Sandstone and aluminium louvers, B-Hotel in Barcelona 
The B-Hotel has a single main facade facing south, so the sun shines on it from dawn until nearly evening; consequently it is necessary to provide a type of filter that is able to regulate the direct sunlight and protect privacy of the rooms, while allowing the exterior views.
The sun protection system that is chosen is double. Firstly sandstone louvers are fixed to metal frames. Then an aluminium louvered shutter slides among them. Both located in the external plane of the facade protect the small balcony.
Being horizontal louvers they permit a bigger space between them, what allows a better view of the outside. In winter, when the sun's rays are lower, some of them may pass through the shutter if the width of the louvers is not enough in relation to the space between them.