International comparison Building and energy. Transparent walls with high thermal performance in Northern Europe. CSTB, Prebat, ADEME, PUCA
Summary document on ongoing research and development on opening elements and windows in order to improve their thermal or acoustic performance. (U <1 W / m².K) National and Local Context
The development of transparent walls (windows and bay windows - glazing + frames) with high performance thermal insulation (U <1 W / m²) is in Northern Europe (Scandinavian countries) and Central (Germany, Austria, Switzerland). K) is the most significant. This report focuses mainly on thermal insulation and therefore on the U coefficient. In fact, reducing losses is a major axis for saving energy. Nevertheless, within the framework of a global approach to the building, the window should not be seen only from the “loss” point of view but also from the “gain” point of view, in particular by taking into account solar and light contributions. , without forgetting the acoustic performance. The common conditions encountered which favored their development are as follows:
- a harsh climate and a long cold season
- a strong energy dependence on foreign countries (with the possible exception of Norway, which despite everything has developed a program of low-energy buildings: the Smart Energy Efficient Building - SmartBygg project)
- a high cost of providing energy (transport, distribution networks)
- strong public awareness of environmental issues
- unspecific building codes, often open to innovation
- a commitment by the public authorities at national or local level (specific national R & D programs with substantial budgets, local initiatives promoting ecological solutions and with good energy efficiency). At the local level, some actions are carried out to combine energy efficiency and ecological aspects. The budgets dedicated to these activities can be very significant at the level of certain countries (Austria for example)
- the presence of labels or certification devices (Passivhaus, Minergie) to signal the energy performance of buildings and structures. These mechanisms bring together lobbying and energy efficiency groups and promote demonstration operations.
Moreover, in most of these countries, resource management and environmental constraints appear to be the main drivers of the development of technologies that reduce the energy needs of buildings. In addition, all these countries are committed to reducing their greenhouse gas emissions (Kyoto Agreement).
Locally, as in Austria, where tourism is an important resource, the preservation of natural sites leads to a collective awareness of the need to preserve energy, which remains the largest producer of greenhouse gases (GHGs). during production, transportation and consumption.
In most countries, the development of windows and windows with high thermal performance remains limited. The choice to install high-performance joinery remains voluntary: national or local regulations are not binding and do not impose
performance levels involving windows and bay windows with high thermal performance (U <1 W / m2 C), even if the performance calculation codes evolve on this point.
- Passiv haus (Germany Austria)
- Minergie (Switzerland France)
These labels impose today high levels of performance (0,8 W / m2 K) and encourage window manufacturers to offer adapted products.
In addition, professional or environmental associations promote energy savings and high energy performance among public decision-makers.
In most countries, incentive mechanisms to save energy have been put in place. The incentive takes the form of bonuses or tax credits. In the United States, for example, the installation of high-performance Energy Star-labeled windows allows you to benefit from a tax credit of 10% of the purchase price, with a maximum of $ 200.