What is the focus of the "greening" of your home? Is it for energy efficiency, indoor air quality, renewable resources, or something else? I'm of the belief that is it much "greener" to use an existing home that to go with new construction. Even massive remodeling of an existing home uses less new resources than new construction.
But, ignoring that tangent, here are a bunch of things you can do. Some may be may not be doable since you are building new and using a builder. We are doing a lot of these, but we are remodeling an older home.
Energy efficiency:
* programmable thermostats
* proper insulatation and use an air-exchange
* oil heat with bioheat
* tankless water heater, but only if you have gas. Last I heard, there wasn't an oil version, and electric ones aren't the best.
* orient the home to take advantage of the sunlight for lighting
* Shade the south side of the house with deciduous trees, use evergreens on the north side to protect from winter winds
* Have your outlets wired up to switches so you can turn off power to things like coffee pots, toasters, and tvs when not in use.
* energy star appliances
* line-dry your clothes
* CFL bulbs where possible
* put every light on a dimmer so you can only use the light you need
Renewable resources
* Bamboo and cork flooring are both renewable resources.
* Use
FSC-certified woods, especially for cabinets
* Investigate the options in recycled counter tops - there are many options
* Instead of vinyl, use linoleum flooring (real linoleum is made with linseed oil and hemp, vinyl uses petroleum products)
* Shop are salvage stores for fixtures, tiles, and other supplies
* Shop local, buy things made within 200 miles of your building site.
Air quality
* If you go with glue down flooring, look for low-VOC, non-petroleum glues.
* Low-VOC paints and finishes
* Make sure your woods are not treated with formaldehyde
* Have a fresh air exchange installed with the HVAC (if you are using any type of forced air HVAC).
And a tip for those who want cheaper rain barrels. Check with you local Pepsi or Coke bottling plant. Many of them sell 55-gallon food-grade drums for a token ($5-10).