Window selection requirements for new builds and renovations

When purchasing windows for new construction or renovation, technical requirements and design choices differ significantly. In new builds, triple glazing is largely the standard, allowing for full freedom in arranging window surfaces based on room layout and orientation. Under the GEG, new buildings are evaluated based on the overall energy balance of the building envelope and technical systems rather than a single window value.

For renovations of existing buildings, the focus shifts to reducing heat loss. Modern triple glazing can achieve Uw-values of approximately 0.7 to 0.9 W/m²K, a major improvement over 1980s double glazing which typically ranges from 2.7 to 3.0 W/m²K.

Material selection for frames is also critical for thermal insulation, measured by the Uf-value. Lower values indicate better insulation. Common materials include:

• Plastic (PVC): Low cost and low Uf-values, but often less aesthetically suited for historic buildings. • Wood: A classic material offering natural insulation and climate regulation, though it requires regular maintenance. • Aluminum and various combinations: These offer different strengths in terms of durability and insulation performance.