Energy efficiency improvements for office space

[Bharath Raj]

I am under contract to buy a ~4700 sq ft office space in a great location near Houston. The building' exterior is mostly glass (single storey). The inspection report noted the 15 ton HVAC unit to be in very poor condition. The other 5 ton HVAC is in fair/poor condition. I am wanting to improve the energy efficiency of the building. The electricity bill in the T12 has averaged ~$700/month. The tenant has a full service gross lease. So, it' in my best interest to cut the cost of utilities where I can. I read several articles regarding achieving these, but was wondering what you guys would advise as the priorities. Is it expensive to hire a company to do energy audits in a space as small as mine?