Building modernization

Modernization improves an existing building beyond its previous condition. Measures can enhance its energy efficiency, technical equipment, usability, accessibility, or living and working comfort. Unlike basic maintenance, modernization is not limited to preserving or restoring the original condition.

Up-to-date information about the geometry, building envelope, technical systems and actual condition of the existing structure provides an important basis for targeted building modernization planning.

Why is building modernization important?

• Preserving and increasing property value: Modern equipment and technical systems improve a property’s long-term usability.
• Reducing energy consumption: Measures affecting the building envelope and building services can reduce heat loss and operating costs.
• Improving user comfort: Modern heating, ventilation and lighting systems can improve the quality of building use.
• Adapting buildings to new requirements: Floor plans, technical infrastructure and usage concepts can be adapted to changing needs.
• Extending service life: Targeted measures can keep existing buildings usable over the long term.
• Supporting decarbonization: Energy-efficient modernization plays an important role in reducing emissions from the existing building stock.

What types of building modernization are there?

Building modernization is an umbrella term covering different types of measures in existing buildings.

Energy-efficient modernization

The objective is to reduce energy demand and energy losses.

Typical measures include:

• insulating façades and roofs
• insulating basement ceilings
• replacing windows and doors
• reducing thermal bridges
• modernizing the heating system
• using renewable energy
• optimizing ventilation and control systems

Energy-efficient modernization overlaps considerably with the concept of energy-efficient refurbishment.

Technical modernization

This involves renewing or expanding a building’s technical systems.

Examples include:

• heating and cooling systems
• ventilation systems
• electrical installations
• building automation
• lighting
• measurement and control technology
• digital building technology

Functional modernization

Buildings can be adapted to changing usage requirements.

Examples include:

• new room layouts
• conversion of existing spaces
• adaptation of circulation routes
• improved space efficiency
• expansion of technical or functional areas

Modernization for greater accessibility

Modernization measures can make buildings more accessible and easier to use.

Examples include:

• lifts
• ramps
• step-free access
• wider doors
• adapted sanitary facilities

Digital modernization

The digitalization of a building can also form part of a modernization project.

Examples include:

• building automation
• sensor technology
• energy monitoring
• digital building documentation
• CAFM systems
• digital twins

What does the building modernization process involve?

1. Capture the existing conditions

The building’s actual condition must be understood before planning begins.

Relevant information includes:

• floor plans
• building dimensions
• room layouts
• building envelope
• windows and doors
• technical building systems
• energy performance
• existing damage or deviations

Existing documents are often outdated or incomplete. A digital building survey can therefore provide an up-to-date geometric basis.

2. Analyze modernization requirements

The next step is to assess which areas should be improved.

Possible objectives include:

• reducing energy consumption
• upgrading technical building systems
• changing the building’s use
• improving comfort
• reducing barriers
• lowering operating costs
• preserving the building’s value

3. Prioritize measures

Not every measure has to be implemented at the same time.

Dependencies between the building envelope, building services and intended use should therefore be considered at an early stage.

For example, improving the energy performance of the building envelope first may change the heating capacity required later.

4. Planning and calculations

The modernization measures are planned in detail on the basis of the existing building data.

Depending on the project, the following may be relevant:

• area and quantity calculations
• energy calculations
• heating load calculations
• transmission heat loss
• building services planning
• cost calculations
• funding planning
• BIM or CAD models

5. Implementation

The modernization measures are carried out in a coordinated manner.

Interfaces between trades and measures that depend on one another should be taken into account.

6. Update the documentation

Once the work has been completed, the changes should be incorporated into the building documentation.

This may include:

• as-built drawings
• updated floor plans
• BIM models
• room data sheets
• technical documentation
• CAFM data

This ensures that the digital building records remain up to date after modernization.

Modernizing existing buildings

A reliable data basis is particularly important for existing buildings.

Typical challenges include:

• outdated as-built drawings
• undocumented alterations
• varying construction conditions
• unknown component assemblies
• building services modified at a later date
• missing area and quantity data

One possible digital workflow is:

Digital building survey → Floor plans and geometric data → As-built model → Analysis → Modernization planning → Implementation → As-built documentation

Digital building data can be reused for several purposes, including area calculations, planning, energy calculations and subsequent documentation.

The existing-building survey therefore becomes a reusable data basis for multiple stages of the modernization process.

Building modernization vs. building refurbishment

The terms are often used together in the construction sector, but they have different areas of emphasis.

Building modernization

• improves the building beyond its previous condition
• can increase energy efficiency, technical standards or comfort
• can include technical and functional improvements
• does not have to be prompted by existing damage

Building refurbishment

• focuses more strongly on the building’s structural or technical condition
• remedies defects and improves the building fabric
• can also include extensive improvements
• is often combined with energy-efficiency measures

In practice, the two concepts overlap considerably. Façade refurbishment, for example, can also constitute energy-efficient modernization.

Building modernization vs. energy-efficient refurbishment

Building modernization is the broader term. It can also include new building technology, improved accessibility or functional changes.

Energy-efficient refurbishment, by contrast, focuses specifically on improving a building’s energy performance. Typical measures affect:

• the building envelope
• windows and doors
• thermal bridges
• the heating system
• ventilation
• renewable energy

Energy-efficient refurbishment is therefore often part of a wider building modernization project.

Building modernization vs. renovation

Modernization and renovation are not the same.

Renovation

• often concerns cosmetic or surface-related renewal
• may be used to refresh rooms
• can include painting, wallpapering or replacing surface finishes

Building modernization

• improves a building’s functionality, equipment or technical quality
• typically goes beyond purely cosmetic renewal
• changes the building’s utility value or its energy or technical standard

Applying a new coat of paint is therefore typically a renovation. Installing a more efficient heating system, by contrast, is a modernization measure.

Building modernization vs. maintenance

Maintenance primarily serves to preserve a functional condition.

Examples include:

• servicing technical systems
• minor repairs
• replacing worn components
• ongoing care

Modernization, by contrast, creates an improved condition.

Replacing a defective system with a technically equivalent system may primarily constitute a repair. If the work also involves switching to more efficient or significantly improved technology, the measure may be considered modernization.

The precise legal classification may depend on the specific context.

Modernization under german tenancy law

Under German tenancy law, the term “modernization measure” has its own statutory meaning.

Section 555b of the German Civil Code (Bürgerliches Gesetzbuch, BGB) includes structural changes through which:

• final energy is sustainably saved
• primary energy is saved or the climate is protected
• water consumption is reduced
• the utility value of the rental property is increased
• general living conditions are permanently improved
• new housing is created

The definition under German tenancy law should not automatically be applied to every technical or planning-related use of the term.

Depending on the modernization project, additional statutory, energy-related and federal-state requirements may also be relevant.

Building modernization and energy planning

Energy-related measures should not be considered in isolation.

Improving the building envelope, for example, affects:

• transmission heat loss
• heating load
• heating system sizing
• internal surface temperatures
• energy demand

It may therefore be beneficial to consider the building envelope and technical building systems together.

A typical relationship is:

Building geometry → Building envelope → U-values and thermal bridges → Transmission heat loss → Heating load → Building services modernization

This allows measures to be coordinated and helps prevent systems from being oversized or incorrectly dimensioned.

What building data is needed for modernization?

The specific information required depends on the project.

Typical data includes:

Geometric data

• floor plans
• room dimensions
• wall and ceiling areas
• window and door areas
• building volume
• façade and roof areas

Building physics data

• component assemblies
• U-values
• thermal bridges
• thermal anomalies
• energy performance indicators

Technical data

• heating system
• ventilation
• cooling
• electrical installations
• building automation

Usage and existing-building data

• room use
• occupancy information
• consumption data
• existing planning documents
• previous alterations

Not every modernization project requires all of this data. The scope and level of accuracy should be based on the specific planning objective.

Common mistakes and misconceptions

• Treating modernization and renovation as the same: Cosmetic renewal does not automatically improve a building’s technical or functional standard.
• Planning without up-to-date existing-building data: Outdated drawings can lead to incorrect quantities, costs and planning assumptions.
• Considering individual measures in isolation: The building envelope, building services and intended use influence one another.
• Idealizing the existing geometry: Older buildings in particular often differ from their original plans.
• Sizing the heating system before improving the building envelope: Energy-efficiency improvements can reduce the required heating capacity.
• Failing to update documentation after implementation: This creates an outdated building dataset immediately after modernization.
• Treating terms as legally interchangeable: Modernization, refurbishment, maintenance and repair can have different meanings depending on the technical and legal context.

Related terms

• existing building refurbishment
• energy-efficient refurbishment
• refurbishment plan
• refurbishment roadmap
• building envelope
• building services
• heating load calculation
• transmission heat loss
• digital building survey
• as-built modeling
• as-built documentation

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