Windows and LEED
By Greg Zimmerman, Executive Editor - July 2010 - BOM
Facility managers who may have worked on successful LEED for New Construction projects probably already understand the strategy required to achieve a 90.1 or 189.1 performance compliance option: integrated design. LEED, especially in its newest iteration released last year, encourages integrated design by awarding more points for energy efficiency than any other strategy —35 of the possible 100. To be certified at all, a building must be designed to be 10 percent below the ASHRAE 90.1-2007 standard.
Thoughtful window and glazing selection can help facility managers meet LEED certification goals in other ways as well. LEED-NC offers points for strategies that provide building occupants with daylighting and views. The first credit — Indoor Environmental Quality Credit 8.1 — gives facility managers four options for showing that 75 percent of interior space has access to daylighting. From modeling to some pretty intense calculations, the options try to incorporate just about any way possible for facility managers to work with their engineer and architect to make daylighting possible.
The second credit — IEQ Credit 8.2 — gives one point if a building can offer a direct line-of-sight view outside to 90 percent of occupants.
Window selection can play a role in another credit, IEQ Credit 6.1, which deals with controllability of systems for occupant comfort. The credit specifies that operable windows may be used in lieu of controls. The requirements are based on ASHRAE's ventilation standard 62.1.
Finally, facility managers can achieve a point for reducing light pollution. The credit has both interior and exterior requirements for reducing lighting, but one option for achieving the interior portion of the credit — Sustainable Sites 8 — is to use shielding on all envelope openings that have a direct line of site to nonemergency lights. Because using shielding on windows may have implications in product selection and how much daylight enters a building through windows and glazing, facility managers looking to achieve this credit have a lot to consider.