Around £265m worth of energy is wasted in Wales every year.
And it is estimated that £96m worth of energy will be wasted in the UK in the next week alone.
The warning came from the Energy Saving Trust (EST) in the run up to Energy Saving Week, which began on Sunday.
The trust, a non-profit making organisation funded by the UK Government and the private sector, said statistics showed that the average person did not believe that his or her energy use was harming the environment.
ENERGY WASTED IN WALES
Phillip Sellwood, chief executive of EST, said there had never been a more pressing need to address reckless energy consumption in the home.
"Consumers often fail to make the connection between their consumption of energy at home and the impact this has on our environment," he said.
"Domestic energy use is such that our own homes are the largest contributors to carbon dioxide emissions in the UK and account for a massive 26% of the UK total." During Energy Efficiency Week, the EST is calling on the UK Government to lower VAT to 5% on the most energy-efficient appliances, so making them more affordable to consumers.
The EST is urging everyone to take part in the UK`s first national "energy pledge", by adopting five simple measures during Energy Efficiency Week.
The organisation's tips include swapping one traditional light bulb for a new, energy-efficient one - to help save the UK £1.5m a week.
Another simple suggestion is switching off the TV, video, DVD, and digibox at the end of the day instead of leaving them on standby - which would save the UK more than £3.4m.
And, when you boil the kettle, only boil the amount of water you need - and save the UK £1m.
^ Back to top | BBC Sport Home | BBC Homepage | Contact us | Help | ©