The fax transmits copies of images over the public telephone network.

A fax machine comprises three different devices: a scanner, a modem, and a printer.

Since fax machines are usually in operation 24 hours a day, a special focus should be put on low standby consumption. Only approximately 25 % of the overall energy is consumed for transmitting and receiving, the remaining 75 % are used up during standby operation.

More than 75 % of the energy consumed by a fax machine is merely used for standby operation. A commonly available additional ballast unit will help avoid such unnecessary power consumption.

Fax machines with laser printers should only activate the printer upon receipt of a document, thus also reducing standby consumption.
Fax machines with ink-jet printers are more energy efficient than those featuring laser printers.

Fax receivers should not be installed in PCs or laser printers if this results in longer operating hours than before.

If, for example, a PC is to serve as a fax, it will be running 24 hours a day compared to an original 8 hours.

This can be avoided by using a fax modem which can store incoming fax messages.

When buying a new fax machine pay particular attention to the energy requirements indicated by the manufacturer and consequently, give preference to energy saving appliances! These are often marked with a special label in order to enhance consumer recognition.