If you have sky-high energy goals, don’t let the roof cap your potential.
Typically dismissed as out of sight and out of mind, your roofing system is likely underutilized.
“The roof is a platform for energy conservation,” explains Matt Barmore, product manager of sustainable systems for manufacturer Firestone Building Products. “Many of us don’t think about the roof until it leaks, but it can do a lot more than keep out water. It can save you money.”
Skylights are an increasingly popular way that your roof can work for you. Let the following factors guide your next new construction or retrofit project.
Types and Tools
First determine your options, which are dictated by building type, size, and orientation.
“There are a number of choices, and your decision depends on the space and how to configure it based on the designer’s vision,” Barmore explains. “Clerestory windows are growing in popularity, and there are a growing number of solutions with prismatic lenses.”
Domes and tubes with prismatic systems capture and diffuse light to reach the right effective skylight to floor area ratio (eSFR).
“These advanced lenses can provide almost three times the light as a conventional flat, translucent panel,” says Randy Ahland, business development manager of building products for manufacturer Varco Pruden Buildings. “The coverage difference is almost literally night and day.”
In overcast climates, light scoops – tilted south-facing skylights – are ideal. They can be customized to provide less direct sunlight in the summer and more in the winter, and for other considerations.
“Daylight availability is a curve around noon. You want to flatten it by collecting at low angles and rejecting at high angles,” explains Lisa Heschong, principal at energy efficiency consultant Heschong Mahone Group. “General advice for choosing skylights is the highest transmission, best diffusion, and double glazing.”
To make the right selection, use the free tool SkyCalc from research group Energy Design Resources.
“SkyCalc will give you an eight-page engineering document with a lot of helpful information. I suggest flipping to the executive summary on the last page,” Barmore says. “It tells you the number and size of skylights needed as well as your upfront cost, estimated savings, and ROI.”