Paint a week of thermostat setpoints hour by hour. Pick your climate, house and heating system, then see what the schedule costs this winter versus holding one temperature—and where heat-pump backup strips eat the savings.
Planning estimate. Climate values are approximate monthly normals, and the heat-loss model is deliberately simple. Use it to compare schedules, not to predict a utility bill.
Start with a household
Preset 1 is loaded on the first visit. Any painted or edited value becomes your custom scenario.
Place & house
Heating system
Paint the thermostat week
Click or drag across cells. On touch, drag to paint; use the scroll area outside cells to pan.
55°F · cold setback75°F · warm
What this schedule does
One modeled week
SetpointModeled indoorOutdoorStrip heat hourTap, drag or use ← → to scrub
October–April
ScheduleFlat
Heating schedule report
How it’s calculated
The city table uses approximate monthly mean outdoor temperatures for October through April plus a typical daily low-to-high swing. Each modeled day bottoms out near 6 AM and peaks near 3 PM.
House heat-loss coefficient UA is floor area × 0.45 (leaky), 0.30 (average), or 0.18 (tight) BTU/hr·°F. Hourly envelope heat is max(0, UA × (indoor − outdoor)).
On a setback, indoor temperature coasts down no faster than 1.5°F per hour with the heat off. On a rise, the system reaches the new setpoint within the hour; a small recovery allowance of UA × 4 × degrees recovered represents warming the house’s effective thermal mass.
A furnace divides delivered BTU by AFUE and 100,000 BTU/therm. Baseboard uses COP 1. The heat pump COP slopes from about 3.5 at 47°F to 1.8 at 5°F. Below 25°F, backup-strip share rises toward 100% at 5°F; recovery above 2°F also assigns a rising share to strips.
The shown month repeats the painted week for that month’s calendar days. The season adds October through April. Flat comparison holds the user’s baseline temperature.
Verdicts: BIG SAVER ≥12% saved; SOLID 6–<12%; MODEST 2–<6%; NO REAL SAVINGS 0–<2%; COSTS MORE below 0%. STRIP HEAT appears when strips supply heat; COLD WAKE when any setpoint rises more than 6°F in one hour; PIPE RISK for a setpoint below 55°F; EMPTY when every hour equals the flat baseline.