ABSTRACT
Heat is transferred by conduction, convection, and radiation, and the ratio of heat transfer by the three modes can vary widely depending on amount of insulation, number and types of windows, radiation barrier, and infiltration. Air infiltration through open windows, doors, and vents and through cracks in the envelope of the house or around windows and doors can account for 20% to 55% of the heat loss. Even the damper in the fireplace must be closed when it is not in use.
