Owning a historic building means living with a special responsibility: The historic structure must be preserved, and at the same time, the law imposes energy efficiency requirements that apply as a matter of course to every other building. The energy performance certificate for historic buildings addresses precisely this intersection. It documents a building’s energy performance, but for historic buildings, it is subject to specific rules, exceptions, and special considerations that neither owners nor planners should ignore.

• What the energy performance certificate is and the two basic types
• The legal framework governing energy performance certificates for historic buildings
• When historic buildings are exempt from the energy performance certificate and when they are not
• Why the energy requirements of the Building Energy Act are applied more leniently to historic buildings
• What special considerations must be taken into account when issuing an energy performance certificate for historic buildings
• How historic preservation affects renovation measures and their energy performance assessment
• What practical consequences the energy performance certificate has for sales, rentals, and new leases
• What funding options are available for the energy-efficient renovation of historic buildings

What Is an Energy Performance Certificate? Definition, Types, and Legal Basis

The energy performance certificate, also known as an “energy pass” in technical terminology, is a standardized document that describes a building’s energy performance and allows for comparison. It provides information on how much energy a building requires for heating, hot water, ventilation, and, if applicable, cooling, and classifies this energy demand on a color-coded scale from A+ to H. Thus, the energy performance certificate serves a dual purpose: It is an information tool for buyers and tenants and, at the same time, provides proof to authorities that a building meets—or at least documents compliance with—the applicable minimum energy requirements.

In general, the Building Energy Act (GEG), which serves as the authoritative legal basis for energy performance certificates in Germany, distinguishes between two types: the energy demand certificate and the energy consumption certificate. The demand certificate is based on a computational analysis of the building, its envelope, its building services, and its geometry. It is independent of actual user behavior and provides a theoretical energy demand derived from the building’s physical properties. The consumption certificate, on the other hand, is based on the measured energy consumption over the past three years and reflects the residents’ actual consumption patterns. For residential buildings with fewer than five residential units that were built before the first Thermal Insulation Act of 1977, the demand certificate is generally required, unless an exception applies.

The European basis for the energy performance certificate is the Energy Performance of Buildings Directive (EPBD), which has been transposed into national law by the EU member states. In Germany, this was initially done through the Energy Saving Ordinance (EnEV), which was fully replaced by the Building Energy Act in 2020. The GEG consolidates the provisions of the EnEV, the Energy Conservation Act, and the Renewable Energy Heat Act and has since served as the uniform legal framework for energy performance requirements for buildings, including special provisions for historic buildings.

Energy Performance Certificates for Historic Buildings: When Does the Exemption Apply?

Section 2 of the Building Energy Act contains an explicit definition of buildings classified as historic monuments, and Section 105 contains a key exemption provision. Accordingly, historic buildings and other structures of particular preservation value are exempt from the energy requirements of the Building Energy Act (GEG) to the extent that compliance with these requirements would impair the substance or appearance of the historic building or other measures would result in a disproportionately high cost. This wording is intentionally kept open-ended because the balance between historic preservation and energy efficiency is always a case-by-case decision made by the competent state historic preservation authorities.

However, the exemption does not automatically apply to the energy performance certificate itself. An important distinction must be made here: Exemption from the minimum energy efficiency requirements of the GEG does not necessarily mean that an energy performance certificate does not have to be issued. Whether an energy performance certificate is required for a historic building depends on the specific circumstances. In the case of the sale, new lease, or rental of a building, there is generally an obligation to provide a certificate. However, Section 80(4) of the GEG provides that historic buildings are exempt from the obligation to present an energy performance certificate if compliance with the requirements would impair the substance or appearance of the historic building. This exemption is therefore not blanket but must be justified on a case-by-case basis.

In practice, this means that many historic buildings, particularly those that have undergone extensive renovation or where energy-efficiency measures could be implemented without altering their appearance, require an energy performance certificate just like any other building. The exception applies primarily when even minimal insulation measures or the replacement of windows would jeopardize the building’s heritage value. Owners should clarify this issue with the relevant historic preservation authority at an early stage to ensure legal compliance in the event of an upcoming sale or new lease.

Special Considerations for Issuance: Energy Performance Certificates for Historic Buildings

When an energy performance certificate must be issued for a historic building, the unique construction methods and architectural history of these structures present specific challenges. Historic buildings were constructed according to principles that differ fundamentally from modern construction methods. Solid exterior walls made of natural stone, brick, or half-timbering; windows with single glazing or historic casement windows; uninsulated roof structures; and heating systems with low flow temperatures are typical features that require specialized knowledge when calculating energy demand.

The energy performance certificate for a historic building must reflect the building’s actual thermal properties. This requires that the certifier—who must demonstrate the appropriate qualification under GEG—be familiar with the specific characteristics of historic building structures. Heat transfer coefficients (U-values) for historic masonry cannot simply be taken from standard tables because the composition and condition of the masonry vary greatly. In many cases, on-site measurements—or at least detailed component analyses—are necessary to obtain reliable input data for the calculation.

Compounding the challenge is the fact that historic buildings often have a complex construction history: additions from different eras, retrofitted elements, changes to the floor plan, and different materials in various parts of the building often make simplified calculations using standard methods inadmissible. Qualified energy consultants familiar with historic preservation therefore often opt for more complex calculation methods or combine computational approaches with consumption data to paint a realistic picture of the building. The resulting energy performance certificate then reflects the building’s actual energy status without distorting the unique characteristics of the historic structure.

Energy-Efficient Renovation of Historic Buildings: Scope and Limits

The energy-efficient renovation of a historic building is always caught between two legitimate goals: the preservation of cultural heritage and the reduction of energy consumption. The GEG explicitly acknowledges this tension and grants historic buildings far-reaching exemptions from the otherwise applicable requirements. Specifically, this means that when renovating historic buildings, the requirements for thermal insulation, airtightness, and building services do not apply in full if compliance with them would compromise the preservation of the building’s heritage.

In practice, this opens up considerable leeway. Exterior wall insulation—which would be the most cost-effective measure for improving the energy balance in a typical older building—is generally not approvable for a historic building with a historically significant facade design. Instead, interior insulation is an option; however, this poses challenges in terms of building physics because it shifts the dew point within the wall cross-section and, if installed incorrectly, can lead to condensation and damage to the wall structure. Capillary-active insulation systems, which can absorb and release moisture, have proven particularly suitable for historic masonry because they respect the moisture dynamics of the old building.

Windows are another key issue. Historic windows with single-pane glazing or casement window constructions are significantly less energy-efficient than modern thermal insulation glazing, but they often play a decisive role in defining the appearance of a historic building. In many cases, historic preservation authorities permit the retrofitting of existing windows by installing secondary glazing or box-frame windows with modern glazing in the inner sash, without altering the exterior appearance. Such measures significantly improve the U-value and must be taken into account accordingly in the energy performance certificate. The energy performance certificate for historic buildings thus not only documents the current condition but can also serve as a planning basis for renovation measures that comply with historic preservation guidelines.

Building services often offer the greatest potential for energy savings without altering the building’s structure. Replacing an outdated heating system with an efficient heat pump, a pellet heating system, or a district heating connection does not affect the appearance of the historic building and is therefore generally possible without restrictions related to historic preservation. The installation of solar thermal systems or photovoltaic panels on non-visible roof surfaces is also often eligible for approval and significantly improves the building’s energy balance. These measures are factored into the energy performance certificate and can significantly raise a historic building’s energy efficiency class, even if the building envelope largely remains in its historic condition.

Requirement to Provide the Energy Performance Certificate and Practical Consequences for Sales and Rentals

The requirement to present the energy performance certificate is clearly regulated in the GEG. Anyone selling, re-renting, or re-leasing a building is obligated to make the energy performance certificate or a copy thereof available to the interested party without being asked. Real estate advertisements in commercial media must include certain key figures from the energy performance certificate, including the energy efficiency class, energy demand or energy consumption, and the primary energy source. Violations of these obligations may be punished as administrative offenses.

For owners of historic buildings, this results in an important obligation: They must either be able to present a valid energy performance certificate or prove that their building falls under the exemptions provided for in the GEG. Providing this proof is no trivial matter. A simple assertion that the building is a historic monument and therefore exempt is not sufficient. As a rule, a certificate from the competent historic preservation authority is required, stating that compliance with the energy efficiency requirements would impair the substance or appearance of the historic building. This certificate should be obtained well in advance, as administrative procedures can take time.

Buyers and tenants of historic buildings should carefully review the energy performance certificate or the exemption certificate. An energy performance certificate with a poor efficiency class is not a flaw in the usual sense for a historic building, but rather a reflection of its historical construction methods. However, it provides important insights into expected heating costs and potential for renovation. Anyone purchasing a historic building should consider the energy performance metrics in the context of preservation requirements and opportunities to improve the building’s energy balance, rather than viewing them in isolation as a measure of the building’s quality.

Subsidy Programs for the Energy-Efficient Renovation of Historic Buildings

The Federal Funding Program for Efficient Buildings (BEG), administered by the Kreditanstalt für Wiederaufbau (KfW) and the Federal Office for Economic Affairs and Export Control (BAFA), takes into account the special conditions of historic buildings. For historic buildings, the BEG applies less stringent requirements regarding the energy efficiency target that must be met to qualify for funding. This means that historic buildings can receive funding even if, after renovation, they do not meet the efficiency standards that apply to ordinary older buildings. This special provision takes into account the fact that comprehensive energy-efficiency renovations of historic buildings are often not possible without jeopardizing their heritage value.

In addition to the nationwide funding programs, many federal states offer their own funding for the renovation of listed buildings. These state programs are often tailored to the specific requirements of regional historic preservation and can be combined with federal funding. Owners should contact the relevant historic preservation authority, energy counseling centers, and KfW early on to learn about currently available funding options, as programs and conditions change regularly. A qualified energy consultant who is familiar with both the requirements of historic preservation and the funding programs can be of considerable assistance here.

The energy performance certificate for historic preservation also plays an important role in the context of funding: It is often part of the application documents and documents the building’s initial energy performance. Once the renovation work is complete, a new energy performance certificate is issued, which verifies the improvement in energy efficiency and serves as proof for the funding agencies. This comparison between the energy performance certificates before and after renovation is a key tool for quality assurance and provides owners, planners, and authorities with a transparent basis for evaluating the measures that have been implemented.

The Energy Performance Certificate for Historic Preservation in a Broader Context

The energy performance certificate in the context of historic preservation is not a bureaucratic obstacle, but rather a tool that, when properly understood, offers considerable benefits. It provides transparency regarding the energy performance of a historic building, identifies renovation potential, and creates a solid foundation for decisions regarding investments in energy efficiency. At the same time, the regulatory framework respects the fact that historic buildings possess cultural value that cannot be measured solely in kilowatt-hours.

Balancing energy efficiency and historic preservation is not an either/or question. Many historic buildings can be significantly improved in terms of energy efficiency through carefully chosen measures that respect the building’s integrity, without jeopardizing their historic value. Building services, interior insulation with suitable materials, window replacement in accordance with historic preservation guidelines, and the use of renewable energy offer a wide range of possibilities. The energy performance certificate documents these improvements and makes them transparent to all stakeholders.

Architects, energy consultants, and historic preservationists working on historic buildings bear a special responsibility: they must combine knowledge of building physics, an understanding of historic preservation, and familiarity with the landscape of available funding. In the context of historic preservation, the energy performance certificate is not an end in itself, but rather a starting point for an informed discussion about a building’s future. Those who know how to read and interpret this document understand not only the energy performance of a historic building but also the scope and limitations within which historic structures can be preserved for future generations while also being put to contemporary use.