4-21-2013 HVAC Gains with No Budget Pains
Helping to Secure a Healthier Future – for People and the Planet – One Building at a Time
It’s hardly news that buildings use 40 percent of the natural resources and more than 70 percent of the electrical energy in the United States. And facility managers know there are plenty of ways to get buildings to use less energy — measures that send savings directly to the bottom line. By now, most facility managers have replaced magnetic ballast T12 lamps with electronic ballast T8s, or even more efficient lamps. Many have installed motion sensors. If the lighting retrofit was good enough, the organization might have received a tax deduction of up to $0.60 per square foot under the Energy Policy Act of 2005 (EPAct 2005).
But what about the “heart and lungs” of a building: the HVAC system? The thermal energy plant and HVAC systems can go from “green” to “gray” in a very short time after they have been installed or retro commissioned. Nevertheless, implementing HVAC upgrades is far from easy in many organizations. Many companies put off having an energy audit by an outside team because they don’t want to spend the money on what the recommendations in the audit might cost. Fortunately, there are many ways to improve HVAC performance that do not cost a lot of money to implement. Some have more to do with the manner in which the building is operated than the actual HVAC system itself.
Most low- and no-cost items fall into four categories:
· Equipment Scheduling. HVAC equipment running when not required is a major source of energy waste. HVAC equipment running when it’s not needed, along with plug loads for chargers, computers, copiers and printers, task lights and other items that are on when not necessary, can account for as much as 10 percent of electricity use. Chargers typically use more energy when left plugged in 24/7 than the equipment they charge.
· Sensor Error. Sensors are seldom calibrated after installation, yet over time they drift from their set points. Or use of the area has changed but location of the sensor or its set point has not.
· Simultaneous Heating and Cooling. To make working spaces more comfortable, many older HVAC systems use some form of reheat. That in itself is an energy hog, but if the cooling and heating setpoints are incorrect, more energy will be used than is necessary.
· Outdoor Air. The amount of outdoor air brought into a building to provide proper indoor air quality (IAQ), usually mandated by code, is a function of the number of people, area of the space and type of work. Issues like outside air dampers that are stuck in the open position or artificially held open (or closed), sensors that aren’t working properly — or are incorrectly wired to the return and the outside air damper so that the damper is wide open, instead of being at minimum position during extremes of hot or cold temperatures — contribute probably more than almost anything to increased energy use, as well as potential comfort problems.
There are many ways to reduce energy costs by addressing these four areas without spending a lot of money. Equipment Scheduling HVAC equipment often operates during hours it is supposed to be off, even though the building automation system (BAS) says it is off. Checking the BAS to make sure it is operating properly does not take an extraordinary amount of time but can save an extraordinary amount of money. Don’t stop with HVAC if the goal is to find low-cost ways to reduce energy use. Put plug loads on a power strip that sits on people’s desks and teaching them to turn off the toggle switch when they leave at night. There are also power strips that automatically turn off after a period of time where there’s been no load. Of course, occupants must be taught to save the work on their computers before they leave their desks. Education of occupants is an important part of a successful energy program, as is getting buy-in before the program begins and consulting them throughout the planning process. Close Attention To Sensors Problems with sensors are another common source of energy waste. Many “I’m too hot” and “I’m tm too cold” complaints are because people are reading numbers on thermostats as opposed to how they really feel — and the thermostats are reading incorrectly. Frequent travelers know there are many times when the hotel thermostat has to be set up or down well beyond what it reads to get the HVAC unit in the room to turn on. Also, look at where the thermostat is placed in the area. Is it now just above a microwave oven or a coffee maker? Or has it been closed in by shelving and boxes so it’s sitting in a dead air space where it cannot possibly be sensing correctly? Being aware of where the thermostats are and recalibrating them on a regular basis is another low-to no cost fix to conserve wasted energy and save money. Another area of energy waste lies in enthalpy (humidity) sensors, typically used in air-side economizers. While newer designs maintain sensitivity for longer periods, older ones need to be checked and re-calibrated at least once a year; otherwise, they might bring in excess outside air when the outdoor humidity in warm weather is higher than that indoors.