Listed buildings make a significant contribution to sustainability by their very existence: they preserve valuable building fabric, use existing resources and avoid energy-intensive new buildings. The responsible use of these buildings combines climate protection and cultural preservation.
Listed buildings make a significant contribution to sustainability by their very existence: they preserve valuable building fabric, use existing resources and avoid energy-intensive new buildings. The responsible use of these buildings combines climate protection and cultural preservation.
Historic buildings are long-lasting. Their materials, such as wood, natural stone, clay or brick, were usually sourced regionally, crafted by hand and are characterized by high quality and durability. Many of these buildings have only been carefully altered over the centuries. They contain a considerable amount of so-called grey energy - i.e. the energy that has already been consumed in the production, transportation and installation of the building materials.
In many cases, the continued use of this substance is ecologically more advantageous than demolition and new construction. Life cycle assessments show that the refurbishment of a listed building is often significantly more resource-efficient and climate-friendly than the construction of a new building.
Windows in listed buildings - preserve, improve, adapt
In terms of their materiality, proportions and design, windows are an essential feature of a listed building or building substance worthy of preservation. In the course of energy-efficient refurbishment, the question often arises as to whether windows can be replaced.
As a general rule, historic windows should be preserved: They are characteristic of the appearance and testify to the quality of craftsmanship and contribute to the authenticity of the building.
Energy improvements are possible through
- the careful renovation of existing windows
- the installation of seals or insulating glazing, provided the profile allows this
- Creation of a box-type window by adding a second window level
The complete replacement of historic windows is only permitted under monument protection law in justified exceptional cases if restoration is not possible. This must be justified and proven by a company experienced in the preservation of historical monuments by means of an expert opinion.
In individual cases, the monument conservation authority checks which measures are possible and sensible and advises on solutions that are compatible with the monument. All changes to historic windows must be coordinated with and approved by the monument preservation authorities. If the existing windows are not historic, they can be replaced in consultation with the UDB. We would be happy to advise you on this!
Interior insulation for listed buildings
Internal insulation offers an opportunity to improve the thermal insulation of listed buildings - without changing the external appearance.
Because every listed building is individually constructed, it requires tailor-made solutions. The monument preservation department checks whether the measure is compatible with the preservation of the historical substance.
One important aspect of interior insulation is:
- the physical compatibility of the building (e.g. moisture protection)
- installation that is as reversible as possible
- the sensitive handling of historical components
All measures on a listed building must be coordinated with and approved by the monument preservation authorities. Early consultation supports planning and helps to avoid damage later on.
Heat pump in a listed building
The use of a heat pump can also make sense in listed buildings - as long as the structural and technical requirements are taken into account. The widespread assumption that heat pumps are only efficient in well-insulated buildings with underfloor heating is outdated. Today, modern systems also work reliably in less well-insulated buildings - under certain conditions and with an adapted design.
Nevertheless, it is advisable to integrate the planning of a heat pump into a holistic renovation concept. In this way, insulation, heating surfaces and system technology can be sensibly coordinated.Important points in planning and coordination with the monument preservation authorities:
- Minor interventions in the historical substance
- Installation location of the heat pump
- Inconspicuous cable routing
- Preservation of historic radiators
The monument preservation department examines each individual case and advises on suitable solutions in terms of monument preservation. Coordination with and approval from the City of Aachen's monument preservation department is required.
Solar systems on listed buildings
Solar energy systems are generally also possible on listed buildings. '
The monument preservation department advises on the appropriate arrangement, shape and color of the modules.
Preference is given to inconspicuous surfaces - in particular:- Roof surfaces of outbuildings
- Rear or less visible roof sides
- Systems that adapt well to the shape of the roof surface (formats, colors).
Furthermore, it must of course be checked whether a historic roof can bear the weight of the solar system. The material of the roof covering also places requirements on the solar system that need to be checked.
Whether and in what form a system can be implemented is always examined on a case-by-case basis. Early coordination and joint planning with the monument preservation authorities helps to avoid conflicts and make sensible use of the building's potential. Every solar installation on or near a listed building must be coordinated with and approved by the monument preservation authorities.
Energy measures - individual and coordinated
Energy improvements are also possible in listed buildings - while preserving the historical substance and design quality. The individual measures that make sense and are compatible with listed buildings always depend on the specific property. Not all standard solutions can be transferred; instead, individual concepts are required.
Energy upgrades should be considered holistically and developed with a view to preserving the building's substance, ease of demolition and compatibility with the listed building. Measures can be bundled into sensible packages and implemented step by step. It is often advisable to insulate the envelope surfaces first (e.g. with internal insulation) before adapting the heating technology - because as the heat requirement decreases, so does the necessary heating output.
Conservation and energy efficiency are therefore not opposites, but part of a common goal: the sustainable, responsible treatment of our built environment.
Advice and approval
As every monument is unique, energy measures must always be individually coordinated and approved. Please contact the Lower Monument Authority at an early stage - ideally during the planning phase.