Are there things that individual tenants in commercial buildings can do to be more energy efficient in their space? Is building management typically amenable to assisting tenants in making these changes? Or does energy efficiency need to be effectuated on a building-wide basis? If not, what are some examples of changes that individual tenants can make and can they reap the economic rewards from saving energy?

Tenants can do a number of things for energy efficiency. Some of the basics would be to make sure that all of the employees are shutting off their lights when they leave. When you design your space plans you should centralize any special computer or server areas to just one location. If you have control on purchasing your own specialized AC to handle a computer type room, then you should try to utilize a system that has a large economizer system so that you can utilize the free outside air cooling when available.

The same goes when you design the space, if you are reconfiguring the space a lot then often the ceiling grid and lighting maybe altered. If so you should get a good energy management company or lighting consultant to try to see if it is cost effective to improve the lighting systems. If there are extensive changes you might be able to go to what is called scoptopic lighting and have very few fixtures.

The other thing to remember now is that with our economy being in a recession and likely to remain weak for at least some time aftwards, you the tenants have a lot of leverage. You should benchmark what the landlord is charging you for utilities and understand that cost. As of January next year all buildings in California will have to disclose to all tenants the EPA Energy star score of their building. Scores of 75 or higher are enegy star award level. If you find out that the building you are in is inefficient you can often negotiate a lower rate or motivate the owner to improve the efficiency as you could threaten to go somewhere else.

Also the USGBC has a LEED certification specifically just for tenants so that the commercial interiors are designed to address all of the green building aspects including energy, types of materials, air quality, recycling, etc.

Although this won't help to make the building itself more energy efficient as a tenant the absolute best way to conserve energy is to leave everything unplugged, minus the fridge, and only plug it in when you use it. People don't like doing this for say, the microwave or the TV because then you have to reset the clock. But honestly, why does every appliance need to remind you what time it is? That's what a watch or cell phone are for. If you leave everything unplugged or put everything in a power strip that can be turned off then you will save loads of electricity and money.

Yes those are what is called "phantom loads". Often electrical items some more than others consume a fair amount of energy on stand by mode.

While trying to unplug all items is not normally very likely in a typical large company, one easy way is to provide a motion activated powerstrip at each cubical. That is a great way for task lights, computer monitors, and other employee plug load to be automatically shut off when they are not using their cube.