1988 1.5 story home with heat pump/electric backup

Project: Affordable Green Upgrade to Net Zero Energy

Specs today:

2000 sq. ft., standard 2×6, fiberglass batt, OSB sheathing, no tape, no building wrap, no rim-joist insulation, and vented roof leaking warm inside air. 40 million BTU annual heat load.
R-5 true whole-wall R (R-19 glass batts perform poorly in leaky wall at low outside temps)
R-15 attic/roof (R-38 glass batts with venting leaking heated air out)
R-1 cellar (R-11 batts 1″ off wall, short of floor by 1′)
R-.5 rim joist (no insulation, no caulking)
R-1 windows (double pane, not well installed, no spray foam used)
Passive solar ( Great southern exposure, poorly adapted, few windows to south, 2 garage doors dominate)

Plan; divide 40 million BTU 1/2 shell retrofit, 1/4 low temp heat, source 1/4 warmer temp HVAC system.

1-Insulation retrofit:

R of the existing shell may be as low as R-7. Retrofit to true R-20 whole assembly at 25 pascals say. (makes ICF sound good doesn’t it!?)
Plan; add used 3″ ISO roof deck board over existing OSB sheathing, tape both well, foam joints. Entails removing siding, adding furring & residing. Roof; needs replacement so add 3″ ISO to roof, tape seams, furring, vent, reroof with 50 year shingles.
Windows; remount, foam seal, retrim, add pane to North windows, add windows to south for added passive gain. Cellar; remove insulation, spray CC Soy foam 2″ including rim joist, replace fiberglass and build wall to floor, add no paper waterproof ext drywall. 40mBTU/2=20mBTU

2-Divide heat load: 1/2 extreme cold, 1/2 other temps

Coldest temp heat source: sealed-combustion wood heat, use during all hours of lowest temperatures (say 30 degrees F and lower) Burn 10 million BTUs of wood. Carbon neutral renewable plenty in this area in waste wood alone. Cost $200/yr. 16mBTU/ton(70%)=11

Primary base load heat source- Altherma Daiken air to water unit. Use mainly at 32 degrees and higher, if temp set back to 45 degrees/vacation lower delta T, let it run. COP if used in this manner could go up at least 1 maybe 2 points. Say seasonal COP hits 3.5, 9 million BTU needed+. 3400BTU/KWHx3.5COP~12,000BTU 9mBTU/12,000BTU=750KWH needed. = 1KW PV array. With summer AC double both. 1500KWH=2KW PV array.

Costs: (Material only, Subcontractors would charge at least 2M to make a reasonable fee, more if general contractor with subs.)

$15,000 Shell insulation other.
5,000 Wood heat Pellet stove/sealed woodstove/fireplace w/ chimney.
10,000 Daiken Altherma electric heat pump, with solar package for hot water. Domestic water costs drop to ~1/6. (6000KWH annual/4=1000KW domestic water)
10,000 photovoltaic array Spring of 2011 price is predicted to be wholesale $1/watt. 28 panels and 2 inverters 5.6KW system. 5,000 KW annual production. 5000 KW minus 1000 KW (hot water) minus 1500 KW (HVAC) = 2500 KW other use. Home reduced to 2500 KW by monitoring use/making changes. Go for 100 watts continuous use with 6 hours of added 400 watts use. Need super efficient small refrigerator kept in cool part of home, next to outside wall winters with cold wall mod. Wash with cold water, new low water unit, dry on line.
2000 Monitoring/Control System to keep tabs on all, log all and control all and make improvements.

$50,000 Total Project Cost $25/sqft materials for this 2000sqft retrofit. $50-75/sqft contracted.

This now is a Net Zero Energy Home possibly and very green if soy and recycled foam is part of the renovation.

Version 1.0 June 1, 2010

Please discuss this and your projects, insights corrections welcomed.
aj