Reflective curtains 
The radiation reflected on an inner reflective curtain can pass through the glass again, dissipating in the exterior air and minimizing the gain of calories in the inner space. That is why, with the use of curtains or other reflective materials, we can build glass buildings without excessively penalizing energy savings. It is great news for those who want to keep the exterior glazed image while reducing the consumption of energy used for refrigeration.
Actually, it is a very traditional solution. For centuries we have been placing very light shades and curtains to get this reflecting effect. They have also been used a lot under sloping glazed roofs, as in the Pilwood house, which links to the latest Piano’s Study in Genoa.
Nowadays, more reflective materials are used and therefore they reflect much more effectively. Some of the architects who most consistently used this solution are Lacaton and Vassal. They have placed silver inner curtains in some domestic buildings.
More and more, architects resort to these reflective inner protections in as diverse situations as in this museum in Ohio or these offices in Zurich.