You’d probably start thinking about the lights in your data center if they all went out at the same time. But the truth is most data center and IT managers don’t spend a lot of time thinking about lighting. Because today’s economy is forcing most SMEs to decrease cooling costs and make the most efficient use of their space, even items including lighting are worth a look. Do data centers have to spend big dollars on retrofitting light fixtures, or are there other, less expensive solutions that work just as well? What are the proper lighting levels for SME data centers? And can data centers cut costs simply on darker rooms?

Lighting Impact

Ray Dableh, director of research and development at Fifth Light Technology (www.fifthlight.com), says data centers generally don’t focus on lighting because it represents a very small fraction of the total load in the facility. He says, “Unlike a normal commercial building, where lighting represents 20 to 40% of the total electrical load, data centers draw more than 90% of their power in servers. Furthermore, lighting retrofits in data centers are very labor-intensive, with the need for special consideration to air quality and security.”

Dableh says most data centers are vastly overlit, and some simple strategies can go a long way in conserving energy. He says it is important to be aware of the trade-offs of each measure.

According to Jeff Bisberg, president and co-founder of Albeo Technologies (www.albeotech.com), lighting only plays a small part in a data center, but do give it the attention it deserves. “In most small data centers, the folks that own the servers are different than the folks that own the space. The server folks are busy keeping the servers running, and as far as facilities are concerned, they are mainly interested in the cooling system. Very few are willing to talk lighting. Usually the folks that own the space will talk lighting,” explains Bisberg. “The main point, however, is that lighting probably only accounts for 5% of the energy consumption in the data center (that’s my guess), and people are focused on where the problem is greatest—so lighting should only get a smaller amount of time.”

Dark Or Light?

Do data centers need to be as brightly lit as they currently are? Bisberg says yes and no. “Take, for example, the difficulty in commissioning a server; there are many connections to make. If you cannot see well, and you plug in a cross-connect into the wrong port, the impact can be bad. So in this case, over-lighting is perceived to be a good thing to ensure that fewer bad connections are made.”

Bisberg says the main issue is making sure the light is where it needs to be and not in the aisles. He notes, “Light needs to be on the panels, not in the aisles. Unfortunately, server room designers have not figured that out, and the result is an overlit space just to get light into the server racks.” Bisberg says motion-sensing your aisles is also a good compromise and can save a data center up to 75% of the lighting load.

Lighting Strategies

In Dableh’s opinion, data centers can turn to some simple strategies in the quest to conserve energy. “For starters,” Dableh says, “let’s look at removing bulbs. Although simply removing fluorescent bulbs can be done at little cost, doing so will likely significantly reduce the life of both the ballast and the remaining bulbs. We strongly advise our clients not do this. Next, consider retrofitting to a more efficient ballast. This can save significant amounts of power, especially if the existing ballasts are the older magnetic type.” Dableh notes that the vast majority of data centers already use efficient electronic ballasts, so there may be limited amounts of savings available by using a lower power bulb and ballast combination. “The retrofit costs may not yield an attractive payback,” he says.

Dableh continues, “And if you are considering removing your light fixtures, decreasing the number of fixtures does lower the lighting power density but requires large amounts of labor to reposition the remaining fixtures to ensure even lighting distribution.” Dableh says on top of this, some of the fixtures you remove could be powering neighboring fixtures, so you end up with a pretty complicated power wiring issue.

When it comes to saving money in the lighting department, the best way to save, according to Dableh, is to convert the lighting system from a static system to a dynamic system. “In other words, intelligent control is the best way to get savings. Dimmable lighting can lower the lighting power density, without having to remove fixtures, and can dim or shut off lights that are in vacant areas,” says Dableh. “The idea is simple: Provide just the right amount of light, only if and when needed. Advanced dimmable lighting systems use low-voltage occupancy sensors, smart ballast factor tuning technology, dynamic scheduling, and personal control to communicate to each fixture on an individual basis.”

Dableh says the DALI (Digital Addressable Lighting Interface) is a worldwide open communication protocol that transmits information to and from each fixture so that it can be controlled and managed in an intelligent way.

Dableh concludes, “Given that data centers have lighting on the UPS system, reducing lighting power allows more servers to be added to the facility. So there is a big top line, as well as bottom line, impact by using advanced dimmable lighting.”

by Chris A. MacKinnon