Laundry
Cold vs Hot Washing: Which Electricity Is Counted?
Compare cold and hot washing without missing water-heater energy. Use suitable fabric settings, complete-cycle measurements, and clear cost boundaries.
Cold washing can reduce water-heating energy when it suits the load. A washer's plug reading may exclude a separate water heater. Compare the same cleaning result and energy boundary.
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Cold washing can reduce the energy needed to heat water. The saving depends on the washer, the hot-water supply, and whether the selected wash cleans the load properly.
ENERGY STAR's washer guidance recommends considering cold washing and suitable load choices. This does not mean every fabric, stain, or cleaning requirement should use the same temperature.
Follow the fabric and machine instructions
Check clothing care labels, detergent directions, and the washer's manual. Use a program suitable for the load and soil. Special cleaning needs may require a specific temperature or cycle.
Do not change a required hygiene process based only on an electricity estimate. A load that needs another wash can use more total energy and water than the first comparison suggests.
Record the full program name. A “cold” option, an Eco program, and a shortened program can change more than just temperature. Comparing them without noting the differences can hide the reason energy changed.
Identify where water is heated
Some washers heat water internally. Others receive water from a separate heater. Some use both routes. Check the model and installation rather than guessing.
A plug-in monitor measures only electricity passing through it. The P3 manual describes cumulative kWh for its compatible loads. It does not measure energy used at a separate gas or electric water heater.
If the hot water comes from another source, a small difference at the washer's plug does not prove there was little water-heating saving. The measurement boundary excluded that energy.
Compare clear example boundaries
Suppose a hypothetical washer uses 0.2 kWh in one cold cycle and 0.3 kWh in another cycle. At an example $0.20/kWh, measured appliance costs are $0.04 and $0.06.
If the second cycle also receives hot water heated elsewhere, that cost is not in the $0.06 figure. You need reliable water quantity and heater-energy data to add it. Do not invent a heating allowance.
Apply the same calculation to your measured cycles. Keep the water-heating source and selected program with each result so the energy comparison stays clear.
Measure comparable full loads
- Use similar loads and soil conditions.
- Record program, temperature selection, and spin setting.
- Measure complete-cycle electricity when safe and compatible.
- State whether separate water heating is excluded.
- Check cleaning performance before calling the change useful.
Keep the amount of laundry comparable. A cost per cycle can favor a tiny load even if you need several cycles to wash the same clothes.
The DOE's Energy Saver guide discusses laundry settings and full-cost thinking. Apply the advice within your appliance and fabric instructions, rather than copying old prices or savings percentages.
Include the later drying stage
If you machine-dry the clothes, the washer's spin setting can affect the moisture reaching the dryer. Keep that setting unchanged when isolating wash-temperature effects.
For the overall laundry routine, record washing and drying energy for the same amount of clothing. A good wash-only result does not automatically establish a cheaper complete routine.
Use cycle mode in the calculator for the energy you actually know. State the missing hot-water or drying costs next to the result.