Controlling method and system for saving energy of building

A controlling system for saving energy of a building, comprising:

• an input interface, used for obtaining a user environment requirement of the building, wherein the building comprises an opening, a sunshade device, an air conditioning equipment and a lighting equipment;
• a total electricity consumption calculation module, coupled to the input interface, used for defining a plurality of cover ratios of the sunshade device on the opening, calculating a total electricity consumption required by the air conditioning equipment and by the lighting equipment under each of the cover ratios according to an environment parameter and the user environment requirement, and obtaining one of the cover ratios corresponding to a minimum total electricity consumption;
• and
• an equipment controlling module, coupled to the total electricity consumption calculation module and used for automatically adjusting a shading area of the sunshade device covering the opening according to the cover ratio obtained by the total electricity consumption calculation module, and automatically adjusting the air conditioning equipment and the lighting equipment respectively according to redundant heat and indoor light of the building corresponding to the cover ratio obtained by the total electricity consumption calculation module.