Before locking up the house and jetting off abroad, most Brits will make sure they've turned off unnecessary utilities to save on costs and energy use.
It's every holidaymaker's worst nightmare to return home and realise you've perhaps left a light on, or worse, something much more expensive - the heating.
This is the reality Roben Gallagher-Peer, 22, faced when she unlocked her front door in West Sussex after a trip to Valencia in June last year.
She soon realised her gas central heating had been left running throughout her entire two-week absence.
'I walked in and it felt like stepping into a sauna,' she revealed. 'The house was absolutely boiling, I couldn't believe it.'
At first, the set designer assumed something must have broken while she was away but she soon found the thermostat set at a cosy, but costly, 21°C.
'I must have forgotten to turn it off before we left,' she said. 'It was completely my fault, but I just didn't expect it to make such a difference.'
Roben quickly opened all of the windows of her two-bedroom semi-detached home to try and cool it down, but it took hours before the temperature felt normal again.
She admitted the situation 'didn't feel real'.
Weeks later, the full extent of the heating blunder was revealed when she received a heating bill that was £350 more than her usual monthly cost.
'I was shocked when I saw the bill,' she said. 'It completely threw off my budget for the month.'
Roben added: 'It felt like I'd just burned money for no reason; I was honestly gutted. That holiday suddenly became a lot more expensive because of such a silly mistake.'
Since then, the Brit says her approach to leaving the house has completely changed.
'I now triple check everything before I leave - heating, lights, appliances, the lot,' she said.
'It’s such an easy mistake to make, but it can cost you hundreds. I didn’t realise it would be such a big deal and now it is the first thing I think of when I travel.'
But Roben isn't the only Brit to make the mistake; many people are leaving things turned on when they are out of the house.
According to research by heating and cooling specialists BOXT, a whopping 74 per cent admit to leaving appliances on standby.
Heating is also an issue, with around 64 per cent of households saying they leave heating on longer than needed, while 53 per cent run the heating 'just in case'.
Adam Knight, lead gas safe engineer at BOXT said: 'Leaving your heating on while you're away is more common than people think.'
He added that small changes can make a noticeable difference to household bills.
'Most people find 18°C a good starting point, increasing slightly if needed. Avoid constant adjustments as thermostats are designed to regulate automatically.
'If you lower the thermostat by just 1°C, the small change can reduce heating costs and could save you up to £100 a year.'