In nearly zero energy buildings special attention must be paid to window design

When analysing the different impact of static and dynamic solar shading on nZEBs, the research group developed a tool that the architects and engineers can easily use in software programs in order to facilitate reduction of heat losses already in the designing phase. Dynamic solar shadings (which, unlike static shadings, can be operated automatically as necessary) proved to be more efficient.

Hendrik Voll says, "We developed a calculation method for determining the portions of the façades of buildings that receive the required direct solar access in an urban environment . This allows you to determine which portion of the facade needs shading and which does not. In addition, this method can be used to determine whether to select vertical or horizontal shading.

As regards the third subtopic—window models in nZEBs—detailed window models should be preferred to simplified models. "Our study clearly illustrates the importance of different variables, such as accuracy of window models, construction costs, energy prices, interest rate and inflation. The lowest energy use was achieved with large quadruple windows and automated venetian blinds with an advanced control algorithm," says Voll.

The research project based scientists' recommendations to prefer dynamic solar shadings to static ones, detailed window models to standard windows and to design buildings based on the daylight factor, not the solar radiation criteria are taken into account in the EU construction requirements for nZEBs, which will come into force at the end of 2020.

Provided by Estonian Research Council