Energy cost meters  »  Save electricity easily

Energy cost meters help to detect "power guzzlers" and to get an overview of the power consumption of connected consumers. An electricity meter tells you more about the energy consumption 
in your own home, office or business.

Find out how energy cost meters work and what you should look out for when buying one in our guide.

What is an energy cost meter?

They are small devices whose main task is to determine and display the current electricity consumption.

This recording is useful because it is difficult for people to estimate the consumption of all the devices connected in the household or work area. Although the energy consumption of the devices is usually stated by manufacturers, the duration of use, set modes and fluctuating intervals of use over the seasons make a spontaneous estimate almost impossible.

Power meters provide clear information with real-time displays and can map the total power consumption in different living and working situations through their work over months and years.

Energy cost meter with and without display

Basically, the power consumption meters can be divided into two subgroups: Models with and without display.


Energy cost measuring device with display


Anyone who wants to read the energy costs directly at the socket with a quick glance is well advised to use a display model. Small control surfaces can be used to query various values and set functions such as cost forecasts or alarms. In addition to the display, some electricity meters have a coloured LED ring that alternates between red, yellow and green to provide immediate feedback on the energy demand of an electrical consumer.

Energy cost measuring device without display

However, a digital energy cost meter can also do without a display and only transmit the power consumption to an evaluation programme via software. This can be done conveniently via an app on a smartphone or tablet. Users do not have to stand directly in front of the energy cost meter to read out the power consumption and control it. Some models nevertheless offer the coloured LED ring for a rough assessment of the power consumption without looking at the app.

Energy cost measurement devices

Energy cost meter: What data is collected?

As electricity consumption meters, the primary task of the measuring devices is to determine the energy consumption. This function is therefore always present as a basic function.

Many devices are additionally capable of generating a cost forecast based on the electricity consumption. For this, users can enter their selected electricity tariff and the electricity consumption meter calculates the costs for a desired period.

Some electricity meters offer the input of two tariffs to display different variants. This helps when deciding on a tariff.

In addition to specifying the electricity consumption, many energy cost meters collect further data, including effective factor and effective power. The latter means the power in watts that is actually consumed by the connected device. The active factor, in turn, indicates the 
ratio of active power to apparent power.

The apparent power in volt-amperes indicates how much current flows into the device and what voltage is present.

Other data that an energy cost meter can record:

  • Rated voltage
  • Power
  • Current
  • Frequency
  • CO2 emissions


How must an energy cost meter be connected?

For its smooth functioning, the electricity consumption meter must be correctly connected to the mains. This varies in complexity depending on the model chosen. A distinction is made between three types of connection.

Plug-in adapter


In private households as well as offices, plug-in adapters are most frequently used. These electricity meters are simply placed between the end device and the socket and can collect the desired data from this position. According to the plug-and-play principle, the washing machine or the printer, for example, are plugged into the power consumption measuring device and operated normally.

Mobile current measuring devices


They are not intended for permanent use, but for mobile use. The electricity consumption meters have plugs and couplings and provide digital results on energy consumption as intermediate meters. Many models have MID approval, which means they are set according to the European Measurement and Verification Act. The data collected can therefore be officially used for energy cost billing.

Professional models for assembly


In addition to plug-in adapters and mobile electricity meters, both of which are comparatively inexpensive, there are energy cost meters in the professional sector that may well have four-digit acquisition costs. They are used in industry and in property management. They are installed by specialists directly on distribution boxes in the building.

AC & Three Phase Electricity Meters

As a rule, AC and three-phase meters are provided, installed and operated by the utility company. However, there are situations - especially in an industrial environment - in which an additional separate meter makes sense. For example, to control the electricity consumption of individual machines or systems.

In our guide, you can find out which types and designs are available and how they differ.

What are AC and three-phase electricity meters?

They are measuring devices for recording the electrical energy taken from a supply network. The devices are usually calibrated in billing units, the most common being the kilowatt hour, abbreviated to kWh.

While alternating current meters measure single-phase electricity at 230 volts, three-phase meters measure three-phase electricity at 400 volts.

Both are usually based on the mains frequency of 50 Hertz, which is common in Europe. The analogue meters are usually installed in switchboards, in most cases directly by the utility company. For sub-distribution networks, however, additional electricity meters can also be installed.

Types and designs of alternating current and three-phase electricity meters

There are electromechanical - so-called Ferraris meters - and electronic meters. With both single-phase and three-phase power supply, the electromechanical Ferraris meter works by induction, counting the revolutions of a non-magnetic but electrically conductive metal disc. The speed of the disc is proportional to the active power flowing through the meter and thus proportional to the energy consumption.

Another disadvantage is the analogue technology, which can still be calibrated, but which is subject to wear and tear due to the system. The biggest hurdle is the Measuring Instruments Directive, or MID for short. This is Directive 2004/22/EC of the European Parliament and of the Council on measuring instruments. Among other things, it also applies to electricity meters. The MID is independent of verification under calibration law, for example in the case of Ferraris meters. Thus, in Germany, measuring instruments are only considered to be calibrated if their conformity has been established in a prescribed conformity assessment procedure and they are marked accordingly as MID-compliant.

Despite some disadvantages, analogue electricity meters still find many customers. This is due on the one hand to the favourable prices, and on the other hand to the possibility of calibrating analogue types in conformity with the MID. Modern mechanical alternating current and three-phase meters with roller counters without Ferraris technology are also available. They are also MID-compliant and are suitable, for example, for industrial environments or - in plug-in design - for construction sites.

The future of electricity meters naturally lies in digitalisation. Not least because of the EU directives and their implementation by the Federal Network Agency. As early as 2020, consumers of up to 6000 kilowatt hours per year must have a modern electricity meter installed. However, these so-called smart meters are not online. The ability of the meter to communicate via the internet is only mandatory for annual consumption of 6000 to 10,000 kilowatt hours.

How digital AC meters and three-phase electricity meters work

Conventional mechanical electricity meters are based on magnetic induction, as mentioned above. They have a rotating aluminium wheel and numerous gear wheels. Since a correspondingly large number of mechanical parts are involved, technical defects and failures can occur after a certain time. In addition, there is a risk of manipulation and electricity theft.

Electronic electricity meters, on the other hand, work completely without moving parts. The energy consumed is displayed on an LED or LC display instead of a roller counter. Communication-capable types can also transmit the measured values to remote locations. In addition to voltage and current inputs, digital energy meters have a voltage reference, sampler and quantiser, followed by an analogue-to-digital conversion section to obtain the digitised equivalents of all inputs. These inputs are then processed by a digital signal processor. An S0 interface and an S0 pulse output are usually also present.

In addition to measuring the energy consumed, some electronic electricity meters also record parameters of the applied load and supply, including, for example, the instantaneous and maximum consumption value, the voltage, the power factor and the active and reactive power used. They often also support time-of-day billing, for example by recording the amount of energy consumed during peak and off-peak hours.

Thermal imaging cameras » Easily measure surface temperatures with infrared radiation

A thermal imaging camera is an infrared camera that, like an infrared thermometer, enables non-contact temperature measurement of surfaces. The result of the measurement is output as a thermal image.

Thermal imaging cameras are used, for example, in industry, construction and hunting.

In our guide, you can find out what the specific features of the devices are and what you should look out for when buying them.

How does a thermal imaging camera work?

The warmer a body or object is, the more intense the infrared radiation emitted by the body or object. A thermal imaging camera makes use of this property. Thermal imaging cameras are imaging measuring devices, similar to a conventional 
digital camera, that enable non-contact temperature measurement. 
They make heat radiation visible and display the surface temperature of objects in the form of an image. The technical term for this method is thermography.

Like a digital camera, a thermal imaging camera is equipped with a lens, a sensor, an integrated display and an electronic system. However, unlike a digital camera, the sensor is not an image sensor but a detector that picks up infrared radiation. The electronic 
system makes the radiation visible on the integrated display by converting the corresponding signals into electrical signals and displaying the temperature of the recorded environment as a coloured image. Orange and red stand for warm temperatures, blue and green for 
cold temperatures. Because the thermal image only shows the thermal environment, it is sometimes difficult to understand which specific object the measurement refers to. For this reason, some devices are additionally equipped with a digital camera, so that the surroundings 
or the object are also recorded as a photo at the same time as the 
thermal image. 
Thermal imaging cameras are available as mobile devices, as more complex infrared cameras with accessories and as pyrometers. Mobile devices, so-called pocket cameras, can be used without further accessories and are used in the private sector. For professional 
use, larger and more powerful IR cameras are used, for which you can obtain accessories such as different lenses or software for thermography. A pyrometer is an IR thermometer with a display that shows not only the measured temperature but also a thermal image. The battery of a thermal imaging camera can be charged via micro-USB or USB-C. 

Examples of how to use a thermal imaging camera

Thermal imaging cameras were originally developed for the military and are used by the military, police and fire brigade to locate people.

In hunting, thermal imaging cameras are used to find animals hidden in the undergrowth or animals that have already been killed. 

In industry, thermal imaging cameras can be used to inspect workpieces. In construction, a thermal imaging camera can be used to find leaks or leaking parts.

The fire brigade uses thermal imaging cameras to find hard-to-see hot spots.

In medicine, a thermal imaging camera can be used to diagnose inflammation or circulatory disorders. 

In private use, the cameras are mainly used as gadgets.But a thermal imaging camera also makes sense in private households from the point of view of saving energy, in order to detect leaking windows and doors, because the temperature is lower in a draughty place.

Thermography software: manage recordings professionally

A thermal imaging camera has an internal memory where the recorded images are stored.

The memory can often be expanded with the help of an SD card.

Most cameras can be connected to a printer or computer via a USB port so that you can print or process the images.

Special thermography software is available for professional documentation.

In addition to the chronological storage of images, this software also enables image analysis, a diagram display and the simple creation of reports.

It is also possible to track and evaluate live images from the thermal imaging camera via software.

As a rule, the software solutions are compatible with Windows, Mac and Linus.