We found lots of resources to help calculate greenhouse gas emission based on the type and weight of materials. Because we record weights of all my artworks, it was easy to get started:

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First, we separated all the all artworks I’ve made since college by medium (glass, bronze, ceramic, etc.) and calculated the total weight of each.

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Then, we increased the weight by 20% to capture excess materials like reservoirs and waste.

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Using the Greenhouse Gas Conversion Factors issued by the UK government, we calculated the emissions impact of the raw materials.

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Glass casting involves holding kilns at high temperatures for a long time, so over several months, we measured how much electricity was used to cast my sculptures and converted that into megawatt hours per kilogram of sculpture. Since most of my artwork has been made in the Czech Republic, we used their Default Emission Factors (which let us convert Mwh into tonnes of CO₂ equivalent).​

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The UK conversion factors include coefficients for calculating the emissions from air freight (which adjust for radiative forcing, a measure of the additional environmental impact of aviation). Calculating the emissions from transportation required figures for weight and distance, so we added up the crated weight of all the artwork. At each step, we wanted to err on the conservative side to be sure we captured everything—so we decided to calculate the emission total as if I had sent all my artwork by air from Prague to Los Angeles!

Finally, we added up all the miles we have flown since 1997 and used them to calculate the CO₂ equivalent with radiative forcing.

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Alice Roberts, a sustainability consultant recommended by Cool Effect, reviewed our calculations and made several helpful corrections.

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I didn’t want to merely neutralize my carbon footprint—I wanted to make it carbon-negative. I wanted to net reduce greenhouse gasses. Knowing we couldn’t possibly capture everything, we decided to double the total emissions we had calculated.​