Windows with improved energy performance

Peter Anders Noyé (Invited author), Jacob Birck Laustsen (Invited author), Svend Svendsen (Invited author)

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


    According to the Danish energy protocol, Energy 21, one of the goals with highest priority is to reduce the CO2-emission. Energy consumption for domestic heating is a major contributor to the CO2-emission; hence one of the primary efforts to reach the goal is by saving energy in the households. Heat loss through windows represents a considerably part of the total heat loss from houses. However windows provide a unique potential of solar energy gain to the building besides from providing daylight access and view. This results in a need for development of windows with improved energy performances. During the last 20 years the U-value of the glazing part of windows has been improved considerably, but the frame part has not followed the same development with respect to energy performance. Therefore an increasingly large part of the total heat loss through windows is relating to the frame part, for which reason, as far as energy efficiency and total economy are concerned, it has become more interesting to further develop frame structures. Traditionally, the energy performance of windows has primarily been characterised by the heat loss coefficient, U-value. However as the heat loss has decreased the total solar energy transmittance, g-value, has become much more important since the solar gain through windows contributes to the heating of houses. This paper describes potential improvements of the window elements with respect to the overall energy performance of the window. Most importantly the paper describes how the net energy gain from a complete typical window can be increased in a fairly simple way by reducing the frame width and using glass with low iron content. The changes primary increase the g-value. All improvements are based on existing technology and manufacturing methods. The obtained results imply a considerably improvement in the overall energy performance of the window which after accomplishing the improvements has an overall positive net energy gain during the heating season in Danish climate.
    Original languageEnglish
    Title of host publicationBuilding Physics in the Nordic Countries : Proccedings of the 6th Symposium Trondheim, June 17-19, 2002
    Number of pages8
    Place of PublicationTrondheim, Norway
    Publication date2002
    ISBN (Print)82-91412-02-2
    Publication statusPublished - 2002
    Event6th Symposium on Building Physics in Nordic Countries - Trondheim, Norway
    Duration: 17 Jun 200219 Jun 2002
    Conference number: 6


    Conference6th Symposium on Building Physics in Nordic Countries


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