How To Turn Your Aging Home Into A Net-Zero Home

Before the upgrade, Bindley's home was a quite conventional ranch home

"Jane Bindley had a dream: to turn her 1978 ranch in central New Hampshire into a net-zero-energy house. How hard could that be?"

Quite difficult, but possible. Bindley's home had mostly north-facing windows, and with a hill to the south of the property the project became quite costly and comprehensive. The solution became wrapping the house in 1/2-inch-thick structural insulated panels (SIP's), creating a thermal envelope with a rather good insulation rate (R-35). In addition, the walls were sprayed with closed-cell spray polyurethane foam, bringing the R-value of the walls up to R-52, while the roof achieved a rate of R-73. The windows were replaced with triple-glazed fiberglass windows from Thermotech. For heating, the house uses ductless minisplit air-source heat pumps which are much less expensive than ground-source heat pumps (GSHPs).

"Utility bills confirm that in 2009, Bindley’s renovated house produced 1,732 kWh more electricity than it used".

Although Bindley reached her goal of owning a Net-Zero home, it became a costly affair:

Insulation Package: $110,000
PV Array: $60,000
Triple-Glazed Fiberglass Windows: $37,000
Warmboard Subflooring: $ 20,000
Additional Costs: Approx $40,000

These numbers, totaling a staggering $267,000, proves that converting old homes into modern green homes is costly, and labor-intensive. However, all props to Jane Bindley for spending such an amount of money on upgrading her home into green-friendliness.

See the entire article at http://www.greenbuildingadvisor.com/blogs/dept/musings/leaky-old-house-becomes-net-zero-showcase