3 Concepts You Should Be Familiar With
Energy Waste: Energy waste occurs when your building is using more energy than it should for the present intended operation, and is, thus, wasting dollars. This can be caused by a malfunction, sub-par sequence of HVAC operation, behavior of occupants, and many other factors. As electricity is invisible, identifying waste and quantifying the dollar-impact is a complex problem to solve.
Automation (the steady state/regular area of energy): This is the regular or ‘routine’ area of managing consumption. You get this by managing the control systems in the building.
Anomalies (the unexpected/irregular area of energy): This is when energy consumption spikes, or when energy consumption is otherwise behaving differently than usual. An anomaly can indicate an energy-wasting condition, but often not. To better tell if an anomaly is truly a wasteful condition, a deeper dive is needed in normalized consumption trends, EMS data, and sequence, business operations, etc.
A Big Problem: Up to 43% in Energy Savings
The BOMA International Building Energy Efficiency Program (BEEP; BOMA 2006a) reports energy potential savings are 10.5-43.2% through changes in O&M and occupant behavior (i). This means that between 10.5-43.2% of your energy costs can be avoided and are thus considered waste.
But why so much waste? There are a few factors driving this:
- Most buildings are designed with business continuity in mind. So, when a malfunction occurs in a component, in most cases it will default to “fully-open” status. That way continuity of business is a default. But it comes at the cost of wasting energy.
- Buildings and systems are engineered with safety factors. Thus, when a wasteful malfunction takes place, waste rate can be higher than the normal usage rate.
- Consumption (kWh) is a function of time. A “small” waste running extended hours will always add up to a considerable amount of waste.
Big Risks from Small Instances
As with most blind spots, they are often hidden in plain sight. And so we need to re-train ourselves to see them. Here is an example to illustrate. Imagine two different sized tanks. Both are always full of water. One of your tanks is larger, while the other is smaller (see Figure 1).
Knowing a fact about the nature of tanks that, on average, 30% of tanks leak and waste water—which of the two tanks will you spend your time monitoring?
The common practice is to monitor the larger tank, because, the thinking goes, since it is larger, it will leak more. But this is a false assumption. The reality is that we don’t know which tank will leak more. It is possible that the larger tank never leaks. Or, if it leaks, it could be at a much lower rate than the smaller tank (as in Figure 2).
This is because, in most cases, the size of the system is only one factor amongst many others that determine the size of the risk.
The same concept applies to energy consumption in buildings. Energy waste can occur in any area of the building and can be generated from smaller systems—and it is not limited to the nominal capacity/size of the system. Meaning, just because the system is small doesn’t mean it cannot be a large waste risk.
Consider another example: a malfunctioning VFD on a 30% oversized motor can more than double the consumption, and waste 137% of its normal consumption. Meaning, if such motor normally consumes $100, a failed VFD can end up wasting $137 on top of the normal $100 (ii).
Another example of small consumption adding up to considerable waste would be a space heater under a cubical that is run for an extended period.
The Blind Spot
Now that we know waste can occur in considerable amounts in almost any electrically powered system in the building, detection of such waste requires monitoring of every possible cause of waste. But using data generated by the control/automation systems (associated with mostly larger systems) as a waste monitoring strategy leaves a large area of the building unmonitored. Smaller systems, like the VFD, space heaters, or myriad others show us this.
Put another way, the blind spot in energy efficiency comes when we try to manage waste in the same way we manage the normal consumption, that is using controls. We must think differently and use a different approach to capture energy waste. One way to eliminate this blind spot is by monitoring general areas, and not systems.
- Waste isn’t limited to systems under automation/controls; Waste can occur outside of controls coverage.
- Automation itself can be a cause for waste. Thus, waste mitigation strategy must be built outside and independent of the building’s controls.
- Waste isn’t only correlated to the kW power of the system, it is also dependent on its fail-to defaults, runtime, applied safety factors, and other factors.
- Controlling the large systems that normally consume large amounts of energy is encouraged and in most cases necessary.
- Managing energy waste is a totally different area of energy efficiency than managing the normal consumption of systems. It requires a different approach and way of thinking.
- To accurately detect energy waste, you must have the kWh, Amps, etc. of the main feed(s) and sub-meters. Detecting waste through controls data, status and command is not reliable, and neither it is a substitute for understanding your building’s consumption behavior and trends.
- If detecting waste through controls data analytics has been a success for your portfolio, there is a high chance (statistically speaking) that you have a large opportunity that you haven’t tapped into yet (within the blind spot).
- For waste mitigation purposes, if you can’t monitor every possible energy point/system, monitor areas instead.
(i) BOMA 2006a. Energy Efficiency Program (a series of six courses) – referenced in ASHRAE’s Energy Efficiency Guide for Existing Commercial Buildings: The Business Case for Building Owners and Managers, 2009, page 5.
(ii) First Affinity Law: (P2/P1)=(N2/N1)3
Thus, P2= (60/45)3 * (P1) = 2.37 (P1)