Toplighting Strategies
Large single level floor areas and the top floors of multi-story buildings can benefit from toplighting. The general types of toplighting include skylights, clerestories, monitors, and sawtooth roofs.
Skylights
Horizontal skylights can be an energy problem because they tend to receive maximum solar gain at the peak of the day. The daylight contribution also peaks at midday and falls off severely in the morning and afternoon. There are high performance skylight designs that incorporate reflectors or prismatic lenses that reduce the peak daylight and heat gain while increasing early and late afternoon daylight contributions. Another option is lightpipes where a high reflectance duct channels the light from a skylight down to a diffusing lens in the room. These may be advantageous in deep roof constructions.
Roof Monitor
A roof monitor consists of a flat roof section raised above the adjacent roof with vertical glazing on all sides. This design often results in excessive glazing area, which results in higher heat losses and gains than a clerestory design. The multiple orientations of the glazing can also create shading problems.
Sawtooth Roof
A sawtooth roof is an old design often seen in industrial buildings. Typically one sloped surface is opaque and the other is glazed. A contemporary sawtooth roof may have solar collectors or photovoltaic cells on the south-facing slope and daylight glazing on the north-facing slope.
Unprotected glazing on the south-facing sawtooth surface may result in high heat gains. In these applications an insulated diffusing panel may be a good choice.