Shining Light on Daylighting with Metal Roofs

Metal roofing and wall systems of insulated metal panels, or IMPs, have been shown to provide exceptionally durable, energy-efficient and sustainable enclosures. The systems typically have a thick layer of polyisocyanurate insulation protected by metal sheathing on one or both sides, creating an effective air and moisture barrier with good thermal resistance. Recent studies and field evidence, however, have shown that coupling these opaque roof and envelope systems with integrated daylighting and electrical lighting systems -- in particular, with skylights, windows and translucent panels -- contribute to enhanced occupant experience and improved overall building performance.

As recently as a decade ago, applications of skylights and other daylighting products were considered costly and required extensive detailing and coordination among various building trades. Early skylight designs often also displayed poor U-factor. In the last few years, however, skylight assemblies are significantly improved, with more effective seals and thermal breaks as well as better thermal performance.

Today in the nonresidential building industry, a range of novel daylighting products and technologies have been introduced in recent years that facilitate the uncomplicated and proper deployment of natural illumination for a range of occupancies. These include pre-engineered, integrated metal envelope and roof solutions with compatible curbless skylights, light tubes, pan-type prismatic skylights, automated dimming controls for lighting, motorized shades, and other components.

These systems also take advantage of new tools to maximize daylighting effectiveness while also maintain the envelope’s barrier and thermal performance. For example, the effectiveness of conventional flat skylights has been eclipsed by the newer domed and pan-type units with prismatic embossing, which refracts and directs two to four times as much illumination into the indoor spaces when solar incidence angles are more acute, such as in the early morning and late in the day. These prismatic elements also help eliminate “hot spots” and reduce glare and ultraviolet (UV) deterioration from daylighting...

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