“Using high-performance glass to bring more natural daylight into buildings, an important strategy for green building, dramatically reduces energy usage and provides a better work environment”, said R…
“Using high-performance glass to bring more natural daylight into buildings, an important strategy for green building, dramatically reduces energy usage and provides a better work environment”, said Russell Huffer, chairman and chief executive officer of Apogee Enterprises, Inc., in a keynote speech to the Building Envelope Contractors Conference on 17 February 2009 in Las Vegas. The event was hosted by the Glass Association of North America, serving flat glass manufacturers, fabricators and glazing contractors. Mr. Huffer went on to say, “Today“s architects, building owners and developers value the look of the glass incorporated in a building“s facade, as well as the view and daylighting provided by floor to ceiling glass. Using high-performance glass provides these benefits while lowering ongoing energy costs, which is why it has become an important design strategy for many green buildings”. He said recent studies have shown that green buildings have higher occupancy rates, lease rates and resale values, adding to the already compelling energy savings. “Daylight is approximately half heat and half light”, said Mr. Huffer, who added, “Today“s highly energy-efficient glass and windows control both the heat and the light. Proper window selection and design will reduce up-front heating and air conditioning system costs, cut ongoing peak electricity and cooling loads (thereby avoiding costly peak demand charges), and ease the need for new power plants”. He was citing the book, “Window Systems for High Performance Buildings”, written by principals from the Lawrence Berkeley National Laboratory and the University of Minnesota Center for Sustainable Building Research. “Making greater use of energy-efficient glass and windows in commercial buildings is especially critical since these buildings consume almost 20% of the country“s energy and over 35% of its electricity. Artificial lighting and air conditioning alone consume nearly 40% of the power used in these buildings”, said Mr. Huffer. “In addition, over half of existing commercial buildings have single-pane glass and over 65% is clear, uncoated glass (which does not manage heat and light), according to Department of Energy statistics”. “Using coated, insulating glass that manages both the light and heat has a big impact on reducing energy consumption”, he said. It can reduce lighting, heating and air conditioning consumption in a typical commercial building by over 25% compared to single-pane uncoated glass, according to the Lawrence Berkeley National Laboratory and University of Minnesota experts. In addition to harvesting daylight for lighting, the other key green opportunity in building facade design is in using high-performance aluminum systems to frame glass. These systems reduce the transfer of heat and cold between indoor and outdoor environments, and are especially effective in cold-weather climates and high-humidity conditions. In closing, Mr. Huffer warned that there can actually be too much light coming into buildings, adding to air conditioning costs and causing fading and glare. “Today, the preference is for light, bright buildings that transmit high amounts of visible light, rather than darker glass facades, which would manage more of the light”, he said. “However, with large amounts of glass, ideal visible light transmission is below 50%”. Mr. Huffer recommended the use of high-performance glass that allows less than 50% of the visible light into a building, in combination with light shelves or light-reflecting material just below the top portion of the glass to redirect light to the ceiling in order to achieve optimal results: comfortable levels of abundant natural light that enable a dramatic reduction in artificial light and generate very little heat, fading or glare