Nest Thermostat: Snug as a bug in a rug

When Tony Fadell, who had worked on the first iPhone, left Apple to set up Nest my interest was piqued. I sat on the fence (an activity in which I have an MSc with honours) after the first and second generation Nest thermostats came to the UK. I heard good things from friends in the London Mac User Group but decided to wait a little longer. Nest was acquired by Google and now we have the third version of the little thermostat that can also handle your hot water supply, if required.

I gave in three months ago and ordered a Nest III which was installed by a local expert a few days later. Since then it has been learning and adjusting the indoor environment and, I am convinced, saving money.

Before the Nest we had used the basic system of fixed-time heating, morning and late afternoon—come rain hail or shine—aided (or, as I suspected, hindered) by a 20-year-old mechanical thermostat situated in the entrance hall, the coldest part of the house. I knew this was not ideal and certainly wasteful and the arrival of the Neat has provided a long overdue opportunity to rethink heating requirements.

Easy installation

Installation, by a local Nest specialist, was far less intrusive than I imagined. I opted not to incorporate hot water control which meant that the base station could be mounted on the wall near the front door as a direct replacement for the old mechanical thermostat. No additional power was necessary since the device could take its power from the existing thermostat cabling. This is not always so, which means an additional power supply.

In fact, had I realised just how simple installation and setup would be I would have opted to do it myself. A screwdriver and half an hour is all that was needed.

The Nest thermometer is wireless, apart from a low-voltage power supply, and can be mounted anywhere you think best. You can even have additional thermostats to cover different parts of the house.

I opted for a portable stand—a very handsome affair—instead of a fixed wall-mounted location. My reasoning was that I could move the thermostat around until I found the ideal place. So far it has been sitting in my office and has been doing a great job.

Surprise

The first surprise was that we can get away with a lower general temperature setting than I imagined. I had thought 21 or 22 degrees would be a comfortable temperature but I now know that 20 is perfectly acceptable during the the day.  Initially I did a very simple setup—20 degrees between 8.30 am and 9pm.

In practice, using the “radiant heat” function, the thermostat will bring the boiler online around 6.30 am, if necessary, to pre-heat the house to to the set temperature by 8.30. Outside these hours the thermostat defaults to 9 degrees (as a precaution against freezing) although I find that the house cools very slowly and is still at 19.5 or 19 even after eight hours without heating. 

With the old mechanical thermostat there was no feedback and it was difficult to know just what was happening. I now feel in control of things. After a week or so I decided it would be more comfortable to raise the temperature to 21 degrees during the evening when a lot of time is spent sitting and doing nothing.

During the day the Nest monitors the conditions and brings on the heat if necessary. It has now learned our habits and the “auto away” function comes into operation if the device detects no movement for a period (I am not sure how long but I find the auto away comes on usually after about 30-60 minutes if no one is the house). Conversely, when movement is detected the Nest is ready to switch on the boiler if necessary.

Savings

The history function is fascinating and very useful. In the first few days after the installation (on January 15) I noticed boiler use had dropped significantly. On the first full day of Nesting the outside temperature was under five degrees and the boiler operated for nearly eight hours.

Temperatures, as usual in a British winter, fluctuate dramatically. But the Nest has been tracking accurately. Boiler usage soon dropped to three or four hours a day and, now with the daytime temperature is averaging 15 degrees, we are seeing activity of little more than an hour a day. I’m looking forward to the first day with no use.

Under the old regime the boiler would have been working on a set schedule every day, aided or hindered by an unreliable mechanical thermostat placed in the coldest part of the house. Trying to decide what temperature to set in that location in order to ensure comfort in the living area was nigh on impossible. In addition, seasonal adjustments were hit or miss. Bringing heating into effect in the autumn was perhaps done too soon; and not casting a clout until May (or, well, perhaps the end of April) was out became the norm. Now the Nest decides and it has my confidence.

Remote control

The Nest can be controlled by pushing the screen and twiddling the surrounding chrome bezel. But it is much easier to use the iPhone app which gives you full control wherever you happen to be in the world. In cold winter weather the heating during absence can be kept to the bare minimum needed to avoid icing problems in the plumbing (it is set to nine degrees but can be altered).

There is also a small Mac app (Climate) which places the Nest control panel on the toolbar of your computer. As with the iPhone app, you can switch the heating on and off, monitor usage and set schedules.

I can say with confidence that the Nest has learned a lot about the household in a short time and is gradually whittling down boiler use to the bare minimum to maintain a comfortable environment.

The first quarterly bill has not yet arrived but last week our energy supplier wrote to say they were reducing the monthly advance payment by 40 percent. I hope this is a reflection of the real effect on the bill. I now wish I had bought a Nest years ago when it was first announced and I have little doubt that the £249 cost (including installation) will  be repaid in the first year. The desk stand is an additional £35.

RESULT: the fuel bill for the first quarter of the year arrived today and showed a reduction of 18% in gas usage compared with last year’s total. However, the Nest was in operation for only ten weeks of the quarter and it is therefore reasonable to extrapolate this to an overall saving of 20% in gas. Another factor is that this winter has been a little warmer than last, again helping keep down energy use. It will be interesting to see how the Nest performs over a full year.