Calculator Inputs
Example Data Table
| Scenario | Loads/week | Gal/load | Hot fraction | Inlet °F | Setpoint °F | Type | Rate | Est. annual cost |
|---|---|---|---|---|---|---|---|---|
| Baseline | 6 | 17 | 0.60 | 60 | 120 | Electric | $0.16/kWh | ~$75–$95 |
| Mostly cold | 6 | 17 | 0.10 | 60 | 120 | Electric | $0.16/kWh | ~$12–$20 |
| Warm mix | 8 | 20 | 0.35 | 55 | 125 | Gas | $1.50/therm | ~$18–$35 |
Ranges are illustrative; your results depend on your exact inputs and efficiency.
Formula Used
- Annual loads = loads_per_week × 52
- Annual hot gallons = annual_loads × gallons_per_load × hot_fraction
- Heat required (BTU) = hot_gallons × 8.34 × ΔT
- Adjusted fuel/energy = BTU ÷ efficiency × seasonality_factor
- Conversions:
- kWh = BTU ÷ 3,412
- therms = BTU ÷ 100,000
- Cost = energy × rate
- Estimated savings = current_cost − target_cost
How to Use This Calculator
- Enter your average loads per week and gallons per load.
- Set your current hot fraction based on your usual wash setting.
- Choose a target hot fraction to model switching to colder washes.
- Enter cold inlet temperature and your heater setpoint.
- Select heater type and add the matching energy price.
- Adjust efficiency and seasonality for realism.
- Press Calculate Savings, then download CSV/PDF if needed.
Practical Notes
- Cold washing can reduce hot-water energy, but stain removal may vary by fabric and detergent.
- If you lower your heater setpoint, be mindful of health and safety guidance.
- High-efficiency washers often use less water, reducing heating costs.
- Actual hot-water share depends on your washer’s internal mixing behavior.