How this calculator works
Every hand dry costs something. Paper towels cost trees, pulp, bleaching, transport and landfill. A cotton roll costs water and energy for laundering as well as the cotton itself. A warm-air dryer uses an electric heating element for about 30 seconds, which is a surprisingly large amount of electricity; a high-speed dryer moves a smaller amount of faster air for 10 to 15 seconds and uses roughly a third as much. The calculator multiplies the number of dries by the materials and energy of the chosen system, converts electricity at the Canadian average of 0.12 kg CO2e per kWh and paper at 1.0 kg CO2e per kg for virgin tissue and 0.7 for recycled. The comparison table holds the number of dries constant, so the systems are ranked on the same use. Provincial grids range from about 0.01 kg per kWh in Quebec to over 0.5 in Alberta, so the electricity part can change several fold.
Formula
dries per year = dries per person per day x people x days. electricity (kWh) = dries x power (kW) x seconds per dry / 3600. paper (kg) = dries x towels per dry x grams per towel / 1000. CO2e = electricity x 0.12 + paper x tissue factor. The custom system uses your own power and time; the presets use typical values for each machine class.
Worked example
Ten people drying six times a day for 250 days is 15,000 dries. With two virgin paper towels per dry, that is 30,000 towels, or 36 kg of paper, and about 36 kg CO2e. A high-speed hands-in dryer at 1.6 kW for 12 seconds uses 15,000 x 1.6 x 12 / 3600 = 80 kWh, or 9.6 kg CO2e on the Canadian average grid, and no paper.
Advertisement
Frequently asked questions
Which is better for the climate?
On the Canadian average grid, a high-speed dryer usually beats virgin paper towels on carbon, and by a wide margin on waste. On a coal-heavy grid the picture can reverse. The table keeps the number of dries fixed so you can see the crossover.
Does paper recycling change the answer?
Recycled tissue is lower than virgin tissue, about 0.7 instead of 1.0 kg CO2e per kg in this estimate, but it still needs collection, de-inking and transport. It narrows the gap but does not usually close it.
What about the health argument?
Dry hands carry fewer microbes than wet ones, and the World Health Organization advises drying after washing. A dryer that is used properly, with hands rubbed together under the jet, dries hands in about 10 to 15 seconds; leaving them wet is the worst outcome for hygiene.
Why does a cotton roll do so well?
Its footprint is spread over many uses. A roll segment is washed and reused dozens of times, so the material and laundry cost per dry is small. The catch is that laundering is only efficient when the roll is washed with a full load.
Sources
- Environment and Climate Change Canada: emission factors and reference values for greenhouse gas quantification (national inventory edition, updated annually)
- World Health Organization: hand hygiene guidance, including hand drying
- UK Department for Energy Security and Net Zero: conversion factors for electricity and paper