I am hoping to either build or remodel an existing house with a green energy source within the next year to 2 years. I live in CT. From what I have read, geothermal is not as efficient when the outside temperature is below freezing. On the other hand, I don't know how effective solar is in the winter either, especially when there's snow on the roof.

Any recommendations from the pros? What about geothermal and solar? Between the two of them would there be enough energy to heat a 2500 to 3000 ft2 home in the winter? I keep my house fairly cool. My goal is to be free of fossil fuels.

Opinions, input, and references welcome.

On the east coast, there generally isn't enough sunlight to make solar practical. Too many cloudy days. I don't know why the outside temperature would affect geothermal heating at all, because it derives its heat from deep within the earth, where the temperature is a relatively constant and infinitely available middle 50 degrees. It's just a matter of designing the system to transport enough of that heat to maintain the house at your desired temperature.

Geothermal is fine when the outside weather is below freezing. What your confusing this with is a air source heat pump system. Which uses outside air as the source of the heat needed to warm up the inside of the house.
Geothermal systems pump water out of the ground which always remains a constant temp year round and are not effected by below freezing conditions.
Also because your custom building. The way the house will be constructed will make a geothermal heat pump work real good.
Solar is fine as a supplement system. It does work real good when the sun is out. But during winter times the gray skys tend to lower the output of the heating ability. You could however use solar for electrical. There still are a handfull of rebates out there that help offset the expense of installing such a system. If properly done, it will pay you back if you attach to the grid system that powers your home now. Check with the local power company for more information about this and how to apply for the permits to connect.

Thanks for the info. Do you know of any modular builders in the area who are open to using alternative power/heating sources? Depending on cost, I'd like to have geothermal for heating & hot water and solar for electicity. I'd like to find a modular builder that has some experience with those systems.

As far as modular builders no do not have any info. But the heating and electical energy saving systems are often installed once the house is done. Its not built into it other then running pipes or wires. And that nees to be discussed with them before they build the unit. Their design people will help you on that end.

I do know that Home Depot has contractors that install solar electical panels. This may only be in our area, but I would check with them.

Also check with the utility company in your area. They often have programs and information on these systems.

I've priced solar panels for both electricity and radiant floor heat and they were both a little too expensive for the homeowner in my neck of the woods. Although they may be cheaper where you are or you may feel the money is worth it.

The misconception that geothermal heating systems aren't efficient in the winter stems back to the earlier systems where they laid the outside piping horizontally in ditches that weren't quite deep enough. Geothermal heating has come a long way since then and now they can be just as efficient during 0 degree temps as they can during 35 degree temps.

If you decide to go with the geothermal option, just remember to do your research and find a reputable heating contractor to install it for you. This is one area where a cheaper price is definitely not what you want.

Geothermal is very well suited for CT, and there are some incentives from the state for doing this. Although geothermal still used electricity for it's energy source and unless combined with PV, you will still be using fossil fuels. There are two primary types of geothermal systems, closed loop, and open loop. The type of system, depends on site factors. Closed loop systems have two distinctive sub-systems, horizontal loop and vertical loop. Both of these systems re-circulate the same water through a continuous loop. Open systems comprise of wells, were the water is pumped from the well through the system and then returned to the earth. Open systems take up much less space, and can be done in very small yards. The main concern with open systems is the water quality, if you have poor quality water closed systems are your only choice.
I know of several people in CT that would be glad to help you. Joel Gordes is a very good resource for more info. Google his name and I am sure you will find him. Tell him Tom, from the MIT solar decathlon project refered you to him. He has been a prominent speaker in the field of renewables for many years. Good luck and let me know if I can help. Tom from www.eebt.org

Thank you so much for the information. I may have to delay my plans a bit because of some changes at work but I want to get as much information as I can so that when the time is right, I know what to do.

I am very encouraged by what I have learned. If I can afford it, I intend to use geothermal for heating/cooling and solar for electricity. My goal is to get as close to a net zero energy status as possible. I think that with proper planning I can get there.

Thanks again.