4 FM quick reads on HVAC
1. Fans May Offer Surprising Energy Savings
It’s no secret that HVAC systems account for a significant percentage of the energy used by a building. But it’s not only the heating and cooling systems that present opportunities for big savings.
Facility executives should also take a close look at the fan systems in a building. In doing so, however, facility executives should understand how the energy consumption of a fan varies with its speed.
The amount of power used by a fan is proportional to the cube of the speed of the fan. That’s counterintuitive. Chillers, for example, use less energy to produce a ton of cooling at full load than at part load. Fans are just the opposite. At full speed, they are at their least efficient. That means even a small reduction in fan speed can produce surprising energy savings.
One option for cutting fan speeds is to install variable frequency drives on fan motors. That way, fans can be slowed down when conditions in the building don’t require them to operate at full speed.
2. When Selecting HVAC Products, Look at Part Load Performance
I'm Ed Sullivan, editor of Building Operating Management magazine. Today's topic is the importance of the part-load performance of HVAC systems.
HVAC systems are designed to handle extreme conditions. Components of the system are sized for the hottest and coldest days of the year. On those days, the chiller or boiler is running at full load and at maximum efficiency.
But for the rest of the year, the system is running at part load. And in the past that has meant a sharp drop off in energy efficiency.
Today, that needn't be the case. Variable frequency drives, for example, can bring significant improvements in the part load performance of chillers. On the heating side, consider modulating boilers to achieve the same goal.
When you're evaluating HVAC equipment, determine how often your system will be running under part-load conditions. And if that will be a frequent occurrence, look for a system that will be efficient at the part-load conditions that it will actually be facing.
3. HVAC, Lighting: Symbiotic Relationship
Hello. This is Greg Zimmerman, managing editor of Building Operating Management magazine. Today’s topic is energy efficiency as it relates to lighting and HVAC systems. Facilities should be designed so that HVAC and lighting energy use can both be minimized simultaneously. The two are related in that the more artificial lighting that is used, the more energy will be required to cool the air heated by those lamps and ballasts. Of course, the lighting itself uses energy, too, so the fewer artificial lights that are on, the more energy efficient the building. Increase the amount of natural light in a building and use efficient lamps to cut lighting energy. Use sensors to dim or turn off lamps when natural light is abundant. Make sure that daylighting strategies are considered when sizing HVAC equipment so that equipment is not oversized and inefficient.
4. Tax Breaks for Efficient HVAC Systems Extended
I’m Ed Sullivan, editor of Building Operating Management magazine. Today’s topic is the fate of tax breaks for very efficient HVAC systems.
For the past few years, federal law has allowed tax deductions for the installation of extremely efficient HVAC systems. Under the original version of the Energy Policy Act of 2005, known as EPAct, new or upgraded HVAC systems that were at least 16.7 percent more efficient than required by ASHRAE 90.1-2001 could qualify for tax deductions of up to 60 cents per square foot.
That deduction was set to expire at the end of 2008. Although there was widespread support for an extension, the measure was stalled in Congress.
But the EPAct extension finally did pass, as part of the financial bailout bill approved by Congress. The deduction is now available until Dec. 31, 2013. That five-year window provides ample opportunity for facility executives considering very efficient HVAC systems to take advantage of the tax break. That planning time is important, because of the fairly demanding requirements that must be met to gain the deduction. If an HVAC project will be using energy modeling, for example, in a building aiming for LEED certification, it’s worthwhile to investigate whether the project will qualify for the tax break.
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