The easier part is that you shouldn't even be considering an architect who doesn't have a really high sustainable quotient. On the flip side - the hard part - how do you really know if an architect is green or not? How do you know if they are sustainable?
Here are my top five tips that you can use to sift through the options and get to the sustainable design firm that will be the best fit for you and your project:
1) Really understand how long they've being doing it.
There are a lot of people who are saying they are a "green architect" or a "green design firm." And the truth is there's a lot of green washing going on. Determine how long a firm has executed sustainable design and that will tell you how committed they are to it.
2) Ask about what kind of tools and resources they have within their firm to assure that you're getting the best sustainable project possible.
To us, this is just a good business practice. Why would you not want a building that saved energy, conserved water and created a better environment for your employees? Measuring this is paramount and having the tools to do so is key (ask if they provide energy audits, energy master planning, carbon calculators, etc).
3) Visit some of their projects, on site and in person.
There's nothing like being there and seeing how a project feels and how the building relates to its environment in order to really understand its sustainable quotient. Ask how the building is performing on its design goals for energy and water use.
4) Investigate how sustainability will be done.
Is there a small, centralized group that will make your project sustainable? Or is it a Director of Sustainability who will "oversee" and "inject" sustainability into your project? I suggest you look for companies that offer a firm wide approach, in which a high percentage of the overall firm are LEED Accredited Professionals and sustainability is incorporated in a holistic, more comprehensive fashion.
5) Anyone you hire to work with for the next year or two must have an incredible amount of passion for your project, and for sustainability as well.
Look for a commitment to your project and sustainability on the same order of importance, these two really go hand in hand.
If you look for a combination of the items above, you will find the right design firm for your project. You'll experience less stress, increased productivity and a superior finished product from a better matched partnership between you and your architect.