Low-energy house

A low-energy house is a building that, thanks to its highly energy-efficient construction, requires significantly less heating energy than conventional existing buildings. It is considered a precursor to the passive house and the KfW Efficiency House. Low-energy buildings are generally defined by improved thermal insulation, thermal bridge-free construction, and controlled residential ventilation-while there are no exact legal limits in Germany, these features do serve as classification criteria for various subsidy programs.

Energy Performance Metrics and Definitions

The term “low-energy house” is not legally defined in Germany but has become established in practice. Typical performance metrics include:

• Annual primary energy demand: significantly below the statutory GEG minimum standard, often under 70 kWh/(m²·a)
• Heat loss through transmission: reduced by highly insulated exterior walls, windows, and roof
• Air exchange rate: controlled ventilation prevents heat loss from uncontrolled ventilation

In comparison:

• Existing buildings constructed before 1980: often 150-300 kWh/(m²·a)
• Low-energy house: approx. 50-70 kWh/(m²·a)
• KfW Efficiency House 55: max. 55% of the GEG reference building value
• Passive house: under 15 kWh/(m²·a)

With the entry into force of the Building Energy Act (GEG) in 2020 and the further increase in minimum standards in 2024, today’s new GEG buildings effectively meet the standard of a former low-energy house-which is causing the term to fade into the background in the new construction sector. In the renovation sector, however, it remains significant.

Design Features of a Low-Energy House

Typical construction measures that make a house a low-energy house:

• Exterior wall insulation: External thermal insulation composite system (ETICS) or double-shell masonry with core insulation
• Triple-pane glazing: U-value of the glazing below 0.8 W/(m²·K)
• Thermally insulated roof: above-rafter insulation or between-rafter insulation
• Heat recovery: Controlled residential ventilation system with heat recovery exceeding 75%
• Minimization of thermal bridges: structural measures on window reveals, balconies, and building corners

These measures work together and must be coordinated. A building with excellent exterior wall insulation but poorly sealed windows does not meet the low-energy standard. Therefore, comprehensive planning by an energy consultant is essential.

Funding Opportunities and Market Value

Low-energy buildings in Germany benefit from KfW funding programs, which offer low-interest loans and repayment subsidies for energy-efficient new construction and renovations. The Federal Funding for Efficient Buildings (BEG) covers both new construction and renovation projects and can be applied for through the BAFA. The most important step: An energy consultant must apply for the funding before construction begins-funding is not available retroactively.

In the real estate market, low-energy buildings generally command higher selling prices and are increasingly in demand among buyers-not least due to rising energy prices and growing awareness of sustainability. A building’s energy efficiency class (A+ to H) also influences real estate financing, as banks increasingly offer more favorable terms for energy-efficient properties.

Practical Tip for Homeowners in Nuremberg and Franconia

In Nuremberg and the Franconia metropolitan region, we are seeing a significant rise in demand for energy-efficient buildings among prospective buyers. Homeowners who renovate their homes to meet low-energy standards can not only significantly reduce their energy costs but also increase the property’s market value.

We recommend consulting an energy consultant from the German Energy Agency (dena) or a qualified energy consultant from the Consumer Protection Agency in Nuremberg before undertaking an energy-efficient renovation to make optimal use of subsidies and plan the correct sequence of measures (building envelope before heating system). We can provide contacts to certified energy consultants in Nuremberg and the region upon request.

Frequently Asked Questions

What is the difference between a low-energy house and a passive house?

A low-energy house significantly reduces heating requirements compared to existing buildings, but still requires a conventional heating system. A passive house achieves an annual heating energy requirement of less than 15 kWh/(m²·a) and requires no separate heating system-heating is provided by solar radiation, internal heat sources, and heat recovery from the ventilation system. Passive houses require more complex planning and are more expensive to build, but have even lower operating costs.

Is renovating to a low-energy house economically worthwhile?

That depends on the building’s initial condition, energy prices, and available subsidies. In many cases, a comprehensive energy-efficient renovation pays for itself within 15-20 years-especially when KfW repayment grants or BAFA subsidies are utilized. Added to this is the increased market value of the property, which can be realized upon a future sale.

What subsidy programs are available for low-energy buildings in Bavaria?

At the federal level, KfW offers the “Federal Subsidy for Efficient Buildings” (BEG) program. At the state level, Bavaria supports energy-efficient renovations through the Bavarian Housing Construction Subsidy Program. In addition, federal funding through the BAFA can be utilized for individual renovation measures such as roof insulation, window replacement, or ventilation systems.

Low-Energy Houses and Energy Performance Certificates

Since the introduction of the Building Energy Act (GEG), the presentation of an energy performance certificate has been mandatory for the sale and new leasing of real estate. The energy performance certificate documents a building’s energy quality and indicates its energy efficiency class (A+ to H). Low-energy buildings typically achieve classes A or B, while poorly renovated existing buildings are often classified in classes E through H.

The energy performance certificate is available in two versions: as a demand-based certificate (based on calculated parameters, independent of actual user behavior) and as a consumption-based certificate (based on actual consumption data measured over the past three years). For low-energy buildings, the demand certificate is recommended, as it better reflects the structural quality and is independent of actual user behavior.

When purchasing real estate, buyers should pay attention to the property’s energy efficiency class: It influences ongoing utility costs, financing terms at some banks, and increasingly also the resale value. Buildings in classes F, G, and H will come under pressure in the future, as the EU Energy Performance of Buildings Directive (EPBD) will gradually introduce stricter minimum energy standards.

Heating Act and Its Impact on the Low-Energy Standard

The Building Energy Act 2024 (colloquially known as the “Heating Act”) has tightened the requirements for new heating systems: Starting in 2024, newly installed heating systems must be powered by renewable energy sources for at least 65 percent of their energy needs. For low-energy buildings, which already have low heating energy requirements, this opens up special opportunities:

• Heat pumps operate particularly efficiently in low-energy buildings because the flow temperatures can be kept low
• Pellet heating systems and biomass systems can also meet the 65 percent requirement
• District heating from renewable sources meets legal requirements when connected to suitable networks
• Photovoltaics combined with a heat pump enable largely self-sufficient operation

Owners of older low-energy buildings still using conventional heating should plan ahead to determine which heating system is suitable for the next replacement-while keeping in mind the combined requirements of the GEG and municipal heat planning.

Low-Energy Homes as a Selling Point in the Nuremberg Real Estate Market

In the Nuremberg real estate market, we are observing growing buyer sensitivity to the energy efficiency of buildings. While just a few years ago location was virtually the only price driver, buyers today increasingly consider expected utility costs and renovation expenses.

A low-energy house in a prime Nuremberg location-such as Schweinau, Kornburg, or Valznerweiher-is significantly easier to market than a comparable property with energy efficiency class G or H that still requires extensive renovation. Buyers are increasingly factoring renovation costs into their offers. Owners who have invested in the energy efficiency of their property can realize this added value on the market-provided the measures are documented and verified by a current energy performance certificate.

We recommend that sellers document energy-efficiency upgrades with invoices, contractor confirmations, and the current energy performance certificate to present the added value transparently and clearly during the sale.

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