Find where the heat comes from
Check whether the washer heats its own water, receives hot water from another heater, or can do both. If a shared building system supplies hot water, your personal electricity bill may not capture its energy cost directly. Record who pays for water heating before assigning a dollar saving to a cold cycle.
ENERGY STAR’s washer guidance considers both machine use and associated water heating. This explains why an appliance-only measurement and a standardized efficiency figure can describe different boundaries.
Use a complete illustrative comparison
Suppose a warm cycle uses 0.15 kWh at the washer plus 0.50 kWh of separately attributed electric water heating. A suitable cold cycle uses 0.15 kWh at the washer and no incremental hot-water energy in this simplified model. The difference is 0.50 kWh per load.
At $0.18/kWh, that is nine cents per load, or $1.44 for 16 loads. These figures are hypothetical, exclude drying and water charges, and cannot be transferred to a gas-heated or shared-water system without changing the calculation.
Keep cleaning performance comparable
Use similar load sizes and soil levels, and follow care labels and detergent instructions. A cycle that needs to be repeated may erase an apparent energy advantage. Do not assume cold water is appropriate for every item or hygiene requirement. Note any pre-treatment or extra rinse that changes the routine so the comparison remains about equivalent clean laundry.
Record the change for a month
Count loads actually switched, not all laundry loads. Keep drying settings stable if you want to isolate the wash-temperature change. Where water-heating energy is unavailable, label the result as a washer-only observation and describe the missing component. Use the resulting range to set priorities; buying a new machine solely for a small, uncertain monthly difference requires a separate purchase-cost comparison.
Choose your next step
Continue with the question that matches your next decision:
Sources & further reading
Numerical examples are illustrative unless explicitly described as measured. This guide does not claim hands-on product testing. Read the methodology and editorial disclosure.