When you want to enjoy a delicious espresso, you don't immediately think about power consumption, kilowatt-hours, or standby mode. Yet in the world of coffee, awareness of environmental issues has increased significantly in recent years, and many consumers increasingly value sustainable products.
As coffee makers, we have been integrating power consumption into our machine tests for several years now. To further refine our tests, we have developed a more detailed power measurement protocol with Tobias, our Head of Sustainability.
In this blog, we want to explain to you in basic terms how we measure power consumption and how different espresso machine systems differ in terms of their consumption. We strive to use only the absolutely necessary technical terms so that readers without electrical engineering knowledge can follow along.
Why is machine power consumption important at all?
Of course, we don't want to constantly think about every little detail. When we enjoy an espresso, we want to do so with a clear conscience, without having to think of a nuclear power plant. Nevertheless, it makes sense to include power consumption in the pros and cons list when purchasing an espresso machine.
After all, every little bit counts. Let's do a quick thought experiment: In your household, you drink two cappuccinos each in the morning and afternoon. There are machines that consume about 0.42 kWh for this. If you use your machine for a year, you consume around 150 kWh.
If your machine, however, only consumes 0.18 kWh to prepare the cappuccinos, your annual energy requirement drops to 65 kWh. That's a saving of 85 kWh per year – quite simple. This roughly corresponds to the amount of electricity an LED TV needs when it runs all year round. https://www.enbw.com/blog/wohnen/energie-sparen/was-man-mit-1-kwh-so-alles-machen-kann-2/
If we assume that it's not just you, but many other passionate cappuccino lovers as well, the numbers increase significantly. The forum "Coffee-Net" has over 65,000 members. If each of them saved 90 kWh annually, that would add up to a total of 4,225 megawatt-hours. This corresponds to the amount of electricity an offshore wind turbine can produce in half a year. And not every owner of a portafilter machine is active on Coffee-Net. So you see, a machine's power consumption can make a significant difference.
What does our measurement protocol look like?
We use three professional power measurement devices, the Christ CLM1000 Professional Plus. Why three? If a value seems odd to us, we can verify the measurements with another device. These measuring devices offer the advantage that they measure to a tenth of a watt accurately, i.e., to 0.0001 kWh – that's extremely precise!
We record all values in kWh. This unit is also displayed on your electrical panel, and you pay for your electricity based on consumption per kilowatt-hour (kWh).
In our power measurement, we also take into account the warm-up time. But how long does it actually take for a machine to be ready for operation? First, we measure how long it takes to reach the target temperature of 92 °C for the first brew in the portafilter. To avoid skewing the values, we always use a cold machine, that is, a machine that has been off for at least ten hours. In addition, the water filled always has a temperature of 20-24 °C. With thermoblock machines, heating up takes only a few minutes, while dual boiler machines can take up to 40 minutes.
Once the machine is at operating temperature, we do a flush shot, which warms up the portafilter.
Now we come to the "extraction measurement".
Espresso Extraction
To simulate espresso extractions, we perform five extractions of 27 seconds each. In addition, there is a so-called "flush" of 2 seconds, which simulates cleaning the brew group. Between each extraction, we pause for one minute to simulate grinding, tamping, and further steps.
If the machine offers the option to turn off the steam boiler, we perform the energy measurement for espresso twice: once with the steam boiler on and once with it disabled.
Americano
To simulate power consumption for an Americano, after the espresso extraction we always drew 70 ml of hot water.
Cappuccino
To simulate the cappuccino extraction, after each espresso extraction we heated 300 grams of water from 6° C to 60° C with the steam wand. Here we simulate the frothing of the milk foam you need for a cappuccino.
Coffee Maker Protocol
Already in older videos, we frequently talked about a "coffee maker protocol" to compare the energy consumption of different machines. This protocol included a warm-up phase of 25 minutes, regardless of machine type, followed by five espresso extractions with a one-minute pause between each. Since we did not determine the warm-up time for each machine with this outdated protocol, machines that heat up quickly were at a disadvantage. Even if they were ready to use after just 5 minutes, they still had to run for 25 minutes before the first extraction. This is one of the reasons we developed a new protocol. However, to ensure comparability with the old videos, we also provide the values for new machines within the framework of the "Coffee Maker Protocol" and show the power data in the article as in the following table.
Why are there such large differences in energy consumption?
The majority of energy consumed goes to heating water. To brew an espresso, a brewing temperature of about 92 °C is required, which is handled by the heating system of the espresso machine. For milk drink enthusiasts, additional water steam is needed, which is about 120 °C hot.
The way a machine heats the brew and steam water significantly affects energy consumption. A boiler machine works differently than a dual boiler or a thermoblock. Below we briefly explain the differences between the heating systems of the different machine types.
Boiler Machines
Boiler machines are often referred to as "single boiler machines" if they have a single heating circuit. Typical representatives of this type of machine include, for example, the Gaggia Classic and the Rancilio Silvia.
Single boiler machines have a small boiler in which water is heated to the desired temperature by electric heating elements. Depending on the size of the boiler, which is often between 0.3 and 0.5 liters, energy consumption varies. If you want to prepare a cappuccino, after extracting the espresso you must heat up the boiler to reach the required steam temperature. This process sometimes takes several minutes and requires additional energy.
Simplified, you can compare a single boiler machine to an electric kettle.
Dual Boiler Machines
As the name "dual boiler" already suggests, machines of this type have two separate boilers. The smaller boiler is responsible for the brew water, while the larger one is responsible for steam generation. When both boilers are activated, they must first reach their target temperature before you can make espresso. During operation, the temperature in the boilers is kept constant by reheating. Depending on the size of the boilers, power consumption can be considerable. The La Marzocco GS3, for example, requires a full 0.6 kWh in the first hour with its 1.5-liter brew boiler and 3.5-liter steam boiler.
Dual boiler machines primarily offer temperature stability, often even under load, and high comfort, since steaming and espresso extraction can happen simultaneously and the temperature can be adjusted precisely. However, they are quite power-intensive in terms of energy efficiency. Simplified, it's two electric kettles heating simultaneously at different temperatures (high and very high). The better the boilers are insulated, the less power is needed to reach and maintain the temperature.
Note: Retroactive insulation is not an option because without adjustments to the control electronics, temperature adjustment will no longer work reliably. While you can save some power this way, it comes at the cost of taste.
Heat Exchanger Machines
Heat exchanger machines have a single boiler that serves two separate water circuits. Many classic Italian espresso machines equipped with the Faema E61 brew group use this heating technology. The boiler is responsible for steam generation and is heated to temperatures between 120 and 130 °C. The brew water is drawn from the tank through a tube past the steam boiler. The heat from the steam boiler warms the water in the tube similar to a heat exchanger. This brings the brew water from 20 °C in the water tank to the desired 92 °C in the brew group.
Although only one boiler needs to be brought to temperature, most heat exchanger machines still consume a lot of energy because the steam boiler must be kept at a very high temperature at all times.
Thermoblock Machines and Thin-Film Heaters
Thermoblock machines and thin-film heaters represent interesting alternatives. Instead of bringing an entire boiler to a target temperature, an aluminum block or thin metal plate is heated. Water from the tank flows through tubes in the respective unit, which is heated directly. With a thin-film heater, even less mass needs to be heated than with a thermoblock.
Since the water is only heated upon extraction, the machine's warm-up time is significantly shorter than with the various boiler machines. The Zuriga E2, for example, is equipped with a thin-film heater and is ready to use after just two minutes. That's extremely fast and also very energy efficient. An Ascaso Steel Duo PID equipped with a thermoblock also reaches temperature in under ten minutes.
Depending on the machine's design, the thermoblock or thin-film heater may need to be heated for the steam temperature. However, there are also models with two separate thermoblocks or thin-film heaters, one for the brew temperature and one for the steam temperature.
Multi-Heating Systems
There are espresso machines that combine different heating systems. For completeness, we want to mention this category of espresso machines, even though they are not very numerous.
The Ascaso Baby T, for example, has a steam boiler and a thermoblock for the brew temperature. Since many thermoblock machines don't offer the same steam power as dual boiler or heat exchanger machines, Ascaso pursues a hybrid solution with the Baby T to combine energy efficiency and performance.
Conclusion: Should I throw my dual boiler in the trash?
In our detailed blog post on performance measurement, we continuously update a list with the power measurements of all our tested machines.
Anyone who looks at the list quickly realizes that thermoblock machines and especially thin-film heaters are generally significantly more energy efficient than boiler machines.
However, energy efficiency is far from the only criterion for a good espresso machine. Factors such as temperature stability, programmability, steam power, ease of use, design, and many other aspects also play a decisive role in deciding which machine to buy.
So have we reached the end of the dual boiler or heat exchanger era, as we teased in our video? Yes, that could increasingly be the case in the coming years. Modern espresso machines are characterized by high temperature stability and can be adjusted extremely precisely. We are therefore curious about the developments that lie ahead.
After all, energy efficiency is directly related to warm-up time. Who doesn't want a machine that's ready to use after just a few minutes instead of having to wait three quarters of an hour to make an espresso?
Should everyone now switch from their boiler machines to thermoblock machines? A very clear no! The manufacturing of a machine and the raw materials it requires (stainless steel, cables, hoses, electronics) are far more energy-intensive than its operation. So if you own a heat exchanger machine that will work without major problems for at least another 10 years, you should definitely continue using it!
After all: 1. The less we buy new, the more resources are saved. 2. Durability and repair of machines also contribute to resource conservation. However, if you're thinking about getting a new machine and value energy efficiency and sustainability, you should carefully review our performance measurements and factor them into your purchasing decision.
