A photo illustration of a hand adjusting a Google Nest smart thermostat to adjust the temperature in the living room on October 12,2021 in Kampen, Overijssel, The Netherlands .Image source, Getty Images
Image caption, The makers of smart thermostats say the devices can cut energy bills

Dominic realized that his thermostat had a lot of data. He decided to hack it because he wanted to know what his boiler was doing.

He used open source software to plot boiler activity against the changing temperature of a room. The system instantly captured the difference that was made when he upgraded the bi-folding door in his dining room to a triple glazed model.

"If I do this, I'll save this amount of energy," he said. He was able to save money over time.

He had a technical background and was helped by it. He is the director of the firm. He was in a small minority when he tinkered with his thermostat.

Image source, Dominic McCann
Image caption, Dominic McCann hacked his smart thermostat to find out more about his energy use

With rocketing energy prices and the associated cost-of-living crisis, more people are asking how to reduce their energy bill.

A smart thermostat is a connected version of a traditional central heating controller that you can program and adjust via a mobile device.

Money saving gadgets have been promoted by manufacturers for many years. They have provided more detailed information about users' energy use over the years.

Some research shows that installing a smart thermostat doesn't always result in a reduction in energy use.

Some brands say their systems make it easier to manage heating. Many offer to teach you how to heat your home, or detect when you're out, in order to save you money.

The man was ahead of his times. Tado recently launched a software update that provides monthly bill predictions to help users keep within their budgets. People can see which rooms in their home need the most heating by comparing them.

The majority of Tado's users are able to save money, according to a spokesman for the company.

According to Neil Barbour, an analyst with S&P Global Market Intelligence, there are more than 75 million smart thermostats installed around the world.

According to The American Council for an Energy-Efficient Economy, smart thermostats can reduce home heating and cooling costs by 10%.

If every home had a smart thermostat, the US could reduce its total energy consumption by roughly the same amount of energy used by the entire state of Mississippi in 2020.

It would be a lot of money. The research shows a mixed picture. Users of smart thermostat tend to ignore the benefits of the gadgets by manually altering their heating or cooling schedules, according to one study.

Some people eroded their energy savings because it was easy to increase the heating.

Image source, Getty Images
Image caption, The work of a smart thermostat can easily be disrupted by a manual override

An analysis of data from 20,000 Ecobee smart thermostats in the US found that users sometimes overrode their schedule in a way that used less energy. It was not as expensive as expected. Ecobeefunded the study.

The lead author of the second study, who now works for a tech firm, said that smart thermostats may struggle when users expect them to do all the work.

Someone who knows how to fix their own system is more likely to do better than a smart thermostat.

He says it's difficult to beat someone who manages their heating and cooling schedule.

The number of opportunities the smart device has to shut the heating off will be limited when people work from home.

Technical quirks are something to be aware of. Some highly energy efficient boilers on the market in the UK can be adjusted in response to the amount of heating required.

To take full advantage of this, you need a smart thermostat that is compatible with your boiler. Information about this has been published online by the Heating Hub.

Jo Alsop says it's a big deal for households.

Image source, Brent Huchuk
Image caption, Brent Huchuk says a smart thermostat might not be as effective as someone managing their heating closely

In the future, smart thermostats could allow people to heat their homes when it's cheapest to do so.

The idea was explored in a study by Costanza and colleagues. The participants received specially designed thermostats.

That may be too much for some people. The study suggested that this could lead to a reduction in energy consumption.

Prof Costanza believes that it would be better to give people information about their energy use over a longer period, such as a month, or a forecast that explains how much someone could save by heating the house less in the morning.

Prof Costanza says making it simpler for people to understand how they spend energy can make a difference.