1 A second-hand electric kiln runs efficiently with regular element changes, a new 3-inch-thick lid, and double bottom. Firing to cone 6 takes 70 kWh and just over 7 hours on average
Greening a small-scale production studio is easier than you think! Here are several simple steps you can take to lower your carbon footprint as well as your bills for materials, electricity, and water.
Keeping your kiln well-tuned is a planet-saving act. Electric kilns use more energy than any other studio equipment or home appliance. In one hour, my 7-cubic-foot kiln uses as much electricity as a typical American uses at home in a day. The electricity generation required to run a bisque firing plus a glaze firing produces 161 pounds of CO2e (carbon dioxide equivalent). The CO2e outweighs the pots.
To find out how your kiln is doing, subtract the number of kWh on your electric meter when you start a firing from when you stop. For a rough estimate, you don’t need to separate the kiln energy use from other studio use during the firing. The kiln dwarfs everything else.
Ask your manufacturer how long your elements should last. Change them regularly. Aging elements can decrease your efficiency for months before actually failing, unless you are watching the kWh pattern in your kiln log. A properly installed kiln vent will help extend the useful life of your elements.
Get a model with the thickest brick you can find. The extra insulation will pay for itself. Consider buying a kiln rated for higher temperatures than you need. It will sail easily through glaze firings. Use the smallest model that meets your needs, so you never run it half full to meet a deadline.
If you need to replace a cracking kiln lid, upgrade to thicker brick on the new one. Reuse the old lid stacked between the bottom of the kiln and the stand to make a double bottom. You may need to drill some holes for your vent system. For my kiln, a thicker lid and double bottom reduced electricity use by 14% and glaze firings now finish two hours faster.
Many neighborhoods experience voltage drops during times of peak energy consumption, which will slow down your firings. Ask your utility about off-peak hours. Starting your kiln early to beat energy rush-hour can result in shorter firings and thus save energy. I start at 6am for best results. Weather is also important. Air conditioners, space heaters, and electric radiators are energy hogs. Plan ahead to avoid firing on especially hot or cold days. Take good notes and use the patterns in your kiln log for future planning. Your data set will save energy and yield consistent, predictable firings.
Water can be reused almost infinitely in the studio with some planning. As a side benefit, your sink won’t plug up with clay. Fill a bucket with clean water and throw pots. When you’re done, clean your tools in the bucket, and tip the sludgy water into a big tub to settle overnight. In the morning, siphon clear water from the top for throwing, wiping down shelves, cleaning tools, etc. Repeat! If you just need a little water, dip a sponge in the clear water at the top of the tub instead of siphoning. When the clay sludge in the tub begins to accumulate, recycle it into new clay.
You can even mix glaze waste into your settling bucket. This is not recommended for a group studio, but if you know your materials, and don’t constantly test glazes, creating lots of glaze for disposal, this works fine. Use fresh water and a sponge to clean the feet of your pots and your glazing tools. This water can be added to your recycling tub. In my studio, it does not affect the recycled clay quality. The volume of clay trimmings and throwing sludge I produce vastly outweighs the amount of glaze in the rinse water and oxides and fluxes make up a small proportion of my glazes. I have noticed no difference in color, plasticity, or body defects between the recycled clay, and clay straight from my supplier. Your clay and glazes may be less amenable, but try a few tests. It’s a way to keep your glaze waste out of the landfill and the water table.
Small Changes, Big Benefits
A cost-benefit analysis has informed other studio greening steps. Fluorescent shop lights provide me with much more light for about the same electricity as the former incandescent bulbs. Swapping the old, solid-panel door for a French door the neighbor put out on the curb and painting the walls white brightened my space, without any electricity. For less than $10 each, a tube of caulk and some weather stripping make the studio more comfortable in winter. Planting native perennials around the studio gives me wildlife to watch and cuts out lawn watering.
Running your own business means an opportunity to do things right. Think about which changes can make your studio more sustainable.
Note: Numbers in this article come from consulting my electric meter and electric bill and doing some math. I keep a thorough kiln log and crunch the numbers regularly. CO2e numbers come from the book How Bad Are Bananas? The Carbon Footprint of Everything by Mike Berners-Lee. (CO2e refers to CO2 equivalent, which is the equivalent amount of CO2 you’d need to produce to equal the greenhouse impact of all the various climate-changing gases (like methane, CO2, and black carbon) produced from an activity.) Clay recycling poundage numbers come from weighing some pots before and after trimming and doing some math.