Sun protection on windows would work

Windows that darken themselves: is smart glass worth it?

Purists don't like fluttering curtains, roller blinds or pleated blinds: all too much. This is where intelligent glass as integrated sun protection comes in handy.

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Here you can read how self-darkening windows work, what the differences are between electrochromic, thermochromic and photochromic glasses, what they cost and what advantages and disadvantages they offer.

Sun protection directly in the glass: intelligent window panes

While solar control glass darkens the room all year round, even if sun protection is not absolutely necessary, "intelligent" glass only changes its color when necessary. This happens automatically with thermochromic or photochromic glass. With electrochromic glass, also called switchable glass, by means of a switch or remote control.

Due to the darkening, the sun and thus also the heat remain outside. Instead of roller blinds, blinds or awnings, the shade provider is built into the glass at the same time.

For retrofitting, there are also foils that turn an ordinary window into an intelligent window.

Sun protection by magic: thermochromic and photochromic glass

A thermochromic film or a special resin layer in the laminated glass makes it possible: the glass darkens automatically when the sun shines on it and the temperature on the pane reaches a certain value (for example 40 degrees Celsius). The substances in the film create an effective sun protection glass.

There is also photochromic glass that tints itself when exposed to sunlight. It does not change due to the heat, but due to the UV radiation. The principle is known from self-tinting sunglasses. So far it has not been used for larger window areas, but there are photochromic sun protection films that can be retrofitted to windows.

Thermochromic glass has the advantage that in winter, when warming solar radiation is definitely desired, it darkens less than photochromic glass, which only reacts to brightness.

Advantages of self-darkening windows

Thermochromic or photochromic glass has several advantages:

  • The room does not heat up so much in summer, the heat input from the sun's rays is reduced by up to 90 percent.
  • If a UV filter is installed, thermochromic window panes even become real sun protection glazing.
  • The furnishings and the floor covering are protected against UV light. Leather and plastics do not become brittle as quickly, and colors do not fade.
  • Air conditioning or fans are no longer necessary.
  • You also don't need blinds or shutters - at least not as sun protection.
  • In contrast to electrochromic glass, no switches or cabling are necessary. No electricity is used.

Disadvantages of self-darkening window panes

But thermochromic windows also have disadvantages:

  • They are (still) very expensive to buy.
  • The blackout cannot be controlled.

Sun protection window at the push of a button: electrochromic glass

With electrochromic glass, the coating in the glass reacts by applying a voltage. When the switch is operated, electricity flows - and the panes immediately change their color, turn milky white or bluish.

On or off - with switchable glazing, this works either via a normal light switch or wirelessly via the remote control supplied. It becomes really convenient when the control takes place entirely without us, with the help of smart home technology. When the sun is shining, sensors detect it and send a signal to the central controller. This in turn delivers the command: "Switch on the film, please."

This does not create an effective privacy screen, but this electrochromic glazing, also called EC glass, is suitable as sun protection, for subdued light or for temperature control in the room.

Anyone who decides on an electrochromic window later will also receive the switchable film plus accessories for retrofitting. The covering is then glued neatly to the pane.

Advantages of switchable glass

Switchable glass has a number of advantages:

  • The sun protection is not only switchable, with EC glass you can also dim the window in steps.
  • The tinting process takes around ten minutes from the lightest to the darkest level on a one-square-meter window.
  • Despite sun protection, you can still look outside: The heat and light permeability of the glazing is changed in the case of electrochromic glass without the transparency of the glass being clouded. It just changes the color.
  • The total energy consumption of a house can be reduced by up to 20 percent with electrochromic glass.

Disadvantages of EC glass

Electrochromic glass is quite expensive and there are not that many manufacturers offering EC glass yet.

Who makes smart windows?

Since the production of intelligent glass is still relatively expensive and such glasses have not yet conquered the broad market, there are not too many manufacturers.

If you are interested in self-darkening windows or switchable glass, you can contact the following manufacturers:

It is also possible to retrofit existing windows with photochromic, i.e. self-darkening window film. Such a film is, for example, the product Haverkamp Dynamic. Ifoha also offers a photochromic sun protection film and electrochromic film.

What do darkening windows cost?

Smart glass is not exactly cheap. Switchable, i.e. electrochromic, windows cost around 700 euros per square meter, plus controls and switches.

Switchable foil for retrofitting is available from 400 euros per square meter.

When retrofitting with photochromic film, you pay 80 to 120 euros for the square meter of self-darkening film.

Conclusion: is a window with built-in sun protection worthwhile?

If you don't have to look at the price, electrochromic glass is an effective and very easy-to-use sun protection for the window that is almost completely invisible when not in use.

EC glass acts as heat protection glass in winter and as sun protection or climate protection glass in summer. It thus reduces long-term energy costs that would be incurred for heating and / or cooling and, if necessary, provides a switchable privacy screen.

There are no costs for air conditioning or for roller shutters or other sun protection. Thanks to these advantages, the high acquisition costs can be amortized over the years.

But if you opt for a thermochromic lens, you won't get rid of this sun protection again.

Intelligent glass can also be of interest to owners of listed buildings: Thanks to the intelligent sun protection glass, no external sun protection devices have to be installed - these are often forbidden in monument protection.