VELUX products suitable for low-energy buildings

Currently, as the negative consequences of human activity manifest in the form of slow global warming due to long-term fossil fuel combustion and other negative impacts of civilization on the environment, construction is increasingly focusing on low-energy and passive building. A significant argument for why investors and builders also welcome this direction is the energy savings, the cost of which is continuously rising.

Achieving an energy-efficient balance in construction requires a perfect project and also the use of the highest quality construction technologies. In the case of attics, the company VELUX offers a solution that creates an optimal indoor environment and energy efficiency. The system includes roof windows, installation accessories, blinds and shades, automatic systems, and solar collectors, which in mutual cooperation ensure maximum energy savings during both summer and winter periods. At the same time, it provides ample daylight, fresh air, and a pleasant indoor temperature in the attic. To make the resulting solution maximally effective, it is recommended to use the entire VELUX system and pay great attention to selecting its individual components.

Roof windows are chosen with regard to their year-round balance. This means that the heat transfer coefficient U and the solar heat gain coefficient g must be taken into account. Passive solar gains improve the energy balance in winter; however, they cause overheating of attic spaces in summer. Therefore, it is necessary to find a solution that best meets the seemingly contradictory needs of both climatic periods. There are three types of glazing available, namely low-energy triple glazing 65 (Uwindow = 1.0 W/m².K, g = 0.45), passive glazing 62_65 (Uwindow = 0.77 W/m².K, g = 0.39), and special noise-reducing glazing 62 (Uwindow = 1.0 W/m².K, Rw = 42 dB, g = 0.5).

For a roof window to exhibit the declared thermal-technical parameters, it is not sufficient to choose optimal glazing alone. It must also be perfectly sealed into the roof structure, which is accomplished using system mounting accessories. The recessed flashings EDJ 2000 with insulation kit are designed for energy-efficient buildings, eliminating the risk of mounting errors. Using this flashing, the roof window is recessed 40 mm lower into the roof structure compared to mounting with EDW 2000 flashing. This ensures both waterproofing and protection against weather influences, improves the thermal-technical properties of the window by up to 18%, and additionally provides a discreet installation in the roofing from an aesthetic perspective. The cooled area of the window frame protruding above the roof plane is also reduced, contributing to further improvement of thermal insulation properties.

However, perfectly installed windows do not solve the problem of passive solar gains during the summer months. While they reduce the need for heating energy in winter, they cause overheating of the under-roof space in summer. The most effective way to eliminate solar gains is through VELUX outdoor awnings and roller blinds, which can block up to 95% of heat gain. Their operation can be manual or remote with electric or solar drive.

The mentioned automatic systems allow for regulating a pleasant indoor temperature and ensuring a supply of fresh air through controlled shading and ventilation. By programming the remote control, it is possible to automatically manage the operation of electrically controlled roof windows and VELUX shading accessories.

Automatic systems can be powered from the grid or using solar energy, saving energy needed for their operation. With adapters, even originally manually operated windows can be adjusted for automatic control.

The complete VELUX system also includes solar collectors, which serve for direct conversion of solar energy into heat. The advantage of VELUX flat solar collectors is their integration into the roof plane and the possibility of a combined assembly with VELUX roof windows. In the roof plane, they create an aesthetic architectural addition that functionally contributes to the comprehensive solution of a low energy consumption building with a healthy indoor environment.

With the presented VELUX system, it is possible to meet the requirements for energy efficiency while ensuring the demands for a healthy indoor environment and comfortable living for the building's occupants. Thanks to the complexity of the low-energy home concept, the individual products of the VELUX system are included in the Green Savings subsidy program. Detailed information about the entire VELUX system and its individual elements can be found at www.velux.cz.