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How we test smart thermostats

By Matt Clear

Find out how Which? experts test smart thermostats, and what a smart thermostat has to do well to be rated as a Best Buy.

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The smart thermostats that have been awarded our Best Buy logo are those that have proven themselves to be easy to set up and use, and are packed with useful features.

Watch our video, above, to find out the lengths we go to so that you can choose the best smart thermostat for your home. We test every smart thermostat in the Which? test lab to the same high standard and ensure that each of our smart thermostat reviews answers your key questions. This includes:

  • Is it easy to set up and connect to your wi-fi?
  • Is it easy to adjust settings and programme schedules?
  • Does it have a wide range of features?
  • Should I buy it?

Read on to find out more about how we answer each of these questions, or head straight to our smart thermostat reviews.

Is it easy to set up and connect to your wi-fi?

Our expert testers go through the process of connecting each smart thermostat to wi-fi, getting the app set up on the smartphone and linking the two together. They look at how simple and straightforward it is to carry out each of the steps involved in the setup process, how long it takes and whether you're likely to run into any hiccups along the way.

Is it easy to adjust settings and program schedules?

Our testers really get to grips with each thermostat and its smartphone app to find out how easy they are to use. 

We look at everything, from navigating around the app to using it to carry out tasks. This includes adjusting the temperature, programming a schedule, manually overriding the schedule, displaying energy usage reports and switching between heating modes.

We look at how much time and effort our testers have to put in to carry out each of these tasks, and whether the steps they have to takes are straightforward and obvious.

Does it have a wide range of features?

We're looking for smart thermostats that have a wide range of useful 'smart' features, such as 'learning' functions that adjust the schedule automatically according to your behaviour, thermostats that respond to the weather, and motion detection and GPS tracking that can sense whether you're in or out of the house and alter the settings accordingly.

We haven’t been able to look at how well each of these features work. It’s very difficult to test these in a way that’s fair and comparable, as they all work slightly differently.

However, if you do want to find out more about how these features work in practice, our research team has installed the Hive, Honeywell Evohome, Nest, Netatmo and Tado in their own homes. You can read their personal opinions on these features in our full smart thermostat reviews.

75%The score a smart thermostat needs to earn to be considered a Which? Best Buy

Should you buy it?

We answer this question by combining our test results into a total test score which tells you how good the smart thermostat is overall.

Our total test score ignores price and is made up of the following parts:

  • 60% Ease of use
  • 15% Setting up and connecting
  • 15% Instructions
  • 10% Features

Smart thermostats with a total test score of 75% or above earn our Best Buy recommendation.


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