Appliances

Nine appliances, one question: how much energy each month?

However different they are, a furnace, a cooktop and an EV all answer to the engine the same way: 12 monthly numbers, in kWh for electric or therms for gas. That shared interface lets the model price, compare and swap any of them the same way, while each one uses as much detail as its physics needs.

The shared interface

Every appliance takes its settings from your home profile and, if it depends on weather, the climate pipeline. It returns 12 values. The engine prices those with each month's rate. Electric appliances also get spread over a 24-hour day using the NREL load profile for their end use, so peak and off-peak hours can be priced separately.

Swapping an appliance

Each appliance has a baseline (usually gas) and an electric version. The do-nothing home keeps the baseline for all 20 years (replacing it like-for-like when it wears out); your journey switches in the swap year and books the install cost, less rebates, that year.

Default HVAC plan: furnace years 1–2, heat pump from year 3. An appliance that is already electric today stays electric in both homes.

Four levels of detail

The model spends detail where it changes the answer. Heating and hot water swing with the seasons and dominate the bill, so they get climate physics. A cooktop's use is steady, so a per-meal energy figure is enough.

The nine

Code

src/devices/base.py · EnergyConsumer.monthly_consumption() src/devices/physics.py src/devices/seasonal.py src/devices/schedule.py src/devices/vehicle.py src/journey.py · DeviceSlot src/load_profiles.py · DEVICE_END_USE data/homes/journey_slots_default.json

Turn on Show code (top right) to see the files behind each part.