Energy
The Energy calculators help you size, cost and compare the systems that power and cool a home. Work out the BTU cooling load and AC tonnage for any room, turn watts and running hours into a real electricity bill, size a solar array from your consumption and sun hours, and pick a backup generator that actually carries your essential loads.
Each tool shows the assumptions behind the number — insulation, sun hours, performance ratio — so you can adjust them to your home instead of trusting a single flat estimate.
Frequently asked questions
How many BTU do I need per square metre?
A rough baseline is about 215 BTU/h per m² (20 BTU/h per ft²), but the BTU Calculator adjusts this for insulation, sun exposure, ceilings, kitchens and occupants to give a room-specific load.
Why is an oversized air conditioner a bad idea?
An oversized unit hits the setpoint fast and shuts off before dehumidifying, leaving a cold, clammy room and a compressor worn by constant restarts. One size step above your calculated load is the sensible maximum.
How do I estimate the running cost of an appliance?
Enter the appliance wattage, daily hours of use and your electricity tariff in the Electricity Cost Calculator — it returns cost per day, month and year.
How many solar panels do I need?
The Solar Panel Calculator divides your monthly kWh by your local peak sun hours and a 0.75 performance ratio to get system size in kW, then divides by panel wattage for the panel count.
What size generator do I need for backup?
Add up the running watts of the essentials you want to power (fridge, lights, router, pump) and add the highest single starting surge — the Generator Size Calculator does this and converts to kVA.