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Bill of Materials and Embodied Carbon

Bill of Materials

Below is a (mostly complete) bill of materials used to build the Tiny Research Station up to this point.

As we've mentioned before, we took a number of factors into consideration when choosing materials to use, including locality, ingredients, and embodied carbon. For making embodied carbon comparisons, we usually relied on Environmental Product Declarations (EPDs) of the product or of similar products from the same company. These documents include a life cycle assessment (LCA) of the product, from cradle to grave, presenting most of the environmental impacts of each stage of the product's production, use, and disposal, and tally up the total greenhouse gas emissions produced during each of those stages. The total emissions is presented as a sum with units kg CO2-eq, converting other emissions to their equivalent CO2 emissions based on their global warping potential (GWP), or how strong of a greenhouse gas they are.

If we couldn't find an EPD for a particular product, we searched for its embodied carbon in other databases, such as the Athena Institute's Impact Calculator, or published Life Cycle Assessments. This doesn't provide data for the exact product we use, but it does usually provide an accurate estimate for a type of material (like wood). Unfortunately, it was extremely difficult to find  embodied carbon or life cycle information for some components (like the door) so these have been left blank in the table, and left out of the semi-final embodied carbon total. Obviously, these components add embodied carbon to the building, and so our current estimate should be taken as a minimum sum.

At the moment, the sum of the components for which we could find reliable embodied carbon estimates is 394,498.4 kgCO2-eq, or the equivalent of 82.5 passenger vehicles driven for 1 year, according to the EPA's emissions equivalency calculator. That's a lot, for a small building! And doesn't even include the emissions from energy used by the TRS over its lifetime (which should be zero or close to it because of the rooftop solar PV system). 

Certain materials, like the ZIP system (which happens to contain a huge proportion of the structure's embodied carbon), were installed prior to our involvement with the project.

Material
Use in building
Estimated Quantity
Embodied Carbon (kg CO2-eq)
Source
Red List-free?
Points of Interest
References
Marmoleum Click Tiles
Flooring
120 sf
<11.15 m2 * 6.69 kg CO2 eq = 
<74.6
Europe (final manufacturing location in UK)
yes
Almost 100% natural + renewable ingredients; end-of-life can be reused, recycled, or incinerated as waste-to-energy
link
Pine Siding
Interior Siding
46.5m^2
88.4 
(cradle to gate)
New Hampshire
Yes
Locally sourced
link
Loose-fill Havelock Wool
Ceiling, floor and wall insulation
550lbs = 250 kg
2.44 kg CO2 eq/.607 kg * 250 kg = 
610 
New Zealand
Yes
2 ingredients: sheep's wool and boric acid (fire retardant); wool is bought as a byproduct of the meat production industry; compostable at the end-of-life stage; 5-10kg wool/sheep/year
link
link
Cedar shingles 
Exterior Cladding
74.3m^2
39.1 
(cradle to gate; Using bevel cedar siding as proxy)
Maine
Yes
Natural insect repellent; moisture resistant; decay resistant; durable
link
Zip System
Exterior walls and weatherproofing
632 ft2 = 58.7 m2
6,602 kgCO2/m2 * 58.7 m2 = 
387,537.4 
US
unknown
link
link
Metal roof
Roof Cladding
2080ft^2
3746
N/a
n/a
Athena Impact Estimator
Marvin Triple Pane Low e2 Windows
ED
Foam board Insulation in floor
Installed in initial floor construction (contracted out)
Estimated 164 ft2
93.82 kg CO2 eq/m2 * 15.24 m2 = 
1429.81
Assumed Quebec or Ohio
unknown/ probably not
none
link
Siga sealing tape
ED
Exterior door
Envelope
1 unit
57.5
n/a
unknown/ probably not
None; the door was bought before we took over the project
Wenker, et. al.
Lead Acid Battery
PV System
2 units (58kg each)
348
n/a
n/a
link
Inverter
PV System
1 unit
164
n/a
n/a
Sustainable Minds
Solar Panels
PV System
2 units
174
n/a
n/a
Sustainable Minds
Electricals
wait
Ventilation System
Ventilation, heat recovery and humidity control
1 unit
unknown
Germany
Yes
Red list free electronics! 85% heat recovery, 20% humidity recovery
link
Local Dimensional Lumber 
Framing
0.904m^3
84
 (Cradle to Gate)
NH
Yes
Local
Current embodied carbon does not take into account CO2eq of transportation from source
link
Dimensional Lumber  (THNE)
Framing
1.00m^3
92.89
(Cradle to Gate)
Assumed NE/NC
yes
Lumber used by THNE contractor
Current embodied carbon does not take into account CO2eq of transportation from source
link
Plywood
Floor
0.28m^3
52.7
n/a
n/a
Lumber used by THNE contractor