It may be freezing outside but the Church of England is encouraging its churches to think about reducing their energy use.
Its free sMeasure toolkit has been made available as part of the Church's national energy audit and enables church buildings to understand and reduce the amount of energy they are using.
As well as reducing their carbon footprint, churches can cut their energy costs.
The toolkit was developed by Shrinking the Footprint, the CofE's national environmental campaign.
The online tool requires regular meter readings to be submitted and gives users tips on how to save money and reduce their carbon footprint.
One church that has seen significant long-term benefits is St Mary the Boltons, in London, which even has a thermometer in the pulpit to make sure the church is the perfect temperature for the congregation.
The Reverend Ruth Lampard, Associate Vicar at St Mary, talks about the impact in a new CofE videocast published today.
The Bishop of London and chair of Shrinking the Footprint, Dr Richard Chartres said: "It is a God-given imperative that we guard the earth for future generations.
"This energy audit aims to build a better understanding of our energy usage and total carbon footprint for our national network of 16,000 parish churches, so we can support energy saving actions and meet our commitment to protecting God's creation."