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An energy efficient retrofit includes all measures designed to improve the energy performance of an existing building. The aim is to permanently reduce energy consumption for heating, hot water, ventilation or cooling while also increasing living or user comfort.
Typical measures relate to the building envelope, building services, heating system replacement or the use of renewable energy. The basis for a successful energy efficient retrofit is reliable building data and a sound analysis of the current condition.
Why is an energy efficient retrofit important?
A large proportion of the building stock in Germany was built before today’s energy standards were introduced. As a result, heat losses, operating costs and CO₂ emissions are often high.
An energy efficient retrofit helps to:
- reduce energy costs in the long term
- maintain or increase the value of a building
- meet legal requirements such as the German Building Energy Act (GEG)
- reduce CO₂ emissions from buildings
- improve living and user comfort
Especially in light of the European Buildings Directive (EPBD) and national climate targets, the energy modernisation of existing buildings is becoming increasingly important. To advance the energy efficient retrofit of buildings, federal and state authorities as well as other institutions provide various funding programmes. These support owners and companies financially in measures to improve energy efficiency, for example through grants or low-interest loans. The aim is to reduce the energy consumption of buildings, cut CO₂ emissions and make retrofit projects more economically attractive. For an energy efficient retrofit, funding, subsidies and qualified energy consulting are therefore often key planning factors.
How an energy efficient retrofit works in practice
- Data collection: Digital measurement, existing building plans/as-built documentation, thermography/thermal imaging camera, where necessary U-value measurements; recording of building services and consumption data as a basis for energy consulting and a retrofit roadmap.
- Analysis: Identification of thermal bridges and leaks, assessment of the building envelope (roof/facade/windows) and building services inefficiencies; comparison with standards and target values.
- Measure planning: Prioritised packages such as insulation, airtightness, windows, generation, ventilation and control; cost-benefit assessment of energy retrofit costs and funding eligibility.
- Implementation: Coordination of trades, quality assurance, for example thermography and blower door test reports, documented tolerances and acceptances.
- Documentation/monitoring: Updated as-built and existing building plans, renewal of the energy performance certificate, measurement of effects and optimisation of operation.
Typical measures
- Building envelope: Insulation of roof, facade and basement ceiling, airtight connections, high-quality windows and doors.
- Building services: Efficient heat generation, hydraulic balancing, ventilation with heat recovery, smart control and monitoring.
- Data basis: Existing building modelling (BIM/IFC) for quantity take-off, clash detection and lifecycle data.
Common mistakes and misconceptions
- Retrofitting without data: Measures without a reliable assessment of the current condition can lead to poor investment decisions.
- Individual measures without a system view: The building envelope and building services must be coordinated. Otherwise, mould, loss of comfort or limited savings may occur.
- Lack of quality assurance: Without thermography or blower door test reports and a change log, evidence and billing can be challenged.
- Media discontinuity: Paper-based processes and scattered files create losses. Digital workflows ensure completeness and verifiability.
Energy efficient retrofit vs. modernisation
- Modernisation: General improvements to comfort and equipment.
- Energy efficient retrofit: Data-based efficiency improvement and preservation of the building fabric, with documented impact and evidence.
FAQ
What data do I need before an energy efficient retrofit?
Current geometry (measurement/existing building plan), component structures, thermography/U-value measurements, current building services condition and consumption data. Ideally, this data should be captured digitally and made centrally available.
How can I secure funding eligibility?
Through standards-compliant evidence, for example documented U-values and thermal bridge assessments, qualified planning and complete execution documentation, including as-built records and inspection reports.
Is a single measure enough?
Rarely. The greatest effectiveness comes from coordinated packages covering the building envelope and building services, prioritised based on data and supported by quality assurance.