While no one can say those in the “Green” / Energy Efficiency fields march in lock step like the Borg, I couldn’t resist using that line from Star Trek. The reason, well it appears that a big part of the collective is moving towards using kBtu/SF for measuring usage. For more on this aspect & an interesting look at the numbers I invite you to check out Joshua Lloyd’s post on this subject; Sym-Home Energy Targets (and maybe to see what that picture is about.)
For those wondering what kBtu/SF is, it simply measuring home many BTU’s are used per square foot of space. In this case the k stands for 1000, so how many thousands of BTU’s are used per square foot. Ahh, but how does one get that number? Well in keeping with a promise back from my CEA training, here is a conversion chart to convert the most standard (and not so standard) items into kBtu.
|Source||Measurement||Multiply / Conversion Factor|
|Electricity – Site||kWh||3.41|
|Electricity – Primary / Source||kWh||9.77|
|Fuel Oil (No. 1, 2, 4), Diesel||Gallons||138.7|
|Fuel Oil (No. 5, 6) aka residual||Gallons||149.69|
|Coal (anthracite) *||Tons||25,090|
|Coal (bituminous) *||Tons||24,930|
|Gasoline (10% Ethanol)||Gallons||120.9|
|District Steam *||Lbs||1.19|
|District Hot Water *||therms||100|
|District Chilled Water *||Ton Hours||12|
* These numbers can vary so when in doubt we defaulted with ENERGY STAR’s numbers used for Portfolio Manager. For example the wood figure can vary based on type of wood, wetness, etc… For more on the numbers for wood; Wood Values.
For example – a 2432 SF house that used 364 Gallons of Propane last year & 10505 kWh’s of Electricity would = 28.46 kBtu/SF — (10505 kWh times 3.14 = 35,843.06) + (364 Gal times 91.65 = 33,359.73) = 69,202.79 — divide 69,202.79 by 2432 Square Feet you get 28.46.
A few more interesting conversions;
- 1 short ton (ton) = 2,000 pounds = 6.65 barrels (crude oil)
- 1 metric ton (tonn) = 2,200 pounds
- 1 barrel (bbl) = 42 gallons = 5.615 cubic feet = 159.0 liters
- 1 standard cord of wood = 8 feet x 4 feet x 4 feet = 128 cubic feet
- 1 face cord of wood = 8 feet x 4 feet x 16 inches = 42.7 cubic feet