Many data center owners are ignoring an opportunity for power-consumption saving.
By Mark Hirst, Cannon Technologies
The pressure to cut power consumption in data centers is leading many facilities managers to get more creative. Having raised temperature and lowered power consumption, these managers are still looking for savings.
Once you have dealt with the obvious big drains on power, it can be hard to discover other areas in which to save money. Getting creative with the resources at hand can deliver some unexpected savings.
For example, reusing hot air to heat loading bays, offices, reception and canteens is something that very few data centers do. Yet in the winter, they spend money to heat these areas, which is a waste.
The use of solar panels to provide enough power to light offices, reception and loading bays is also underway at some facilities. Even though these deliver some savings, there are still more to be made. All it needs is a little lateral thinking.
Every data center has looked at the issue of lighting. In the United States, electric lighting is blamed for 25 percent of the national power consumption. Inside a data center it is a little less than that, but the figure is still 3 to 5 percent of the power costs for a data center facility.
An increasingly common solution is to use intelligent lighting solutions that only come on when someone is in the data center. These systems help to reduce costs but have to be properly designed. If someone is working inside a rack, they may not trigger the lighting system frequently enough to keep the lights on. This can result in being plunged into darkness and having to keep stopping to walk down the aisle to force the lights back on.
Another solution is to use longer-life, low-power bulbs. This can result in several savings. Longer life means fewer replacements. This leads to lower inventory costs. Fewer replacements also mean less time spent by maintenance crews changing light bulbs.
The type of light fitting also has an impact on the efficiency of the lighting. Direct light can be harsh and too much reflectivity off of surfaces is hard on the eyes. One solution is to use recessed light fittings so that the light source is not directly reflecting off of a surface.
A second alternative for light fittings is to use a lighting channel. This works by creating a scatter effect on the light, giving it a more-even distribution around the room.
It takes more light to illuminate a server room than an operating-room theater. The reason for this is the way light is absorbed by color. The light reflective value (LRV) of a color determines how much light the color absorbs. Black reflects as little as 5 percent of the ambient light while gray-white reflects up to 80 percent of the light.
This means that a server room filled with black cabinets, many of which are filled with black cased hardware, absorbs a lot of light. For this reason, it is not unusual to find engineers working at the back of cabinets wearing headlamps to ensure they have enough light to see by.
Gray is the new black
Changing the color of the server cabinets from black to gray or even white can make a significant difference to the amount of available light in a room and the cost of lighting that room.
Using the LRV of the server cabinet color, it is not unrealistic to see a saving of around 30 percent on the lighting in a data center. It may even be possible to get a greater saving, but one of the problems of making an environment too bright is that it becomes difficult to work in.
A small, 1-MW data center with 5 percent of its total power consumed by lighting is spending 50 kW just to light server rooms. Reducing that by 30 percent delivers a saving of 15 kW.
The savings are not just on power. The larger the data center, the more it will be paying in carbon taxes. This means additional savings are made through the reduction of power.
An additional benefit is that it creates a more-engineer-friendly environment. If the engineer does not need to use a headlamp, then they can work more easily around the cabinet.
Changing the color of walls, floors and equipment to a higher light reflective value delivers unexpected and unlocked savings. Who can argue with that? ::
Mark Hirst is T4 product manager for Cannon Technologies Ltd. (www.cannontech.co.uk).