As we’ve argued in the past, consumers won’t be able to really start making savings calculations until we get smart meters installed in our homes. These will tell you exactly how much you’re burning through in real, financial terms and (hopefully) will allow you to be a little cleverer about your energy use. Nest isn’t a smart meter.

What it does do is flash up a little green leaf whenever you’ve turned the temperature down to an energy-saving level. In terms of temperature, Nest generally defines this as anything 16.5°C or cooler, a goal which might be achievable in spring and autumn months, but let’s be honest, that won’t even touch the sides for most homes in winter.

As Nest learns a little more about your heating habits the green leaf parameters will shift, which will see you challenged to pick temperatures a few degrees lower to those which you’re used to.

Diving into the History page of the app will give you an overview of the last ten days of energy use. Because we’re environmentally conscious goody two-shoeses, you can see that we’ve aced the green leaf target for most of January. Go us.

Whatever your feelings on the climate change debate are, the rule of thumb is if you see the green leaf, you should be saving money. Nest says that turning the heating down by one degree represents a saving of 5 per cent on heating bills.

Results of a US-based trial from last year also claimed that a Nest learning thermostat will save you around 10-12 per cent on bills versus the savings you’d get with a typical thermostat.

It should go without saying that weather varies greatly across the United States and the relevance of such findings for potential UK buyers should be taken with a pinch of salt.

Or, as Nest’s own white paper says:

“It’s important to note that thermostat savings in any given home can vary significantly from these averages due to differences in how people used their prior thermostat and how they use their Nest Learning Thermostat, as well as due to occupancy patterns, housing characteristics, heating and cooling equipment, and climate.”

You should note that this trial was undertaken with Nest’s 2nd gen thermostat as well. At the time of writing, Nest hasn’t been able to tell us whether or not its latest device improves on this.

That’s not to say that it won’t save you money; by sheer virtue of the fact that it endeavours to not burn any gas if you’re not at home it will save you something.

While Nest sends you a regular monthly report, this currently only tells you how long you heated your home for, in hours. This could be useful, depending on how you’re billed by your supplier, but it doesn’t break down any costs for you.

The real issue is, we can’t say how much until we get our government-approved™ smart meters. Until then, we’ll have to wait for our energy provider’s statements and compare them with those from last year to find out how much we’ve actually saved.


Verdict: You will save sexily with Nest – we just can’t say how much

Nest’s third-gen thermostat is a beautifully designed appliance that affords you a great degree of convenience. As for how much money it can save you, that depends on how fastidious you are as much as Nest’s own scheduling algorithms.

If you’ve got an OpenTherm-branded boiler then there’s potential for even greater savings, although we unfortunately can’t currently tell you how great and as we found out, not every boiler out there will meet this specification.

Given that loft insulation can save you on average £140/year and condensing boilers are 25 per cent more efficient than the older non-condensing ones, there’s some more immediate savings to be had, if you’ve nto already explored these routes.

The lack of a location-assisted away setting, while surmountable via third party options, is a bit of a drawback. If this is a dealbreaker, you might want to reach for something like Tado or Hive.

That said, if you’re the type of person who often finds themselves working late and you’re living in a house where there’s plenty of people coming and going at all hours of the day, you and your co-habitants will no doubt appreciate the freedom Nest offers.