Cloud Lighting — Tips for Data Centers

a guest post by Lisa J. Reed, Lighting Designer

Cloud Lighting – Tips for Data Centers

Of all of the places we expect to see futuristic lighting design and control, it is in the high-tech world of data centers. Unfortunately, all too often this is not the case, and these spaces are illuminated with old technology without regard for the layout of the equipment within the space.

Multiple Lighting Levels

The Telecommunications Industry Association publishes a standard for Data Centers. The latest version is TIA-942-A. A nice summary of the lighting recommendations in this document (and many other TIA document summaries) can be found here. For lighting, three levels of lighting are recommended – Low, Medium, and High.

  • Low Level: Provide adequate illumination for video and security surveillance equipment for an unoccupied data center.
  • Medium Level: Automatic controls of lighting when space is occupied to provide adequate illumination for moving about the space, including the aisles between equipment racks.
  • High Level: When the space is occupied for maintenance or other interaction with data center equipment, light levels need to increase to 50 horizontal footcandles at the equipment being serviced, and 20 vertical footcandles on the equipment. It makes sense that this level of lighting is not required throughout a large data center, but should be zoned so that light levels are increased only where they need to be.

Locating the Fixtures

In addition to creating three brightness levels, a well-designed data center will have lighting locations coordinated with the equipment rack layout. Ideally, light fixtures should be located in aisles, not right on top of equipment racks. To do this, rack plans have to be designed in conjunction with the lighting. Use lights with a wide distribution pattern and vertical footcandles in order to cast light into the equipment racks where it is needed. The design of the aisles should be similar to library stack lighting.

Also, be aware of reflectances within the space when calculating anticipated light levels. White reflects light and makes a space feel brighter, but black absorbs light so that more light (and more energy) is needed to achieve the recommended light level. Unfortunately, most of the equipment on today’s racks will be black.

To achieve the greatest potential energy savings, white data center equipment, racks, and enclosures would create more reflectance for more brightness. This means fewer lighting watts and consequently fewer HVAC watts. Could future integration between disciplines lead to white data center equipment? For now, expect black or dark gray finishes.

Selecting the Fixtures

The historic use of fluorescent fixtures in these spaces is not actually bad. Shadow-free, uniform illumination (the quality of light fluorescent provides) is exactly what is needed in this kind of space. But today the use of LED fixtures allows for lower energy consumption and longer life through integrated controls. Frequent switching shortens fluorescent lamp life, but does not reduce LED life; hence energy is saved while fixture life is simultaneously increased when switching off an LED light. As an added bonus, well-designed LED fixtures may reduce HVAC loads because heat from LED fixtures escapes through the back of the fixture instead of going into the conditioned space.

Controlling the Fixtures

State-of-the-art lighting controls mirror general trends in data center design such as virtualization and automation.

  • Virtualize – Take advantage of LED fixtures and incorporate smart technology for lighting controls and even remote access and control of lighting. Look for a system that is easily expandable for future growth.
  • Automation – Install “follow-me” lights that turn on and off as people pass through a space, or instead of occupancy sensors, consider vacancy sensors (which require the occupant to switch on the lights if they want them on, but will automatically turn the lights off if a space is unoccupied.) For maximum energy savings, use this bi-level option: occupancy sensors for up to 50 percent of the lights but manual “on” switches with vacancy “off” sensors for the rest of the lighting in the space.

In many ways, data center lighting is similar to the lighting for any other space. Use the right light; put it only where you need it; turn it off when you can; use the most energy efficient sources available.

 

Lisa J Reed photo - Lighting Blog

Lisa J. Reed has been attracted to lighting (like a moth to a flame) for 20+ years. She is the Founding Principal at Envision Lighting Design, LLC in St. Louis, where she designs, teaches, and writes about architectural lighting. Connect with Lisa J. Reed on Google+.

 

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