Saving energy
At the highest level of analysis there are 4 principal ways to go about improving energy efficiency

4 pillars of energy optimisation
Before launching into any action, it is critical to drop in a measurement (M&V) layer so that you are clear on your current consumption patterns, and can monitor the benefits (or otherwise) of your future interventions. This should always be the first step in an energy management programme.
Thereafter your programme will attend to a varying mix of these pillars, depending on your circumstances and your time lines.