2) Conserve Energy Although durability and low maintenance help keep long-term costs down, a sound roof design also helps conserve energy and generate substantial savings over a building’s life. As part of a tested assembly, a standing-seam roof system can result in energy savings of up to 40%.
Energy efficiency in buildings is not just desirable — it is becoming mandatory with more stringent building and energy codes. ASHRAE Standard 90.1 and the latest version of IECC signal a new era of accountability for building efficiency.
The roof is often the least energy efficient part of the building envelope. Heating and cooling typically consume about 30% of a building’s energy, and half of that results from heated or cooled air lost through the roof. A well-designed and properly installed roof helps reduce those losses and maintain more consistent interior temperatures.
Thicker insulation is part of the answer. However, when applied to conventional built-up roofs, the added insulation may negate the energy savings by speeding deterioration of the roof surface. Metal roofs, on the other hand, can accommodate more insulation — to an R-value of 40 with no effect on roof service life.
Better still, metal roofing assemblies are available that have achieved these values through testing to meet code requirements. Guarded Hot Box tests for U-factor are proven compliant with the IECC and ASHRAE standards.
3) Reduce Air Conditioning Metal roof systems can also function as cool roofs, helping owners save money by repelling, rather than absorbing, the sun’s heat during summer. This can ultimately reduce air conditioning costs.
Roofs painted in light colors reflect more solar radiation and reduce the roof temperature. Infrared reflective pigments enable roofs to reflect significant sunlight even when darker paints are used. In addition, on cloudy days or after sunset, metal roofs give up their heat faster than other roofing materials.
Cool metal roofs perform well even when compared with white membrane roofing. A study at the Oak Ridge National Laboratory in Tennessee found a metal roof system more effective than conventional roofs in reflecting the sun’s rays and in preventing solar heat transfer into a building.
The effect of cool roofing on buildings can be dramatic. For example, the Heat Island Group at Lawrence Berkeley National Laboratory in California has reported that reflective roofing can directly save up to 40% in cooling and heating costs.
Cool roofs are gaining popularity in part because governments offer rebates and energy credits to contractors and building owners to change dark, absorptive roofing materials to cool roof systems. Some utilities also offer rebates to building owners using cool metal roofs that help reduce peak energy demand during the cooling season.
In addition, cool roofs have the added benefit of mitigating the urban heat island effect, thus helping reduce smog formed from the reaction of nitrogen oxides and volatile organic chemicals.[ii]