Pattern 18: Fixed Building Shading (Fixed Classroom Shading)

South Sunny: No Shading

This sequence uses a south classroom under a sunny sky at noon in September. In this step there is no shading shown and the sun penetrates onto the floor and onto the first row of desks near the perimeter. This would likely result in all blinds being closed and unwanted heat gain. It is also likely to mean that a seated student would see the disc of the sun causing glare. Furthermore, In the morning, the sun would strike the white board and cause veiling glare for all students in the room. Almost the entire floor area (99%) is above 300 lux and over 40% is above 2,000 lux.

Pattern 18: Fixed Building Shading (Fixed Classroom Shading)

South Sunny: Horizontal Shading Device

Pattern 18: Fixed Building Shading

In this step an opaque exterior overhang is added and was sized to be about as deep as the window it is trying to shade is tall. This 1:1 ratio is a good rule of thumb for shading windows on the south façade located near 45-degrees latitude from March through September. The sun nearest the south façade is no longer on the floor, however the same problem persists on the desks as the previous step. Almost the entire floor area (98%) is above 300 lux and the area above 2,000 lux dropped from 41% to 28%, a marked improvement.

Pattern 18: Fixed Building Shading (Fixed Classroom Shading)

South Sunny: Horizontal Shading Device and Light Shelf

Pattern 18: Fixed Building Shading

In this step an opaque interior lightshelf is added was sized to be about as deep as the window it is placed beneath is tall. This 1:1 ratio is a good rule of thumb for shading windows on the south façade located near 45-degrees latitude from March through September. The sun that was falling on the desks is now eliminated and there is no sun penetration in the room. Note that the heat gain from the upper ‘daylight’ window, below which the lightshelf is placed, still enters the room, however glare is greatly reduced throughout the space. The lightshelf bounces light onto the ceiling and reduces the contrast at the perimeter window. Almost the entire floor area (98%) remains above 300 lux and the area above 2,000 lux dropped from 28% to 20%.

Pattern 18: Fixed Building Shading (Fixed Classroom Shading)

South Sunny: Translucent Horizontal Shading Device and Translucent Light Shelf

Pattern 18: Fixed Building Shading

In this step the overhang and lightshelf are changed in material from opaque to translucent. This has almost no effect on the illumination values (99% above 300 lux, 21% above 2,000 lux) but improves the balance of brightness across the space. In particular, note the increased brightness below the overhang and lightshelf on the perimeter opaque walls around the windows as compared to the previous step. The brightness on the ceiling is very slightly diminished since more light is passing through the shading elements.

Pattern 18: Fixed Building Shading (Fixed Classroom Shading)

South Overcast: No Shading

Pattern 18: Fixed Building Shading

Since fixed shading devices are usually permanent, it is important to understand effects under overcast sky conditions as well. The same permutations are now repeated under an overcast sky at noon in September. Note that the illumination area above 300 lux is substantially reduced due to the lower outdoor illumination levels, irrespective of the shading devices. The floor area above 300 lux is 48%.

Pattern 18: Fixed Building Shading (Fixed Classroom Shading)

South Overcast: Horizontal Shading Device

Pattern 18: Fixed Building Shading

In this step, the opaque overhang was added. This reduced the floor area above 300 lux from 48% to 42% representing just over a 1/10th illumination reduction from the baseline without shading. This is a modest penalty to pay in order to provide the improved comfort and energy benefits associated with shading elements.

Pattern 18: Fixed Building Shading (Fixed Classroom Shading)

South Overcast: Horizontal Shading Device and Light Shelf

Pattern 18: Fixed Building Shading

In this step, the opaque lightshelf was added. This reduced the floor area above 300 lux from 42% to 30% representing just over a 1/3rd illumination reduction from the baseline without shading. This is not insignificant; however it may be a useful tradeoff in order to provide the improved comfort benefit during sunny conditions.

Pattern 18: Fixed Building Shading (Fixed Classroom Shading)

South Overcast: Translucent Horizontal Shading Device and Translucent Light Shelf

Pattern 18: Fixed Building Shading

In this step, the opaque overhang and lightshelf were changed to a translucent material. This slightly improved the floor area above 300 lux from 30% to 31% compared to the previous step.