asked the Secretary of State for the Environment what is his Department's estimate of the balance of benefit in energy and cost terms between the cost of earlier replacement of lights switched on and off at frequent intervals and the saving through such operation of lighting.
It is not possible to give a simple answer; the economics of switching off lights vary according to the electricity tariff, the type of lamp and the cost of replacing it. Frequent switching on and off does shorten the life of a tubular fluorescent lamp, but unless it is in an inaccessible place where it is difficult to replace it is usually more economic to switch off. In Government offices occupants are encouraged to turn off unnecessary lights every time.
I have been asked also to reply.The balance must depend on the size, nature and use pattern of each particular installation, and the relevant detailed information is not available to the Department.