When you want to enjoy a delicious espresso, you don't immediately think about power consumption, kilowatt-hours, or standby modes. Yet in the world of coffee, awareness of environmental issues has increased significantly in recent years, and many consumers are placing greater importance on sustainable products.
As coffee professionals, we have been incorporating power consumption into our machine tests for several years. To further refine our tests, we have developed a more detailed power measurement protocol with Tobias, our Head of Sustainability.
In this blog post, we want to give you a basic overview of how we measure power consumption and how different espresso machine systems differ in terms of their consumption. We strive to use only the strictly necessary technical terms so that readers without any background in electrical engineering can follow along.
Why is machine power consumption important at all?
Of course, we don't want to overthink every little thing. When we enjoy an espresso, we want to do so with a clear conscience, without having to think about a nuclear power plant. Nevertheless, it makes sense to include power consumption in the pros and cons list when buying an espresso machine.
After all, every little bit helps. Let's do a quick thought experiment: Your household drinks two cappuccinos in the morning and two in the afternoon. There are machines that require about 0.42 kWh for this. If you use your machine for a year, you will consume around 150 kWh.
If, on the other hand, your machine only consumes 0.18 kWh to prepare those cappuccinos, your annual energy requirement drops to 65 kWh. That is a saving of 85 kWh per year – as simple as that. This corresponds roughly to the amount of electricity an LED TV needs if it runs all year long. https://www.enbw.com/blog/wohnen/energie-sparen/was-man-mit-1-kwh-so-alles-machen-kann-2/
If we assume that there are many other passionate cappuccino lovers out there just like you, the numbers increase significantly. The “Kaffee-Netz” forum has over 65,000 members. If each of them were to save 90 kWh per year, that would add up to a total of 4,225 megawatt-hours. That is the amount of electricity an offshore wind turbine can produce in half a year. And not every espresso machine owner is active on Kaffee-Netz. So you see, the power consumption of a machine can make a significant difference.
What does our measurement protocol look like?
We use three professional power meters, the Christ CLM1000 Professional Plus. Why three? If a value seems strange to us, we can check the measurements with another device. These meters have the advantage that they measure accurately down to a tenth of a watt, or 0.0001 kWh – that's extremely precise!
We record all values in kWh. This unit is also shown on your electricity meter, and you pay for your electricity based on the consumption per kilowatt-hour (kWh).
In our power measurement, we also take the heating-up time into account. But how long does it actually take for a machine to be ready for use? First, we measure how long it takes until the target temperature of 92°C for the first brew is reached in the portafilter. To avoid falsifying the values, we always use a cold machine, meaning a machine that has been out of operation for at least ten hours. In addition, the water added always has a temperature of 20-24°C. For thermoblock machines, for example, heating up takes only a few minutes, while dual boiler machines can take up to 40 minutes to do so.
Once the machine is at operating temperature, we perform a flush shot to warm up the portafilter.
Now we come to the “extraction measurement”.
Espresso extraction
To simulate espresso extractions, we perform five shots 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 leave a break of one minute to simulate grinding, tamping, and the other steps.
If the machine offers the option to switch off the steam boiler, we perform the energy measurement for espresso twice: once with the steam boiler switched on and once with it deactivated.
Americano
To simulate the power consumption for an Americano, we drew 70 ml of hot water after each espresso extraction.
Cappuccino
To simulate the cappuccino extraction, we heated a quantity of 300 grams of water from 6°C to 60°C using the steam wand after each espresso shot. Here, we simulate the frothing of the milk foam that you need for a cappuccino.
Kaffeemacher protocol
In older videos, we have often spoken about a “Kaffeemacher protocol” to compare the energy consumption of different machines. This protocol included a 25-minute warm-up phase, regardless of the machine type, followed by five espresso extractions with one minute of break in between. Since we did not determine the heat-up time of each machine in this outdated protocol, machines that heated up quickly were at a disadvantage. Even if they were ready to use after only 5 minutes, they still had to run for 25 minutes before the first extraction. This is one of the reasons why we developed a new protocol. However, to ensure comparability with the old videos, we still provide the values for new machines in the context of the “Kaffeemacher protocol” and show the electricity data in the article as in the following table.
Why are there such large differences in energy consumption?
The largest part of the energy consumed is used to heat up water. Preparing an espresso requires a brewing temperature of about 92°C, which is handled by the espresso machine's heating system. For lovers of milk-based drinks, additional steam is required, which is about 120°C.
The way a machine heats the brewing and steam water significantly influences 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 various machine types.
Boiler machines
Boiler machines are often referred to as “single-circuit machines” if they have a single heating circuit. Typical representatives of this machine type include, for example, the Gaggia Classic and the Rancilio Silvia.
Single-circuit machines have a small boiler in which the 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, the energy consumption varies. If you want to prepare a cappuccino, you have to heat up the boiler after drawing the espresso to reach the required steam temperature. This process can take several minutes and requires additional energy.
Simply put, a single-circuit machine can be compared to an electric kettle.
Dual boiler machines
As the name “dual boiler” 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. If both boilers are activated, they must first reach their target temperature before you can prepare espresso. While the machine is running, the temperature in the boilers is kept constant by reheating. Depending on the size of the boilers, the power consumption can be significant. 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 offer, above all, temperature stability, often even under load, and high convenience since frothing and espresso extraction can occur simultaneously and the temperature can be adjusted precisely. However, they are quite power-intensive in terms of energy efficiency. Simply put, these are two electric kettles heating simultaneously at different temperatures (high and very high). The better the boilers are insulated, the less electricity is needed to reach and maintain the temperature.
Note: Retroactive insulation is not an option, because without adjustments to the control electronics, the temperature setting no longer works reliably. You might save some electricity, but at the expense of taste.
Heat exchanger machines
Heat exchanger machines have a single boiler, but it 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 guided from the tank through a pipe past the steam boiler. The heat of the steam boiler warms the water in the pipe similarly to a heat exchanger. As a result, the brew water is brought 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, as the steam boiler must be kept constantly at a very high temperature.
Thermoblock machines and thermocoil heaters
Thermoblock machines and thermocoil heaters represent an interesting alternative. Instead of bringing an entire boiler to a target temperature, an aluminum block or a thin metal plate is heated. Water from the tank flows through pipes in the respective unit, which is heated immediately. With a thermocoil heater, even less mass has to be heated than with a thermoblock.
Since the water is only heated during extraction, the heating-up time of the machine is significantly shorter than with the various boiler machines. The Zuriga E2, for example, is equipped with a thermocoil heater and is ready for use after just two minutes. That is extremely fast and also very energy-efficient. An Ascaso Steel Duo PID, which is equipped with a thermoblock, is also at temperature in under ten minutes.
Depending on the machine's concept, the thermoblock or thermocoil heater must be heated for the steam temperature. However, there are also models with two separate thermoblocks or thermocoil 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 the sake of completeness, we would like to mention this category of espresso machines, even if 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 do not offer the same steam power as dual boiler or heat exchanger machines, Ascaso follows 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 power measurement, we are constantly updating a list with the electricity measurements of all our tested machines.
Anyone looking at the list will quickly realize that thermoblock machines and especially thermocoil heaters are generally significantly more energy-efficient than boiler machines.
However, energy efficiency is by no means the only criterion for a good espresso machine. Factors such as temperature consistency, programmability, steam power, ease of use, design, and many other aspects also play a decisive role in the decision to purchase a machine.
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 set extremely precisely. We are therefore looking forward to the developments that are still to come.
Ultimately, energy efficiency is directly related to the heating-up time. Who doesn't want a machine that is ready to use after just a few minutes, instead of having to wait three-quarters of an hour to prepare an espresso?
Should everyone switch from their boiler machines to thermoblock machines now? A very clear no! The manufacture of a machine and the raw materials required for it (stainless steel, cables, hoses, electronics) are far more energy-intensive than its operation. So if you own a heat exchanger machine that will still function for at least 10 years without major problems, you should definitely continue to use it!
Finally, the following applies: 1. The less we buy new, the more resources are saved. 2. Longevity and repairing machines also contribute to resource conservation. However, anyone thinking about purchasing a new machine and valuing energy efficiency and sustainability should carefully check our performance measurements and incorporate them into their purchasing decision.
