Great question: an enormous question, but a good one. Let's beginwith the feasibility and design process -- knowing your goals before pen ever hits paper is key.
- An excellent place to begin the establishment of these goals can often be researching and selecting a recognized certification or standard to certify your project under, such as Passive House, LEED for Homes, Living Building challenge, Built Green, and Energy Star.
- Hiring the right green professional designer with a much deeper background than designing to any certification is extremely relevant, but a sustainable approach is really only supported and quantified by third-party documentation and review.
As I reference in an earlier Ask A Pro Q&A, the quickest route to a "green" project is through reducing operational energy (conservation, essentially).
- My preference, for reasons of cost benefit, comfort, and longevity, is Passive House, but this is just a very big piece of the pie, not the whole pie by any means.
- For a truly, comprehensively sustainable project, there is a lot more than just efficiency: for example, reducing potable water consumption, using durable, low-emitting, recycled, locally sourced materials, noninvasive and native landscaping.
- Some certifications are broader than others; for example, a LEED for Homes project I designed recognized the relationship of the site to a greater community, bus lines, parks, proximity to amenities -- this reduces the dependency on driving and takes better advantage of an existing infrastructure, thus encouraging a lower carbon footprint on a daily basis.
- LEED for Homes also awards more points for a small home than a large home. The smallest home that effectively meets your needs is always the most environmentally conscious choice.
As I mention above, picking the right certification for your project is a great place to begin, and I can't stress enough how hiring the right team to support that with experience and creativity is equally as potent. For example, not every choice on a checklist makes sense for every home, only experience can judge this, and conversely, not every choice that can affect the greater impact of a home will be addressed by any single certification.
For example, an element I like to design into my work when possible are spaces that can serve a greater house or be separated off and rented as studios or be mother-in-law spaces. This allows the homeowner flexibility and freedom to their lifestyle: they can have a full family in an efficient home, and when they are empty nesters and life changes, they can work from home in their studio, or house their aging parents, or rent out the space providing supplemental income, and a wonderful living option besides an apartment for other individuals.
Invest time and resources in enduring beauty and design, something that is valuable by its design is better cared for, and so becomes as much a part of sustainability as longevity, energy consumption and social equity. Put something on the planet worthy of care, and it will be cared for.
For more information:
Read Polly Osborne's Q&A "How much does green construction add to the cost of a new home?"
Also, read David Bergman's answer to the question, "I am just starting to design a home and want to incorporate green elements. Do I start now or wait until I start working with a builder?"