When Rose Watson moved into her Nottingham home nine years ago, there was no central heating, the gas heater in the living room was leaking carbon monoxide, and any warmth in the building tended to leach out of the draughty single-glazed windows.

Her gas bill was huge; her priority was the battle to keep her house warm, never mind carbon footprints. "I thought, if the money's there and I need gas, I'll just put it on," she says.

Watson, a beauty therapist, used to think nothing of jumping into her car to drive to the nearest shops, a short walk away at the end of her road. Her hair straighteners stayed on standby all day, and her children would leave mobile phone chargers and games consoles switched on even when they weren't being used. "It was easy for me to switch something on and just forget about it," she says. "Lights would be on all the time – I'd walk into a room and see a light on and wouldn't turn it off."

But even with the heating left on, the house where she lives with her partner and three children stayed cold. Finally, when she was pregnant with her youngest son, who is now five, things changed. Fed up with rising energy bills and an uncomfortable home, Watson agreed to take part in a telephone survey about her energy use. In return for answering some questions, she would get some energy-saving lightbulbs and tips on how to make her house more environmentally friendly.

Over the next two years, following the tips from the Energy Saving Trust (EST) and others, Watson got hooked on simple ways to green her home. Her paper-thin loft insulation was topped up to the recommended 200mm, energy- saving lightbulbs went up in all the rooms, the single-glazed windows were replaced with double-glazing, and draught excluders were fixed under all the doors and around the front door. She even blocked up the hatch between the dining room and kitchen to stop draughts blowing through the rooms.

At its most energy hungry in 2007, the three-bedroom end-of-terrace, built around the 1930s, used around £19 of gas in winter and £17 of electricity per week. "Now it's about £11 on gas and it's not even been on since Christmas," says Watson. "The electricity is now £9 per week." A rough calculation by the EST shows that Rose's family has halved its carbon footprint at home since 2007.

Energy use in homes accounts for more than a quarter of the UK's carbon emissions, so retro-fitting houses with energy-saving measures will play an important role in most households that sign up to 10:10, the Guardian-backed campaign to persuade people to reduce their emissions by 10% in 2010. Making your house energy efficient is an easy way to cut a large part of your carbon footprint: it also, as Watson has found, saves money.

In the winter, she used to set the central heating thermostat to at least 22C and often higher. Now it never rises above 16C. "Before, every single room used to be constantly hot but now I've got used to the cold and I just stick a jumper on," she says.

Her children have also been trained to keep their energy consumption down. "The kids will let their phone drain out of power now – before they'd charge it just for the fun of it, if the battery had gone down by one bar they'd just charge it back up. But now they let it run out first." She insists they never leave anything on standby. "It's not that much effort – once they've stopped playing with something, they'll just turn it off at the plug."

"If it's not being used then I turn the Wii off," says her son, seven. "If a light's on in a room and no one's in it then I turn it off."

Watson says her mother never taught her about saving energy because, she suspects, it wasn't a necessary part of her lifestyle then. "At least if I teach my family, they can get it into their head. If one family can do it, 10 more can do it, a hundred can do it."

Water is also used with care. She never fills the kettle with any more than she needs, long ago turned down the washing machine cycle from 60C to 30C, and the whole family have switched from baths to showers, so using less water. (Hot water is an important chunk of a home's carbon footprint: the EST calculates that Britons could save 30% of the carbon emissions associated with heating household water by following simple advice such as lagging pipes and using low-flow taps. It estimates that installing just a few water-saving measures could save a typical household hundreds of pounds a year on combined water and energy bills.)

This year, Watson's family made one of their biggest sacrifices. Normally they would jet off to Greece or Spain for the summer holidays but, this time, their destination was closer to home: Bournemouth. This is one sacrifice that might not stick, though. Holidays are about getting some good weather, says Watson, and Bournemouth wasn't too impressive on that front. Next year it might be back to the Mediterranean.

On the plus side, the family has become less reliant on its car habit. Travelling across the country to visit friends or family still involves driving (trains are too costly) but going to the local shops now means a walk or a bike ride. When her son needs to get to football practice, Watson arranges shared lifts with other local families.

Caroline Rams of the EST says Watson shows what an average British family can achieve with ease when trying to make their first cut in carbon emissions. "Rose has a busy life and a large family who certainly keep her on her toes. Yet she has always found time to prioritise her energy- saving behaviour; so much so that it has become second nature. She is the perfect example of how you don't have to change too much of your lifestyle to become green."

It's simple to think of Watson and her family as selfless green pioneers, cutting their consumption for the sake of the planet. She is more pragmatic about her actions, though. "I don't wake up and think I need to save the world; really it's about benefiting your purse first. But I do get worried about the environment sometimes because I have children and they'll have to deal with it."

Watson's partner agrees that saving energy and reducing carbon footprints are practical necessities. "Oil's going to run out, isn't it," he says. "The market will then dictate things – as energy gets more scarce, the cost will go up and that will drive people to actually conserve energy."

He thinks more people need to get as active as Watson in dealing with the carbon footprint of their homes. "The basic fault is that people don't realise that the cumulative amount can be a lot. One house can't do it, everyone's got to do their bit. Everyone's little bit adds up to a lot."

• This article was amended on 23 October 2015 to remove personal details at the request of the individual concerned.