Sky's the Limit
When it comes to green features and sustainable design in data centers, lighting design does not get a lot of attention, after all, there is so much focus on energy savings from newer technologies in cooling, IT equipment, and power generation, which account for more significant energy savings in these critical facilities.
Thanks to LED lighting technology, today our lighting power consumption has dramatically decreased compared to the old days. Lighting power consumption in data centers accounts for approximately 4% of total energy consumption in a data center, by using LED light fixtures instead of fluorescent and HID, we are able to cut down significantly on lighting power consumption.
So, one might ask, what else is there to further reduce, eliminate and save energy from lighting?
In today’s world, data centers are pushing the envelopes to conserve energy to meet sustainability goals and improve power usage effectiveness (PUE). As all building systems are closely integrated to operate a more efficient building, effective and efficient lighting design not only affects its power usage, it also decreases cooling demand since light fixtures dissipate heat.
Effective lighting design will not only help improve PUE, but more importantly, a good lighting design will provide significant cost savings with proper illumination, creating a better visual environment for all operators and users, and hence attract potential clients - particularly for colocation providers.
Lighting Fixture Selection
Too often we find a generic office lighting layout applied in a data hall with lighting from 2x2 or 2x4 troffers in the aisle between the racks. This puts lights where you want them but lacks focus and efficiency to where you actually need them.
Data hall rack layouts are much like book stacks in the library, vertical plane illumination is more important than a horizontal plane, to make sure technicians can see and service the racks from top to the very bottom server. An energy-efficient, asymmetrical LED stack light would be a good design solution in server rack aisles to provide proper vertical plane illumination where you need it.
Lighting sensor control
A good, effective lighting design cannot be done with just proper fixture selection, it needs to be combined with proper lighting control in order to achieve sustainability. TIA-942-A provides guidance on data center lighting design with three levels:
Level 1 is designed for unoccupied conditions, with enough illumination for video surveillance equipment.
Level 2 is designed for initial entry to the data hall and to provide sufficient lighting for safe passage in the hall.
Level 3 is designed for occupied space, to provide sufficient lighting for maintenance of equipment, with 500 lux in a horizontal plane and 200 lux in a vertical plane.
Grouped or zoned LED fixtures controlled with multiple smart, dimmable occupancy sensors per zone can be programmed to provide proper light levels when and where you need them. When the data hall is unoccupied, the lights can be dimmed to a minimal level enough to support video surveillance, without having the entire data hall lights on full brightness. As you enter the data hall, the individual occupancy sensor will turn on the lights to a pre-programmed level, and ‘follows’ you as you walk around to provide a sufficient and safe light level for navigation.
Once you have reached the server rack, the sensor will then turn on to full brightness to support maintenance tasks. These smart, dimmable occupancy sensors will provide lights only where and when you need them, to minimize energy consumption.
Lighting design should be viewed not as a standalone design, but rather as part of the entire building system, as it contributes to its overall efficiency. As technology thrives, sensors are getting smarter every day. Since control, monitoring, and building management systems are all a necessity in data centers, why not integrate lighting occupancy sensors into a combination sensor/control device, creating a device that can perform multiple functions in one? Today, there are sensors on the market that can detect motion to turn lights on/off, as well as sensing temperature and providing energy metering all at once. These combination sensors can be tied into building a BMS system to enhance overall building monitoring and control, and in addition, provide more robust security measures with motion detection.
Take the Next Step
LED is one of the most efficient light sources today, but even with LED lighting technology, there are still some drawbacks. LEDs are powered by DC current, and in order to operate a LED fixture, one will need a ‘driver’ to convert AC voltage to DC. This driver is often built into the fixture housing itself and creates and then dissipates heat when energy is converted to drive the LED light, which means more heat gain in the data hall and hence puts loads on cooling units. One of the options to eliminate heat gain is to take the driver out of the LED fixtures. There are fixtures today that offer ‘driverless’ LED fixtures called PoE lighting. These fixtures share a central driver remotely, then power and control are supplied via low voltage Cat5/6 cables to each fixture. This will help take the heat gains out of the data center aisles and reduce loads on HVAC systems even further as well as provide a precise means of controlling fixtures.
As you can see, through proper lighting design via fixture selection, dimming controls, and efficiency measures, a significant amount of energy can be saved, but there are always more options to evaluate as we head toward a sustainable future. This is where we as professionals think outside of the box and find different alternatives to reduce the carbon footprint. Since by nature light reflects off lighter, whiter surfaces and gets absorbed in dark, black surfaces, there will be more light reflected in a room with lighter color walls and ceilings, than a room with darker shades.
There are studies on utilizing white color server racks instead of traditional black. By doing so, not only the visibility improves dramatically inside of the rack, the quantity of light fixtures required to light the entire data hall can be reduced up to 25% or more, hence saving more in material and installation cost, electric power consumption, and reducing cooling demand even further.
As data center design professionals strive for a more responsible and sustainable future, the sky is the limit. Who knows what other innovations will come around the corner tomorrow?
Please contact us at EYP Mission Critical Facilities regarding any questions or needs around data center lighting design.
Angelica K. Hermanto, PE, LC, LEED AP, is an energetic and result-driven senior electrical engineer with almost 20 years of experience and expertise providing power distribution, fire alarm, lighting, and low voltage system designs within various building sectors.
Angelica is a senior electrical engineer at EYP MCF, she is an experienced project manager in leading multi-discipline design professionals and has a diverse background in project management, engineering design, and study of electrical distribution, emergency power, lighting, and fire alarm systems.
Angelica holds a Bachelor of Science degree in Architectural Engineering from The Pennsylvania State University. Angelica also holds a Lighting Certification from the LC (National Council on Qualifications for the Lighting Professions, NCQLP), and is a LEED accredited professional.