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4  FM quick reads on energy efficiency

1. Energy Savings and Comfort Depend on Sensor Calibration

Today's topic is the importance of keeping sensors calibrated.

We all know the saying, garbage in, garbage out. That phrase applies to the building automation system as much as to any other computer system.

One sure way to reduce the effectiveness of the BAS is to fail to check and calibrate sensors on a regular basis. The BAS uses data from those sensors to control HVAC and other equipment, to issue alarms, and to develop reports. But over time those sensors go out of calibration or stop functioning. The only way to make sure they're delivering accurate data is to put them on a regular maintenance schedule.

Of course, that's easier said than done. Like many preventive maintenance activities, sensor calibration is easy to put off when staff is busy or the budget is tight. But false readings and failed sensors can waste a considerable amount of energy. What's more, they can produce occupant complaints about uncomfortable conditions. If that happens, the facility staff may very well wind up spending time trying to figure out what's wrong and mollifying occupants.

A building automation system is a substantial investment. Keeping sensors calibrated is an important step to getting the value from that investment.

2.  Infrared Cameras Can Help Find Leaks in Ductwork

Today's tip is finding leaks in HVAC ducts.

Leaking ducts can be a pernicious energy waster. They lose heat or cooling &emdash; into the ceiling plenum or other space &emdash; rather than delivering it to occupied areas. What's more, they increase fan energy use because more air has to be moved.

Infrared cameras &emdash; more formally known as thermal imagers &emdash; offer an easy way to find leaks in ducts. The cameras capture an image of heat patterns in objects. An image of a duct would show hot and cold spots, allowing the facility staff to pinpoint leaks in the duct.

Advances in technology have produced cameras that are smaller, offer better resolution, have more features, and cost less than cameras in the past.

Repairing leaks in ducts can produce significant savings. That's because fan energy use is proportional to the cube of the speed of the fan, so they become more efficient at lower speeds. Once duct leaks are repaired, fans will save energy because they are moving less air and moving it more efficiently.

3.  Retrocommissioning Quickly Pays for Itself in Energy Savings

Today's topic is payback for retrocommissioning.

Problems with controls &emdash; HVAC controls in particular &emdash; can waste energy and raise operating costs significantly. The way to find and fix those problems is well-established but too rarely used. Retrocommissioning applies the principles of commissioning to existing buildings rather than to new ones. Studies have shown retrocommissioning to be a cost effective way to improve the performance of controls and to remedy other problems within a building.

Retrocommissioning takes a relatively modest upfront investment. According to a study by Lawrence Berkeley National Laboratory (LBNL), the average cost for retrocommissioning is $.30 per square foot. But the return on that investment comes quickly: The median payback time is a little more than a year. That's not surprising considering that the median energy savings is 16 percent. And those savings last, says LBNL: "Energy savings tend to persist well over at least a 3-to-5 year timeframe." Savings may last longer than that, but the study didn't have data for longer periods.

4.  Be Water Efficient to Save Energy

Today's tip is about how to strengthen the justification argument for water efficiency projects by also considering energy impacts. Many facility executives have a tough time justifying water efficiency upgrades like new fixtures or removing landscaping to use less irrigation on strictly a return on investment basis.

Reducing water use almost always reduces energy use, especially in facilities where lots of hot water is used, and this can be a key component of the ROI argument. The Massachusetts Water Resources Authority calculated that running a sink for five minutes in which 70 percent of the water is heated uses the same amount of energy as leaving a 60-watt light bulb on for almost 14 hours. Additionally, water for irrigation requires energy to pump and disperse it over landscaping, so reducing landscaping reduces that energy spend.

But there's a community facet to the water and energy link as well. Water is heavy, and requires an enormous amounts of energy to treat and transport. According to the California Energy Commission, 19 percent of California's electricity is used for water treatment and transportation. So, an organization can use water conservation strategies to show how it is contributing to reducing carbon emissions, both at organizational and community levels.

Finally, many cities New York and Boston, for example are offering rebates and incentives for water efficiency projects. The theory is that by conserving water, additional supply and additional infrastructure won't be needed saving the city millions. The notion of avoiding more capacity is also one of the reasons why energy utility offer rebates. It's time to start thinking of water as the new energy!


energy efficiency , comfort , energy management , building automation system , sensors , calibration

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