Heat Protection for Renters in Germany: What May Change in Building Law

Introduction

Summers in Germany are getting hotter. In recent years, the country has experienced record-breaking heatwaves, and millions of renters — including a large share of expats and immigrants — have found themselves sweltering in apartments with no air conditioning, poor ventilation, or south-facing windows that turn rooms into ovens. Now, Chancellor Friedrich Merz has publicly stated that Germany's building law needs to be amended to give tenants better protection from extreme heat. If you rent an apartment in Germany, this debate directly affects your living conditions and potentially your landlord's legal obligations.

Why Heat Is a Growing Problem for Renters

Germany's housing stock is old. A significant portion of residential buildings were constructed decades ago, long before climate change made 38°C summers a regular occurrence. These buildings were designed to retain heat in winter — which is useful in January but becomes dangerous in July.

Unlike countries with warmer climates, Germany has no legal standard requiring landlords to provide cooling or shading in residential properties. There is no equivalent to the heating obligation (landlords must provide heating that keeps apartments at a minimum of 20°C in winter) for summer heat. This legal gap means tenants have very limited recourse when their apartment becomes unbearably hot.

According to public health data, extreme heat is responsible for thousands of excess deaths in Germany each year, disproportionately affecting elderly people and those living in urban heat islands — including many densely populated city districts where expats tend to live.

What Chancellor Merz Has Proposed

Chancellor Friedrich Merz has stated publicly that Germany's building law (Baugesetz) needs to be revised to address heat protection. While no specific draft legislation has been published yet, the debate in parliament is centred around several possible measures:

• Mandatory external shading: Requiring new buildings — and potentially retrofits of existing ones — to include external blinds, shutters, or awnings that block direct sunlight before it heats the glass.
• Ventilation standards: Updating building codes to ensure adequate cross-ventilation is possible in residential units.
• Green roofs and façades: Incentivising or requiring vegetation on rooftops and building exteriors to reduce the urban heat island effect.
• Cooling obligations for landlords: Potentially introducing a legal maximum indoor temperature above which landlords would be obliged to act — mirroring the existing winter heating obligation.

No firm timeline has been set. The proposals would need to pass through both the Bundestag and Bundesrat before becoming law, and experts note that retrofitting existing buildings at scale would be both expensive and logistically complex.

What Tenants Can Do Right Now

While the legislative process plays out, there are practical steps renters can take to protect themselves and understand their current rights.

Check your rental contract and building rules: Some rental contracts or house rules (Hausordnung) restrict tenants from installing their own external shading, awnings, or window films. Review yours carefully before making any changes to the apartment.

Document heat problems: If your apartment regularly reaches dangerous indoor temperatures (above 26°C is generally considered uncomfortable; above 30°C in a bedroom is potentially a health risk), document it. Take temperature readings at different times of day, photograph conditions, and write to your landlord formally. This creates a paper trail if you later need to pursue a rent reduction (Mietminderung).

Explore rent reduction options: Under current German tenancy law, tenants may be entitled to a rent reduction if an apartment has a defect that significantly impairs its habitability. Courts have occasionally recognised extreme heat as such a defect, particularly where it results from construction flaws. Consult a tenants' association (Mieterverein) for advice specific to your situation — many offer affordable membership with legal support included.

Use portable cooling strategically: Portable air conditioning units are permitted in most rentals, though you should check your contract for clauses about modifying windows or installing hoses. Ensure any unit you use is energy-efficient to manage electricity costs.

Frequently Asked Questions

Does my landlord have to keep my apartment cool in summer?

Currently, no. German law requires landlords to provide adequate heating in winter (minimum 20°C in living spaces), but there is no equivalent legal obligation for cooling in summer. This is precisely the gap that Chancellor Merz's proposed building law amendment aims to address. Until new legislation passes, tenants have limited legal grounds to demand cooling measures — though extreme cases may be arguable as habitability defects.

Can I install an air conditioning unit without my landlord's permission?

It depends. Portable, freestanding air conditioning units generally do not require permission. However, if installation involves modifications to the building — such as drilling through an exterior wall for a split-system unit — you typically need your landlord's consent. Some landlords refuse; if yours agrees, get it in writing. Installing a through-wall or split system without permission could result in you being required to restore the apartment to its original state when you leave.

What is a Mieterverein and how can it help me?

A Mieterverein is a tenants' association. Germany has a strong network of these organisations, and for a modest annual membership fee (usually €60–€100), you gain access to legal advice and representation on housing disputes. If you are dealing with heat-related habitability issues, an unresponsive landlord, or considering a rent reduction, contacting your local Mieterverein is one of the most practical first steps you can take.

Will these changes affect my current apartment?

Potentially, yes — but not immediately. If building law changes introduce retrofit obligations, landlords of existing buildings may eventually be required to make improvements. However, major retrofits typically come with long transition periods and may also lead to modernisation rent increases (Modernisierungsumlage), where landlords can pass on a portion of the upgrade costs to tenants. This is a known concern among tenant advocacy groups and is likely to be part of the parliamentary debate.

Conclusion and Next Steps

The proposed changes to Germany's building law represent a meaningful shift in how the state thinks about tenant rights in a warming climate. For expats and immigrants — who are statistically more likely to rent than own, and who may be less familiar with German tenancy law — staying informed is important.

In the short term: document heat problems in your apartment, connect with your local Mieterverein, and review your rental contract for any clauses that might limit your options. In the medium term: watch for updates from the Bundestag on the building law reform, as any new obligations for landlords could give you stronger legal grounds to demand improvements.

For personalised advice on your rental situation, always consult a qualified tenancy lawyer or your local Mieterverein.

Source: DW English