ECOFYS releases new study on minimum performance requirements for window replacement
A new study commissioned by Glass for Europe to ECOFYS provides a clear picture of the minimum requirements for window replacement in the residential sector.
Under the Energy Performance of Building Directive, EU Member States are required to put in place minimum levels of energy performance for building envelope elements, such as windows, when they are retrofitted or replaced. While the recast EPBD has been in place for over five years and while European Institutions are reviewing the directive, a new study commissioned by Glass for Europe to ECOFYS provides a clear picture of the minimum requirements for window replacement in the residential sector.
Over 85% of glazed areas in EU buildings are equipped either with single glazing or uncoated double glazing[1] and over 1 billion of new windows will be sold by 2030[2]. Ensuring the enforcement of minimum performance requirements for windows is essential to unleash the massive energy saving potential that lies in the European building stock.
“Despite the priority given to energy efficient buildings and the vast amount of energy that could be saved if consumers opt for energy-efficient windows, this study demonstrates that regulatory measures in place are insufficient or not properly enforced,” says Bertrand Cazes, Secretary General of Glass for Europe.
This study by ECOFYS shows that in most countries, minimum performance requirements do not drive the market towards energy efficient products, as they often refer to sub-optimal choices or apply under very restrictive conditions only. Based on the findings of this study, Glass for Europe makes three recommendations for improving the EPBD and fixing the identified problems.
1. Minimum performance requirements should be based on the energy balance approach. The study shows that national requirements are too often sub-optimal and based on the sole U-value. Only Denmark and, indirectly the United Kingdom, apply minimum requirements for windows based on the energy balance approach, which correctly combines both solar heat gains and heat losses of the window into a single value.
2. National updates of energy performance requirements should be made at more regular intervals to improve energy efficiency. Eight countries have not updated their building codes for at least five years. In other countries, recent updates of building codes do not include updates of the requirements for windows, despite advances in window technology and the untapped energy savings potential.
3. Minimum requirements for windows should apply from major renovation down to single window replacement. In 11 Member States, windows for the residential sector with a performance below the minimum requirements can still be installed on buildings. This is made possible because requirements apply only in case of new construction or when a renovation permit is requested or when the requirement is linked to a minimum window area to be renovated.
“The study illustrates how the realisation of the energy savings potential of windows is impeded by an inadequate EU legislative framework. To make minimum performance requirements a real energy efficiency driver, the current EPBD must provide better guidance to Member States on how to assess the energy performance of windows and it must correct today’s loopholes to ensure minimum performance requirements are implemented more thoroughly, concludes Bertrand Cazes.
[1] TNO Built Environment and Geosciences – Glazing type distribution in the EU building stock – February 2011
[2] VHK, ift Rosenheim – Ecodesign Preparatory Study on Windows (ENER LOT 32) –
June 2015