Without specifics then, I’ll keep my advice general. Two basic green building tenets are “build small” and “build to last”. From the “small” point of view, ask yourself if you need a garage at all. Well-designed carports require fewer materials and can provide space that is much more flexible. For example, enclosing the back of a carport for tool storage gives you a much larger workshop than an enclosed garage.

Another angle on the same topic is to build a larger garage that fulfills other needs that might require a separate addition. The most familiar of this ilk is to build a second story to create the ubiquitous “garage apartment” or “teenager’s cottage” (if you’re exposed to the bizarre force of nature known as teenage culture).

Regardless of what you build, always go with quality. My advice is to fork out the extra cash for a primo roof surface. Clay or concrete tile can be beautiful and extremely long lasting. My favorite is a “living roof,” which (if designed carefully) can be not only incredibly long-lived but comes with many added benefits, including reduced storm-water runoff, better insulation, reduction of the “heat island effect” (phenomenon whereby city temperatures are consistently higher than surrounding countryside) and replacement of wildlife habitat. In the right situation, they also make great food gardens and/or patios.

Finally, if your roof is south facing without undo solar obstructions, consider installing a solar hot water system with the collectors mounted on your new garage roof.