A METHOD OF MAINTAINING TEMPERATURE IN A CHAMBER WITHIN A STRUCTURE
A method for maintaining a temperature in a chamber (26) within a structure (1) that is higher than the temperature of the environment. The structure has a surface (18) through which heat from the structure tends to escape to the environment when the temperature of the environment is lower than that within the structure. The method includes: providing within the structure a thermal screen (30) which separates the chamber from most of the surface and from the remainder (28) of the structure that is contiguous with the surface. The thermal screen is located so as to ensure that most of the heat escaping from the chamber passes through the thermal screen into the remainder of the structure; withdrawing heat from the remainder of the structure for reducing temperature difference between the remainder of the structure and the environment. Due to the heat difference, heat transfer from the remainder of the structure to the environment is at least reduced; and releasing into the chamber the heat withdrawn from the remainder of the structure. This, at least partially, compensates for the loss of heat associated with its escape from the chamber into the remainder of the structure.