Worried AC will wreck your electricity bill? It's usually cheaper to run than people fear — and in winter it's the cheapest way to heat a Lisbon flat. Here's a plain-English look at what cooling and heating actually cost, what drives the number, and how to keep it low. (For the one-off install price, see our cost guide.)
Brought to you by the local team behind AC Rental Lisbon — years of keeping Lisbon homes and apartments comfortable.
Running cost depends on the unit's power draw, how long you run it, and the price per kWh — but here's the shape of it.
A typical A++ split for a bedroom draws far less power than people expect once it reaches temperature — a modern inverter throttles right down rather than blasting. Running it a few hours an evening costs a fraction of what an old on/off unit would.
This is where it shines: as a heat pump it delivers about three units of warmth per unit of electricity, so heating a room costs roughly a third of what an electric heater would for the same warmth. It's the cheapest practical heating for a Lisbon flat.
Unit efficiency (choose inverter A++), correct sizing (an undersized unit runs flat out), the temperature you set, insulation and how many hours you run it. Small changes here move the number a lot.
Less than most people expect, especially with a modern inverter A++ unit. In cooling, running it a few hours an evening costs a fraction of an old on/off unit. In heating, it's actually the cheapest option — a heat pump delivers about three times more heat per unit of electricity than an electric heater.
AC, by a wide margin. A heat pump (which is what a split is) delivers roughly three units of warmth per unit of electricity, versus one-for-one for an electric heater. For the same warmth, running the AC costs about a third — a real saving across a Lisbon winter.
It depends on the temperature gap the unit has to bridge. In Lisbon's mild climate both are efficient, but heating on a cold morning can draw more than gentle evening cooling. Either way, a heat pump is far more efficient than the electric heaters most flats rely on.
Choose an inverter A++ unit, size it correctly, set a sensible temperature (around 24–25°C for cooling), keep it serviced, and only cool or heat the room you're using with doors and windows shut. Together these make a big difference to the bill.
Not necessarily — an oversized unit short-cycles and wastes energy, while an undersized one runs flat out. The cheapest to run is the correctly sized unit for the room, which is why we size from your actual space rather than guessing.
Tell us the room and how you'll use it and we'll recommend an efficient, correctly-sized unit that keeps running costs down — and quote it honestly. Minutes to reply on WhatsApp.
Tell us your place and we'll size an efficient, low-running-cost system and send an honest quote within one working day.