance images from the soſtwares. The same bay is analyzed with 3 different shading strategies: no-shading device, Retrosolar venean blind, and Lutron tensioned shade. In addion, Four different blinds posions (fully closed, posive 45, negve 45, and fully opened) are simulated to beer achieve dynamic strategy. Heang, cooling, and transion season are simulated under sunny and overcast weather condion, respecvely. Preliminary result shows that for both summer and winter, skylight with roller shades is the best to prevent glare, and for blinds at various angle, negave 45 is opmal to prevent glare. For providing a comfortable light level for paper based work, shades works beer in summer and blinds at fully open posion works beer in winter under sunny weather. The skylight team used HOBO data loggers and Globe Thermometers to measure temperature, lighng intensity and relave humidity. We also used FLIR Infrared Camera, Fisheye lens to analyze surface temperature and glare. The pictures are from 5 PM of 03/17/2014. The average temperature of three bays were almost same at 9 am and then began to increase. Since the air gap between blind/shade and glazing trapped solar heat, these two bays reached a higher temperature compared with control bay at 1 pm. At 1 pm, three bays all reached their temperature peak. The average temperature of three bays have decreased from 1 PM. At 5 PM, three bays almost had same temperature and remained this temperature ll 7 PM. In conclusion, the high performance mesh shades kept the surface 10 o F warmer than the control bay with no shading thereby decreasing the heang load. The above pictures show glare condion of three bays. From two light contrast diagram, it is shown that contral has a severe glare problem. Compared with Control Bay, other two bays show a slighter glare condion. For monitor, blind and shade bay comply glare requirement for the whole day and control bay only complies in aſternoon. For background, Control Bay excess requirement for the whole day. Based on this, it is recommended to use shade or blind in morning. Under overcast weather, blinds at negave 45 performs beer both in summer and winter. Next steps consist in developing an opmal daily dynam- ic algorithm for the venean blinds and tensioned shades. Fully Closed Fully Open Negative 45 Positive 45 Skylight
