It is very important to insulate a structure against heat, since this means that the indoor temperature can be kept comfortable and energy is saved. Insulation materials such as fiberglass, cellulose, and foam can be used to prevent heat from escaping out of a building. This they do by trapping the air within the material in pockets which act as a barrier to heat transmission. Effective insulating, both in terms of reducing the energy needed for heating and cooling as well as creating a stable indoor environment that is conducive to life. Without good insulation heat gain and loss can seriously affect occupier comfort--use it to resolve problems during design phase even before construction begins. Insulation in the form of insulation boards and/or fibrous fill is quite important therefore--if the building envelope itself can be made warm or cool, individual rooms will be able to remain at a more or less constant temperature all year round.