Keep cool for less

Energy prices remain volatile, carbon emission caps and trades seem inevitable and everybody wants to see more green, so energy efficiency continues to climb higher in our priorities. It’s clear that high energy efficiency is becoming a critical competitive advantage.

Even before the current economic meltdown, analysis by the American Council for an Energy Efficient Economy (ACEEE, www.aceee.org) found investments in energy efficiency to offer average annual returns of 25% at a risk of 8% — higher returns than any class of stocks with risks comparable to long-term bonds (Figure 1).

Figure 1. The American Council for an Energy Efficient Economy says investments in energy efficiency offer higher returns than stocks with risks comparable to long-term bonds.

There’s plenty we can do, especially in the area of space heating and cooling. Compared to the European Union, on average U.S transportation systems use 1.2 times as much energy per passenger-ton mile, and U.S. industries use 1.4 times as much per unit output. “But 39% of energy in the United States goes to buildings, and on the average, U.S. buildings use 2.5 times as much energy as in the European Union,” says Peter Garforth, principal, Garforth International, and Plant Services’ “Energy Expert” columnist. “That’s climate-adjusted, comfort-adjusted and per square foot. A huge opportunity.”

Know what’s going on

Compared to lighting, motors, process heating and even compressed air systems, HVAC energy consumption is complex. It’s also subject to outside influences (weather), internal whims (thermostats) and changes in production loading that make analysis difficult. Our experts described some low-hanging fruit that’s relatively easy to pick, but first it’s important to recognize that large, long-term gains depend on seeing and understanding your energy spend.

In the past, plant personnel never looked at energy costs. They were considered a fixed overhead, sometimes managed by general conservation strategies like thermostat setpoints.

“One of the biggest problems is visibility. Where are the energy dollars going?” says Ken Kolkebeck, president, Facility Diagnostics, Inc. (www.facilitydiagnostics.com). “The utility meter isn’t granular enough. You need weather information and measurements on individual systems like cooling towers, chillers and air handlers, on an hourly basis. That lets you see where the inefficiencies are and attack them.”

When energy costs are tracked to individual systems, it also becomes possible to detect deterioration. “About 20% of HVAC energy is lost because of incorrect maintenance,” says Rod Ellsworth, vice president, global asset sustainability, Infor (www.infor.com). A good monitoring system increases visibility of operating performance and energy consumption, and reveals efficiency deficiencies. Some can proactively alert so assets can be maintained to get them back into specification.

Performance can be mapped to degree-days, temperature differentials and other operating conditions with direct and indirect measurements. “We measure every minute or five minutes, compare actual values to those predicted for the operating conditions,” says Ellsworth. “Whether it’s a rooftop unit, chiller or air handler, it doesn’t matter. We monitor the components — compressors, fans, economizers — for design versus actual consumption via submetering at the system or component level. When it goes out of spec, we notify knowledge workers so they can correct it.”

A combination of measures can reduce energy consumption at most industrial facilities as much as 40%, according to Dave Konye, area sales manager, Schneider Electric (www.schneider-electric.us). The first 2% to 5% comes from raising awareness through measuring and monitoring. Then 10% to 15% typically can be gained by more efficient devices such as motors, drives or lights. Active control of usage through scheduling and automation can gain 5% to 15%, and another 2% to 8% comes though continuous monitoring and improvements using the same measuring and monitoring system.

“It adds up to a potential 19% to 40% energy use reduction, with many energy efficiency funding sources available — state government, utility, federal government stimulus, etc.,” Konye says, adding as an aside that Schneider Electric Energy Solutions is beginning to provide a service to assist clients in proposing and submitting applications for such funding.

Funding help also is available on the private side, “Energy service companies will performance contract, for example, for a boiler replacement,” Konye says. “They’ll provide leasing options, power purchase agreements or a percentage of energy savings as payment.