Is heat a reason to reduce the rent?

When an apartment heats up to the point of being unbearable day and night, it quickly leads to heated debates between tenants and landlords. But where is the line drawn? At what point does excessive heat justify a rent reduction? The Federal Court of Justice has not yet ruled on this question.

So far, there are only a few relevant court rulings regarding rent reductions due to heat. This could change due to climate change. Extremely hot days are no longer a rarity in Germany, and the hot summer of 2019 is expected to be followed by an even hotter one this year: meteorologists are forecasting temperatures exceeding 40 degrees Celsius.

Even though prolonged summer heat can have significant health consequences, high temperatures in an apartment are generally not considered a defect in the rental property. The Frankfurt Higher Regional Court, for example, has argued in the past (January 19, 2007, 2 U 106/06) that high summer heat is part of the general risk of life. But must the tenant really wait until their hamster and pet dog succumb to heatstroke?

Actually, it is the landlord's responsibility to ensure that the apartment is habitable in the summer. A rent reduction under Section 536 of the German Civil Code (BGB) is generally justified if the usability of the apartment, as stipulated in the lease, is significantly impaired. Whether this is the case must be assessed on a case-by-case basis; there is currently no binding regulation.

The case law is contradictory: While the Hamburg District Court deemed a 20 percent rent reduction appropriate in the case of an upper-floor apartment where the temperature reached 30 degrees Celsius during the day and over 25 degrees Celsius at night (May 10, 2006, 46 C 108/04), the Leipzig District Court found no defect in a maisonette apartment with the same temperature conditions (September 6, 2004, 164 C 6049/04). The decisive factor in the Hamburg case was that the thermal insulation of the south-facing apartment with its glass front did not meet the state of the art prescribed at the time of construction.

While it had previously been argued that a tenant in an attic apartment must expect the rooms to heat up in the summer, the court in this case set limits and declared that a defect also exists "if the heating caused by solar radiation and ambient temperatures reaches a level that impairs the suitability for the contractually agreed purpose." The tenant was therefore entitled to reduce the rent by 20 percent for the month in question.

Generally, a rent reduction is not possible across the board, but only proportionally for the days on which the quality of living was significantly impaired. A thermometer that records the room temperature serves as evidence. Should the dispute end up in court, witnesses will also be required.

Before tensions escalate, affected tenants should talk to their landlord, advises the property owners' association Haus & Grund. The landlord can then assess whether the thermal insulation can be improved. "Ultimately, it should also be in the landlord's interest for the tenants to feel as comfortable as possible," explains lawyer Ralf Schönfeld – and improvements such as better insulation, the installation of air conditioning, or the addition of awnings and shutters sustainably increase the value of the apartment. However, tenants do not have a legal right to these improvements. If they want to take matters into their own hands and, for example, install an awning, they need the landlord's permission, as with all structural alterations.

Conclusion: Tenants have a right to a rent reduction primarily if the excessive heating of the apartment is due to a structural defect. However, case law refers to the year the apartment was built, not to current standards.

Sources: dejure.org, Haus und Grund, Mieterschutzbund, focus.de, sueddeutsche.de, mietrecht.com, haufe.com