As beautiful as a sunny day is, it can also take a toll.
Rooms that receive direct sunlight, even at moderate outside temperatures, get hot quickly. But closing the curtains or pulling down the blinds and working in the dark with artificial light is also not the best solution.
"Large windows are in style as they bring a lot of light and warmth into the house," says Juergen Benitz-Wildenburg from the Institute of Window Technology.
Shading systems, such as roller or window shutters, external blinds and awnings, provide good protection against heat, explains Martin Brandis, energy consultant at the German Consumer Advice Centre.
"Since they're installed outside the window, they don't let much of the sun's heat into the home."
"With external systems like this, sun exposure can be reduced by 60-75%," emphasises Frank Lange, managing director of the Windows + Facade Association.
Interior sun protection systems are less effective, but still useful. These include roller and pleated blinds or curtains.
However, if you only rely on interior protection from the sun, your rooms will get warmer than with exterior protection. This is because the heat comes into the house through the window pane and can only be partially reflected outwards, even by fabrics or blinds coated in a special chemical solution.
"UV protection films are effective, especially when placed on the outside of the window pane," says Brandis. However, they make the room darker, which is annoying on days with less sunlight.
If you're planning on modernising or renovating your home, you should think about installing UV protection windows. They let daylight in while also reducing heat from the sun's ultraviolet (UV) rays.
There are three types of UV protection windows.
"Covered glass reflects and absorbs the sun's rays thanks to almost invisible coatings in the space between the panes," explains Lange. This reduces energy loss by up to 50%, depending on the type of glass selected.
Smart or switchable glazing takes a somewhat different approach. By using electricity, the panes change their colour in several stages from crystal clear to a deep blue, for example.
And with the third option, the systems in the space between the panes, blinds or shutters are integrated into the glazing. – dpa