Energy is the second or third biggest cost of running an apartment after platform commissions, and yet most hosts know only one number about it: the size of the monthly advance payment. The real consumption shows up once a year in the annual bill, which gets read, the balance paid, and filed away. That's a shame. There's more in it than meets the eye.

What to look for in the bill

An electricity or gas bill always has the same building blocks; each supplier just lays them out differently:

• Billing period — from when to when. It's rarely the calendar year.
• Meter readings at the start and end of the period, plus interim readings if the price changed.
• Consumption in kWh or m³; for electricity often split into high and low tariff.
• Total amount and advance payments made — the difference is what you owe or get back.
• New advance payment for the next period.

Distribution charges, the electricity tax and the OTE fee (the Czech energy market operator) together make up roughly half the price; the electricity itself is only part of it. That matters when you compare supplier offers — only part of the invoice changes.

Why break it down by month

A bill covering March to February won't tell you what the summer cost. And that's exactly what you want to know: an apartment's consumption isn't even, it tracks occupancy and the heating season. Splitting consumption across months in proportion to the number of days is a rough but usable estimate; it's more accurate to have interim figures from your own meter readings, for example at each guest changeover at the start of the month.

From the monthly consumption and occupancy you then get a number that actually tells you something: consumption per occupied night. Between similar apartments this number commonly differs several times over — and the difference comes from the air conditioning a guest leaves running with the window open, and the water heater that keeps heating an empty apartment.

What to do with that number

• Pricing. When you know that one night costs you, say, CZK 80 in energy in summer and CZK 250 in winter, you can set your winter rates so it doesn't turn into a loss.
• Advance payments. The supplier sets the advance based on last year. If you've added air conditioning or increased occupancy, the balance due arrives once a year at an unpleasant size. It's better to adjust the advance yourself.
• Faults. A jump in consumption in a month when the apartment was half empty means something is heating or leaking. That's how you find a water heater with a faulty thermostat before the invoice finds it for you.
• Comparing apartments. Two similar apartments, double the consumption: it's either a difference in equipment or in guest behavior, which you can address with an instruction in the guest portal.

How I do it

I upload the annual bill as a PDF, the consumption and amounts are read from it, the period is split into months, and next to occupancy I see the consumption per night and the year-on-year change in percent. When a supplier changes the invoice format or the reading fails, I enter the numbers by hand — it's four values. Once a year, ten minutes, and I know how much the apartment costs me when someone is sleeping in it.