FM Issue: Power To The Core
By Carey O'Connor & Henk Vande Wetering
Published in the September 2006 issue of Today's Facility Manager
Currently, the United States loses $80 billion per year due to power outages and interruptions, and the losses are accelerating. Utility demand continues to amplify. So how reliable are power sources? And how reliable will they be in three years? More importantly, how valuable is the facility department’s time and the company’s data?
Anyone responsible for an organization’s data center is expected to maintain data access and integrity without interruption. But there are several key elements necessary to establish consistent, reliable power in these types of facilities.
The old saying “an ounce of prevention is worth a pound of cure” rings true for businesses’ energy equipment. Lighting, heating, ventilation, and cooling have the biggest impact on usage, but these are also the easiest avenues to resolve when addressing costs.
By raising the thermostat setting by just 1ËšF on warm days, a business can save up to 5% on cooling costs. Keeping the daytime temperature up near the recommended 77°F, and turning the thermostat to 84°F or shutting the cooling system off when the building is not occupied will keep costs down.
These recommendations can be achieved automatically by installing a programmable thermostat. For example, a programmed thermostat could reduce cooling and heating loads during unoccupied hours to save up to 10% to 15% on annual costs.
Keeping an HVAC unit in shape is another way to increase efficiency. An air conditioning system typically loses 1% to 2% in output efficiency for every year it operates without proper maintenance. A system check up should be performed at least once a year to avoid a steady increase in cooling costs.
An efficient HVAC system is of little use if windows and doors have cracks that allow outside air to enter while cool air escapes. A 1⁄4" gap can let in as much air as a softball sized hole. Sealing these cracks will help save money and increase comfort levels.
Retrofitting lighting fixtures with T8 lamps and electronic ballasts can reduce electricity consumption by 30% to 40%, depending on the configuration of the lamps. T8 lamps and electronic ballasts also offer better color rendering characteristics, eliminate most light flickering, and generate less heat than T12s, which can help reduce overall cooling costs.
Replace indoor lighting fixtures using incandescent lamps with compact fluorescents, which consume 60% to 70% less energy and last about 10 times longer than standard incandescent lamps. Considerable energy savings can be achieved by using high intensity discharge (HID) fixtures for outdoor lighting. High pressure sodium lamps offer significant energy savings without turning off the lights. As an example, consider that a 32-watt metal halide lamp can replace an incandescent bulb in the range of 100 to 150 watts, thus saving more than 50% in outdoor lighting costs.
Installing occupancy sensors in frequently unoccupied rooms, such as rest rooms, break rooms, and conference rooms, will ensure the lights are off when the space is not in use.
Simple things such as choosing a setting that will switch equipment to a power saving mode can typically save up to 60% of the operating costs of the whole system.
Several factors impact the amount of energy used and the efficiency opportunities available. These factors include the type of business, size of the facility, location, number of sites, and electricity demand levels.
Facility managers should evaluate their company’s energy usage to determine the best solutions to lower overall operating costs, even during times of increased consumption. Doing so can result in big savings.
Porter is a vice president with Direct Energy, provider of energy services throughout North America.
Get To Know Your Backup
First and foremost, a manager must understand all components of a power quality system and know how they function together. Second, a strong, viable maintenance routine that provides a high level of security must be instituted. Finally, a facility manager must be able to respond to any issues detected during maintenance and prevent any major load loss.
Currently, the best power continuity solution for data centers is an uninterruptible power supply (UPS) system and generator for all critical systems. UPS systems manage the transition to generators in the event of sustained power outages and are very effective during power interruptions that are minimal in duration.
Some larger data centers also require that a second utility, one from a different substation or grid, be used as a backup or shared AC source, thus increasing the overall protection of the data center. However, properly designed and implemented, UPS systems and related peripherals can manage all necessary power requirements.
What Happens During A Power Surge?
Design run time criterion for UPS applications is typically 10 to 15 minutes. During a 15 minute outage, a complex sequence of events occurs. The UPS recognizes that the input power vanished; the battery associated with the UPS ensures power integrity; and the generator starts and maintains power. The UPS then cycles to generator power, and the battery begins recharging.
Unfortunately, many things can go wrong during this sequence of events. Often, if the UPS system fails, it is due to the batteries.
Batteries are the least reliable component of the UPS. The chemical reaction that creates the DC current in batteries renders them extremely sensitive to any deviation in temperature, barometric pressure, or humidity. Moreover, variances in charging profiles and the type and duration of discharge events drastically alter the lifespan and performance of the lead acid cell. Add to this linear deterioration caused by age, and the result is the dramatically variable operation of a constantly degrading system.
Although predictive failure analysis is very difficult, some companies have made advances in resistance and conductance battery testing instrumentation. One assessment factor consists of the length of the battery’s service.
After a certain time, the chances of cell failure become statistically relevant and increase exponentially. Without redundant battery “strings,” an open DC cell renders the available current and voltage to the UPS at a zero level. So during a power outage, the UPS would be unable to support any load, the data center would go down, and the firm would be hemorrhaging money.
While most components remain functional throughout the life of the UPS, batteries require replacement every two to five years. The battery is also one of the most expensive components of the UPS, typically accounting for 25% or more of the initial purchase cost. Consequently, for a UPS with a service life of 10 years and a battery life of two years, the total cost of battery replacement will equal or exceed the original purchase cost of the UPS.
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