Proposal for an energy rating system of windows in EU

Mette Belling Skou, VELUX A/S
Jesper Kragh, DTU Byg

In their proposals for revision of the energy labelling directive the European Commission has suggested to include windows.

The paper introduces a proposal for a European energy labelling scheme of windows for replacement of windows in the existing building stock taking into consideration the energy per¬formance of windows in both the heating and cooling seasons. The labelling scheme evaluates a methodology where the energy performance in the heating period is established with focus on heat loss and utilization of passive solar energy, whereas the energy performance in the summer (cooling) season will focus on reduction of solar radiation into the building. The methodology is developed with focus on CEN and ISO standardization.

With inspiration from the American Energy Star programme for windows, Europe is divided into climate zones where the methodology for each zone is developed on basis of a reference building and climate data. A proposal for labelling will be presented for both heating and cooling seasons in order to enable the user to choose the right product for a specific performance.

Based on data from the building stock in the individual climate zones, an energy saving potential for replacement of old windows with new low energy windows will be presented.

The possibility for using energy labelling of windows as reference and requirement in the building legislation as an alternative to U-values, will be presented with among others examples from legislation in UK and Denmark.

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The Authors