The concept of daylighting isn't necessarily a new idea: Before the invention of electric light, the incorporation of daylighting was a necessity for those in the business of building design and construction. Along with Thomas Edison's convenient discovery came a whole host of new design possibilities that steered professionals away from the need to design a building around the sun. But now, nearly 130 years later, we're getting back to basics ... or are we? Most daylighting designers and experts agree: The concept of today's daylighting design is innovative, distinct, and unlike notions of the past. Even as recently as just five years ago, Joel Loveland, director of Seattle's BetterBricks Daylighting Lab and associate professor of architecture at Seattle's University of Washington, remembers when conversation about daylighting revolved around electric lighting controls. There was very little discussion about bringing the daylight into the building. It was all about controlling the electric light,” he explains.
But engage in a dialogue with a daylighting expert on the topic now, and you'll find that the focus of the conversation is shifting. Today's goals in terms of daylighting design involve appropriate incorporation of the diffuse light of day” into facilities, describes Loveland, whether that light is sunlight or the light from an overcast sky.
Since there are many things to take into consideration when dealing with this particular topic, we can't tell you exactly how to go about achieving good daylighting design in your particular facility; but we can answer some of your most pressing questions to make daylighting design decisions a little bit easier.
Sunlight and daylight - are they the same?
Despite what many facilities professionals might think, daylight does not equal sunlight. Daylight is cool in color and temperature, and by definition, it actually involves keeping direct sunlight out of buildings and bringing diffuse light in. Glazing systems, shading systems, daylight harvesting instruments, and devices such as light shelves and solar sensors are all quality approaches that need to be considered in order to distribute the light of day properly; and to ensure that the incoming daylight works with (not against) your other building systems (HVAC, electric lighting, etc.).
Even sunlight can be somewhat cool in color and temperature, but it's hot - in its effects on a building's HVAC and lighting systems. The concentrated amount of visible light and heat it generates aren't ideal for lighting spaces. It may cause glare, discomfort, eye strain, overheating, and can fade interior finishes; and those problems are just as detrimental as not having any daylighting at all.
Our facility is located in an area with many overcast days. Is daylight even an option in locations that aren't frequently sunny?
Daylighting is an option. Almost every state provides a suitable environment for incorporating daylight; even areas that are often overcast offer abundant diffuse light, which is ideal for good daylighting design. "To let the daylight in, you do pay a small price if you're in a very cold environment. Windows are not as good insulation as walls,” explains Jim Benya, IALD, PE, principal at Benya Lighting Design, Tigard, OR. But the overwhelming majority of the United States is appropriate for daylighting.
"The New York Times wants a LEED-rated building, so they're daylighting it. It's proof in the pudding. Instead of people in New York saying, 'Oh, that daylighting stuff - it's just for people in California,' one of New York's most prominent new buildings is going to be daylighted. I think that's progress. If there's one building that says '[daylighting] is not a southwest desert California initiative,' that's it,” Benya says.
The LEED (Leadership in Energy and Environmental Design) Green Building Rating System is a voluntary, consensus-based national standard for developing high-performance, sustainable buildings from the Washington, D.C.-based U.S. Green Building Council (www.usgbc.org).
How will my building systems benefit from the incorporation of daylighting?
In terms of general system expenses, overall operation costs will go down if your daylighting is designed correctly. Good daylighting allows electric lights to be dimmed or turned completely off during the day (assuming the weather cooperates), when the majority of other facilities have their lights on. Keeping your lights off during these peak demand periods (when utility companies sometimes charge higher rates) will save money. Daylight also produces less heat per unit of illumination than electric light, saving on cooling costs for your facility. When we have extreme heat or cold waves, our electrical systems begin to break down. It's caused by the fact that we're operating too close to the capacity edge of our systems. So we have to have rolling brownouts, rolling blackouts, and other things to compensate. If we were to daylight buildings, we would gain back a pretty significant portion of our system - a few percent - and when we're talking about running close to the edge, a few percent is a huge number,” says Benya. [Daylighting] rescues or recaptures a portion of the generating capacity of our current systems without us having to build any more power plants. It's a form of conservation, it's a wonderful opportunity to solve system [capacity problems], and it makes buildings more energy efficient.”
How does good daylighting play into profitability and the productivity level of building occupants?
We're sure you've heard it before: Daylighted schools report better test scores; big-box retail stores with daylighting bring in more dollars per square foot; residents in senior-living facilities sleep better and live longer when regularly exposed to daylight; hospital patients located next to windows recuperate more rapidly than those farther away from daylight and views. The evidence is everywhere and the list is continually growing: Daylighting reduces absenteeism and turnover, and increases health, happiness, and productivity - all of which translates easily into dollars.
The biggest benefit of daylighting is the impact it has on people in the space. "If it wasn't for people, we wouldn't be designing interior environments. Your highest overhead walks into the office on two legs every day. The cost of loss of productivity is incredible to a corporation,” says Stefan Graf, IALD, principal at Ypsilanti, MI-based Illuminart.
To further support productivity benefits, Loveland refers to Pittsburgh-based Carnegie Mellon research studies: They're finding that good design, which includes daylighting, can provide up to a 20-percent uptick in productivity. "Bad design (no daylight, a disconnection from the outdoors) can cause up to a 20-percent downtick in productivity,” he says, providing an example: "Assume the cost to employ a worker is roughly $75,000 per year. If that employee works in approximately 150 square feet of space that originally cost around $15,000 to build, a 20-percent productivity uptick on a $75,000-per-year worker pays back the entire cost of building construction in the first year ($15,000). These productivity benefits are just huge,” emphasizes Loveland, "and we know that they're most directly correlated to daylight.”
And, according to the U.S. Department of Energy's Office of Energy Efficiency and Renewable Energy, good daylighting may also reduce the loss of productivity in the event of a power failure. Several studies declare that, if an employee in a daylighted space can continue being productive for just an hour during a power outage, the dollar savings are equal to the lighting costs in the employee's work area for an entire year.
How is daylighting related to sustainability and green design?
If sustainable design is important to your organization, then daylighting is essential. "A daylighted building delivers the most [LEED] points, which means, to paraphrase the whole purpose of the LEED system, it's the most sustainable approach you can use. That's why it's become a big deal,” explains Benya. Good daylighting design gives LEED participants credit for providing windows with natural views, for achieving energy savings and efficiency, and (of course) for good daylighting. In fact, Loveland explains that by incorporating appropriate daylighting design, building owners can meet 25 to 33 percent of the requirements necessary to obtain a Silver-rated LEED building.
Doesn't incorporating daylight into my facility mean more money?
Daylighting doesn't have to cost more. "Capital cost savings in HVAC reductions due to reduced cooling loads by well-shaded glass, for example, can be resources to capitalize investments in good windows, good shading, and good electric lighting controls to work with the daylight,” Loveland explains. "We hear it all the time: 'Well, I can't afford that - it's daylighting.' It doesn't have to cost more.” Loveland and his staff recently completed a daylighting project for a Boys & Girls Club in Seattle where a utility incentive for energy savings (due to turning electric lights off) paid for all the skylights in the building.
What do I need to know about daylighting in terms of possible drawbacks?
While overwhelming support shows that good daylighting design improves surroundings and occupant productivity, there are a few things you need to keep in mind. While occupants are often the reason a facility integrates daylighting in the first place, occupants can also be the reason some facilities choose not to take advantage. Getting employees to understand that the lights are off for a reason can be a challenge. As Graf reports, he has worked with clients to integrate daylighting into a space; and he has also watched his clients deal with complaints and work orders once building occupants saw that the lamps weren't turned on. The benefits of daylighting are diluted when employees inadvertently turn lights on or forget to turn lights off when there is adequate daylight (or don't understand the reason for lights being off).
Daylighting can also be unpredictable. The position and intensity of the sun, cloud cover, and shading from nearby hills or other buildings can all affect the amount of daylight available to your building from day to day. For this reason (and because buildings must still be accessible after dark), daylight can't entirely replace an electric lighting system. And as Loveland explains, there is a direct connection between feeling productive and electric lights being on. "We very carefully try to position accent lights that use little energy to illuminate something that puts a little sparkle in the space “something that cues everybody that the place is up and running and is interesting,” he says.
The purpose of your space is also something to consider - if your building consists of leased space and tenants with different tasks are moving in and out, it's harder for professionals to design accordingly.
Another point to remember is that, when designed improperly, daylighting can be trouble. If daylighting isn't designed correctly, it will increase the consumption of energy in the building, and increase it at the worst possible times - especially during the summer. "There's a way to design daylighting so it allows in just the right amount of light - so it doesn't increase the air-conditioning loads compared to a building with just electric lights on, but it reduces your electric load because the lights aren't on,” explains Benya.
We're not planning any new construction. Is it possible to incorporate daylighting into a facility that already exists?
It is possible, but it's not the easiest option. Facilities already standing may not be ideally oriented for correct daylighting design. "You have to be really careful; sun control is such an issue,” says Loveland. "If you have a lot of spaces that are north- and south-facing, and you can retrofit some sort of sun control, then renovation is possible.”
Professionals say that single-story buildings with simple roof structures are easiest to update. Having high ceilings helps, too. Seventy-five percent of commercial space in the United States is one story and is directly under a roof (counting the top floors of the rest of the U.S.'s commercial space, that number is over 75 percent); approximately 60 percent of commercial floorspace is within 25 feet of an exterior wall. This indicates that close to 90 percent of commercial space is accessible to daylight via skylights or windows.
In new construction projects, incorporating a daylighting designer as early as possible is most beneficial “even before architects present design plans. The BetterBricks Daylighting Lab works on more than 150 buildings per year, and Loveland estimates that between 90 and 95 percent of those daylighting projects are new construction.
Is daylighting design something I can do by myself?
No one suggests that you take on the task of achieving appropriate daylighting design yourself. "It's too often oversimplified “the process of integrating the design properly,” says Graf. That's the biggest problem we run up against. People don't understand what all the complex issues are; there are a dozen different issues with daylighting that should be addressed. [People] take one or two of those and think they've got it - that they understand it.”
Professionals can answer specific questions related to your building, provide life-cycle cost analyses, explain return-on-investment options, and present various alternatives for problem-solving. And although Graf states that more building owners are becoming conscious about sustainability issues and the elements that go into building design, he emphasizes: "It's complex - it's not rocket science, but you should get professional design help with this.”
There are many options for professional assistance in the daylighting world. "The BetterBricks Daylighting Lab sees three or four new projects from northwestern states per week, and offers testing of design ideas by simulating plans via physical or digital models. People who do good daylighting test their solutions to make sure they really work,” says Loveland.
How do I know the design is working for my building and its occupants?
There are some indications you can look for to ensure your daylighting is performing as planned. First: Are the electric lights still on most days? If so, that means something isn't right. If direct sunlight is hitting windows without any sort of exterior or interior protection, that's also a warning that something could be wrong. Direct sunlight will cause glare and discomfort for employees working nearby. Make sure you ask yourself if the daylight is fulfilling original design principles.
"Skylights and windows should both have some sort of shading mechanism (either on the exterior or the interior) - they shouldn't be clear. The idea of a hot spot of light on the floor is very dramatic,” says Benya, but it's not good lighting practice.” If your skylight is bigger than approximately five percent of the floor area of the space it's illuminating, that could also be a problem. Anything bigger than that is probably letting in too much light.
Still unsure? Conduct an informal survey and ask the occupants how the daylighting is working for them.
Leah B. Garris (firstname.lastname@example.org) is associate editor at Buildings magazine.
Do you have specific questions about daylighting design in your facility? If so, experts at the following organizations can offer even more information:
Â• International Association of Lighting Designers (IALD) (www.iald.org)
Â• Energy Center of Wisconsin's Daylighting Collaborative (www.daylighting.org)
Â• Windows and Daylighting Group, Lawrence Berkeley National Laboratory(http://windows.lbl.gov)
Â• Daylight Dividends Program, Lighting Research Center
Â• BetterBricks Daylighting Lab (www.lightingdesignlab.com)