_lamp timers_ in line with small electric fans for the summer, can make as much energy saving difference in the heating season as in cooling.

in a more sophisticated sense, thermostats reduce the need for interactivity, but lamp timers in particular can be a good investment.

the physical theory that must not be excluded, is called the "Principle of Intermediate Temperatures".

in any proper model of thermodynamics (heat flow) there is the consideration of the temperature of intermediate spaces (which are the spaces which do _not_ share convection currents with the insulated space, or share convection currents with the unmaintained environment.

exterior space temp <2> intermediate space temp <2> maintained space temp

if the intermediate space temp is not maintained, (usually by baffling convection with pink stuff), the intermediate space will simply assume the exterior temp -eventually-.

it is also a good point that all spaces between barriers will demonstrate a _loss_ of insulating efficiency (as an otherwise dead air space) _if_ the walls are separated by more than 3/4 of an inch because of _convection_. There is an exception when the space between panes of window glass is evacuated of filled with nitrogen or argon.

in general, when rooms which can be kept at an intermediate temperature (which also seperate the prefered heated space from an exterior wall), energy saving _definitely_ improves.

the physics facts of life are that (other than shared convecting air, through a doorway for example) the heat transfer rate (Power) is _directly proportional to the Temperature Difference.

you will Feel The Truth... right in the pocketbook.