Welsh households have been challenged to save £60m in energy waste every year.
British Gas says it wants to encourage people to make simple changes to save money and be environmentally friendly.
It said turning a thermostat down one degree or completely turning off a TV could each save a household nearly £50 annually.
British Gas said its survey showed a million households in the UK wasted £5bn worth of energy every year.
"Our goal is for every household in Wales to save £50 a year which will collectively save the country £60m in wasted energy and help reach our UK £1bn target," said Angela Bassett-Jones, energy efficiency adviser for British Gas Wales.
"I think it's something people are really starting to think about - being energy efficient.
Turning off all stand-by products: £133.51 saving each year
Switch to energy saving light bulbs: £33.27
Only boil amount of water needed in kettle: £30.50
Only using dishwasher when full: £15.37
Putting silver foil behind radiators on external walls: £15
Figures: British Gas
"It's a win-win situation - save money and the environment at the same time, and it's so easy to achieve," she added.
Donna Davies, 30, who works for British Gas, said she was determined to save energy in her home in Cardiff.
As a busy working mother with a 22-month toddler and another baby on the way she said she wanted to maker her family more aware of the small but significant changes they could make.
"We will turn the DVD and digital box off and I'm going to buy energy efficient bulbs because they now have decorative bulbs which are quite nice shapes," said Mrs Davies.
Red areas show high temperatures at Donna Davies' house in Cardiff
As part of the campaign British Gas has been showing householders exactly how they waste energy.
It has taken thermal images which shows temperature distribution around the house.
The highest temperature is seen as red while the green and blue areas in the pictures show that less energy is wasted in those areas.
The campaign also includes thermal images of landmark buildings including the Senedd - the new Welsh assembly building in Cardiff Bay - and the nearby Wales Millennium Centre.
The £67m Senedd has won praise for its construction on "green" principles using energy saving and recycling features.
Mrs Bassett-Jones said: "Our images prove that these two iconic Welsh buildings are extremely energy-efficient, as I'm sure they were designed to be.
Donna Davies says she intends to wash her laundry at a lower heat
"We hope they will serve as an inspiration to the people of Wales to play their part to save energy in their own homes - saving money and the environment at the same time."
Features in the Senedd include using the ground as a heat source and the use of wood chips or pellets for the boiler.
Rainwater is also collected via the steel columns supporting the roof to supply the toilets and to wash the windows.
Architect Lord Rogers said energy conservation was a central principle in the design of his building as well as creating a space where politicians and members of the public could meet.
The assembly government said: "The building is at the cutting edge of sustainable design and construction.
"Its low environmental impact was achieved through the careful use of renewable and low energy solutions to construct, heat and maintain the building.
"Sustainability is at the heart of Welsh Assembly Government policies.
"We are committed to setting a good example to both the private and public sectors and the Senedd building demonstrates that buildings can be designed to achieve long term savings in running costs and emissions."
People can enter their postcode into the British Gas "save a billion" website - to get information specific to their area to find out how energy efficient their home is and receive advice on reducing energy waste in their home.