Demonstrated in seven pilot projects in Finland, Sweden, the Netherlands, France, Germany and the UK, the approach leverages new technology, from 3D imaging to decision-support tools, together with offsite industrial production processes to modernise building renovation.

“The construction and retrofitting sector in Europe is highly traditional, characterised mainly by onsite work, which can be inefficient in terms of costs, material wastage and construction time,” explains Christina Claeson-Jonsson at NCC Construction Sweden. “Onsite work is often dirty, creates a lot of noise, and inconveniences tenants over prolonged periods of time. For workers it can also be an unsafe and unhealthy working environment.”

As scientific coordinator of the E2ReBuild project, Claeson-Jonsson oversaw the development of an innovative approach to retrofitting residential properties that aims to move as much of the construction work as possible from the building location to offsite factories, minimising inconvenience for tenants and improving worker safety.

The E2ReBuild strategy focuses on the entire retrofitting process from planning and design, materials and technology selection to construction and the subsequent operation and use of buildings.

Information about the structure, including original architectural plans and updated 3D scans that show changes over time, is compiled in a building information modelling system, providing all stakeholders with detailed data about the current state of the property and what improvements can be made. Comparable to the technical platforms used in the automotive industry for car and component design, it provides a platform for product development, processes and operation adapted to the specific needs of the construction sector.

A decision-support tool developed during the project, the European Retrofit Advisor, uses  systematically characterised data together with input about stakeholders’ goals and desired features to generate a simple but detailed evaluation of retrofit options. This also includes financial aspects and the social and environmental impact of proposed changes. Crucially, the approach is highly scalable and can be applied to any residential building in any European country.

Cost-effective, quicker construction

Once a design is decided upon, the detailed information allows many new building elements, such as facade panels, roofing and siding, to be constructed to specification somewhere offsite, and assembled quickly and efficiently during the retrofit process.

“During traditional construction, a lack of information about the building often leads to mistakes being made, new water and sewage pipes may be sized wrongly or angles may be miscalculated, for example. This causes the retrofit process to take longer, generates more waste, increases costs and greatly inconveniences tenants and workers,” Claeson-Jonsson says.

The advantages of adopting E2ReBuild’s industrialised approach have already been demonstrated across Europe in seven pilot projects in which a variety of houses and apartment buildings originally built in the 1950s through to the 1970s were renovated.

In all cases, the retrofitting carried out by E2ReBuild partners greatly improved the energy efficiency of the properties, introduced many modern features and added design elements to increase the comfort of tenants. Wastage and onsite construction time were also reduced.

“The response from tenants was generally positive, especially as they were less inconvenienced by the integrated construction process that enabled more of the work to be performed offsite,” Claeson-Jonsson explains. “The reception from companies in the construction sector has been more mixed. It is a very traditional industry, and there is some resistance to change.”

In the long term, more efficient retrofitting processes will benefit businesses and society, especially as millions of buildings across the EU require renovation over the coming years to meet new environmental and energy standards.

Currently around 35 %of buildings in the EU are over 50 years old, and buildings in general are responsible for 40 %of the EU’s energy consumption. By improving the energy efficiency of buildings, total EU energy consumption would be reduced by 6 %.

The system developed in E2ReBuild, which continues to be used by the project partners, many of them small and medium-sized businesses, could help meet those targets more quickly and efficiently, with less inconvenience for tenants and fewer risks for construction workers.