If you perform a greenhouse gas audit of your museum, you will no doubt discover that your facility is the source of at least 30% of your emissions. As the major consumer of electricity and possibly one or more fossils fuels, you will recognize that if you plan on committing to greenhouse gas reduction or elimination, you will ne to address your facility.  That may mean just a building, or it may include your grounds depending on your site.   

Establishing a baseline by inventorying your current energy consumption will be a great first step.  And then getting your team involved in thinking of ways to reduce or eliminate that energy consumption will be critical.  And maybe you will even find ways to renewably produce your own energy!