Pattern 19: Fixed Building Shading

In almost every climate, control of direct sun penetration is a key design criterion in order to avoid unwanted heat gain and excessive glare. While operable blinds can be very effective at minimizing glare if used properly, they are only marginally effective at minimizing heat gain. Furthermore, blinds are often simply left closed far more than is necessary if they are not motorized. External motorized blinds, operated with some form of automation system can be extremely effective at minimizing both heat gain and glare, however including these devices is often not feasible due to cost or other limitations. Fixed architectural shading strategies, such as exterior overhangs, vertical fins and interior lightshelves can serve to minimize both heat gain and glare and greatly reduce the number of hours per year that manually operable blinds are required.

This pattern analysis explores the effect of basic fixed architectural shading strategies on glare, daylight availability and very high illumination levels. The case study used to examine these design alternatives is Ash Creek Elementary School in Monmouth, OR. It is a one-story school building designed by BOORA Architects. This pattern sequence highlights simulations under sunny sky and overcast sky conditions during September at noon with workplane illumination data represented in lux. Classroom ambient lighting criteria range from 300-500 lux and 300 lux was selected as one of the daylighting design criterion examined herein. The percentage of floor area above this value is presented for each permutation. For permutations shown under a sunny sky, the percent of the floor area above 2,000 lux is also noted as a means of illustrating the amount of direct sun penetration and potential for unwanted heat gain. It is important to note however, that illuminace values often have very little to do with heat gain. Furthermore illuminace values have little to do with human perception of glare, and the luminance maps are more useful in this assessment.