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Wind and solar farms have always had faithful adherents in the environmental movement but now more than 3,500 churches have turned their back on fossil fuels to embrace renewable energy.

Churches from a range of denominations have either made such a switch or registered their interest in doing so, but Catholics have proved especially keen, according to figures from religious charities released on Thursday.

Nearly 2,000 Catholic parishes have forsaken conventional energy in favour of green electricity in 16 dioceses, the charities said. Some made the decision after Pope Francis issued an encyclical last year urging the world to cut its dependence on fossil fuels.

“Pope Francis challenges us all to ‘care for our common home’, and by adopting renewable energy we will directly help people threatened, and already most severely affected, by climate change,” said John Arnold, Bishop of Salford, one of the 16 dioceses to have switched.

“There are many ways in which we may respond to the threat and the reality of climate change and adopting renewable energy for our church buildings must be a priority.”

In some cases, churches had banded together to use their collective buying power to secure green energy tariffs from companies that bought or produced at least 80 per cent of their electricity from renewable sources, said Tim Gee, campaigns leader at Christian Aid.

A number had saved money but in certain instances this was because the churches had not switched suppliers in a long time, he said.

“The very cheapest electricity supplier is still fossil fuels,” he said, but the churches had still been able to obtain the cheapest available renewable energy tariffs.

The overriding reason for acting, he added, was to send a message to governments and investors that there needed to be a shift away from fossil fuels if the world were to avoid dangerous levels of climate change.

“There really is a wave of enthusiasm for it,” Mr Gee said. “It’s relatively recent and it’s really sped up in the last year.” Some synagogues and mosques had also made the shift, he said.

Some of the companies benefiting from the churches’ shift are smaller green energy groups such as Ecotricity and Good Energy rather than the larger “big six” suppliers.

At least 100 Quaker meeting houses have switched to renewables by dealing directly with seven-year-old Good Energy.

The move is part of a wider trend, according to the Energy UK trade association, which represents big six companies as well as smaller groups. “There is a real and increasing demand in the market for an energy supply contract which is based on more renewable sources,” a spokesman said.

Christian Aid and the other charities that have collected data on churches are switching to green energy have not yet calculated the financial impact of their move on more established energy companies. “It’s certainly millions that have been shifted,” said Mr Gee.

More than 900 Salvation Army buildings have switched to renewable energy suppliers, according to the charities’ data.

Nearly 700 churches from several denominations have individually signed up for green power tariffs through the Big Church Switch website, which offers a simple way for churches to shift to green tariffs.

Nicholas Holtam, the Bishop of Salisbury and the Church of England’s lead bishop on the environment, said the churches’ move was a response to a complex environmental crisis.

“It is important that Christians rediscover older traditions of a godly relationship of humanity to the wider created order,” he said. “One simple thing we can do in response to such a crisis is to switch to using clean energy in our homes, communities, schools and places of worship.”