Essay On Heating And Cooling Loads

In order to identify methods of minimising heating and cooling loads in buildings, it is essential to define the ways heat is transferred in and through them. [1, 5] The mechanisms that heat is transferred between building’s indoor and outdoor environment are conduction, convection, radiation and phase change. The same mechanisms are responsible for internal heat transfer exchanges to or between building elements. [1, 5] [2, 3] Conduction is the process of heat transfer through kinetic energy, from one molecule to another, without macroscopic material movement. Heat passes from the hot to the cold parts of a solid, liquid or gas, whilst it requires direct physical contact. [2, 3] [4] At buildings, conduction takes place through the exterior walls,

When solar radiation enters building through windows, indoor temperature is raised and heating loads are reduced during heating days. To increase solar heat gain, opening must face the beneficial direction which depends on the latitude of the building’s location. Furthermore, shading windows should be avoided during winter and windows must be clean to allow maximum sunlight transmission. Also, solar radiation is stored in structure and furnishings, so using materials that can store heat effectively (such as PCM’s) helps increasing solar heat gain and release it at night or during cloudy periods.

(v) Avoiding radiation effects to cold surfaces. Interior surfaces of exterior walls and windows are usually colder than building’s occupants during winter. When this happens, people radiate heat to the colder surfaces. Therefore, they demand higher indoor air temperature to achieve thermal comfort levels. In order to avoid that and reduce heating load, people should sit away of the exterior walls and windows during winter. Moreover, when sun is not shinning during winter, window blinds should remain closed to reduce such radiating effects to the cold