Server Rooms: Racking up energy savings

Server rooms use a significant amount of energy, and surveys suggest that much of that energy is wasted. The Uptime Institute estimates nearly 30% of servers are unused, with each costing about $4,000 to operate and maintain. Those extra servers also generate a lot of heat, driving up air-handling system costs.

Although servers are critical for data processing and storage, that kind of waste doesn’t compute with a healthy bottom line. Fortunately, there is a number of cost-saving measures facilities can take to help contain server room energy use.


Consolidate inventory servers to track the number of applications running on each. Identify unused servers or units with low utilization. Consolidate, reassign or switch off servers to optimize usage.

Go virtual

Traditionally, server room operators installed one physical server for each application. Server virtualization uses software to convert one server into a virtual machine that can perform multiple tasks. Virtualization combines processing power into fewer units operating at a higher capacity. You’ll reduce energy consumption and waste, and save space as well.

Vary fan speed

Server room air-handling fans consume a lot of power. Most fans run at a constant speed, while server load fluctuates. Variable frequency drives (VFDs) save energy by adjusting fan speed according to demand. However, VFDs can cause harmonic distortion, which may result in costly downtime and loss of critical data. Work with your supplier to ensure you have the appropriate protections in place.


Air-side economizers bring in cool outside air and distribute it to the servers, reducing the need for air conditioning. Economizers are integrated into the central air handling system, with ducting for intake and exhaust air. Because servers require continuous cooling, economizers are effective even in hot climates, where they can take advantage of cooler evening temperatures. Water-side economizers eliminate concern about outdoor air contaminants.

Blow hot and cold

Servers typically take in cold air through the front, and exhaust hot air out the back. Arrange servers in parallel rows so that the front of the servers are facing each other. This will improve air flow and reduce the need for cooling. Hot aisle/cold aisle arrangements can reduce air-handling fan energy use by up to 25%, according to the U.S. Department of Energy.

Raise the temperature

ASHRAE recommends a server inlet temperature setting of 65°F to 80°F, yet many server room operators set temperatures as low as 55°F. Raising the temperature to within the recommended range can produce significant energy savings.

Looking to replace older servers? Purchase ENERGY STAR®-certified units, which are 30% more energy efficient than standard models and deliver more processing power. And if your facility needs upgrades, you can receive Power Moves® rebates for qualifying energy efficiency improvements. Contact your local electric cooperative’s energy advisor for details.