lite control
image from wikipedia
Sometimes sun light protection with simple and energy saving solutions like exterior window shutters or non electric mechanical window blinds (see above image) is not so easy feasible like in the case of big windows, like in business applications or in urgent cases, where a fast shield is necessary like e.g. in aviation.
An alternative to electro-mechanical (and thus energy costly) window blinds (in german also called Jalousie) are may be smart windows like e.g. the SPD light-control technology by research frontiers Inc. who seem to head for a big commercalization of their product see pressrelease from Feb 1.
->see also the information brochure by frontier research.