Thermal retrofit

Thermal retrofitting refers to all measures that improve a building’s thermal insulation and energy efficiency-from facade insulation and roof insulation to the replacement of windows and doors. The goal is to reduce heating energy consumption, lower operating costs, and improve living comfort. In light of rising energy prices and stricter legal requirements, thermal retrofitting is now both economically and legally necessary for many property owners-and increasingly a decisive factor in property value and marketability.

Typical measures for thermal retrofitting

Thermal retrofitting encompasses a wide range of measures that can be implemented individually or in combination:

Facade insulation: The external thermal insulation composite system (ETICS), the rear-ventilated curtain wall, or core insulation in double-shell masonry reduces heat loss through exterior walls by up to 60%. The ETICS is the most common option for post-war apartment buildings and typically costs €80-150 per square meter of wall surface in the Nuremberg region, depending on the material and insulation thickness.

Roof insulation: Over-rafter, between-rafter, or under-rafter insulation protects against heat loss through the top building envelope. For attics that are not converted into living space, insulating the top floor ceiling is the most cost-effective option (starting at approx. €15-25/m²) and is also a legal requirement under the Energy Conservation Act (GEG) when the property changes hands.

Basement ceiling insulation: Prevents cold air from entering from below and is relatively cost-effective (approx. €20-40/m²), but with a total savings of 5-10%, it has the lowest impact among individual measures.

Window and door replacement: Modern thermal insulation glazing (triple-pane, U-value ≤ 0.8 W/m²K) eliminates thermal bridges at openings. Window replacement costs €400-1,200 per window, including installation, depending on size and quality, and is particularly effective for old single-pane windows from the 1950s-1970s.

When combined, these measures can reduce heating energy consumption by 30-70%, depending on the building’s initial condition.

Subsidies and Cost-Effectiveness

Thermal retrofitting is supported by various programs:

The Federal Subsidy for Efficient Buildings (BEG) from the BAFA and KfW offers grants and low-interest loans for individual measures (BEG EM) and complete renovations (BEG WG/NWG). For individual measures, grants of 15% of eligible costs are available; if an existing individual renovation roadmap (iSFP) is in place, the bonus increases by 5 percentage points, up to 20%. For complete renovations to a recognized energy-efficient building standard (EH 85 to EH 40 Plus), grants of 15-45% are available. Important: The grant application must be submitted before construction begins-retroactive applications will not be accepted.

The payback period varies between 10 and 25 years depending on the measure and decreases as energy prices rise. With gas prices of 12-15 cents/kWh and a 50% heating energy savings in a single-family home, a complete thermal renovation typically pays for itself in 12-18 years-taking the subsidy into account.

Thermal Renovation and Property Value

A well-documented thermal renovation measurably increases a property’s market value. The energy performance certificate shows a higher efficiency class after the renovation-an improvement from Class G or H to Class C or B is realistic for older buildings from the 1960s-1980s. Buyers and tenants are increasingly focusing on energy efficiency; properties with poor energy performance (classes F-H) command price discounts of 10-20% on the market compared to comparable renovated properties. This value gap widens as energy renovation requirements become stricter.

Particularly relevant for landlords: The EU Energy Performance of Buildings Directive (EPBD, to be transposed into national law) mandates minimum energy standards in the medium term that will require the worst-performing buildings (Classes F and G) to undergo renovation. Those who renovate now avoid a future obligation under potentially less favorable conditions (higher construction costs, reduced funding).

Practical Tip for Property Owners in Nuremberg and Franconia

Nuremberg and the Franconian region have a large stock of older buildings constructed between 1920 and 1980, which offer significant renovation potential. Especially in the Wilhelminian-style neighborhoods (Südstadt, Gostenhof, Johannis), many buildings still have inadequate facade insulation and old windows. In addition to federal funding, the City of Nuremberg supports local climate protection projects and offers free energy consulting through the Bavarian Consumer Center. Those seeking on-site expert advice can contact the Northern Bavaria Energy Agency or the Nuremberg Chamber of Commerce and Industry (IHK).

We recommend hiring an independent energy consultant (certified under GEG, listed in the federal government’s Energy Efficiency Experts List) before renovation to create an individual renovation roadmap (iSFP). This roadmap determines the optimal sequence of measures (e.g., roof first, then facade, then windows, then heating), maximizes subsidy rates, and prevents costly mistakes-such as having to break open exterior walls after window replacement. The cost of an iSFP is approximately 1,500-2,500 euros and is itself eligible for up to 80% in subsidies.

Frequently Asked Questions

As a property owner, am I required to perform thermal retrofitting?

The Building Energy Act (GEG) requires that, in the event of a change of ownership, the top floor ceiling be insulated (if not already sufficiently insulated) within two years of acquisition. Furthermore, there are currently no general renovation obligations under the GEG for existing buildings-only heating systems are subject to replacement requirements (e.g., no oil boilers older than 30 years, except for low-temperature and condensing boilers). However, the EU Buildings Directive will introduce stricter minimum requirements in the medium term, which are expected to come into effect gradually starting in 2030.

How much does a complete thermal renovation of a single-family home cost?

The cost of a full renovation (facade, roof, basement, windows) of a typical 1970s single-family home in the Nuremberg region ranges from 70,000 to 150,000 euros, depending on size, condition, and the chosen quality standard. After deducting the federal subsidy (15-45% depending on the package of measures and efficiency standard), the out-of-pocket cost is significantly reduced. Added to this are the heating costs saved over 15-25 years, which should definitely be factored into the overall calculation.

Does thermal renovation improve the energy performance certificate?

Yes, significantly. An unrenovated older building from the 1970s often has an energy performance certificate in efficiency class F or G; after comprehensive renovation to the GEG-2024 standard, class B or C is achievable. An improved energy performance certificate enhances the property’s marketability, increases the achievable rent (energy efficiency is a factor in rent index classification), and unlocks subsidy programs tied to energy efficiency classes. For landlords, a current, reliable energy performance certificate has been mandatory since 2023 for new leases and sales-violations are subject to fines.

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