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Solar Shading Application: Vancouver Olympic Village
By Stuart Lyons
Solar building shading has become an increasing consideration of exterior building design as interest has grown in conserving energy and improving building comfort levels. At the 2010 Olympic Athletes Village in Vancouver, 16 new buildings are emerging, all with highly sustainable mandates, and all deploying an array of solar screening devises.
Solar screening is designed to account primarily for summer sun angles as they subtend into the building through windows placed in the exterior envelope. This shading is appropriately integrated into south and west facing building facades where the mid and late day sun is most impactful. To effectively deflect the sun’s heat, screens must be located on the outside of the building envelope, interrupting the sun’s rays before they can enter the building.
This is a review of the primary types of solar shading used at the Olympic Athletes Village. These applications are particularly relevant to residential buildings.
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Exterior Roller Blinds
Exterior roller blinds at the village are power operated from within the suite. This is essential for several reasons including convenience of use, potential inaccessibility outside the building, and automatic blind recall in windy conditions. The blinds travel smoothly and securely on vertical wire guides. Blinds are attached to the underside of the building structure either up against the exterior window frame or at the outside edge of the balcony. The advantage of locating the blinds at the outside edge of the balcony is that in this location they greatly enhance the utility of the balcony, creating a ‘lanai’ effect and a more private outdoor realm. Exterior roller blinds have been used extensively on the west building facades where their vertical orientation is most appropriate to intercepting the lower afternoon sun angle. A broad range of colour and density available in blinds promotes personalization of suites, opportunities to enliven the façade, and the ability to adjust transparency.
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Horizontal Aluminum Louver Shades
These shades can be custom designed or selected from manufactured systems. Their extension from the exterior wall is entirely dependent on the amount of shading required, Zoning By-law allowances for projections, and structural support limitations. At the village, these louver systems are either exterior wall mounted or window mounted. Wall mounted louvers require a support structure within the wall capable of supporting the louver plus additional loading. This can lead to significant steel back up and dropped bulkheads above the windows within the suites. These louvers have been used at the village typically where the window openings are ‘punched’. Most window manufacturers will not permit solar shades to be mounted through the window system itself. Window mounted louvers are, however, currently available on a limited basis and primarily as a component of curtain wall systems. When providing exterior horizontal window shading, consideration must be given to conflicts with window washing systems.
Vertical Aluminum Louver Shades
These shades work well where they can be located away from the face of the building and where the floor height is high enough that the vertical louvers do not obstruct views in or out of the windows. At the village, these shades have been utilized on the exterior of the higher commercial frontages, set beyond the face of the building and suspended from the canopy extension above. In this way, the west or south facing commercial frontage, which must often have extensive glass, is protected from direct sunlight and the associated heating and discomfort issues.
‘Bullet’ shades
These shades take their name from the cross sectional shape of the aluminum extrusion. They have been used at the village to intercept highly angled solar heat. The advantage of the solid extrusion over the louver is that it works either horizontally or vertically. It can wrap continuously around the window perimeter in response to solar incidence. Thus, south facing windows are protected from afternoon sun otherwise penetrating into the building from the west side.
Window mullion extensions
Extruded aluminum extensions of up to 8 or 10 inches fastened to the outside of aluminum window frames provide interior shading from high sun angles. This method of solar shading has been used at the village in conjunction with closely spaced horizontal window framing.
Extended floor slabs
Simply extending the floor slabs from the building façade also provides sun screening although a significant projection is generally required implying a balcony or walkway above. At the Olympic Village exterior corridor circulation has been located on the south and west side of several buildings, providing overhangs up to eight feet from the window façade. Although this is an effective way to eliminate direct summer sun from the windows, consideration must be given to the thermal bridging which occurs between the interior floor slabs and the building exterior. This can be overcome by insulating the top and bottom of the exterior slab, a method selected for one of the buildings.
Stuart Lyon, MAIBC RAIC, is a principal in GBL Architects Inc. and has practiced architecture in B.C. for 30 years. His firm is currently completing work on the Vancouver Olympic Athletes Village and is engaged in numerous other sustainable projects around the province. |
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