People have fundamental needs that must be met in order to survive, which include: oxygen, water, food, sleep, and shelter. They also have secondary requirements, one of which is daylight. When thinking about how buildings can keep people healthy, it is important to remember that daylighting is essential to wellness, in fact, human circadian rhythms are dependent on it.
What is Daylighting? Daylighting is the art of placing apertures into buildings to control either direct or indirect sunlight that penetrates the space to provide interior lighting. People have been harvesting daylight for thousands of years. The ancient Egyptians were using windows covered by reed mats in 1500BC. While the principle remains, the technology has developed: first by using shutters, then glass, and now, translucent panels, sun pipes, and smart glass.
In architecture, daylighting has always been one of the most important aspects of design, with buildings being planned around movements of the sun to capture the most lighting. This meant that houses in the Northern hemisphere had fewer windows facing North than facing South. The opposite was true in the Southern hemisphere. Then, with the advent of electrical lighting, daylighting became less important and purely aesthetic or utilitarian. But with artificial lighting people miss out on the proper wavelengths of light required to maintain proper circadian rhythms and bodily functions. Concerns about the carbon footprint of buildings have also made it important to reduce electricity used by artificial lighting and minimize HVAC usage related to solar heat gain and thermal performance. Now, architects and designers are placing more and more emphasis back on daylighting and the benefits it provides.
In science, computers can now run daylight modeling exercises as well as generate lux levels, daylight autonomy reports, levels of radiance illuminance, and glare pattern analyses. This technology can find that ‘sweet spot’ between lighting, visual comfort, climate, warmth, and health benefits.
In art, diffuse daylighting is managed to maximize visual comfort and acuity to improve productivity and human performance. It can be used to highlight architectural features and to bring accents to different spaces. By allowing full-spectrum color rendering, daylighting can provide an ideal space for showcasing artwork.
Transparency vs. Translucency
In order for a design to be successful, it is vital to control the amount of light entering a building through windows. Whether it be preventing excessive solar gain or mitigating glare and hotspots, sunlight has always been constrained using sunshades, brise-soleil, curtains, blinds, louvers, or shutters. Transparent mediums have no built-in filter, which is why translucent solutions that diffuse daylighting are popular. Diffused solutions protect against issues such as light pollution, unlike transparent ones, while still allowing for adequate natural lighting. The broad diffusion of light over a large area also means that more usable light penetrates deeper into the interior space, allowing excellent visual clarity. Furthermore, it has been shown that diffused daylight offers other benefits over transparent options. This goes from the calming and attractive ambiance to enhanced concentration and better responsivity compared to traditional glazing.
Translucent Sandwich Panels
There are three traditional methods for allowing daylight into buildings: Glass, Polycarbonate, and Fiber-Reinforced Composite Panels. Each has distinct advantages and disadvantages.
Glass is the oldest way of allowing natural light into a building. Since Roman times, it has been used to allow light into spaces while blocking out dust, dirt, and wind. Its transparency offers unparalleled visual freedom with inherent biophilic advantages of linking people to nature. However, glass also has several disadvantages. It is heavy, inflexible, and fragile, which causes installation challenges. It also provides relatively poor thermal properties and needs a secondary solution to control solar gain and glare.
Polycarbonate sheeting offers a stronger, more durable, and lighter alternative to glass and helps block harmful UV rays, but it also has several disadvantages. It can be easily scratched and become discolored and brittle over time. In addition to poor impact resistance and structural load capacity, it has very low levels of thermal efficiency and is sensitive to heat.
FRP (Fiber-Reinforced Composite Panels) panels offer distinct advantages over both glass and polycarbonate in terms of thermal insulation (which can be the same as an insulated cavity wall). In addition, translucent sandwich panels offer the highest protection and resistance to wind-borne debris, impact, fire, abrasion, and point loads. Although these panels may sometimes be more expensive than other options, with FRP’s high-performance benefits including low maintenance, energy savings, and durability, the initial cost is offset by a greater life-cycle value. Lastly, while the translucency will not provide a view to the outside, it is perfect if you want line-of-sight protection.
Sometimes, incorporating more than one product offers the best solution. For example, you can achieve the performance benefits of an FRP panel, while incorporating vision glazing for a connection with nature.
Why Sandwich Panels?
The unique composition of Kalwall FRP Sandwich Panels offers superior benefits compared to alternative options in every aspect; from safety and security to weatherability and energy efficiency.
- The aluminum, or thermally-broken grid core with interlocking I-beams, gives sandwich panels incredible strength in a light-weight system, making them substantially lighter when compared to the glass equivalent.
- Sandwich panels are structurally sound, with an outstanding load capacity that makes them man-safe.
- The strength of the panels themselves facilitates larger spans with fewer supporting substrates. It is possible to obtain spans up to 80 feet (25 meters) – unheard of with polycarbonate or glazing.
- An important aspect of using FRP is it's innate shatter/impact-proof nature, making it suitable for use in areas of high security or those at risk from blasts. It is increasingly used in airport design and in areas deemed as high-risk, high-value, or target-rich. These include man-made risks such as terrorism or explosion venting to extreme weather events such as hurricanes.
- When filled with insulation or an aerogel, sandwich panels offer unparalleled thermal performance. The most insulating sandwich panel can achieve a ‘U’ value of .05 (0.28W/m²K), the equivalent of a cavity-filled solid wall.
- In addition to superior thermal performance, a translucent sandwich panel offers the energy efficiency of optimal daylighting design. Utilizing diffusion, the sandwich panel can transmit up to 20% visible light that is scattered deeper into spaces without glare or hotspots, reducing the need for artificial lighting and controlling solar heat gain.
FRP sandwich panels are increasingly being specified as the material of choice as the demand for sustainable, high-performance products increases. The self-supporting nature of sandwich panels, coupled with their lightweightedness, reduces the need for supporting structures. Not only is this aesthetically more pleasing, but it curtails a project’s carbon footprint (as well as saves time and money). The exterior face of the sandwich panel is color stable and includes a permanent glass erosion barrier with a UV-resistant, self-cleaning surface. This means that normal rainfall helps to keep the surface free of dust and dirt while at the same time retaining its original color during the weathering process. Furthermore, the inclusion of an erosion-prevention barrier protects the interior from weather exposure and the risk of fiber-bloom, cracking, and crazing.
Maximizing daylight is an integral part of sustainable design. Translucent panels have the ability to diffuse large amounts of usable light with a relatively low level of light transmission. Less radiant energy is transmitted and this, coupled with diffusion, mitigates hot spots that are common to other light-transmitting sources. It also throws evenly-distributed light further into an interior space, reducing the need for artificial lighting and the loads on mechanical systems.