Amnesty International and Greenpeace are hoping to save £4,410 and £1,286 per annum respectively on their head office energy bills by adopting voltage power optimisation (VPO) technology.

Following in the footsteps of WWF and RSPB, the organisations will each install two powerPerfector Plus units in their head offices, which will optimise the voltage of their power consumption and ensure equipment runs more efficiently and consume less energy.

The units will be installed over the summer, and work by dealing with the discrepancy between the actual supply voltage received (207V - 253V) and the optimum voltage their electrical equipment needs (220V).

Retty Eliades from Greenpeace said: “Greenpeace has always said that saving energy is good for the environment and just as good for the wallet, and we're always looking for chances to put that into practice.

“The powerPerfector system will save us money and reduce our carbon footprint at a time we're looking to spend our supporters' cash as carefully as ever.”

Interest-free loans are currently available from the Carbon Trust for charities wishing to adopt the technology.