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Complaints about misleading Uw-values

In 2018, the VELUX Group filed complaints with relevant market authorities concerning competitors’ Uw-values, based on test results by two notified testing institutes. The tests were done on several variants of VELUX, FAKRO, Roto and Keylite roof windows during 2016-2018. The new round of tests commenced in 2019 and the results will be send to relevant market authorities and are published on this web site, together with the 2016-2018 results.


The tests in 2016-2018 that were the basis for the complaints were organized by the global consultancy Navigant and were done by the independent notified testing institutes ift Rosenheim, Germany, and Centrum Stavebního Inženýrství a.s., Czech Republic. Centrum Stavebního Inženýrství a.s.,has changed its name to Institute for testing and certification since 1. June 2019. The tests were done in accordance with the European standard (EN ISO 12567-2) for testing Uw-values of roof windows using the reference window size as required in the standard. The roof windows were installed in the test boxes in compliance with the respective manufacturers’ guidelines. Therefore, the VELUX Group believe that the test results reflect the actual Uw-value of the tested products.

The test results identified discrepancies between the declared Uw-values and most of the tested products’ Uw-values of FAKRO, Roto and Keylite products. We brought these findings to the attention of our competitors in June 2018 and asked the competitors to act on the findings. Just after this letter FAKRO redeclared one of its variants, FTP-V U3, from 1.2 W/m2K to 1.3 W/m2K, without redeclaring two other tested variants. Roto and Keylite did not redeclare any of their tested variants. 

Against this background, the VELUX Group decided to inform national market surveillance authorities about the findings and filed complaints in Germany, Poland, England, Czech Republic, Denmark and Hungary.

Read the status as of November 2019 below. See the test results of the tested products here:

Status on complaints