A study by Fair Oaks, Calif.-based consultant Heschong Mahone Group, “Daylighting in Schools,” highlights some of the results of daylighting including superior math and reading skills improvement for children in classrooms.
Similarly, a California Energy Commission study discovered that call-center workers with outdoor views performed 10 percent to 25 percent better on tests of mental function and memory recall, adding weight to the case for the crucial role of natural light in human productivity and performance.
The incorporation of natural light in today’s school designs signifies a return to lighting concepts from more than 50 years ago, when the sun was used as a facility’s main light source. While daylighting trends frequently appear in current building designs and facilities, there are several factors to consider before moving ahead with the concept:
Does the glass product accommodate the needs of the building? Daylighting obviously requires an ample amount of glass within the building’s design so it is important for the right type of glass to be specified.
Clemson University International Center for Automotive Research was designed to have an open, interactive environment that would allow ample natural daylight while maintaining energy efficiency.
The design should maintain a balance between high light transmission and low solar-heat gain while preserving the aesthetics of the design. Architects now have a range of options when specifying glass and can tap into the latest glass offerings that provide desirable light transmission with medium- to low-light reflection. High-performance low-emissivity glass offers a variety of visible light transmissions — between 40 percent and 70 percent — while also providing lower reflectivity than previous product. Low-E glass is available in a variety of colors, with emphasis on the neutral range of light gray or green to slightly blue in reflective color.
The right balance also depends on factors such as the occupants of the building, the different elevations of the building, the direction in which the building faces, the amount of sun it receives and the climate.
In some cases, too much light could make it hard for building occupants to see their computer screens. However, a somewhat lower visible transmission with an even lower solar heat gain can be specified to reduce glare.
How will the design impact the building’s energy efficiency? To achieve maximum energy savings, it’s important for architects to understand that not all low-E glass is created equal.
Coated glass made using sputter-coating technology — metallic layers are applied in a vacuum — provides high visible light transmission and optimal transparency, and dramatically lowers heat gain or loss. These types of coatings are sometimes called soft coats.
Sparta High School, Sparta, Mich., was designed to utilize natural sunlight without affecting energy efficiency.
It is common for heat load from solar transmission to burden the cooling system. Energy costs rise higher than they should because the air-conditioning system overworks to maintain a comfortable temperature throughout all sections of the building. In addition to controlling the solar heat gain inside a building, the correct glass can affect the size and efficiency of the HVAC equipment and daylighting systems. Minimizing solar heat gain through low-E coatings can actually reduce the size of an HVAC unit.
Is the building going for LEED certification? The use of daylight is being encouraged as a light source for today’s buildings due to the substantial energy and environmental benefits.
Incorporating low-E glass into daylighting designs can help a facility earn LEED credits.
Utilizing the correct low-E glass is imperative for maximized energy savings since it actively works to maintain a consistent, comfortable temperature within the building and reduce the burden on heating and cooling systems. LEED certification often requires a building to demonstrate a certain percentage in energy savings–reducing the size of the HVAC system and using less electricity will help these savings be realized.
Is the design within the budget? The up-front costs for daylighting designs using the low-E coatings may be somewhat more than traditional school designs, but if the correct glass is used and the building’s energy efficiency is well planned, the immediate savings on capital can often provide a quick payback.
According to the National Center for Education Statistics, 72 percent of the energy expenditures in educational buildings is used for electricity. Adding natural daylight and reduced solar gain through can reduce the building’s energy consumption and costs and allow the school to use its capital dollars more efficiently and in a more environmentally sustainable way.
Christopher G. Dolan serves as director of commercial glass products for Guardian Industries Corp., a position he has held since 2002.