Factors Affecting Daylight

Through a Window

• The shape of the window opening

• The position of the building

• Orientation

• External obstructions

• Reflectivity of internal and external surfaces

• Cleanliness of the glazing and surrounding surfaces

• Type of glazing

(a) Clerestories:- north, west, east, - will give rise to solar ingress from morning and evening sun and shading will be required. The extent of intrusion from the West is more evident because our sports behaviour is not symmetrical around midday. We are more inclined to be playing sport at 6 in the evening than 6 in the morning.

(b) North facing clerestorey - it is advisable to provide more glazing to the North which receives sun only for a short period during the midsummer.

(d) Barrel vault(s) -

(e) North facing curved roof monitors - designing this roof profile can distribute light more effectively.

(f) clerestorey combined with rooflight - increasingly used as a way of evening out the daylight distribution.

(g) as (f) flat roof)

(h) North facing roof light combined with clerestorey - less likely to lead to solar penetration and glare than a central rooflight.

(i) Sunpipes are increasingly popular. They provide daylight from the brightest source (unobstructed sky) but do not require extra shading. The quality of light is excellent but they do not provide the amenity value of windows with views out and hall users may not be aware that it is daylight. They have not yet been incorporated into a sports hall.

(j) Clerestorey and roof monitor combined with light shelf - to reflect light upwards and deep into a space. The overall light available will be reduced but it will be better distributed and reduce glare. Light shelves have special maintenance requirements if they are to be effective but work well with high ceilings with good surface reflectance.

Understanding Daylighting of Sports Halls

Window Design

Window Type and Orientation

With many building types good daylighting requires attention to space planning. Placing rooms which do not require sunlight or daylight on the north, and leaving spaces for daylight enjoyment and with connections to the outside on the south is generally sought after. For sports halls because sunlight is particularly unwelcome, glazing on the south should be avoided.

The use of side windows can offset the perimeter lighting but is unlikely to be adequate for full daylighting in deep plan spaces without

causing interference with the sporting requirements through lack of privacy, glare or sunlight. Clerestories can provide some connection with outdoors but do not provide an even light distribution and are generally insufficient to daylight a deep space. Rooflights provide a more even daylight distribution.

Both clerestories and rooflights are potential sources of glare. Light coloured surrounds and reveals are recommended. Rooflighting is less likely to cause glare than side windows. This, coupled with them being away from the playing area, makes them valuable for sports halls. Rooflights tend to be more expensive than windows due to the structural requirements. They also lose more heat than equivalent glazing specification windows, so increasing the payback period. However, they do provide more light per square metre than windows due to rooflights facing the unobstructed sky vault.

Increasingly clerestories are being combined with rooflights to create a more uniform and higher level of daylight further into a space and this is more suitable for a single storey deep plan space such as a sports hall. North facing windows or rooflights (monitors) are most appropriate. East or west facing windows are prone to low level sunlight access at dawn and dusk, and in winter - requiring careful shading design.

Atria can be designed into the overall space planning of a sports facility and can be used to provide borrowed light into a sports hall. Borrowed light from an internal corridor can also add to the daylighting provision and atmosphere. In all case care should be taken to avoid internal reflections.

Discussion of glazing options

The options for glazing are infinite and the following, along with the case studies, are intended to indicate some approaches. The most popular form of providing natural light is through correctly shaded clerestories and rooflights. Central rooflights or rows of barrel-vaulted rooflights in between courts can be found, and the daylight available from these is sometimes diffused through sailcloth. Other successful daylighting comes from light-coloured, splayed window reveals; light-coloured framing; curved surface transitions between daylit surfaces, and adjustable shading systems. Reflective or diffusive daylighting strategies lower the DFave significantly, but can help reduce any tendencies for glare. Much can be learned from observing daylighting in museums and art galleries.