Tuesday, May 24, 2005

Embodied Energy

This is really interesting:
One insulating unit (insulation required to provide R-20 for a square foot at normal density) of cellulose has 600 BTU of embodied energy. EPS (expanded polystyrene - CFC-free insulation material used for our walls and probably also the roof) has 18,000 BTUs in the comparable amount of insulation...

Our house's surface area is roughly 3,750 sq.ft. for the walls (R-22 with ICFs) and 2,750 for the roof (R-40 with SIPs). This means our embodied energy, in just the walls and roof is 165.6 Million BTU or 48,535 kWh, i.e., as much electrical energy as we plan to consume in over 26 years. And then there is the cement...and the floor slab with EPS...

But hey - if we burn 2 cords a year, it's only as much as 8 years of using our masonry stove ;-)

(in comparison, if we'd use cellulose in the roof, it's only 1/2 year of electrical energy (instead of 16 years))

Electricity ..... 3,412 Btu/kilowatthour
Natural Gas ..... 1,031 Btu/cubic foot
LPG (Propane) ..... 91,330 Btu/gallon
Wood ..... 20 million Btu/cord

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