People are complicated creatures. Influencing them to do what we want is a tricky business. In schools, parents and teachers want kids to learn faster and perform better on tests. In the workplace, employers want people to be more productive. In hospitals, everyone wants people to heal and recover faster. And in retail spaces, businesses want people to spend more money. Disparate problems, to be sure, but one simple thing can help accomplish all these goals. Better still, it doesn’t involve snake oil, outlandish claims or participation in multi-level marketing. It’s real, and today MBCI is going to shed some light on it. It’s simple: Daylighting.
What is Daylighting?
Daylighting is the use of external, natural sunlight to illuminate the inside of buildings, replacing as much artificial light with natural sunlight as possible.
Why does it matter?
For one, daylighting is better for the environment and your utility bills. Commercial lighting is one of the largest consumers of electricity. Installing a combination of daylighting and automatic photo-sensing lighting controls and dimmers that actively respond to daylighting amounts can reduce your annual lighting energy loads by as much as 55-70%. Those savings can pay for their investment in a few short years, and they also reduce greenhouse-gas emissions and your carbon footprint. Daylighting can also contribute toward LEED® credits, ASHRAE standards, green building certifications and more. As recent history has shown, today’s environmental and health-friendly idea or extra mile is likely to become tomorrow’s mandate.
But the real reason to invest in daylighting is the human reason. Study after study shows that humans do just about everything better when they have more natural light. Whether you’re talking about workers, artists, convalescing patients, children in school or shoppers in a store, everyone performs better with the sun’s rays on them.
Natural daylight offers a variety of benefits. It improves mood, stimulates creativity, provides Vitamin D and creates a more comfortable interior environment. All of this makes for happier, healthier people with more energy – and those happier, healthier, more energized people are more productive, heal faster, perform better and typically spend more.
Being exposed to natural daylight – as humans have been since before we even started walking upright – is what regulates our circadian rhythms. This internal clock is responsible for our daily sleep and wake cycles. You can imagine this clock as being solar powered – without regular exposure to natural light, it doesn’t keep time. This results in sleepless nights and sleepy days. Anyone can tell you that sleep-deprived people have poor attitudes, low energy and decreased productivity.
More Artificial Light Then?
The natural solar spectrum of daylight has a mix of colors that we benefit from. It isn’t replicated by most artificial light sources – even the ones that claim to be “full spectrum.” It lacks most of the blues, and consequently doesn’t power our internal circadian rhythm clock, while causing eye strain and poor visual performance. These, in turn, lead to Computer Vision Syndrome (CVS), eye-related headaches and – you guessed it – decreased productivity.
The benefits of daylighting are real, tangible and measurable. As Jeanne Meister, founding partner of Future Workplace, said, “It’s the invisible factors such as air quality and access to natural light that are often overlooked, yet provide a significant influence on workplace wellness, employee productivity and the overall quality of the employee experience.” Studies such as those performed by Heschong Mahone Group, Northwestern University of Chicago and HR advisory firm Future Workplace found some of the following:
- Employees who sit nearer to windows have increased productivity and are less likely to miss work.
- Daylight resulted in better scores on cognitive assessment tests and improved work performance. In some cases, output was boosted by 6% to 12%.
- Employees who worked under artificial light had 46 minutes less sleep than those near windows
- Surveys showed access to natural daylight and outdoor views outranked on-site gyms and a pet-friendly workplaces.
- Compared with students with the least daylighting, those with the most progressed 20% faster on math tests and 26% on reading tests in one year.
- In highly daylit rooms, the average length of hospitalizations decreases by 16% to 41%.
- Daylighting is positively and significantly correlated to higher sales, which has resulted in both Costco and Wal-Mart becoming the largest end-users of skylights.
We can talk about research and quantitative this and that, but doesn’t it also just make intuitive sense? We all prefer daylight. It simply makes us feel better. So, how can we bring more daylight into today’s buildings?
More Isn’t Always Better
Windows, atriums, skylights and devices like tubular daylighting devices (TDDs) allow sunlight in, but the sun is a powerful force and can be challenging to effectively harness. While the typical comfortable indoor light level is around 500 lux, full sunlight is easily over 100,000 lux. It can be harsh, highly directional, hot, damaging to surfaces and produce intense glare.
While daylighting isn’t as simple as opening up more walls and roofs to the sun, it has become much more achievable. According to a recent MBCI white paper by C.C. Sullivan, as recently as a decade ago, skylights and TDDs were costly and required extensive detailing and trade coordination. “In the last few years, however, skylight assemblies are significantly improved. Effective daylighting tools and technologies are producing new and successful ways to bring healthy, natural light deep into buildings.”
What’s more, 3D planning technologies, energy modeling tools like EnergyPlus and skylighting-specific products like SkyCalc make it easier than ever to properly simulate, visualize and plan daylighting methods. These help in the planning process, routing light where it’s needed, diffusing it to appropriate levels, and identifying what might be needed to protect against unwanted glare and solar gain – like louvers, blinds, translucent glazing, light shelfs or the oldest form of seasonal light diffusion, a deciduous tree. They can even calculate projected energy savings.
The most common daylighting source is also the most obvious. Windows allow in daylight, but without light shelves or similar devices, that light tends to illuminate areas nearest the window too brightly, while it doesn’t penetrate further in. Clerestory windows, or windows higher up on a wall can penetrate deeper, and when bounced off a light-colored, reflective finish, can more evenly illuminate an area.
Traditional windows also admit most of the spectrum of light. This is good, in that we want all the colors, but we don’t want the ultraviolet (UV) or infrared (IR) ends of the spectrum, which are damaging and hot, respectively. Sophisticated new transparent magnetron sputtered vacuum deposition (MSVD) – known as solar control or low-E glass coatings – can split the solar spectrum, blocking IR while allowing as much visible light transmittance in from the sun as possible.
Skylights have made leaps and bounds in recent years. They feature improved optics, glare control and high-durability housings, as well as prismatic embossing which refracts and directs two to four times as much illumination. According to Sullivan, “Leading designs include seamless, all-aluminum construction with built-in roof flashing as well as closed-cell insulation between the roof flashing and reflector surfaces.”
New aperture designs can block 85% of IR and 99.9% of UV light, and many skylights can be equipped with motorized darkening screens, active sun-tracking technologies and hybrid lighting. These integrate electric lighting and controls into the daylighting system to create a seamless lighting system, which when used appropriately not only uses daylight instead of artificial light, but also reduces the building’s cooling load since they admit less IR light and reduce the need for heat-producing artificial light. Skylights such as these can also be easily retrofitted into existing framing.
A Tubular Approach
Tubular Daylighting Devices (TDD) – also known as light pipes, tubular skylight or light tubes – can route rooftop light to nearly anywhere in a building. As Mark Robins explained in an article for Metal Architecture, “TDDs use optical technologies to more effectively capture daylight at the rooftop dome, transfer (duct) that light over long and/or convoluted distances within the building and deliver it to nearly any interior space in a highly controlled and predictable manner.”
TDDs may be tubular skylights with reflective inner surfaces, or optical fibers which channel the light. According to Sullivan, solar light pipes require only a basic roof cut with no curbs. They can be specifically designed to receive maximal daylight at any angle, directing it down into the building in strategic locations. They also address the problems of light intensity, harsh angles, heat and UV degradation with refractive and reflective optics that can selectively harvest and deliver daylight deep within buildings, rejecting undesirable angles of light as well as ultraviolet and heat-generating infrared wavelengths of energy.
A Kohler Co.-operated manufacturing and distribution facility in Texas combined solar light pipes, dimmable fluorescent high-bay fixtures and motion control sensors into a single daylighting system. This forward-thinking approach saved them more than $262,000 annually in electricity costs and cut CO2 emissions by 1,880 tons.
Light Transmitting Panels, Strip Lights and Curb Lights
Another approach is using roof or wall panels which transmit light. Some such units are designed for direct seam or joint integration. Usually constructed of translucent fiberglass, they also reduce the number of roof penetrations required. Light transmitting panels can be a simple solution with metal roofs, as their shape usually matches that of the panel, and long, narrow skylights limit the number of ribs to cut out, which makes for easier installation.
Terms to Know
As with any specialty industry, there is some alphabet soup in the daylighting world, but we can help you get a quick grip on it:
Footcandle (fc): One candle’s illumination at one foot’s distance. Equal to one lumen per square foot and approximately 10 lux.
Lumen Per Square Foot (lm/ft2): equal to one footcandle or 10 lux.
Window-to-Wall Ratio (WWR): the specific value of the area of the window and that of the room façade.
Effective Aperture (EA): Per ASHRAE, the overall amount of visible transmittance of the roof via skylights.
Haze Factor: The amount of diffusion on glazing material.
U-factor (or U-value): The rate at which a window, door, or skylight conducts non-solar heat flow. Unlike the R-value (thermal resistance), lower is better.
Solar Heat-Gain Coefficient (SHGC): The fraction of solar radiation admitted.
Top Lighting: Light that comes in from the roof, whether skylights, TDDs or light transmitting panels.
Side Lighting: Light that comes in through traditional windows, roof monitors or clerestory windows.
Shelf Lighting: The use of a horizontal structure either inside or outside to bounce daylight deeper into a building.
Daylight Factor: A comparison of available outdoor brightness to indoor lighting needs.
We hope this exploration has shed some light on the topic of daylighting, and with any luck you’re dreaming up ways skylights, TDDs, light transmitting panels or other solutions will bring more daylight into your structures. It’s undeniable that daylighting not only provides a return on investment in terms of energy usage, carbon footprint and utility costs – it’s a worthwhile investment in all the people who live, work, learn, shop or play in the buildings we construct together.
Architects have taken notice of this fact as well, and are finding increasingly inventive ways to bring more daylight into buildings. We can expect to see more and more designs incorporating this often-neglected feature, and at MBCI, we’re ready for it. To learn more about installation of daylighting features or to include them in your next project, get in touch with an MBCI representative near you.