7 Energy-Saving Myths That Are Costing You Money

Not every energy-saving tip you've heard is true. Some are outdated. Some were never true. And a few are actively costing you money — because they make you spend on gadgets or changes that don't deliver, or they discourage you from the changes that do.

We spent the last few months testing the most common "energy-saving" advice against real bills, real devices, and the physics of how home energy actually works. Here are the seven myths that came up most often, and what the numbers actually say.

Myth 1: "Setting the thermostat higher heats your house faster"

This is the most common one, and it's completely false. A thermostat is not a throttle. Setting it to 80°F in winter does not make your furnace heat the house faster than setting it to 68°F. The system runs at a fixed rate; it just keeps running until the target temperature is reached.

So if you set it to 80°F, the house heats at the same speed — but the system keeps running for an extra 12 degrees, wasting energy the whole time. You'll pay for heat you don't want, and you'll still wait the same amount of time to be comfortable.

Myth 2: "Closing vents in unused rooms saves energy"

This feels logical — why heat a room nobody's using? — but it backfires. Closing supply vents increases pressure in the ductwork, which forces the blower to work harder. In forced-air systems, this can raise energy use rather than lower it. It also creates cold spots and can cause the AC coil to freeze in summer.

The correct approach: keep the vents open and close the door to the room instead. If the room has its own return vent, leave that open too. If you want to isolate a room more aggressively, that's a case for a zoned system, not closed vents.

Myth 3: "Space heaters are cheaper than central heating"

Electric space heaters convert electricity to heat at nearly 100% efficiency, which sounds better than central heating. But the comparison is misleading — central heating usually uses gas or a heat pump, which is cheaper per unit of heat than electricity in most regions.

Where space heaters actually save money is when they replace central heating for an entire house. Heat one room with a space heater while the central thermostat sits at 60°F, and you'll save real money. Heat the whole house with space heaters, and you'll spend more than central heating would have cost.

See our full analysis: How to Use a Space Heater Efficiently.

Myth 4: "LED bulbs are too expensive to be worth it"

This was true in 2010. It hasn't been true since about 2015. Today, LED bulbs cost $2–$4 each in multipacks. Each one saves $6–$8 per year in electricity compared to the incandescent it replaces. Payback time: under six months. Lifespan: 10–25 years.

Even if you buy the most expensive LED on the shelf — around $8–$10 per bulb — the payback is still under 18 months. If you're still using incandescent or halogen bulbs anywhere in your home, replacing them is the single highest-ROI energy change you can make.

Myth 5: "You should leave the AC running all day so it doesn't have to work as hard to cool the house"

This one is at least partially true — but the framing is wrong. Leaving the AC running all day doesn't save energy, and it doesn't make the house cool faster when you get home. It just cools an empty house for hours.

What's actually true is that turning the AC completely off in a hot climate lets the house get extremely hot, and the system then has to run for a long time to recover. This is why "setback" (raise the temperature to 80°F or so) is better than "off." The system runs less, but it doesn't have to recover from extreme heat.

The correct strategy: a 4–6°F setback while you're away, not a full shutdown. See How to Set Your Thermostat for Maximum Savings.

Myth 6: "Washing in cold water doesn't get clothes clean"

Modern cold-water detergents handle almost everything. Cold water removes most everyday stains — food, sweat, dirt — just as effectively as warm. The exceptions are heavy grease, certain medical sanitization needs, and items that genuinely need heat (baby items, cloth diapers after illness).

Meanwhile, washing warm or hot uses 75–90% more energy than washing cold. Switching saves $50–$120 per year depending on your starting temperature. There's no meaningful downside for everyday laundry. See How to Wash Clothes in Cold Water.

Myth 7: "Phantom power is too small to matter"

Phantom power — the electricity devices draw when they're "off" but plugged in — is easy to dismiss because each individual device draws very little. But the total across a typical home is 5–10% of the electric bill, or $75–$150 per year.

The thing that makes phantom power worth fixing isn't the amount — it's the effort. A single smart power strip eliminates most of it automatically, forever. There's no behavior change, no ongoing effort, no risk of relapse. You buy one $25 device and the waste disappears.

See our guide to finding phantom energy users and using a smart power strip.

The pattern behind these myths

Notice something about the seven myths above? They all share one of three shapes:

1. They sound logical but ignore physics — like raising the thermostat to heat faster, or closing vents to save energy.
2. They were true once, but aren't anymore — like "LED bulbs are too expensive."
3. They're true in one specific case, but not in general — like "space heaters are cheaper than central heating."

When you hear a new energy tip, ask yourself which of these shapes it fits. If it seems to ignore how the system actually works, it's probably wrong. If it worked for someone in 1995, check whether the technology has changed since then. And if it works only in a very narrow situation, be careful about generalizing.

What actually saves money

If you strip away the myths, the things that reliably save money haven't changed much:

• LED bulbs everywhere — the fastest payback of anything on this list
• Smart power strips — eliminates phantom load automatically
• A real thermostat schedule — 68°F when home, 60°F when away, all automatic
• Sealing drafts — $30–$50 of materials saves $80–$250 per year
• Washing cold and air-drying — free behavior changes, real savings
• Lowering the water heater to 120°F — 30 seconds of work, $40–$80 saved

Everything else — solar panels on rentals, "energy-saving" gadgets that plug into outlets, expensive window replacements — is worth considering but rarely the best first move. The unsexy basics win on cost per dollar saved, and they win by a wide margin.

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