How do property companies save energy?

There are many energy-saving technologies, all of which are in use now.

Try to say it's free.

Public lighting, strictly implement late opening and early closing. If possible, turn on the light when it is dark and turn off the light when it is bright. In the room in need, people are using electricity and people are leaving the room. Elevator air conditioning is tidal, which is turned on more during peak hours and turned on less or not when there are few people. How to deal with it without a real model? !