How much can I save on heating with a WiFi thermostat – real numbers and experiences
How much can I save on heating with a WiFi thermostat – real numbers and experiences
When a customer comes into the store and asks whether a WiFi thermostat is worth buying, they usually expect some kind of advertising phrase about "saving up to 30%". But the reality is more complex, more interesting and – importantly – in many cases even better than people expect. Over the years of practice, I have seen dozens of installations where the customer came back after the first heating season with a bill extract and their eyes almost gleamed with surprise. And I have also seen cases where the savings were minimal – not because the thermostat didn't work, but because the owner didn't know how to use it properly, or installed it in a house with such poor insulation that no regulation could work miracles.
In this article, I will try to give concrete numbers, real scenarios and honest calculations – without inflated marketing promises. We will look at where the savings are really made, what factors influence them, and we will also show situations where a WiFi thermostat is not a cure-all.
Why a classic bimetal thermostat wastes heat
In order to understand where a WiFi thermostat saves energy, we first need to say where a classic analog or simple digital thermostat without programming fails. Most households with a standard thermostat operate on the principle of "set and forget". The thermostat maintains the set temperature for the entire 24 hours, 7 days a week – regardless of whether you are at home, at work, or on vacation.
Imagine a typical family: both adults leave for work at 7 a.m., the children go to school at 8 a.m. They return home at 4 p.m. to 5 p.m. The house is therefore empty for nine hours a day during the work week. If you have the thermostat set to 21 °C throughout the day, you are heating an empty house. At first glance, this sounds obvious, but when you calculate it in terms of money, the result is surprising.
From the graph, the principle of operation is visible: a smart thermostat reduces the temperature at night and during working hours (reduced mode), and in advance heats it up to a comfortable level before returning home or before the alarm goes off. This area between the red and green lines represents the saved energy.
Where real savings occur – the physics behind the numbers
Heating costs are governed by a simple physical law: the higher the temperature difference between the indoor and outdoor environment, the faster heat escapes from the house. If it is freezing outside at −5 °C and you have 21 °C inside, the difference is 26 degrees. If you reduce the indoor temperature to 17 °C, the difference drops to 22 degrees – and heat losses decrease proportionally. This is not theory, it is the Fourier law of heat conduction.
In practice, it is said that each additional degree Celsius in the apartment represents an increase in energy consumption of about 6 to 8%. Conversely, each degree by which you reduce heating during the reduced period saves 6–8% of the part of the consumption corresponding to that time window. If, therefore, the house is empty for 9 hours a day and you cool it down from 21 °C to 17 °C (a reduction of 4 °C), you save roughly: 4 degrees × 7% = 28% of consumption for those 9 hours. Since 9 hours is 37.5% of 24 hours, the total daily savings move around 10–11%.
These are theoretical numbers. The real value depends on the thermal capacity of the house, the type of heating system and the quality of insulation – we will get to that later.
Concrete calculation of savings for a typical family house
Let's look at a concrete example. Take a family house with a floor area of 130 m², a gas boiler, and heating via radiators. The house is from the 80s, solid but not passively insulated. Annual gas consumption for heating is 18,000 kWh (a typical value for this type of house before smart regulation is applied).
At a gas price of 0.08 €/kWh (an approximate value including distribution charges, which may vary according to the supplier and tariff), the annual heating cost is about 1,440 €.
The family is away every working day for 9 hours, they are at home on weekends. Night lasts about 8 hours, during which the reduced temperature is set to 18 °C (compared to the daily 21 °C). After installing a smart thermostat with a properly set program:
- Night reduction (21 → 18 °C, 8 hours a day, 365 days): savings of about 12–14% of night consumption. Night makes up ~33% of the day → total savings for night about 4–4.5% of annual consumption.
- Daytime reduction during work (21 → 17 °C, 9 hours, 220 working days): savings of about 20–24% of that part of consumption. Working days make up 60% of the year, the time ~37.5% of the day → total savings for working reduction about 5–6% of annual consumption.
- Remote control – vacation (10 days a year, reduced to anti-frost mode 10 °C): savings equivalent to about 1–2% of annual consumption.
Total estimated savings: 10–13% of annual consumption. In our example, this is 1,800–2,340 kWh, which in money terms represents 144–187 € per year. A mid-range WiFi thermostat (for example, Emos P5623) will cost you 50–80 €. The return on investment is therefore 5–7 months. After the first season, you have paid for the thermostat and in the following years you save pure profit.
Real customer experiences – what practice says
Theory is nice, but real stories are more interesting. Over the past few years, I have had the opportunity to observe several households before and after the installation of a WiFi thermostat. Here are a few specific cases:
Case 1: Older brick house, Bratislava region
Mr. Miro, 58 years old, two-story brick house built in 1978, area approx. 160 m², condensing gas boiler Viessmann. Before the installation of the thermostat, it was set to 22 °C constantly without programming. Annual gas consumption was 22,000 kWh. After installing the smart thermostat (program: night 18 °C, day during work 17 °C, evening 21 °C, weekend 21 °C all day), consumption dropped to 19,200 kWh in the first season. Saving 2,800 kWh, at a price of 0.08 €/kWh, that is 224 € per year. Mr. Miro says: "The biggest surprise was the preheating function. The thermostat turns on the boiler half an hour before I come home, and I arrive in a warm house without having to heat the whole house all day."
Case 2: Panel apartment, 3 rooms, Košice
The Kováč family, 4-room apartment 78 m², electric floor heating in combination with electric convectors. This is an interesting case because electricity is more expensive than gas. Before installation: average monthly electricity bill in winter was 180 €. After installing the smart thermostat (Emos P5623 or similar model, set to a detailed weekly program with night setback to 17 °C and day setback during school and work to 16 °C): the monthly bill dropped to 148 €. Saving 32 € per month, i.e. 192 € for a 6-month heating season. At a thermostat price of 65 €, the payback period is 4 months.
Case 3: Cottage with occasional use
Ms. Jarka has a wooden cottage in central Slovakia, where she goes only on weekends and holidays. Before installation, she either left the boiler off (and returned to a cold house) or kept it on constantly (which was expensive). After installing a WiFi thermostat with GSM backup (for example, Elektrobock PT32 GST, which combines WiFi control with SMS commands in case of internet outages), she set up a frost protection mode to 10 °C during the work week and on Thursday evening activated preheating to 21 °C via the app. When she arrives on Friday evening, the cottage is warm. Annual gas savings: estimated 35–40 %, because the house was previously unnecessarily heated most of the time "just in case".
This cottage case is a typical scenario where savings are highest and the payback period is fastest. If you have a property with irregular use, a WiFi thermostat will pay for itself within one season.
What determines how much you actually save
Not everyone saves the same amount. The level of savings depends on several key factors, and it is important to carefully evaluate them before you make your own calculation.
1. Thermal insulation of the building
The most important factor. A house with thick insulation loses heat slowly – which is an advantage, because it cools down slowly during setbacks, but at the same time a disadvantage, because it also heats up slowly. Paradoxically, in a well-insulated passive house, savings from setbacks may be smaller (because you don't consume much energy anyway), but the absolute amount will be low either way. On the other hand, old, poorly insulated houses consume huge amounts of energy, and regulation really plays a role here – but it cannot replace missing insulation.
2. Type of heating system
The speed of the heating system's response to temperature changes is key to the effectiveness of programming. Radiators with a gas boiler react quickly (heating time 20–40 minutes), while floor heating reacts slowly (2–4 hours). For floor heating, it is not suitable to make too deep and frequent setbacks – the temperature is hard to catch up. Smart thermostats can take this into account. This topic is discussed in more detail in the article With what boiler power and type of heating a WiFi thermostat works.
3. Lifestyle and daily routine of the family
The longer the house is unoccupied, the higher the potential for savings. A family where one member works from home will save less than a family where everyone is away all day. This does not mean that a work-from-home household has no reason to buy a smart thermostat – night setback, vacation mode, and remote control still work.
4. Previous heating method
If you previously had a non-programmable thermostat and kept it at 22–23 °C constantly, the potential for savings is huge. If you were already disciplined in manually regulating it before the smart thermostat, there is less room for improvement. This is why some customers report 5 % savings and others 25 %.
5. Correct program setting
And here is the catch, which is often not mentioned: buying a thermostat alone does not save anything. Savings come from correct programming. I have seen households where the owner bought a premium smart thermostat for 150 €, left it in manual mode at 21 °C, and wondered why nothing was saved. A thermostat is a tool – you need to know how to use it. That is why you should also read the article Setting up a smart thermostat via the app – first start and configuration, where detailed procedures are described.
Hidden benefits that do not show up in numbers immediately
Along with the direct financial savings on energy, there are also other benefits that have their value, although they are hard to express in euros:
Extended boiler lifespan: A boiler that operates more smoothly and switches on and off (so-called cycling) less frequently has less wear on the heat exchanger and burner. Smart thermostats with advanced algorithms (TPI – Time Proportional Integral) can reduce the number of switching cycles. Boiler service costs 80–150 € per year and a new boiler 800–2,500 €, so every additional year of boiler life has real value.
Comfort and convenience: Coming home to a warm house without having to heat an empty space all day – that has its own priceless value. Similarly, waking up to a preheated bathroom instead of a cold floor.
Remote management in case of faults: A smart thermostat can send you a notification if the temperature in the house unexpectedly drops (boiler failure, frozen pipes). This can prevent damage worth thousands of euros. This benefit is hard to quantify, but it is real.
Environmental footprint: Reduced gas or electricity consumption means lower CO₂ emissions. With a saving of 2,000 kWh of gas per year, we are talking about a reduction of emissions by about 400 kg of CO₂ – equivalent to 2,000 km of driving by car.
Models and their real range in practice
The market for WiFi thermostats is truly rich today – from simple devices for €40 to premium smart home solutions for €200+. The question is whether a more expensive model will save significantly more. The answer is: not necessarily. The basic programming function is available even in cheaper models and it is precisely this that creates the main savings.
Emos P5623 is a good example of a mid-range thermostat with weekly programming, WiFi connectivity, and an intuitive app. For most households with a gas boiler and radiators, this model covers 95% of the needs. It does not have unnecessarily complex features, but it has everything essential: daily/weekly program, manual override, vacation mode, and remote control via phone. Precisely because of its simplicity, it pays off – because a thermostat you cannot set will not save you anything.
Elektrobock PT32 GST is an interesting hybrid model that combines WiFi control with GSM (SMS) communication. For holiday home customers, where WiFi is not always reliable, this is a practical solution with added value. Likewise for older users who may not have a smartphone – an SMS command is enough for them. The savings this model brings are comparable to a pure WiFi thermostat, but the added benefit of backup via the mobile network can be invaluable in some cases. The differences between WiFi and GSM models are discussed in the article WiFi vs. GSM thermostat – what is the difference and which one is worth it.
When a WiFi thermostat is not worth it (or is worth less)
Frankness also requires saying when the investment may not be optimal:
- Rented apartments with district heating: If you have district heating and radiator heat meters, you cannot integrate an individual WiFi thermostat into the boiler control (the boiler does not exist). Here you can only control the TRV valves on the radiators.
- Houses with very good insulation and low consumption: If you heat a passive house for €400 a year, a 10% saving is €40 – the thermostat pays for itself in 1.5–2 years. It still pays off, but the dynamics are different.
- People who are not willing to set up a schedule: Without proper programming, the benefit is minimal. This is not a criticism of the customer – some people simply do not want to deal with settings. For them, a simple digital weekly thermostat with pre-set profiles is a better choice.
- Very old boilers without a terminal for an external thermostat: Some boilers older than 25 years do not have a terminal for a room thermostat. In such cases, the installation is more complicated and should be discussed with a heating technician. The installation procedure can be found in the article Installation of a WiFi thermostat step by step – how to do it yourself.
Cost comparison with different fuels
The amount of savings in euros also depends on which energy source you use. Electric heating is more expensive, so the absolute savings in euros for the same percentage reduction in consumption will be higher. Here is an approximate comparison:
| Fuel | Approximate price (€/kWh) | Typical annual consumption for 130 m² | Savings of 12% (€) |
|---|---|---|---|
| Natural gas | 0.07–0.09 €/kWh | 15,000–22,000 kWh | 126–238 € |
| Electricity (night tariff) | 0.09–0.12 €/kWh | 10,000–15,000 kWh | 108–216 € |
| Electricity (day rate) | 0.18–0.25 €/kWh | 8,000–12,000 kWh | 172–360 € |
| Heat pump (COP 3–4) | equiv. 0.05–0.07 €/kWh of heat | 15,000–20,000 kWh of heat | 90–168 € |
As you can see, with electric heating in the day rate, savings can be over €300 per year, which means the return on the thermostat is within 2–3 months of the heating season. For heat pumps, the situation is also favorable – although the COP (coefficient of performance) reduces the effective cost of heat, it still results in tens to hundreds of euros in annual savings.
How to maximize savings – practical tips
Purchasing a thermostat is only the first step. Here are a few proven practices to squeeze the most out of the regulation:
- Set a realistic schedule, not an idealistic one. If you know you are working from home on Wednesday, set a different profile for Wednesday. Most thermostats allow individual settings for each day of the week.
- Don't overdo the setback. A deeper setback does not always mean greater savings. If you cool your home from 21 to 14 °C, reheating will consume a lot of energy and comfort is zero. An optimal setback for conventional buildings is 3–5 °C.
- Use the vacation / holiday mode. During longer absences, set the "frost protection" temperature (7–12 °C) – it is enough to protect the pipes, not for full heating.
- Combine with thermostatic valves on radiators. A WiFi thermostat controls the boiler, TRV valves control individual rooms. Together they form an effective zonal control system.
- Monitor statistics in the app. Many smart thermostats record operation history. Check when the boiler ran the longest and optimize the schedule.
- Check the hysteresis setting. Most thermostats have adjustable hysteresis (±0.5–2 °C). Smaller hysteresis = more precise control, less fluctuation = lower consumption.
FAQ – Most Frequently Asked Questions
How much can I save with a WiFi thermostat on heating?
Real savings range between 8 and 25% of annual heating costs, depending on the type of house, fuel, previous heating method, and your lifestyle. The highest savings are achieved in houses and cottages with irregular occupancy, where heating was previously running at full power continuously. An average household with a gas boiler can save approximately 100–250 € per year.
How long does it take for a WiFi thermostat to pay for itself?
With a thermostat price of 50–90 € and annual savings of 130–200 €, the typical payback period is 5 to 10 months – less than one heating season. In cottages or houses with electric heating, the payback period can be as short as 3–4 months.
Do I need a fast internet connection for the thermostat to work?
No. Most WiFi thermostats operate even without an active internet connection – the program runs on the device itself. You only need internet for remote management via the app and any cloud-based features. If you want a backup in case of WiFi failure, consider a hybrid model such as Elektrobock PT32 GST with GSM backup. Issues with connectivity are also discussed in the article WiFi thermostat not working or not connecting to the internet – common causes and solutions.
Does a more expensive smart thermostat save more than a cheaper one?
Not necessarily in terms of energy savings. The basic programming function, which accounts for 80–90% of the savings, is available in models priced at 50–70 €. More expensive models offer comfort features (geofencing, integration with Google Home/Alexa, detailed statistics, AI optimization), not necessarily higher savings. Choosing according to your needs is described in the article How to choose a WiFi thermostat – what to look for before buying.
Can a WiFi thermostat save energy with floor heating?
Yes, but the effect is different. Floor heating has high thermal inertia – it reacts slowly. Therefore, deep and frequent reductions are not recommended here, but rather a smooth reduction of 2–3 °C during the night. Many smart thermostats have a special mode for floor heating, which takes into account the slow heating and cooling dynamics. The correct type of thermostat for your system is discussed in the article With what boiler power and type of heating a WiFi thermostat works.
What if the thermostat fails or disconnects from the internet – will the boiler stop?
Most thermostats have a safety mode (failsafe): in case of communication failure, they switch to the last set program or a predefined safe temperature. The boiler will not automatically set to maximum or stop without warning. Always check the manual of the specific model to see how it behaves during power or WiFi outages.
Conclusion – a realistic view of the investment
A WiFi thermostat is not a miracle device that will halve your bills without your cooperation. It is an intelligent tool that allows you to heat more accurately, efficiently, and comfortably – if you use it correctly. Real numbers speak for themselves: for an average household with a gas boiler, expect savings of 100–250 € per year, and even more with electric heating. The investment pays back within one heating season, and every following year brings a pure profit.
The most important advice I can give after years of experience: don't buy a thermostat, set it up, and forget about it. Spend one evening setting up the schedule, think through a realistic daily and weekly rhythm for your family, and let the thermostat do its job. You'll see the results on your first bill.
If you are looking for a specific model for your situation, check out the entire category of WiFi and smart thermostats at atria.sk – you will find there models suitable for various types of boilers, heating systems, and connectivity requirements.
Do you have a question about this topic?
Having trouble deciding or dealing with a specific situation in your household? Write to us – we are happy to help.