Four innovative ways to make energy usage on campus more efficient?

Energy is not a physical unit. It is a philosophical concept and an accounting technique used to analyze mechanical and chemical exchanges. In nuclear physics it is defined as a wavelength of light, in biology it is a synonym for metabolism, and in public utilities they say energy when they mean connectivity.

I would guess that you are talking about electrical power, since people who talk about gas or coal or other power sources usually say "usage" or "economy" rather than "efficient". Efficiency is defined as output divided by input. What you are looking for is ways to reduce waste.

It's nice that you said "innovative" because that is a proper matter for college level efforts. Innovate means you learn about new things that have already been invented, rather than trying to invent new things yourself.

So now that you know what the words mean you are equipped to do a search. You will find an established industry of photographing buildings in infrared light to reveal exactly where heating and cooling power are being wasted. You will learn that several new kinds of glass have been developed to reduce heat transfer through windows. You will learn of foam insulation materials that can be added to existing buildings about as easily as repainting, although at higher cost.

Go to google.com and see what else you can find.