How do people actually know how much energy is coming out of a solar array? How do people measure energy efficiency savings? How do I know I’m saving what I’m supposed to be? Where’s the proof in the pudding?
The answer to those questions is tools. The very items that separate us from the rest of animalia (ignore those pesky Chimpanzees for a moment) also help differentiate reliable, proven clean energy from guesswork.
As with any tool, having the right one for the job is critical. Since we live in a world teeming with devices that heat, cool, light, ventilate, refrigerate, wash, dry, humidify, make phone calls, and hundreds of other energy consuming tasks, it turns out we need many different tools for many different size jobs. Below is some of the gear that a proper energy study will utilize:
Senses. Your five senses are fast-acting and valuable, albeit imprecise, energy analysis tools. Plus, you can never forget them in the office. Loud noises coming from a rooftop unit might suggest a loose belt. Hearing fans kick on in an unoccupied building in the middle of night tells you that there is equipment in need of a time clock. Strange smells may reveal broken units. Excessive pressure when opening a door alerts you to an air pressure balancing problem. Eyes detect uninsulated pipes and unnecessary lights. Best not to taste anything though.
Data logger. These do what you’d expect them to do: record information. They can be as little as a deck of cards or the size of a brick. Either way, these little boxes are the energy engineer’s favorite pal. You don’t leave home without them. They can record almost anything that can be transformed into an electrical signal: temperature, voltage, current, lighting levels, humidity, magnetic fields surrounding a motor. They can take measurements every second or every hour. They’re limited by memory storage space, but usually provide at least a few months worth of measurements.
Light sensors. These go in a light fixture right near, but not touching, a lamp. Then you link them to a data logger (many data loggers have light sensors built in). They record the lux or footcandles – units of lighting levels – every five minutes. This makes it easy to see how often your lights are on and therefore how much energy you’d save by installing occupancy sensors or more efficient lamps.
CT clips. Not to be confused with ammunition clips or movie clips, these are small metal rings that are wrapped around a wire. Disappointing, it’s true. But current transducer (CT) clips should not be underestimated. Simply by putting them around a wire, one can measure how much current is flowing through a wire. No need to actually touch the wire. Sound impossible? Turns out, electricity and magnetism can do more than make souvenirs stick to your refrigerator door. The amazing basic principle behind most current transducers is the Hall Effect. The Hall Effect is an extremely powerful property of electrical systems used in all kinds of other applications including your anti-lock brakes. (This principle is related but not identical to how transformers work. Transformers are those boxes at the end of your cell phone charger that steps down voltage from 120V to 12V).
Real power meters. Perhaps you’ve learned that Power = Current • Voltage, but that’s not the whole story. In AC circuits, energy is lost when current and voltage get out of phase. The amount of this loss is quantified by a “power factor”. To be efficient, you want Power Factor to be 100%, but that isn’t always the case. A real power meter takes live measurements of current and voltage as well as the phase shift between them (the bigger the phase shift the lower the power factor). This let’s you know exactly how efficiently equipment is using power.
Ratchet. No kidding. There’s no substitute for a good 5/16” ratchet to quickly access packaged air conditioning units.
Humility & Brain. It’s true. A humble brain is your best tool. We try to use it almost every day. Generally, we succeed. If you’re dealing with anything electrical, even if it’s only 120 volts, be humble. Do not touch anything you do not understand, and if you think you understand it, question your understanding. If you don’t know what lineman gloves are or what an arc blast event is, you definitely should not be touching anything.
Energy monitoring gear is fun and powerful. And there’s a lot of it. Hundreds of useful tools were not mentioned here including: carbon dioxide sensors, infrared temperature guns, flow meters, sling psychrometers, motor loggers, and solar pathfinders. But please remember that even for properly-trained personnel, tinkering with electrical equipment can be lethal, even at low voltages. If you’re not trained in how to use this equipment and really want to learn (which we hope you do), get trained! Then start measuring. And you’ll soon be able to quantify how much more sustainable you can make our planet.