Checking the fence line? Use a quarter horse. Entering the Preakness or theKentucky Derby? Saddle up a thoroughbred. Plowing the field or pulling a heavyload? Enlist a draft horse. And a Morgan is just right for pleasure riding.The point is, using the right horse for the job gets better results.
When it comes to building controls, the same principle applies. Like horses, building automation controls come in various “breeds.” Some are better suited for a particular purpose. When shopping for controls, the questions to consider include: “Which piece of equipment do I really want and need?”; “Is my goal to monitor, to control or monitor and control?”; and “What will improve my margins the most significantly and yield the highest ROI?”
Midwesterners generally pay 5¢ to 7¢ per kWh (for energy) and $8 to$12 per kW (for demand). On the coasts, electric rates are almost double. Now,after a nationwide 30-year hiatus, utilities are spending billions to improvethe generation and transmission infrastructure. As a result, electric ratesnationally will increase about 10% per year for the next decadeand electricbills will double within a decade!
Retailers can minimize the impact this will have on their O&M budgetstoday by incorporating conservation methods and improving efficiency with proventechnology. Automation controls can help offset the escalating cost of energyfor several years and provide ROIs up to 40%. But buyer beware, as not all controlswill maximize an operator’s investment.
Monitor, controlor both?
Would even the strongest thoroughbred do well in a plow harness? Would anyoneof sound mind bet on a draft horse at the Kentucky Derby? Certainly not. Thesame maxim applies to controllers. Operators must determine what they want toaccomplish and understand their real wants and needs when it comes to buildingcontrols.
The acronyms for automation controls are many: building automation system (BAS); energy management system (EMS); energy control system (ECS); digital demand controller (DDC). The names, definitions and functions vary widely, so retailers must understand what each system is and what it will or won’t do.
Most of these devices do a great job of monitoring the store and the equipment inside it. Temperature, pressure and humidity information is tracked and can be accessed for off-site analysis. But how much information and monitoring is really neededand is more necessarily better?
One major drawback to EMSs can be the potential for information overload. This is a real threat to facility managers because it can easily cripple productivity. Like scanning, vast amounts of information don’t necessarily make an operator smarter or more efficient if the data isn’t understandable, meaningful, easily accessible and truly informative. It becomes “data smog.”
Like trying to fill a drinking glass from a fire hydrant, the sheer volume of information produced by an EMS, and the manner in which it is delivered, render much of it useless. So, O&M must carefully define the desired information in terms of quality and usefulnessnot volume.
Example: A BAS/EMS indicates that the air flow rate has declined 150 cfm in HVAC #1. There could bemany reasons for this: The economizer is out of calibration or malfunctioning; the fan belt is slipping; the fan blades are dirty; or, plain and simple, the filter is plugged. Frankly, things like this should be caught and corrected during routine maintenance; common sense and an effective, preventive maintenance program will solve 95% of the problems. Operators must be careful not to substitute a $15,000 “knowitall” black box for common sense.
Most automation systems also function as glorified time clocks, providing basic control of selected equipment. Things typically controlled include lights and HVAC equipment that are turned on and off according to a set schedule. Very few provideastronomic control, which compensates daily for the time of sunrise and sunset.
Using automation to take the human element out of the control equation is important and will minimize mistakes, oversight and energy waste. Automation controls provide more accurate control of exterior lighting, snow and ice melting cables, mullion heaters, exhaust fans and water heaters. Tighter control can trim total annual kWh use by 5% to 8%, or $2,000 per store per year. However, much more can be done to reduce operating costs.
Where virtually all EMS/BAS/ECS fall short is that they only monitor and providebasic control, while operators should go a step further and reduce billing demand(kW). To do this, automation controls must receive a pulse input from the utilitymeter. This permits the controller to see the real-time demand level in thebuilding. As demand increases and nears a programmed threshold, the controllermust then be able to coordinate the operation of in-store equipment to minimizetotal billing demand.
About 40% of every electric bill consists of demand (kW) charges, but retailers mustand canlower demand to minimize their utility spend. Besides monitoring and turning things on and off (like a time clock), retailers should intelligently manage and coordinate the operation of equipment.
A programmable digital demand controller, in this instance, is the right horse for the job. A DDC provides all the basic monitoring a facility manager will need and want. It also provides digital and astronomic control.
But just as importantly, it manages monthly billing demand. This last feature can reduce the electric bill for an average convenience store by an additional $1,500 per store per year.
Keep it simple
BAS/EMS/ECS may be the right horse for office buildings but the wrong horsefor a convenience store. They are expensive, complicated, require constant upgradesand training to operate properly and can easily overburden the user with toomuch data. Time after time, energy auditors run across automation systems inthe back room that have been abandoned for all these reasons.
To reduce operating costs, an operator needs only basic information aboutin-store equipment and the utility meter. Like a draft horse, a DDC won’t “winany races,” but it can provide that information and plug along in the plow dayafter day.