Alleviate the heating cost shock: What do smart thermostats do?

Smart thermostats can help reduce energy consumption and thus heating costs.

Alleviate the heating cost shock: What do smart thermostats do?

Smart thermostats can help reduce energy consumption and thus heating costs. According to various calculations, the savings potential is somewhere between 5 and 20 percent. In view of the steeply rising prices for gas and heating oil, that can be a pretty big deal.

Even before the Ukraine war, it made sense to save heating energy because of the rapidly worsening climate crisis. But in view of the looming shortage and further sharply rising prices, many people are now thinking about it more seriously. Smart thermostats are a relatively simple and quick-to-implement means of heating in a more controlled and therefore more efficient manner.

How high the savings potential is through such controllers probably varies greatly from household to household. Manufacturer Tado° puts their savings potential at an average of 22 percent. In a 2019 test of ten different smart thermostats, Stiftung Warentest only came up with savings of five to eight percent. According to BR, Jens Schuberth from the Federal Environment Agency assumes 10 to 15 percent. In view of the exploding energy prices, however, even the more pessimistic product test values ​​can make a noticeable difference in the household budget.

The more expensive fuels are, the more profitable it is to purchase smart thermostats, which are not cheap. At prices between 40 and 70 euros per controller, for example, an apartment with six radiators can add up to 240 to 420 euros, not counting accessories such as window sensors, room thermometers or replacement batteries. If you don’t have a networked home yet, you may have to invest an additional 50 to 100 euros in a smart home center.

In the 2020/21 heating season, according to "Heizspiegel", this would not have paid off so quickly for a small single-family house with 110 square meters of floor space and gas heating at an average cost of 890 euros. But for the current season, the costs have almost doubled to 1755 euros. "From 2023, gas customers will have to expect the discounts to triple, at least," warns Klaus Müller, head of the network agency.

Even those who heat with oil have to dig much deeper into their pockets. According to Statista, the average price for a liter of heating oil has also doubled from 69 cents to around 1.43 euros since June 2021.

At such prices, the purchase of smart controllers may already pay off with a saving of 5 to 8 percent. In some cases, however, more can be obtained. At the time, Warentest assumed that "the residents have a typical eight-hour working day and want to come back to a warm home". But since the beginning of the corona pandemic, many people have been working from home and would like to continue doing so, at least in part. In addition, there are far more detailed gradations than being warm in the evenings and mornings, otherwise cold.

According to the consumer center, every degree less brings about a saving of about six percent. So if you wear a light sweater instead of a T-shirt in the evening or snuggle up under a blanket, energy consumption drops significantly. However, you should not overdo it, because below 16 degrees there is a risk of mold formation. It is often more expensive to bring a completely cold room up to room temperature than to continue heating it moderately when you are away.

Another advantage of smart controllers is their accuracy. A conventional thermostat only allows you to set a value between 1 and 5. Level 1 corresponds to around 12 degrees, each additional level around 4 degrees more. Smart thermostats, on the other hand, allow the temperature to be regulated to within half a degree.

A big plus is the ability to set time periods exactly. For example, on weekday mornings you can heat up the bathroom for exactly the 30 minutes you spend there before you leave the house. Maybe it should be a few degrees higher before going to bed, the rest of the time it can be cooler there.

In addition, networked thermostats offer comfort functions that make saving energy more pleasant. For example, you can operate and set them using an app or notebook while on the move. Many devices also pause automatically when you open a window or leave the house.

There are other situations in which a smart thermostat can demonstrate its advantages. But you can see from the examples that most of this can also be done manually if you have the discipline and are not too forgetful. For the savings potential, it is therefore decisive how the previous heating behavior improves through the purchase of smart thermostats.

The far greater savings potential lies in better building insulation or a renewal of the heating system, among other things. In your own home you can already program night reductions etc. centrally on the boiler. For tenants, on the other hand, switching to smart thermostats can definitely pay off in view of the enormous increase in energy prices. However, if you have been heating very sparingly up until now, the additional benefit is not all that great.

Theoretically, smart thermostats can become problematic for power grids if, among other things, heat pumps are increasingly used. In a study, scientists at Cornell University in the US state of New York found that the morning peak load was 40 percent higher than model calculations would normally lead to by using such controllers in around 2,200 households. However, all households evaluated use the same thermostats from one manufacturer and the researchers suspect that most users left the factory settings unchanged. Because the peaks occurred at exactly 6:05, the preset time of the devices.

If you opt for smart thermostats, you should not only pay attention to the price, but also to the quality. The best solution for Stiftung Warentest was the AVM Fritz DECT301 (approx. 55 euros) for owners of a Fritzbox. The decisive factor was the easiest handling (grade 1.9) among the test candidates, and no additional smart home base is required. The device works without sensors that automatically detect when a window is opened, but according to the product test it also throttles the heating well without it.

As far as heat regulation is concerned, the Devolo Home Control (approx. 60 euros) showed the best performance (1.5). However, because the handling was only rated "satisfactory" (3.0), the thermostat only took 3rd place in the product test comparison. The Homematic IP thermostat (approx. 60 euros), which had the second-best heat regulation (1.9 ) and was only just beaten by the FritzDect 301 in terms of handling (2.1).