Quote:
Originally Posted by red-beard
My next house is going to be "Super Insulated". I plan to install enough panels and batteries to be self sufficient. I also plan to run the A/C with a circulated ground or water loop instead of an air cooled condensor.
There will be 2 type of outlets and wiring, low voltage DC and AC.
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Helped a cousin build an 1800 SF house. The plan was to install a geothermal unit for heat, A/C, and some hot water output. He later decided to purchase a wood-fired boiler to provide heat for the house, enclosed porch and garage.
The walls in the house are double walls (two 2x4s) with a thermal break between, open cell foam stripping. Triple pane windows. Walls are dense-packed cellulose. We decided to drop the geothermal unit and the extra expense and go with a standard ducted split. 2.5 tons cools the house to 72 degrees and keeps the humidity around 40-45%. When I ran the numbers from the amp draw in the compressor, it was going to cost around $75/month to run the A/C 24/7. The A/C doesn't run 24 hours a day, so actual cost would be lower. In that case, I cannot see reasonable payback on the geothermal unit, without government subsidies. It all depends on the specific application.
I definitely recommend spending the time and money for better insulation. However, I haven't found a way to integrate spray foam. It's too expensive, compared to cellulose.
The ideal path, IMO, to obtain energy efficiency in a new home is:
insulated slab (for moderate or cold climates)
Thick walls
Quality windows (with roof overhangs adjusted to take advantage of solar heat gain)
Good construction methods and attention to detail (air sealing)
Ductwork IN conditioned space or an unvented attic (big gains)
It truly is an all-encompassing effort, engaging many trades and skilled craftsmen. It's a shame so many fall for the bigger is better mantra with regards to housing, therefore settling for crappy construction, poor insulation, mediocre HVAC, and poor energy efficiency.
John, for your existing home, insulation in the walls would be a big gain. IN lieu of blowing cellulose in the walls (a compromise solution), you could strip the exterior siding and install foamboard. That's actually a good solution in many ways, but only feasible if you're ready for an exterior facelift.
Also, if you only have 10 years left on your roof, I wouldn't install PV. The panels may delay degradation of some parts of the roof, but the roofing that's left uncovered will continue to deteriorate.