Thermostat settings that actually save money

KiloWise editorial team · Last updated 5 November 2026 · Category: Heating & Cooling

Your thermostat is the single biggest lever on your energy bill. Heating and cooling together make up roughly half of a typical home energy bill, according to ENERGY STAR, so a few degrees in the right direction matter more than almost any other habit you can change. The good news is that the changes are small, free, and reversible: you set a temperature, you live with it for a week, and if it does not suit you, you change it back.

This guide gives you the thermostat settings to save money that are backed by the US Department of Energy (DOE), explains the setback — turning the temperature down in winter or up in summer while you are out or asleep — and covers the cases where the standard advice does not apply, including heat pumps and steam or radiant systems. It is a plan to test on your own bill, not a guaranteed saving. Every number here comes from a named source or from your own bill, and where a figure is a rule of thumb, it is labelled as one.

One warning before you start: comfort is personal, and health comes first. If anyone in your home is elderly, very young, or has a health condition that makes them sensitive to cold or heat, keep the temperature where they need it. The savings in this guide are worth having, but they are never worth a cold house for someone who cannot tolerate one.

The DOE settings: 68°F in winter, 78°F in summer

The US Department of Energy recommends setting your thermostat to around 68°F (20°C) in winter when you are home and awake, and around 78°F (26°C) in summer when you are home. These are starting points, not laws. They are the temperatures at which most people are comfortable in normal indoor clothing, and at which the heating or cooling system is not working harder than it needs to.

If 68°F feels cold to you, try it for a week before deciding. Most people adjust within a few days, especially if they add a layer indoors — a jumper or a pair of warm socks costs nothing and changes what 68°F feels like. The same applies in summer: 78°F feels very different with a fan moving the air than it does in still air, and a ceiling or desk fan uses far less electricity than an air conditioner running several degrees colder.

In the UK and other countries that use Celsius, the equivalent starting points are about 20°C in winter and about 26°C in summer. The principle is identical: pick the warmest winter temperature (or the coolest summer temperature) you are genuinely comfortable at, and stop there. Every degree beyond comfort is money spent on a feeling you did not ask for.

The setback: the setting that does the real work

The setback is simple: when you are out of the house, or asleep, you let the temperature drift. In winter you set the heating back by 7–10°F (about 4–5.5°C); in summer you set the cooling up by the same amount. The DOE says that setting back 7–10°F for 8 hours a day can save up to 10% a year on heating and cooling. Read that carefully: "up to" means it is an upper figure, not a promise. A well-insulated home in a mild climate will see less; a draughty home in a cold climate may see more. Treat it as the best case, and use the thermostat setback simulator to model your own numbers before you commit.

Why does it work? Because heat loss is proportional to the difference between inside and outside temperatures. A house at 68°F on a 30°F day loses heat faster than the same house at 60°F, because the gap is 38 degrees instead of 30. While you are asleep under a duvet or out at work, you do not need the house at full comfort temperature, so you stop paying to maintain the bigger gap. The system then works a little harder for a short while to bring the house back up — and that recovery costs less than the hours of maintaining the higher temperature would have.

A common worry is that reheating the house "uses more than you saved". For most modern forced-air and boiler systems, the DOE's position is that it does not: the energy saved during the setback hours exceeds the energy used to recover. The exceptions are covered below — heat pumps, steam and radiant systems recover differently, and for those the standard deep setback can backfire.

The 1%-per-degree rule of thumb

There is a handy rule of thumb used by energy advisers: for each degree Fahrenheit you set back for 8 hours a day, you save roughly 1% on your heating bill. It is an estimate, not a measured fact for your home — insulation, system efficiency and climate all move it — but it is useful for quick decisions. Set back 7°F and you might expect something in the region of 7%; set back 10°F and the figure is nearer 10%, which lines up with the DOE's "up to 10%" figure.

Use it to compare options rather than to predict your bill to the pound or dollar: a 5°F setback you will actually stick to beats a 10°F setback you override every evening. The worked example below shows the arithmetic so you can run it with your own annual heating and cooling cost.

Heat pumps: do not use a deep setback

If your home is heated by a heat pump, the standard setback advice can cost you money instead of saving it. Heat pumps heat efficiently at a steady temperature, but when they have to recover from a deep setback quickly, many systems call on auxiliary (backup) electric resistance heat, which is far more expensive to run. The saving from the setback hours can be wiped out — or reversed — by a single expensive recovery.

The DOE's advice for heat pumps is clear: do not use a deep setback without a smart or programmable thermostat that is designed for heat pumps. Such thermostats recover gradually, ramping the heat pump up early and avoiding the auxiliary heat. If you have a heat pump and a basic thermostat, keep setbacks small — a degree or two — or none at all, until you have a thermostat that manages recovery properly. The same caution applies in summer: large upward setbacks followed by a demand for fast cooling can be inefficient, so gentle, gradual changes are the rule for heat pumps in both seasons. If you are unsure what system you have, check the outdoor unit or your manual, or ask your installer; getting this wrong is the most expensive mistake in this guide.

Steam and radiant systems recover slowly

Steam heating and radiant floor systems are slow. A steam system has to heat a boiler full of water and push steam through pipes; a radiant floor has to warm a slab or a floor mass before the room feels warmer. Recovery from a setback can take hours rather than the 30–60 minutes a forced-air system needs.

That does not mean you cannot set back at all — it means you should set back less, and start the recovery earlier. A 3–5°F setback with the recovery starting an hour or two before you wake is often the practical limit. A 10°F setback on a radiant floor may leave you cold at breakfast and still warming up at lunchtime, which is a comfort failure, not a saving. If your system is steam or radiant, treat the DOE's 7–10°F figure as a ceiling for other systems, not a target for yours.

What not to do: cranking it up does not heat faster

Turning the thermostat up to 85°F does not heat your home faster than setting it to 68°F. A heating system delivers heat at a fixed rate; the thermostat is a switch, not a throttle. Setting it higher only means the system keeps running past your comfort temperature, overshoots, and wastes energy — and then you open a window to cool down, wasting more.

The same applies in reverse in summer: setting the air conditioner to 60°F does not cool the house faster than 78°F; it just runs longer and overshoots. Set the temperature you actually want, and let the system get there at its own pace. If the house is slow to warm up or cool down, the problem is usually insulation, draughts or system sizing — see our seasonal heating and cooling checklist and the whole-home energy audit — not the thermostat setting.

Two related mistakes are worth avoiding. First, switching the system off entirely in winter in a cold climate risks frozen pipes; a setback to 55–60°F while you are away is safer than off. Second, constantly overriding a programme — nudging the temperature up and down by hand all day — defeats the schedule and usually costs more than leaving a sensible programme alone.

Schedules for out, asleep and home

A workable schedule has three states: home and awake, asleep, and out. In winter, that might look like 68°F when home and awake, 60–61°F overnight (a 7–8°F setback), and 60°F while the house is empty during the day. In summer, it might be 78°F when home, 82–85°F overnight if you can sleep comfortably with a fan, and 85°F while out. Adjust the numbers to your comfort — the structure matters more than the exact degrees.

Programme these into your thermostat once, then leave them alone for two weeks. Check your bill — or your smart meter — against the same period last year, allowing for the weather. If the saving is there and you were comfortable, keep the schedule. If you were cold at 6 a.m., move the recovery half an hour earlier rather than abandoning the setback altogether.

How thermostat settings fit the rest of your home

Thermostat settings work best alongside the cheap fixes that reduce heat loss in the first place. If your home is draughty, the heating has to work harder at any setting; draught-proofing is usually the cheapest first step. And water heating is a separate system with its own settings — it is about 18% of a typical bill (US DOE) and its temperature rules are about safety as much as saving, so read our guide on how to save money on water heating before touching that dial.

Related: try the thermostat setback simulator with your own bill, then read the seasonal heating and cooling checklist and our guide on how to save money on water heating.

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