The Building Energy Act (GEG) for Home Renovations

In the recent past, we were entrusted with the renovation of a historic multi-family building at Hackerstraße, in Berlin, originally built in 1911. As part of our work on this project, we guided our clients through the details of GEG. In this blog, we will also provide a general idea of what the GEG involves and how it can impact your future renovation projects.

A historical photograph of the façade

The existing condition of the façade

What is the GEG?

The Building Energy Act (GEG) has been in effect since November 2020, consolidating previous laws (EnEV, EnEG, and EEWärmeG) into one cohesive framework. It applies to both new constructions and renovations, and sets strict energy efficiency standards that must be met.

What is U-Value?

One vital concept in the GEG is the U-value, which measures the thermal conductivity of a building’s components like walls, roofs, and windows. A lower U-value therefore means better insulation and less heat loss. The GEG mandates specific U-values for various building elements, ensuring that your renovation meets certain energy efficiency standards and helps reduce overall energy consumption.

Typical energy losses in an average building without modernization measures.

What are the Key GEG Requirements for Renovations?

If you're planning to renovate your older building, there are three important GEG requirements that you should consider:

1. Roof or Top Floor Ceiling Insulation: If your roof or the ceiling of the top floor isn’t insulated, it must be improved to meet energy efficiency standards. (This is outlined in § 47 GEG.)

   
   

2. Replacement of Old Boilers: Boilers older than 30 years must be replaced with newer, more efficient models.  (to comply with § 72 GEG).

   
   

3. Insulation of Water Pipes: Hot water or heating fluid pipes need to be insulated to prevent energy loss (as stated in § 71 GEG).

   
   

Facade Renovation and Thermal Insulation

When renovating your building’s facade, the GEG has specific requirements for thermal insulation. If you plan on installing new facade cladding or change the exterior plaster, the thermal insulation needs to meet a maximum U-value of 0.24 W/(m²·K). This normally requires additional insulation to existing facades across Germany. However, minor repairs to less than 10% of the facade are exempt from these regulations (see § 48 GEG).

Maximum U-Value for External Components When Modifying Existing Buildings. Source: Building Energy Act (GEG) – Act on Energy Saving and the Use of Renewable Energies for Heating and Cooling in Buildings, Annex 7 to § 48.

Energy Performance Certificates (Energieausweis)

For homes that are being sold, rented, or significantly renovated, the GEG requires an energy performance certificate (Energieausweis) to document your building’s energy efficiency (per § 80 GEG). This certificate helps potential buyers or tenants assess the energy consumption and potential savings during the time that they occupy the building.

Source: "Law for the Saving of Energy and the Use of Renewable Energies for Heating and Cooling in Buildings (Building Energy Act - GEG), Annex 7 to § 48"

Why GEG Compliance Matters?

A poorly insulated home can lose up to 225 kWh/m² per year in energy, especially in older buildings. By complying with GEG standards, you can reduce heating costs, improve comfort, and increase property value.

Additionally, adhering to these regulations is an essential step toward a more environmentally sustainable future, helping reduce overall energy consumption and contributing to the fight against climate change.

Renewable Energy Requirements for Heating Systems

The GEG also includes specific regulations for heating systems, aiming to reduce reliance on fossil fuels. For new installations or replacements of heating systems, the GEG mandates that at least 25% of the energy required for heating, hot water, or cooling must come from renewable sources.

This can include renewable energy systems such as solar thermal, heat pumps, and biomass heating.

Steps for planning your renovation:

1. Assess Your Building: Check if your home meets the insulation and heating system requirements under the GEG.

   
   

2. Consult a Professional: Work with an energy consultant or architect to understand what GEG-compliant upgrades are needed.

   
   

3. Apply for Funding: Look into government subsidies for energy-efficient renovations.

   
   

4. Ensure Proper Documentation: Keep records of insulation, heating upgrades, and consultations to ensure compliance.

How to save on energy-efficient upgrades?

If you are planning on energy-efficient upgrades, several financial programs can help offset the costs. KfW offers low-interest loans and grants for general energy improvements through its BEG program, while BAFA provides funding for renewable heating systems and energy consultations.

These consultations are often required for funding applications and may be partially subsidized.

Additionally, you can apply for government subsidies for insulation and heating system upgrades to further reduce costs.

Why Choose Archiformus for Your Renovation?

At Archiformus, our team of experienced professionals will guide you through every step, from the initial assessment to securing any necessary government funding.

We focus on delivering energy-efficient renovations that fully comply with GEG regulations.

Whether you’re upgrading insulation, replacing old heating systems, or taking on another part of your renovation, we make sure everything is up to code and designed for long-term energy savings.

We know how complex GEG standards can be, so we provide customized solutions that meet your unique needs—both in terms of aesthetics and sustainability.

With Archiformus, you would be working with a team dedicated to making your renovation project a success—cost-effective and ready for the future. Through some of our upcoming blogs, we will continue sharing insights into our work on the Hackerstraße project.