Designing a passive solar home is not the end of the road for sustainability. There are many more choices you can make to improve your home's sustainability and, at the same time, reduce the impact of traditional living on the environment.
Country versus city
You don't have to build in the country to be eco-friendly. In fact, it may be better to build in higher-populated areas where residential construction has already claimed land, instead of inflicting even more damage on a previously untouched site.
Avoiding city sprawl has a lot of advantages. You're closer to amenities such as public transport, which will reduce car use, and to services such as fire, police, and health centers. Even if you have to use your car, travel distance is reduced, which in turn reduces pollution.
But if a country house is your dream, choose the site wisely. Make sure it has plenty of natural resources – sun, water, wind – and preferably a location that tucks your home out of sight. Instead of building on the prettiest spot, build in the ugliest and turn it into a garden, leaving the naturally beautiful spots untouched.
Every little efficiency gain matters. Placing framing studs 24 inches apart instead of 16 usually provides sufficient support but saves materials. Design rooms that fit the construction materials' natural size, so you don't have to cut every piece of lumber and create waste. Install low-flush or composting toilets to reduce water use.
Above all, rethink the size of your home. Do you really need four spare rooms, a pool, a formal dining room, an extended basement, and a triple garage? All the extra space uses construction materials, paint, stains, furnishings, heating, cooling, glazing, and everything else. Think 2,000 square feet instead of 4,000; 1,500 square feet instead of 3,000. A smaller home doesn't scream your wealth to the world, but it does show you value good sense more than money and pride.
Use better materials
You're already using fewer materials if you build smaller, but you can also use better ones. Natural alternatives exist for most construction materials: wood and straw instead of concrete - even dirt is renewable!
There's still a certain amount of resistance to natural materials in the building community, but they are gaining support as their benefits become better known. Better fire control, cheaper, locally sourced, more sustainable, and just as good structurally as their traditional counterparts, it is only a matter of time until they are accepted into most local building codes and become more popular. Especially as fossil fuel prices rise and carry the price of traditional materials with them.
"Green" building materials are another alternative. They overlap with natural materials but "green" is a wider expression, encompassing products made from recycled scrap. The funny thing is that every single traditional building material has a green equivalent – some of them are still expensive, others won't quite fit a 100% sustainable requirement, and others will require special installation skills, but all of them are more ecologically benign than their standard counterparts.