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 significantly increased in recent years, and many consumers are increasingly valuing 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 briefly explain how we measure power consumption and how different espresso machine systems differ in their consumption. We strive to use only the absolutely necessary technical terms so that readers without electrical engineering knowledge can follow along.
Why is the power consumption of machines important at all?
Of course, we don't want to constantly 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.
Because every little bit helps. Let's do a quick thought experiment: In your household, you drink two cappuccinos each in the morning and in the afternoon. There are machines that require about 0.42 kWh for this. So, if you use your machine for a year, you consume about 150 kWh.
If, on the other hand, your machine only consumes 0.18 kWh for preparing the cappuccinos, your annual energy requirement is reduced to 65 kWh. That means a saving of 85 kWh per year – quite simply. This corresponds to approximately the amount of electricity an LED TV uses if it runs all year. 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 also many other passionate cappuccino lovers, the numbers increase significantly. The "Kaffee-Netz" forum has over 65,000 members. If each of them saved 90 kWh annually, that would amount 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 portafilter machine owner is active in 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 measuring devices offer the advantage that they measure accurately down to a tenth of a watt, i.e., 0.0001 kWh – that's extremely precise!
We record all values in kWh. This unit is also displayed in your meter box, and you pay for your electricity based on consumption per kilowatt-hour (kWh).
In our power measurement, we also take into account the heating-up time. But how long does it take for a machine to actually be ready for operation? First, we measure how long it takes until the target temperature of 92 °C for the first brew in the portafilter is reached. To avoid distorting 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 filled water always has a temperature of 20-24 °C. With thermoblock machines, for example, heating up only takes a few minutes, while dual boiler machines can take up to 40 minutes for this.
Once the machine is at operating temperature, we do a flush shot that warms up the portafilter.
Now we come to the "drawing measurement".
Espresso draw
To simulate espresso draws, we perform five draws, each lasting 27 seconds. Additionally, there is a so-called "flush" of 2 seconds, which simulates cleaning the brew group. Between each draw, we allow a one-minute break to simulate grinding, tamping, and 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 always drew 70 ml of hot water after each espresso draw.
Cappuccino
To simulate the cappuccino draw, after each espresso draw, we heated 300 grams of water from 6°C to 60°C using the steam nozzle. Here we simulate frothing the milk foam you need for a cappuccino.
Kaffeemacher Protocol
In older videos, we often talked about a "Kaffeemacher Protocol" to compare the energy consumption of different machines. This protocol included a warm-up phase of 25 minutes, regardless of the machine type, followed by five espresso shots with a one-minute break in between each. Since we did not determine the heat-up time of each machine in this outdated protocol, machines that warmed up quickly had a disadvantage. Even if they were ready for operation after only 5 minutes, they still had to run for 25 minutes before the first shot. This is one of the reasons why we developed a new protocol. However, to ensure comparability with the old videos, we also provide the values for the new machines within the "Kaffeemacher Protocol" and show the power data in the article as in the following table.
Why are there such big differences in energy consumption?
The largest part of the energy consumed is accounted for by heating water. For the preparation of an espresso, a brewing temperature of about 92 °C is required, which is handled by the heating system of the espresso machine. For lovers of milk-based drinks, steam, which is about 120 °C hot, is also needed.
The way a machine heats the brewing and steaming 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 type of machine include the Gaggia Classic and the Rancilio Silvia.
Single-circuit 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 drawing the espresso, you have to heat up the boiler to reach the required steam temperature. This process sometimes takes a few minutes and additionally requires 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 brewing 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. During operation, the temperature in the boilers is kept constant by reheating. Depending on the size of the boilers, power consumption can be significant. The La Marzocco GS3, for example, with its 1.5-liter brew boiler and 3.5-liter steam boiler, requires a full 0.6 kWh in the first hour.
Dual boiler machines offer primarily temperature stability, often even under load, and high comfort, as frothing and espresso drawing can occur simultaneously and the temperature can be precisely adjusted. However, they are quite power-intensive in terms of energy efficiency. Simply put, they are two 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: Retrofitting insulation is not an option, because without adjustments to the control electronics, the temperature setting will no longer function reliably. So you can save some electricity, but at the expense of taste.
Heat Exchanger Machines
Heat exchanger machines have a single boiler, which, however, 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 brewing water is led from the tank through a tube past the steam boiler. The heat of the steam boiler warms the water in the tube, similar to a heat exchanger. This brings the brewing 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, as the steam boiler must be kept at a very high temperature constantly.
Thermoblock machines and Thick-film heaters
Thermoblock machines and thick-film 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 directly. With a thick-film heater, even less mass needs to be heated than with a thermoblock.
Since the water is only heated during the draw, the machine's heat-up time is significantly shorter than with the various boiler machines. The Zuriga E2, for example, is equipped with a thick-film heater and is ready for use after just two minutes. That is extremely fast and also very energy-efficient. Even an Ascaso Steel Duo PID, which is equipped with a thermoblock, reaches temperature in under ten minutes.
Depending on the machine's concept, the thermoblock or thick-film heater must be heated to the steam temperature. However, there are also models with two separate thermoblocks or thick-film heaters, one for the brew temperature and one for the steam temperature.
Multi-heating systems
Some espresso machines combine different heating systems. For the sake of completeness, we want 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 brewing temperature. Since many thermoblock machines do not 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 power measurement, we continuously update a list of power measurements for all our tested machines.
Anyone looking at the list will quickly realize that thermoblock machines and especially thick-film 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 purchase decision for a machine.
So, have we reached the end of the dual boiler or heat exchanger era, as we teased in our video? Yes, this could increasingly be the case in the coming years. Modern espresso machines are characterized by high temperature stability and can be adjusted with extreme precision. Therefore, we are excited about the developments that are yet to come.
After all, energy efficiency is directly related to heat-up time. Who wouldn'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 prepare an espresso?
Should everyone now switch from their boiler machines to thermoblock machines? A clear no! The production 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 still works for at least 10 years without major problems, you should definitely continue to use it!
Finally, the rule is: 1. The less we buy new, the more resources are saved. 2. Durability and the repair of machines also contribute to resource conservation. However, if you are thinking about buying a new machine and value energy efficiency and sustainability, you should carefully review our power measurements and incorporate them into your purchase decision.
