Installing efficient equipment and encouraging building occupants to make positive choices are great ways to reduce energy consumption, but to make the steepest cuts, you need to think small.
A comprehensive metering plan can monitor energy usage down to the plug loads while displaying data in an easy-to-understand format. It all starts with an energy-slashing strategy.
Set a Game Plan
Cutting your energy use starts with choosing your methods of measurement. Measuring actual energy use is common, and data centers frequently add power usage effectiveness (PUE) to the mix. However, you can also get creative to maximize the returns from your hunt for energy waste – for instance, the number of people per printer or per refrigerator in your facility. Factors like these present a prime opportunity to eliminate unnecessary equipment.
Next, set your energy goal. Simply pursuing a “green building” isn’t measurable. Going after LEED certification sets some performance standards, but doesn’t get down to the micro level. The more specific your goal is, the better – such as saving 50% on energy compared to code or using less than 25,000 BTU per square foot.
Now you’re ready to set up a metering plan, which will compare expectations with actual energy consumption. Due to the cost of the equipment, it might be more cost-effective to phase them in gradually, starting with one area of the building or one natural resource. For example, an Internet-enabled electricity meter that reports data to a Web-based dashboard can cost around $200.
“You’ve got to do something with the data once you have it, so it’s important to have a plan up front,” says Paul Torcellini, principal group manager for the National Renewable Energy Laboratory (NREL). “You want to make sure your investments in energy efficiency are working.”
Don’t Neglect Plug Loads
HVAC and lighting use a large share of your energy, but drilling down to plug and process loads will expose many other opportunities for savings.
“Plug loads are heavily occupant-driven. In a minimally code-compliant building, they can account for 25% of the total energy,” says Torcellini. “As the building uses less energy for heating and cooling, those plug loads become a much more significant contribution. In our facility, 50% is related to those loads.”
As NREL’s new 220,000-square foot research facility in Golden, CO, was constructed, the team planned an ambitious metering project to monitor the facility’s energy profile from day one. The agency aggressively targeted plug loads and even developed a 10-step reduction process (see sidebar).
“We actually set up a metric for how many people per printer we should have,” Torcellini explains. “We had two people per printer, but we’ve reduced it to 30 people per printer. Get rid of equipment that’s not being utilized properly.”
The data generated by metering plug loads will help you make the business case for any needed retrofit projects. NREL’s data prompted a long list of improvements, including energy-efficient traction elevators that turn off the interior lighting when they’re unoccupied and a high-efficiency UPS in the data center.
The result: a 49% reduction in plug loads made possible by a strong measurement and verification (M&V) plan. This provided detailed budgets for end user energy consumption and confirmed the building was performing as designed.
“It’s really critical that you use your metering to ensure your design goals are met,” says Shanti Pless, senior energy efficiency research engineer at NREL. “You also have to communicate that information to the end users.”
Involve Building Occupants
Data should be shared with building occupants to encourage them to cut their energy use. How the data is displayed depends on the audience who will see it. Some departments might need detailed information, while other building occupants would benefit from an overview that allows them to quickly see the big picture.
The display should promote action. The system might set off alarms for the FM department whenever the energy consumption of a boiler veers more than 10% out of normal range.
“What are the acceptable ranges?” Torcellini explains. “If you put out the data and nobody knows if it’s good or bad, it hasn’t helped you. Compare it to your expectations for the building. It takes some thought to motivate people.”
Janelle Penny (firstname.lastname@example.org) is associate editor