A light control process, a light control system and a building, which are capable of increasing, in a short period of time, the amount of light passing through a multiple sheet including a plurality of transparent sheet layers are provided. A light control process including steps of (a) supplying moisture in between the transparent sheet layers 12 of the multiple sheet 10, and (b) reducing the pressure between the transparent sheet layers 12 of the multiple sheet 10 to bring the transparent sheet layers 12 into close contact with each other with the moisture existing between the transparent sheet layers 12, whereby the amount of light passing through the multiple sheet 10 is reduced in comparison with the amount of light passing through the multiple sheet before supplying the moisture in between the transparent sheet layers 12; A light control system including a multiple sheet 10, a moisture supply system for supplying moisture in between the transparent sheet layers 12 of the multiple sheet 10, and a pressure-reducing system for reducing the pressure between the transparent sheet layers 12 of the multiple sheet 10; and A building including the light control system according to the present invention, the building having a roof and/or walls at least partly formed of a multiple sheet 10.
