/ Home & Energy, Money

For and against smart thermostats

Cat on radiator

Smart thermostats are the latest trend in home heating. But do they really help to heat our homes more efficiently? Two Which? staffers put them to the test…

Lisa Barber says:

Lisa BarberYou might think that getting a smart thermostat – which controls your heating from an app on your phone – would cause your energy bills to rise. After all, surely it’s far too tempting to keep yourself cosy by turning up the heating from the comfort of your duvet or sofa?

However, I find I actually spend my time turning my heating down. As I haven’t got to fiddle with the overly complicated control panel on the old thermostat, I’m much more likely to keep on top of making sure we only use the heating when we really need it.

Plus, my smart thermostat lets me control individual radiators. This means that when I’m in front of the TV of an evening I can spend a minute switching off radiators in any rooms I’m not using.

Being able to see the temperature in individual rooms is rather handy, too. It’s much easier to demand that your family put jumpers on if you know it’s already over 20°C. Whereas with our old thermostat, which lived in our draughty hallway, we never really knew what the temperature was and whoever was coldest would usually sneakily turn up the dial.

So for me, having a smart thermostat has definitely reduced the amount of energy I use.

Amy Hupe says:

Amy HupeI was tempted into getting a smart thermostat – not so much to cut my energy bills, but because of the added convenience. That said, I was interested to see if greater control and feedback about my consumption would encourage me to use less – it has not.

I really feel the cold, always seeming to be several degrees chillier than everyone else in the room. The ability to switch my heating on when I leave work, so the house will be cosy as soon as I walk in the front door, has proved stronger than my desire to reduce my heating bills.

My other half and I both have the app installed on our phones, and when we first had our smart thermostat installed we set out with firm resolve to remember to switch our heating off when we went out for the day at the weekend (when our heating is set to 20°C by default).

Sadly though, with nothing to remind us, we only tend to remember about half the time – the same as when we had a standard thermostat. While I feel motivated to turn my heating on when I’m cold, there’s little to remind me to switch it off when I don’t need it.

All in all, while I think it’s been great for convenience, I’m just not as engaged with my energy use as I am with my comfort, and getting a smart thermostat hasn’t changed that.

What do you think of smart thermostats?

If you already have a smart thermostat, tell us more about it – particularly if it has smart learning, as we want to know more about whether this actually works. If you don’t have a smart thermostat, do you think one would work for you?


We went for the Hive earlier this year and really regret it. I should say they have a new model now, so our experience is based on the old model and I would be interested to know if the new model works any better.

Before the Hive, we left the radiators on 24/7 in the middle of winter. The radiators by the entrance doors were turned up full, the rest turned down to maintain reasonable temperatures in the other rooms i.e. low in the bedrooms, a bit higher in the bathroom and living rooms. The downside to leaving on 24/7 was the boiler kicked in every few minutes whether it was needed or not but we were comfortable. We also had a very handy 1 hour boost for hot water or heating with one press of a button.

So having heard about the Hive we decided to go for it. We now go hot, cold, hot, cold, hot, cold………..

The boiler works nearly non-stop until the temperature is reached then stops but the hot radiators continue to heat the room for a while. Then the radiators go cold before the Hive thinks it needs to start up again and the temperature drops a little more before it starts heating again.

The cold weather is only just starting but we are going to try lowering the radiator in the living room where the Hive thermostat is to see if that will maintain a more comfortable temperature.

All the fancy software around a smart thermostat is not much good when the end product i.e. heating does not work properly. We do seem to be using less gas though.


I see my comment has had 2 thumbs up so must agree with me.

It would be good if those people could give their experiences as I would really like to hear them.

Noel says:
18 October 2015

We have a hive but don’ have the thermostat in the living room. It is in the entrance hall away from any radiators. We set the temperature to 18C so it doesn’t heat the whole house too warm but keeps the living rooms at a nice steady 20-21C. So where you place the thermostat is critical and depends on your house design.


Noel, we thought we would try your suggestion of the front hall. It is the area that heats up and cools down the fastest so the Hive does cut in more often.

By turning the temp down to 16-18C and keeping the hall door shut, the rest of the house is maintaining a better temperature overall.

We are still fiddling with the temperatures but there is an improvement.


I’ve had a nest (US import) since before the UK launch, and replaced it with a ‘proper’ UK nest shortly after – it’s great, the “Auto Away” feature has reduced our gas usage by about 20-30% compared to our previous thermostat. The ability to control the heating when away is great too, making sure the house is warm for when you’re home without needlessly wasting energy when out.

Nest is also quite clever in it’s ability to determine how long heating will take to reach a specific temperature, it learns this so if you ask for the house to be *at* 19ºC for when you wake up, then it will automatically turn the heating on earlier taking into account how long it should take to heat up.

Only negative point I’d have is that the UK version of Nest is very basic compared to the US counterpart, and cannot control air conditioning.


I’ve had a similar experience Ross, the Nest is very good at what it does.

From what I’ve read of it all, Nest led the pack, others followed. Perhaps in some measure better but overall I think you’d struggle to beat the Nest, especially as it can talk to other systems, albeit limited for the time being depending on what’s been written for it software wise.

The auto-away is utterly genius, saves running heating when nobody is in the house and I reckon that’s paid for the Nest and then some over the past year os so alone, probably a couple or few times over.

The best bit is, you don’t need to do anything, just let it work it out for you as you say, it figures stuff out so you don’t have to, it just saves burning heating when it’s not required and has proven extremely effective in that.

And, it’s as easy as easy can be for anyone to operate, even total technophobes.

It’s actually hard to find a downside to it.

Previously I used an X10 based stat and have a Z-Wave one that’s never been installed because Nest launched in the UK. So, I’m no stranger to more “intelligent” control and most are an order of magnitude harder than the Nest is to both install and use.



I don’t have what most people consider a smart thermostat, I have a modern Worcester Bosch thermostat. It monitors the temperature in and outside of the house to automatically adjust the various programmes we have set for our weekday and weekend routines. As such we don’t have to remember anything and we don’t need an app to constantly fiddle with the heating. Set it and forget it but stay warm economically .


I have the hive, and upgraded to the new one, I can say I have loved the new feature of boost, most of the time the heating is off, but if it gets a bit chilly I can press the boost button, from a hour up . and it does the job. I would like the smart thermostats if I thought they would be better than the ones I have , but I have always liked the hive, but I must be honest that I do forget I have the app on my phone, but the settings are easy to set, and it has enabled me to heat my home a lot more efficiently, as the dial on my heating was a waste of time . so we had to have it on full blast to turn it on , but having the hive solved that and now I would not live without it. and I must also say that if I have had a problem, and I have rang the help team, they have sorted it out for me. so for me hive was a great addition to have .