Hi,

My husband and I recently closed on a lot and will soon start the building process after we get some plans finalized, etc. We've been reading a ton of info on energy efficient building (wow! lots to figure out!), and are interested in the concrete walls/geothermal concepts.

My question is this - we're in the Nashville TN area. Our home will likely be in the 4500-5300 square feet range (I'm hoping to be on the low end of that) and on a completely flat lot with no trees. We are wondering what the differences are if doing only the concrete walls and then more conventional methods of energy (i.e. regular heat system, lighting, etc) vs. doing an entire enviro-type package for the home. Is doing a mixture feasible/cost-effective/productive? I wondered what the opinions were on what combinations work best. From all the reading I've done, what I gather is the very best way to make the home efficient is to have an airtight shell, so we are just weighing various options and wondering about effectiveness, cost, etc. Any insight is much appreciated, thank you!