 |  |
The shading devices above the windows of the south facades of the LLC do not meet the shading requirements necessary to prevent excessive thermal gain. Many times during spring months the shading exceeded the requirements, and during summer months the shading was insufficient.
The lack of adequate shading creates solar gain. We calculated this gain in Btu's for two examples (3pm on a day in January and in September).
Calculations
Equation: HG= I x A x P
Where...
HG= heat gain in Btu/h
I= solar intensity/ heat gain factor for 40N latitude in Btu/hft(sq)
A= the area of the window in ft(sq)
P= percentage of window not shaded by device
January
160 x 41.268 ft² x .9 = 5942.59 Btu/hr
September
124 x 41.268 ft² x .4 = 2046.89 Btu/hr
When the window is more exposed to direct sunlight, there is more heat gain which would cause occupants to be uncomfortable near the window. More heat would be produced causing the thermostat to be used to cool down the environment. Also, more glare would be produced making blinds necessary and obstructing view. As a result, shading devices should be designed to control solar heat gain and glare, thus creating a comfortable environment.
Pushing our case study a little further, we compared the LLC shading device to other shading devices found on campus. The volcanology building that also faces south, has awnings that span vertically as well as horizontally with no louvers and always provide more than 50% shading. The difference is illustrated in the images below: a SketchUp model of LLC, and photo of the volcanology building at 8am in February--a time when LLC shading is inadequate. (Click thumbnails to enlarge.)
 
|
| |
|