When the mercury falls below freezing, pulling on yet another jumper will only get you so far. Yet cranking up the thermostat will no doubt do serious damage to your bank balance. So, what to do? The ...

Radiators and vents rely on convection. They warm air, which rises, pulls cooler air through the emitter, and sets up a loop. Block that loop with fabric, wood or stacks of books and the emitter heats ...