It seems everywhere we look there is some kind of statement or message about green building and the environment. While the greening of America is a noble trend, as an architect, it can be time-consuming to wade through all the information and figure out what is not only truly good for the environment, but good for your and your customer’s bottom line. Implementing natural daylighting is an easy way to gain a quick return on investment while going green, and doing so can also contribute to LEED credits.
Daylighting Options
There are two types of daylighting options, toplighting (skylights and roof lights) and sidelighting, often called clerestory windows. Shelf lighting, adding a reflective shelf in front of the glazing, is also a popular solution. Today, in addition to traditional agricultural uses, natural daylighting is used in high-end architectural projects, retail facilities, hospitals, schools, offices, warehouses and more.
Energy Codes and Energy Savings
Energy codes-ASHRAE 90.1 2010, ASHRAE 189.1, California’s Title 24, International Green Construction Code
(IgCC)-focus on modifying building construction and renovation practices to save energy in safe, practical ways. First and foremost, daylighting saves energy. Introducing natural light into the building means artificial lighting can be turned off or dimmed. This can be done manually (open loop), or there are photocontrols available that use sensors to read the natural light coming in the room and will adjust the artificial lighting automatically (closed loop).
In addition, artificial lighting creates heat inside the building. Having the ability to dim or turn off the artificial lights greatly reduces the cooling load. According to the U.S. Department of Energy (DOE), two of the highest energy uses in a building are lighting and HVAC. Determining exactly how much energy can be saved depends upon the energy efficiency (U-factor) of the skylights or sidelights, as well as the type of artificial lighting being dimmed or switched off.
Other Benefits of Daylighting
To understand how daylighting affects humans, we have to delve into physics a little bit. The electromagnetic spectrum of radiation transmitted from the sun is called the solar spectrum, comprised of ultraviolet (UV) light, visible light and infrared light.
The visible light spectrum is essential for proper visual performance, and to reduce the effect of metamerism, specifically illuminant metameric failure, where colors will appear differently in different sources of light. Put more simply, natural light is the best source for color comparisons. Artificial lighting, even the options that claim to be full spectrum lighting, lack most of the blues in the spectrum, causing eye strain and poor visual performance.
Natural daylight also offers benefits that create positive changes in people. Humans operate under a circadian rhythm. This physiological process supplies us with an inner clock. The introduction of daylight is one of the most important factors in keeping this process in line. When the circadian rhythm is upset due to lack of daylight, this can contribute to a multitude of problems including hormonal imbalances, sleep disorders and mood disturbances. Along the same lines, daylight is also beneficial in preventing such afflictions as seasonal affective disorder (SAD) and even sick building syndrome (SBS).
Daylighting Integration
There are many configurations available for skylights, including a checkerboard style, ridge-to-eave, mid-span, continuous or horizontal, and saw tooth or north lights, or side lighting (vertical or horizontal). When determining where to place sidelights, a north or south facing wall is best for more even lighting for longer portions of daylight hours. East and west facing sidelights often have harsh glares and provide light for only short portions of the day. For additional or total light diffusion, optional pigments can be added to the glazing to diffuse the natural light, reducing glares and hotspots, and helping to spread the light throughout the structure of space.
Installation
Installing polycarbonate skylights or sidelights is relatively easy. It is virtually the same as any corrugated metal roofing or wall panel with the exception of pre-drilling holes and the type of fastener used for proper installation. The pre-drilling is necessary to allow for expansion and contraction, as polycarbonate expands and contracts at a different rate than metal. Rubber butyl tape or a compatible silicone caulk, along with positive drainage, should alleviate any leakage concerns with skylights. Leaks typically aren’t a concern with sidelight applications. Be sure to read the entire installation guide for any chosen skylight or sidelight system to ensure proper panel performance.
Life Expectancies and Warranties
Most polycarbonate manufacturers offer some type of warranty against discoloration and impact resistance against hail for up to 10 years, although many polycarbonate installations have been in place for 20 years or more. The impact resistance of polycarbonate is superior to other materials available on the market. Commercial warranties might be a bit different considering the product might be installed in an area where it could be subjected to chemical attack (i.e., waste treatment facility or harsh cleaning compounds). It is important to note that UV inhibitors add to the life expectancy of polycarbonate panels. A co-extruded UV layer creates a more permanent bond and will not delaminate or crack.
Summary
The economical and societal impact of implementing natural daylighting outweighs the use of artificial lighting. Daylighting not only saves energy, it also produces positive results in human performance and moods. So, while the electric bill is going down, the shoppers are buying more in retail facilities, the children are doing better on tests in schools, the factory workers are more productive, and the cooling load in the building is dramatically reduced.
Polycarbonate skylights and sidelights allow for full spectrum lighting to be introduced into the building to produce those positive effects and offer the opportunity for LEED credits for your project. As energy codes become more stringent, daylighting is going to be even more important in both new construction and renovations. Implementing daylighting in your current projects will put you ahead of the competition and provide valuable experience for the coming years.
—
Charlene Riegger is the marketing communications team lead at Kutztown, Pa.-based Palram Americas. For more information, visit www.palramamericas.com.