The Leadership in Energy and Environmental Design (LEED) certification process of the U.S. Green Building Council is a powerful tool to deliver desired energy-saving performance in both new construction and major renovation of lodging facilities.

The application of LEED concepts can help determine the energy efficiency of the building envelope—foundation, roof, walls and windows—which is the interface between the building and its environment and a structure’s first line of defense against the elements. Design choices regarding building envelope components affect a project’s ultimate energy efficiency more than the internal systems and components (lighting, heating and cooling, etc.).

Film-based, multi-cavity insulating glass has been saving energy at the Hyatt Regency, San Francisco.

In an era of R-19 walls and ceilings (R being a measure of insulating performance), window glass has been the weak link in conservation performance. From 25 percent to 35 percent of the energy used in U.S. buildings is wasted due to inefficient windows and glass, which themselves account for 10 percent of all CO2 emissions.

Improving the performance of windows represents a significant savings opportunity both for the nation and for individual green building and renovation projects. Glass options alone will have a disproportionate impact on overall building energy efficiency compared to other building components.

That’s why the U.S. Department of Energy’s Energy Star program has revised its window energy conservation performance standards. The first phase of the new standards debuted in January. These and forthcoming standards will require windows eligible to obtain the coveted Energy Star designation to provide increased energy efficiency.

To better appreciate the impact of the new Energy Star standards and energy-saving potential of LEED certification, here’s what property managers need to know regarding how glass impacts the overall efficiency of a window system.

• Single pane glass may keep out the weather, but it does little to insulate against heat loss or reflect the sun’s heat.

• Insulating glass (two pieces of glass separated by a sealed air space or cavity), in which a heat-reflective coating applied to the glass reflects ambient heat both inside and outside, is appropriate in facilities concerned with staying warm in winter and cool in summer.

• Insulating glass with dual heat reflective coatings that simultaneously reflect heat from the sun and ambient heat both inside and outside is even more effective in saving energy and improving comfort. The cavity inside the sealed glass enhances insulation and the coating reflects the sun’s heat to prevent over-heating.

There are two types of glass available today that meet the current and forthcoming Energy Star window performance standards:

• Triple pane glass consists of three panes of glass and two heat reflective coatings. By using a third pane of coated glass triple pane improves insulating glass performance. The bad news is that triple pane glass is 50 percent heavier than insulating glass, requiring stronger window framing, which can be more expensive.

• Heat reflective coated insulating glass contains a transparent heat reflective film suspended inside the air space. This creates multiple cavities that can be filled with a heat resistant gas, which dramatically increases insulation performance while reflecting unwanted solar heat. Glass with suspended film also provides superior protection against UV radiation that can cause fading and reduces the impact of outdoor noise.

With its energy-saving performance, multi-cavity suspended film insulating glass offers an opportunity to optimize design choices and flexibly achieve LEED certification.

The thermal and solar shading performance of suspended film insulating glass as part of an integrated construction or renovation strategy can help earn up to 21 LEED credits, or 54 percent and 40 percent of the total required credits for Gold and Platinum certification, respectively. Superior glass performance can help achieve LEED credits in the following categories:

• Sustainable Sites (SS) Credit 1, Site Selection
• Energy and Atmosphere (EA) Credit 1, Optimize Energy Performance;
• Materials and Resources (MR) Credit 1, Building Reuse;
• MR Credit 5, Regional Materials;
• Indoor Environmental Quality (EQ) Credit 2, Increased Ventilation;
• EQ Credit 7, Thermal Comfort; and
• EQ Credit 8, Daylight & Views.

In assessing energy efficiency, greenhouse gas emissions and guest comfort, understanding the potential of film-based, multi-cavity insulating glass to reduce costs while achieving desired efficiencies will make the choices of decision makers that much more effective in the greening of facilities.

Bruce Lang is vice president of marketing & business development at Southwall Technologies, Inc., Palo Alto, CA. (http://www.southwall.com). He can be reached at blang@southwall.com.