Heat Buildings the Energy-Efficient Way
August 25, 2008
Commercial buildings consume a tremendous amount of energy. In fact, according to the Energy Information Administration (EIA), commercial buildings in the United States consumed 18 percent of all energy used in 2006. That number is expected to increase, as the amount of commercial building floor space is anticipated to grow another 51 percent by 2030.
Annual energy costs for commercial buildings are more than $100 billion, which is why building owners and managers are always looking for ways to save energy. Indoor climate control usually makes up a significant part of a commercial building’s energy bill, and with fuel prices spiraling upwards it’s no wonder that energy-efficient heating equipment is becoming of more interest in the commercial sector.
INCREASED DEMANDBuilding owners are responding to escalating energy costs by becoming more interested in energy-efficient equipment, which has put high-efficiency appliances in greater demand, said David A. George, product manager, Lochinvar Corp. “Building owners and managers are weighing the cost of high-efficiency equipment against rising energy costs and finding that it makes good economic sense to install highly-efficient, long-lasting equipment.”
And the good news is that increasing fuel costs lead to shorter payback times for premium-priced, high-efficiency equipment, said Mark Croce, director of marketing, AERCO International Inc. “We have definitely seen an increase in the sales of high-efficiency boilers in the commercial market. Even more interesting is the increase in segments other than schools and hospitals, which have long embraced high efficiency. High energy costs, as well as green/sustainable design trends, are driving the increase in demand for high-efficiency equipment in all market segments.”
These green design trends include building owners looking to reduce their carbon footprints, and this has a small but growing effect on sales of highly-efficient heating equipment, said Alan Wedal, commercial boiler product manager, Cleaver-Brooks. He adds that while most of the growth in sales of high-efficiency equipment can be attributed to the higher cost of energy, “many building owners are taking a longer view when making decisions on energy efficiency.”
Michael Albertson, vice president, commercial sales and marketing, WaterFurnace International, agreed, noting that first cost is no longer the absolute deciding factor in HVAC system selection. “Return on investment and life cycle cost have become the measuring device when deciding which HVAC system will deliver the most value to the property and to its owners and operators for 20 or more years.”
CONTROLS PLAY BIG PART IN SAVINGSIn addition to investing in high-efficiency heating equipment, building owners and operators are looking to incorporate advanced controls to reduce energy costs. Although some buildings may only need a simple solution, noted Jeff Hartnett, product manager, commercial split systems, heating and IAQ, Lennox Industries Inc., who says, “programmable thermostats are the simplest method of saving energy.”
Ted Cherubin, marketing manager, commercial unitary systems, Carrier Corp., agreed, stating that small commercial applications, in particular, can see big energy savings by utilizing a programmable thermostat. “If the building is not used in the evenings or over the weekend, the thermostat, when programmed to do so, will not forget to reduce the demand on the equipment and will help to control energy use.”
For larger or more complex commercial applications, Cherubin adds that customers should consider, along with energy recovery systems, using advanced controls for their packaged rooftops. One such control is Carrier’s Rooftop Unit Multi-Protocol (RTU-MP) Controller or 3V™® Packaged Control System. The RTU-MP controller’s internal application programming enables a Carrier packaged rooftop unit to run in a 100 percent stand-alone control mode or it can communicate to the customer’s building automation system (BAS). The 3V Packaged Control System also minimizes energy consumption through precise temperature and equipment control.
System controls are important and have become so prevalent that they are changing the way manufacturers design their products, noted George. “In the past, real system control meant a separate and expensive BAS. Lochinvar’s Knight residential and Knight XL commercial boilers feature the Smart System control, which allows the internal control of the boiler to handle functions that would otherwise require a BAS. The built-in Smart System control will optimize each burn cycle and coordinate operation between multiple boilers.”
Gains in control systems have recently allowed Cleaver-Brooks to incorporate an integrated boiler room control system that is based on real-time determination of the heating load (SysteMax ISD), noted Wedal. “This allows optimized control of the entire heating plant from the boiler, to pump and damper control, mixing valves, and ancillary heating equipment such as domestic water heating/pool heating. The control goes beyond a boiler sequencing panel and can pull together the entire heating system as a package because it uses real time flow, return water temperature, outdoor temperature and other inputs to predict actual heating loads.”
George added that the industry’s next phase of improvements would be in controls - designed for optimizing operation and providing better and more comprehensive information. He noted that Lochinvar’s newest commercial boiler offering, Sync, allows easier access to both boiler and system operation through a simple-to-use touch screen display on the front of the unit.
PROPER INSTALLATION NEEDEDOf course, the most advanced controls and the highest-efficiency equipment will not perform as promised unless installed properly. Croce stated that where condensing equipment is concerned, it goes without saying that it must be applied in a system designed to ensure low return water temperatures so the equipment maximizes opportunities to operate in condensing mode.
“Outdoor air reset schedules, low supply water temperatures, and systems designed around 40°F âˆ†T are avenues to ensuring that return water temperatures fall below 130° to drive condensing of flue gases in the heat exchanger,” he said. “In addition, controls contractors should coordinate closely with the equipment manufacturer representative to ensure that their controls sequencing follows equipment manufacturer recommended practices so as not to over cycle the equipment and reduce efficiency.”
With water-source heat pump systems, contractors should follow the standard procedures for typical tower/boiler systems without utilizing the tower/boiler, noted Albertson. However, when utilizing a ground heat exchanger, there are a few design and installation methods that are critical. “A site survey to determine the best type of ground heat exchanger, whether it is vertical, horizontal, or even a lake loop is the first step,” he stated. “If it is determined that either a vertical or horizontal ground heat exchanger is to be used, a thermal conductivity test to determine the rate of heat transfer of the specific job site soil and geology is the next step.”
A proper ground heat exchanger design also needs to be completed for the length and configuration of tubing to be installed to efficiently provide the required heat transfer to and from the ground. As in any commercial mechanical system, a proper system startup and commissioning should be completed, he added.
Cherubin agreed that a commissioning program to ensure the end user assurance of performance ties everything together. He added that proper sizing of the unit to load is a critical factor and that good ductwork design is essential. “All of these actions help save energy. In addition, contractors should take advantage of multi-stage operation units and systems.”
Building owners and operators are already asking for higher-efficiency heating equipment, and this trend will only grow stronger, given current predictions regarding energy prices. The EIA projects that the spot price of natural gas in 2009 will be 65 percent higher than the average spot price in 2007. In addition, prices in the electricity market are projected to increase 9.8 percent in 2009, so it can be assumed that the emphasis on efficient HVAC equipment may be here to stay.
Publication date: 08/25/2008