Sustainable Land Development Today - February 2009 - (Page 21)

LEEDing the Way With its energy-saving performance capabilities, multicavity suspended film insulating glass offers an opportunity for a project to flexibly achieve certification under the LEED program. The thermal and solar shading performance of suspended film insulating glass as part of an integrated construction or renovation strategy can help project manager’s earn up to 21 LEED credits, or 54 percent and 40 percent of the total required credits for Gold and Platinum certification, respectively. provides powerful energy-conserving alternatives to generic low-e glass and about which facility managers need to become familiar. Understanding these superior glass options will help optimize design choices and achieve desired green results. Alternatives to single-cavity, low-e insulating glass are available that can narrow the energy-conservation performance gap between windows and walls. One is triple pane glass, consisting of three panes of glass and two low-e coatings. By using a third pane of glass to create a second insulating cavity, triple-pane, low-e glass doubles the performance of low-e insulating glass from R- 4 to R-9. Unfortunately, triple pane glass is 50 percent heavier than standard insulating glass, imposing size constraints and requiring stronger window framing at increased cost. A superior multi-cavity alternative consists of suspending a very thin, lowemissivity and solar-reflective coated film inside of an insulating glass unit. Without the weight disadvantages of a third pane of glass, suspended film can create two, three or even four insulating cavities that maximize light transmission and provide conservation performance ranging from R-6 to an amazing R-20. Such internally-mounted films do not replace low-e glass. Rather, they leverage the benefits of film-based and glassbased technologies to create a lightweight, multi-cavity insulating glass that offers a level of performance that enables designers to downsize or eliminate other building components (AC systems, perimeter heating, etc) to cost-effectively achieve maximum energy savings. The selection of suspended film insulating glass at Manheim Township High School in Lancaster County, Pennsylvania, played a key role in the school’s abilSuperior glass performance can help achieve LEED credits in the following categories: I Sustainable Sites (SS) Credit 1, Site Selection I Energy & Atmosphere (EA) Credit 1, Optimize Energy Performance; I Materials and Resources (MR) Credit 1, Building Reuse; I MR Credit 5, Regional Materials; I Indoor Environmental Quality (EQ) Credit 2, Increased Ventilation; I EQ Credit 7, Thermal Comfort; & I EQ Credit 8, Daylight & Views. ity to qualify for a LEED Silver designation. This high school facility consists of renovated and newly constructed buildings totaling 432,000 square feet. The use of suspended film insulating glass enabled project engineers to specify a smaller HVAC system, which provided considerable up-front cost savings that made the ROI of the high performance insulating glass much more attractive than otherwise would have been the case. Consider the numbers. Specifying suspended-film insulating glass cost Manheim about three times that of generic low-e glass, saving 40 percent in annual energy costs. The payback: 11.5 years. However, factoring in a $90,000 up-front savings by being able to specify a smaller HVAC system reduced the payback to 6.5 years. This “holistic” approach to green design, in which building components are selected as part of an integrated system to achieve the greatest cost savings and total energy performance, is precisely how LEED architects are designing the “greenest” buildings today. being, window glass specifically, and the building envelope more generally, must be viewed together with all other building components as an integrated system to maximize desired conservation results at the most affordable cost. Understanding the potential of film-based, multicavity 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. SLDT About the author: Bruce Lang is Vice President of Marketing & Business Development at Southwall Technologies, Inc., in Palo Alto, CA. He can be reached at blang@southwall.com. For more information go to: www.southwall.com Conclusion When facility managers are assessing such issues as energy efficiency, greenhouse-gas emissions, occupant comfort and well Circle 113 • or www.SLDTonline.com/webcard www.SLDTonline.com 21 http://www.southwall.com http://www.westernexcelsior.com http://www.westernexcelsior.com http://www.SLDTonline.com/webcard http://www.SLDTonline.com

Table of Contents Feed for the Digital Edition of Sustainable Land Development Today - February 2009

Sustainable Land Development Today - February 2009 Contents Our Voice Modern Flood Disasters Origin of the Sustainability Movement SLDI in Focus Calendar Build Smart Product Innovation Takeoff and Cost Management Industry News Products & Services Advertiser Index Editorial Board SLDT Resources Last Word

Sustainable Land Development Today - February 2009

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