When buildings are to be refurbished, their windows are often identified as weak points and thus replaced with new ones. In many cases, they could be refurbished instead using innovative methods and, as demonstrated in the ENO.SAFE project, achieve a level of thermal insulation comparable to that of new windows. If the entire life cycle is taken into consideration, the preservation of windows is likely to be even more favorable in terms of environmental and climate protection, as CO₂ emissions and resource consumption for the production of new components are avoided. The follow-up project ENO.SAFE2:LCA is therefore investigating this question.

The project focuses on the question of what climate and environmental impacts arise from the refurbishment and upgrading of existing windows and how these compare with the manufacture and installation of new windows. The project also aims to clarify how the different thermal insulation standards of refurbished and new windows and the resulting different heating requirements of the buildings are reflected in the life cycle assessment

• Selection of typical window constructions from different construction periods using representative example buildings and suitable variants for window renovation or replacement and for the building's heat supply
• Comparative life cycle analysis in accordance with DIN EN ISO 14040/44 for the life cycle phases of production (modules A1-A3), installation (A4-A5), use and maintenance (B1-B6) and dismantling and disposal (C1-C4) using specialist software and own calculations/estimates to quantify CO2,eq emissions and primary energy use as well as for qualitative statements on other environmental impacts based on specialist databases, environmental product declarations and own research
• Determination of the energy requirement for heating buildings based on DIN V 18599, taking into account the increasing share of renewable energy in electricity and heat generation
• Consolidation of the results

The aim is to provide planners with a reliable basis for deciding in which cases it is better to maintain and upgrade existing windows with regard to climate and environmental protection instead of replacing them with new ones.