Cold Wash Savings Calculator
Our sustainable living calculator computes cold wash savings accurately. Enter measurements for results with formulas and error analysis.
Formula
Energy = (gal*3.785*4.186*deltaT_C)/(3600*eff)
Energy to heat water uses mass*specific heat*temp change, converted to kWh and divided by heater efficiency.
Worked Examples
Example 1: Family: 5 Loads/Week
Problem: 130F hot to 60F cold, 20 gal/load, $0.12/kWh.
Solution: Energy/hot load: 20*3.785*4.186*38.9/3600/0.90=3.63 kWh=$0.44\nAnnual hot: $113. Annual cold: $3.12. Savings: $110/yr
Result: Save $110/yr | 917 kWh | 356 kg CO2
Example 2: Large Household: 10/Week
Problem: 140F to 55F, 25 gal/load, $0.15/kWh.
Solution: Energy/load: 5.19 kWh=$0.78. Annual hot: $405. Cold: $7.80\nSavings: $397/yr
Result: Save $397/yr | 2,646 kWh | 1,028 kg CO2
Frequently Asked Questions
How much money does cold water washing save?
Switching from hot to cold saves the average household 60 to 150 dollars per year depending on load count and energy costs. About 90 percent of washing machine energy goes to heating water so eliminating that achieves dramatic savings. A family doing 8 loads per week at 0.12 dollars per kWh can save over 130 dollars annually. Over 10 years that adds up to 1,000-1,500 dollars from this single change.
Does cold water clean as well as hot?
Modern cold water detergents with enzymes and surfactants that activate at lower temperatures make cold washing equally effective for most everyday laundry. Consumer Reports found no significant cleaning difference for regular loads with quality detergent. Hot water is still recommended for sanitizing illness-contaminated bedding, cloth diapers, and heavily soiled work clothes. For the estimated 85 percent of normal loads, cold water performs comparably.
What temperature is cold water for laundry?
Cold water for laundry is generally 60-80 degrees Fahrenheit, typically the incoming tap water temperature. In winter in cold climates tap water can drop below 50 degrees potentially reducing detergent effectiveness. Some newer machines have a slightly heated cold option around 65 degrees ensuring minimum cleaning performance. Water below 60 degrees may not fully dissolve powder detergents so liquid detergents are recommended for very cold water.
How much CO2 does switching to cold save?
Switching all hot loads to cold saves approximately 350 to 800 pounds of CO2 per year for a typical household. The US grid produces about 0.855 pounds CO2 per kWh and heating water for one hot load uses 1.5-2.5 kWh. For 300 loads per year that translates to 450-750 kWh saved equivalent to 385-640 pounds CO2. If every US household switched it would prevent approximately 34 million tons of CO2 annually.
Does cold washing affect clothing lifespan?
Cold water significantly extends clothing lifespan by reducing thermal stress on fabrics. Hot water causes fibers to expand and contract leading to faster wear, fading, and shrinkage. Cotton can shrink up to 5 percent in hot water while synthetics may lose shape. Colors fade much faster in hot water as heat opens fibers releasing dye. A Procter and Gamble study found cold washing can make clothing last twice as long as hot washing.
How does water heater type affect savings?
Electric water heaters at 90 percent efficiency with electricity at 0.10-0.20 per kWh make cold wash savings substantial. Gas heaters are cheaper to operate but less efficient at 60 percent. Tankless heaters at 95-98 percent efficiency still show significant cold wash savings. Heat pump water heaters at 200-300 percent efficiency reduce but do not eliminate savings. Regardless of heater type, eliminating laundry water heating always saves energy and money.