Green/Greener/Greenest
It is always "more green" to remodel your present home for energy-efficiency than it is to build a new home. 

Green or Energy Efficient? 
A home can be energy-efficient without being green but a home can not be green without being energy efficient.

Good Advice for a Remodeling Project: 
Use one company for testing and reports, another for consulting, and even a third for the actual work. That's right: There might be three companies involved for a green remodeling job that leans in your favor. 

Everyone knows it is important to get more than one estimate. Not as obvious, though, is that using the same or overlapping companies for your remodeling project could be a conflict of interest that is not in your favor. 

Keeping this separation of companies is very important for your bottom line. It is as important as multiple estimates,  if not more important to to your successful energy-project. 

Take it a step further. Make certain there is no connection between the different companies. Businesses with two different names, but basically the same or overlapping company ownership, are not uncommon in this field.