Ok, let’s stop with the nonsense and discuss something that can actually affect your building’s bottom line: What is an Economizer? You’re likely searching for tips on how to cut back on those hefty energy bills, especially when the AC is cranking, right? You’re not alone. Commercial property owners are ever-searching for ways to save money without compromising comfort.

An economizer is your friend. Think of it like a smart HVAC component, one that leverages the cool outside air to chill your structure instead of forcing your mechanical cooling system to grind away around the clock. It’s all about “free cooling,” whenever nature delivers it.

What Is an Economizer and How Does It Work?

An economizer is, at its heart, intended to cut your building’s energy use from HVAC systems. It does so by drawing in outdoor air, cooling your indoor space only when the weather is at its best. To be clear, we’re talking about an add-on feature that is typically sitting atop rooftop package units one might find at a commercial spot.

So, how does it actually work? Not exactly magic, great engineering instead. Standard on the economizer are the following components:

• Sensors: These are the system’s eyes and ears. They’re always feeling the outdoor air for temperatures and heat and humidity levels. Some measure even enthalpy — effectively the total heat content, sound temperature and humidity.
• Dampers: Consider these as adjustable vents or baffles. When the sensors say to go for it, these dampers open wide, allowing sweet, cool outside air to enter. They also regulate how much air gets in and out of your building.
• Logic Controllers: These are the brains behind the functions. They read the information from the sensors and determine when it’s best to implement “free cooling”.

This is how it works:

1. Feeling the Vibe: Your economizer is feeling the outside conditions all the time!
2. “Free Cooling” Mode: When the outside air is fair (cool temp, low humidity, or low enthalpy), the economizer comes on. Here’s what happens next and it’s wonderful: Your main cooling system compressor is told to go take a rest.
3. Airflow Control: The dampers open, sucking in the precise quantity of that outside air. It then blends this cooler outdoor air with the warmer indoor air of your building until it reaches your thermostat’s setpoint.
4. Back to the Grind (If Need Be): If outdoor conditions have nothing better to do BUT to go south – like, too hot or too humid – the economizer’s dampers swing closed, and your AC compressor says hello again to the good, old-fashioned mechanical cooling.

It’s the equivalent of a natural air conditioner, set to high, always running for free anywhere it possibly can. That’s, like, a cheat code of arm-wrestling energy.

The Irrefutable Advantages of Economizers and Why They’re a No-Brainer

Not only is installing an economizer a good business move, it’s a power move literally for your commercial property. Here’s why it’s a big win:

• Huge Energy and Cost Savings: This is the huge one. When your economizer is working, your heavy-lifting turbine compressor gets to take a break. That’s huge since a compressor from one rooftop unit has the tendency to consume 5,000 watts of power, or 5 kilowatts (kW), -thousands of dollars per month in warmer temperatures. By contrast, the fan in an economizer only requires a couple hundred watts to two kW, and can thereby reduce cooling costs by as much as 50%. There’s a reason we call it “free cooling” — it’s like catching a cool breeze without having to the electric company for it.
• Longer Lasting And Lower Maintenance: Less work for your compressor means less wear and tear on your whole HVAC system. This results in less wear and tear, fewer repair bills, and your expensive cooling system lasting years longer than it would have. Consider it like adding fewer miles to your high-performance engine.
• Enhanced Indoor Air Quality (IAQ) and Ventilation: It’s not just hot or cold; it’s how you breathe. Economizers bring in fresh air from the outside, so you’re not just recirculating stale old indoor air. Top-tier ventilation is not something many older buildings were designed with in mind. Improved air quality leads to happier occupants, and some research even indicates that it results in fewer sick days for employees. Now that’s a flex.
• Installation Ease: Economizers are considered an add-on. They are so common on modern systems that some come with them built-in. If not, it’s pretty easy to retrofit one of these onto your existing HVAC unit, and these things don’t take up much space on the roof.

Going Further: What Types of Economizers are Available for Any Application?

It turns out that not all economizers are equal. They are available in a few different flavors, each with its pros and cons:

• Dry Bulb Economizers: This is the most basic type. It contains sensors that detect only the temperature of the outdoor air. When the air reaches a particular chilliness (say less than 55 degrees), out pops the damper. The catch? It doesn’t detect humidity. So if you’re in a climate that’s cool but muggy, this guy could add a sticky mess to the equation. Of course it’s not great for, oh, San Antonio.
• Single Enthalpy Economizers (aka Wet Bulb): Okay, a hut! It is this type that takes into account both temperature and humidity levels in the process – or more accurately, the enthalpy (total heat content) of the air – of allowing outside air in. It is by far the most popular kind on the market today, although it does require a modicum of ongoing calibration to remain accurate. This is what’s usually suggested for locations such as Central Texas.
• Differential Enthalpy Economizers: Here is the Rolls-Royce of economizers. It employs two or more sensors to primary sense the enthalpy of both the indoor (return) air and the outdoor air. This permits super fine damper control, computing the exact minimum enthalpy for the perfect cooling. These will in many cases work together with your indoor thermostat constantly, and are ideal for larger commercial buildings with multiple zones and air handlers. The energy savings here? Even more significant.

But wait, there’s more. For specialized environments, there are couple of tools to outpace economizers beyond run-of-the-mill commercial HVAC:

Data Center Economizers: They’re pretty much heat factories, really, so cooling is crucial here. Economizers are the answer, and they are heavily in used today to reduce dependence on heavy duty cooling systems such as Chillers and CRACs (Computer Room Air Conditioners).

• Air-Side Economizer: This guy sucks outside air. But you’ve got to be a hawk on humidity levels (40-60% is ideal) and there must be top-notch filters keeping out particulates that can destroy hardware.
• Fluid-Side Economizer (a.k.a Water-Side): Now, this is a whole different animal. Rather than drawing outside air in, it takes that air and cools a coolant (water, glycol, refrigerants) within the building’s cooling system. It’s essentially a day off for mechanical refrigeration. The upside? No more outside air contamination or internal humidity control in the server rooms. While air-side can accommodate a broader temperature range, fluid-side is a clean, no-muss option. You may already be familiar with PUE (Power Usage Effectiveness) in data centers; economizers will directly affect this measure, illustrating their efficiency nimbly.

Industrial Economizers: These don’t involve cooling buildings but making industrial processes more efficient. Economizers are also used in boilers to recycle waste heat to the economizer pre-heat zone to heat boiler feed water. They capture waste heat from the exhaust stream — heat that would otherwise just fly out into the atmosphere — and put it back to work. That means less fuel burned, and sometimes the heat that is recovered can be used elsewhere in the building for things like hot water, a practice known as cogeneration. It’s the art of accomplishing more with less.

Where Economizers Really Shine? (And Where They Don’t)

Economizers are a little persnickety about the weather. They are like that friend who only succeeds under certain circumstances.

• Best Climates: Economizers work the best in areas that have cool winters and mild summers. Why? Courtesy of Free Cooling That’s when you get the most of opportunities for “free cooling.”
• Not-So-Great Climates: If you live in a place where it’s always hot and humid (or even just warm and humid), economizers might not be the best option. Consider drawing in cool air that is also packed with moisture — you’re essentially priming yourself for potential mold and mildew problems. That’s why buildings in places like Florida, Hawaii and Puerto Rico are often excluded from economizer requirements in building codes, after all, they wouldn’t actually save much energy there.
• Building Code Requirements: But it’s not all a matter of preference; sometimes it’s the law. Building codes, like C403. 5 of the International Energy Conservation Code (IECC) tend to require economizers depending on your unit’s cooling capacity. For instance:

Adjusters, listen up: you should always check if an economizer is required for a policyholder’s system when a claim comes across your desk.

Other professional bodies such as ASHRAE also offer good advice on how to effectively implement an economizer (see, e.g., ANSI/ASHRAE/IES Standard 90.1-2019).

The Dark Side: What Can Go Wrong And Why You Need Maintenance

The best tech still has its quirks. Amazing as they are, however, economizers aren’t without their problems. And at times, they’re difficult to find.

• Malfunctions Can Be Sneaky: Because in most cases your large, main HVAC will turn on when your economizer isn’t optimizing, you might not always even realize your economizer isn’t functioning properly unless you specifically track it. It’s as if your backup singer comes in when the lead singer is flat, and you hardly notice.
• Usual Repairs: What breaks most often? -Sensor failure or de-calibration: This is a big one, like a bad set of service wrenches, if the economizer can’t read the air, it can’t adjust anything. You may also have dampers that are hung, which is usually because of actuators or linkages that have gone bad. “If those dampers are stuck open, even by 10 percent, you could be throwing hundreds of dollars out the window, for the privilege of letting in unconditioned air when you shouldn’t.”
• Installation Problems Exist: Here’s a wild stat: almost 50% of all new economizer installations has one or more issues that impact performance negatively. So, in other words, instead of saving you money, a poor install could be costing you money. Which is more like the opposite of a cheat code!
• Fault Detection and Diagnostics (FDD): The good news is that building codes are getting more aggressive. They now even mandate certain fault detection and diagnostics to be present — read also things like, for example, refrigerant pressure sensors — to help catch these things up front.
• Maintenance is a Must: Running that energy-efficient beast will only happen frequently if it’s kept in good running condition. That involves checking and adjusting those dampers, sensors and controls. Don’t pass it up: It’s what keeps everything working right, and keeps those sweet energy savings coming.
• Get a Professional Opinion: If you smell a rat, or if you’re working on an HVAC-related insurance claim, always hire a heating and cooling pro. They have the knowledge and experience to evaluate the economizer and see to it that it is functioning as it should.

Conclusion: Is an Economizer Worth It?

But after all that talk, here’s the bottom line: are economizers worth it? Hansen says yes, they’re almost always worth the investment. Over the long term, they can provide meaningful energy and cost savings.

The best of it is that the savings efficiency brings often mean economizers end up paying for themselves fairly quickly. It’s similar to a high-end coffee machine: more expensive up front, but if you’re using it daily, you’re likely saving a lot of money not buying lattes.

But it’s not right for everyone. It’s really a good idea to work with a local, qualified HVAC contractor to determine whether an economizer is suitable for your building, in your climate zone. You want to make sure this makes sense for your operation.

And there’s a bonus tip: to promote the uptake of economizers, there are incentive programs and rebates offered by local and state governments in many parts of the country. These can defray some of the initial, upfront costs, giving you even more of a reason to say yes. High fuel prices can also make some companies primed for efficiency upgrades, causing economizers to become an even more appealing option, he added.

So, if you want to get smart about how your building uses energy, and how to save some serious coin as a result, knowing what is an economizer, brings you one step closer to achieving the next level of efficiency.

FAQs About Economizers

Q: Can I connect an economizer to my existing residential HVAC unit? A: Economizers are used most often on commercial HVAC systems, specifically rooftops. So while the concept of bringing in outside air for cooling can apply just as well to residential, economizers as presented (and the types offered, and the codes driving them) are more commercial in nature.

Q: What kind of energy can an economizer really save? A: Significant amounts! For a light-commercial building, an economizer can save half the cost of running the compressor when using “free cooling. This could mean big annual saving and reduced utility bill.

Q: How can I determine if my economizer is operating together? A: If they aren’t actively monitoring, people can be tough to catch in a malfunction. Typical signs of problems include sensors that are out of calibration or dampers physically stuck. Some fault detection and diagnostics (FDD) systems are now mandated by building codes to assist in diagnosing problems. Ongoing service, inspection and tuning by an HVAC pro are important to maintain efficient operation.

Q: Is economizer good for all climates? A: Not all. Economizers are most effective in climates with cold winters and moderate summers. They are not well suited for hot and humid climates such as in Florida, Hawaii or Puerto Rico — where drawing in moist outside air can create problems like mold and mildew — and won’t reap energy savings. Typically economizers are not required in these areas.

Q: Economizer versus traditional air conditioner: What’s the difference? A: A common air conditioner works by mechanically cooling the air with a compressor and coolant. An economizer, meanwhile, takes advantage of cooler outdoor air temperatures to cool your building, frequently allowing the compressor to turn off entirely. This “free cooling” requires vastly less energy.

Q: Now what the hell do they mean by Enthalpy when referring to economizers? A: Enthalpy is simply a measure of the heat content of something. For economizers, this entails conditioning of air for both temperature and humidity. It is up to the enthalpy economizer to use the two measurements together to determine if outdoor air is suitable for cooling and offers better control than just temperature.