What does the term "serial retrofitting" actually mean?

In the context of renovating older buildings, one increasingly stumbles across the term "serial retrofitting". But what is actually meant by this? And why is it so important to know this term?
We provide a definition and give an overview of the requirements for funding according to German BEG WG.

Definition 'Serial retrofitting'

Serial retrofitting is the prefabrication of façade and roof elements for the energetic retrofitting of a building. These elements, mostly made in timber post and beam construction, are manufactured in a factory and merely connected and assembled on the construction site. As a result, the main work no longer takes place on the building site itself, but as a standardised process in a factory hall.
In order to be able to manufacture the elements precisely, a digital 3D measurement must be taken beforehand, for example by means of a laser scanner and point cloud. In this way, irregularities in the façade and roof are registered and taken into account during prefabrication. The result provides perfectly fitting renovation elements.
The whole process, from the measurement to the production in the factory, the insertion of insulation and finally the assembly on site, forms a standardised process - the "serial retrofit".
The word "serial" does not necessarily mean that as many identical parts as possible are involved. A serial retrofitting can also be considered for a single-family house and for houses with many different façade parts.

Prefabricated part of the facade, suspended on the truck-mounted crane — The assembly of the prefabricated facade parts on the building often does not require any scaffolding.

What is "Energiesprong"?

Energiesprong is an innovative serial renovation concept developed in the Netherlands that includes the above points. On an annual average, the renovated buildings generate as much renewable energy as the residents need for heating, hot water and electricity. Energetic building refurbishment is thus faster and more affordable. In addition, a new industry for prefabricated renovation solutions is emerging. These modular solutions also speed up climate protection. Serial refurbishment according to the Energiesprong principle should help to achieve the climate targets in the building sector.

In Germany, under certain conditions, a serial retrofitting is also eligible.

Facade part before assembly — The SerSan bonus is up to 15% of eligible costs

Subsidy bonus according to German BEG WG for serial retrofitting

Builders can receive special, additional funding via the Bundesförderung Effiziente Gebäude (BEG) – Wohngebäude (residential buildings) for serial renovation (Serielle Sanierung = SerSan). The SerSan bonus is up to 15% of eligible costs. This applies to all measures taken to achieve the efficiency house (not just for the serially prefabricated parts).
If the bonus for the 'Serielle Sanierung' is combined with a bonus for the renovation of a worst performing building (energy efficiency class H in the energy certificate - over 250 kWh/m²), the maximum rate of the sum of the bonus for SerSan and WPB is limited to a maximum of 20%.

Prerequisites for an eligible serial retrofitting:

The elements must be prefabricated at the factory and have a supporting structure for the thermal insulation.
The window elements must already be part of these façade elements. At least the window frames have to be fixed.
The insulation can, but does not have to be installed at the factory. Loose insulation may also be blown in on site.
Façade elements may differ in the type of construction and in the thermal insulation standard. It is not necessary for the entire area to be executed uniformly.
Façade elements must be at least room-high. The width is not specified.
When assembling on site, it is important to attach the prefabricated elements unchanged.
To the outside, the prefabricated facade elements require a weather level. This can be, for example, wooden paneling or cladding. If the façade is to be plastered, this can be done in the factory or on site.
The roof does not have to be prefabricated.
Instead of façade elements, entire room cells can also be prefabricated (container design)
Only buildings that achieve at least efficiency house 55 (EE 55) after renovation are eligible.
At least 80 % of the façade must be renovated serially, as described in the previous points. The other (up to) 20% of the façade surfaces can be processed conventionally on site, which is often unavoidable, especially in the base or roof area. Here craftsmen can carry out work on the construction site.
Dormer windows are not included in the façade area.

Can a conversion or extension take place at the same time as the serial renovation?

Basically, these refurbishment and new construction measures can be carried out together. However, the newly added facade areas are added to the existing facade area, so that the following applies to ALL facade areas: at least 80% of the total of the existing and the newly added facade areas must be equipped with serially prefabricated facade elements. And: the entire façade after the measure has been carried out must consist mainly of originally existing areas.