LOT 20 is a guideline that applies to all local space heaters. It is part of the European Ecodesign Directive (2009/125/EC), which aims to make energy-using products more environmentally friendly.

For example, according to the directive, electric heaters must have an electronic thermostat and have programmable weekly programs. Otherwise they can no longer be sold in the EU. In addition, they must either be equipped with an "open window" detection or a presence detector, or alternatively have an adaptive heating start function. The heater itself calculates how long it takes to heat up from the economy temperature to the desired temperature. In addition, a low standby energy consumption of the thermostats is stipulated.