1. The embodied energy of this sofa is less than half that of a similar looking but conventionally produced: 2072 MJ vs. 5064 MJ
The components of a typical “high-end” sofa are:
- Cushion filling, with foam being the most common
- Metal springs
- Jute webbing
- WOOD: The total amount of wood depends on the style of sofa selected, but an average 6 foot sofa uses about 32 board feet of lumber. For kiln dried maple, the embodied energy for 32 board feet is 278 MJ.1 But if we’re looking at a less expensive sofa which uses
glulam (a laminated lumber product), the embodied energy goes up to 403 MJ.2
- FOAM: Assuming 12 cubic feet of foam, with a density of 4 lbs. per cubic foot (this is a good weight for furniture foam), the total weight of the foam used is 48 lbs. or 22 KG. The new buzz word for companies making upholstered furniture is “soy based foam” (an oxymoron), which is touted to be “green” because (among other things) it uses less energy to produce. Based on an LCA done by Five Winds International for Cargill Dow’s BiOH polyol, soy based foam uses 1496 MJ of energy to create 12 cubic feet of foam vs. 1958 MJ if conventional polyurethane is used3,4. Natural latex from the rubber plant which we requires 1471 MJ5 for the same amount of foam.
- 3. FABRIC needed for one 6 foot sofa is 60 yards typically which includes:
- 25 yards of decorative fabric
- 20 yards of lining fabric
- 15 yards of burlap, interior wrapping
1 “Life Cycle Analysis of Wood Products: Cradle to Gate LCI of residential wood building materials”, Wood and Fiber Science, 37 Corrim Special Issue, 2005, pp. 18 – 29. CALCULATIONS: 32 board feet = 0.075 cubic meters, and using the data from Table 4 in this study, for kiln dried lumber from the Pacific Northwest, the total embodied energy for 32 board feet is 278.
2 Ibid., From the same Table 4, referencing glulam from the Pacific Northwest.
3 “Cargill Life Cycle Assessment Report for Polyol”, Five Winds International, December 9, 2005.
4 Ibid. Used 89 MJ/kg for petrol based polyol using both renewable and non renewable sources of
energy (89*22 = 1958 MJ), used 68 MJ/KG for soy based polyols (1496 MJ)
5 Embodied energy coeficients in common building materials; University of Queensland,