Heating season: When should you start heating your home?

As the days get shorter, the nights longer and the temperature drops, it is time to wake the heating system from its "summer slumber". But what does that mean exactly? When does the heating season actually begin? Or does a mandatory heating requirement even exist? We explain which laws apply here and what you should consider as the heating season starts.

Are there any laws governing the heating season?

It can be categorically stated that there are no specific laws in Germany governing the heating season and when it starts or ends. Nevertheless, a certain time period has been defined and also confirmed by case law. Accordingly, the heating season begins on the 1st October and ends on the 30th April.

However, depending on weather conditions and the region in Germany, the exact times may differ from this time frame. In certain circumstances, for example, the heating season may start as early as mid-September and continue until mid or even late May.

What do system owners need to consider?

In principle, system owners who do not rent out living space can heat their homes whenever it is too cold, even outside the usual heating season. However, to save energy and therefore reduce heating costs, it is recommended that the Viessmann heating system is set to summer mode. This means the system only supplies the building with DHW.

An advanced Viessmann heating system can also be adjusted via a weather-compensated control system. The key role here is played by the heating curve. The set room temperature is reached when the heating curve, also known as the heating characteristic curve, has been optimally adjusted and the thermostats have been fully opened. However, it can take several days until an optimal setting is found due to the inertia of the system. Should the temperatures then drop so far that the room temperature falls below the set temperature, the heating system starts up accordingly.

Heating in spring and autumn – when should you start heating your home?

For most people, the question of when to start heating their home arises in the transitional periods of spring and autumn. This is because springtime often brings pleasantly warm days, especially if the sun shines for a long time. However, temperatures sometimes drop below freezing at night. The same applies to the autumn months. As shown, there are no laws governing when a property must be heated for tenants. There are only guidelines.

Homeowners are free to switch on their heating system in the spring and autumn whenever it is too cold. Frequently switching a system on and off (known as cycling) can reduce its efficiency. To avoid this, make sure that the heat is evenly distributed in the house and that the heating control unit is adjusted accordingly. Cycling oil and gas heating systems is circumvented, among other things, by modulating burners or by individually adjusting the heating curve (in systems with weather-compensated system controls).

Heating season – predominantly a matter for tenancy law

If, on the other hand, you as a system owner rent out residential space, the heating season issue becomes more important. It is not uncommon for disputes between tenants and landlords to occur over this very matter. Both parties base their arguments on the date. But many other factors have to be considered and weighed up. An individual's perception of temperature often initially determines whether a room is too cold. How the individual ventilates their accommodation and how well the property has been renovated and insulated are also vitally important considerations. But what exactly can tenants and landlords use as guidance?

The room temperature should not fall below this level

Ultimately, however, the heating season is not based on an exact date. When you should start heating a property depends much more on the temperature. There are certain standard values for this that you can use as a guide. During this period, the room temperature should be between 20 and 22 degrees Celsius. Tenants are entitled to these temperatures in the living space during the usual heating season. Although the heating can be turned down at night, the temperature must not fall below 18 degrees Celsius.

Need for heating outside the season

However, the heating season is not set in stone. Because outside the season, it can cool down to the extent that the temperatures mentioned cannot be reached in the rooms. Consequently, the heating may also have to be switched on in May or August. If the outside temperatures fall below 16 degrees Celsius or the temperatures in the apartment remain below 18 degrees Celsius for at least two consecutive days, the tenant is entitled to have the heating system on. But even these figures are only guidelines. Because there are no laws on this either, only various court rulings. So there is no general answer to the question of when you are allowed to reduce the rent.

Legal framework

If the landlord does not adhere to the heating season or rather does not fulfil his/her obligation to ensure a functioning heating system, tenants have various options, including rent reduction. The legal basis here is section 536 of the German Civil Code (BGB). If the rented property has defects or its condition is not in accordance with the contract, tenants can reduce the rent. The extent of the reduction is not defined by law. However, rent reduction tables containing a variety of court rulings on different descriptions of defects, may serve as guidance. In principle, however, the first step is to contact the landlord and report the defect.

Incidentally, the tenant has obligations too. For instance, although he/she is permitted to heat their accommodation whenever they choose, this should not result in damage to the apartment. If, for example, the tenant does not heat the apartment at all and mould develops in the apartment, the tenant could be legally liable.