Our Campus Grand De Morillon is fit with the GeniLac system, that gets water from the bottom of the lake, cools the rooms and during winters, the water is heated up and does the same task.
This seems to have a very less wastage of energy and water.
Every city has a lot of lakes, if they can use the water as resource to regulate the city's building's temperatures. Nothing like it. Interesting solutions for the climate problems.