Growing US interest in energy efficient buildings was underlined last week after the Environmental Protection Agency (EPA) released new figures showing the number of buildings qualified to use the Energy Star label rose by more than a quarter last year.

According to the EPA, 1,400 new buildings earned the label last year which is reserved for the quarter of commercial buildings that boast the highest levels of energy efficiency, taking the total number of facilities sporting Energy Star accreditation 4,056.

The EPA estimated that the office buildings, schools, hospitals, and public buildings that have signed up to the Energy Star scheme are now saving 25bn lbs of CO2 emissions a year compared to average buildings.

Wayne Nastri, EPA administrator for the Pacific Southwest region, said that California was leading the way in its support for Energy Star buildings with almost a quarter of accredited buildings located in the State. "Building owners in California are taking important steps to reduce their carbon footprint by creating ENERGY STAR buildings," he said. "They realise they can reduce energy costs without sacrificing comfort or tenant satisfaction."

The EPA estimates that in California alone owners of Energy Star labelled buildings have saved in $199bn a year on their energy bills.

Under the Energy Star scheme firms submit to an independent assessment of their building's energy performance, which results in a score out of 100. Those that score over 75, indicating they are amongst the top 25 per cent of facilities in the country, are eligible for Energy Star accreditation. On average, those firms that do qualify use 35 per cent less energy and are responsible for a third less carbon emissions than comparable facilities that are not accredited.

The sharp increase in the number of Energy Star qualified buildings further highlights the increased interest in green buildings currently being experienced in the US.