IN-SITU REINFORCED CONCRETE BUILDINGS
 

Because of the excellent ability of concrete to maintain the temperature, an in-situ reinforced concrete dwelling remains warmer in winter and cooler in summer. Concrete saves energy by reducing outside air infiltrations and makes active use of the thermal mass properties to absorb energy, keeping the temperature more constant during the day and also more constant from room to room inside the building. 1.- Thermal mass The ability of concrete to store heat is known as “thermal mass”. High density materials such as concrete take a long time to heat up and cool down. Basically, more heat is required to heat a cubic metre of concrete than a cubic metre of bricks. Thus, while a brick dwelling is subject to temperature variations during the day, a concrete dwelling undergoes more stable temperature changes. When the heating is switched off in a light-structure dwelling, the house loses heat. The same thing happens in summer with the air-conditioning. However, with high-density materials like concrete, much more time is needed for the material to heat up and cool down, thus minimising large temperature variations. Its absorption and loss of heat reduces any fluctuations, which enables it to achieve a more constant temperature with less energy consumption. Expressed in a simpler fashion, an in-situ reinforced concrete house requires more time to heat up in summer and to cool down in winter. Summing up, the thermal mass is the ability to smoothen temperature variations. It maintains the dwelling warm when the outside temperature drops and keeps it cool when the outside temperature rises. Concrete heat and cools as necessary, contributing to energy savings up to 6% in a free ecological manner. (CFA) The following graph shows how the thermal mass will smooth out temperature fluctuations during the day. In winter When the outside temperature is low, heat from the sun (or the house heating system) is retained in the concrete thermal mass of the floors, walls and ceilings to be gradually released when the heat source ceases operation. Thus, the concrete thermal mass works somewhat like a battery, accumulating heat for use when the energy source is no longer present. In summer The temperature increase that takes place as the day wears on, are moderated by the capacity of the concrete to absorb heat due to its thermal mass. 2.- Thermal transfer Thermal transfer is the speed at which heat can be transferred from one side of a wall to another. Concrete has a low thermal transfer and a high thermal resistance, so that the heat is only slowly transferred from one side of the wall to the other. 3.- Air infiltration Another advantage of an in-situ reinforced concrete dwelling is low air infiltration. This term refers to the amount of air that enters the building. When an in-situ reinforced concrete dwelling is constructed, the formwork prevents the concrete escaping when it is poured in its plastic state. For this reason, it fills all small voids in the formwork without leaving any empty space, especially if the walls and framework are monolithically concreted. In this way, the dwelling will have minimum air infiltration compared to brick dwellings that a made up of thousands of small components. This advantage is also significant with respect to air quality. The quality of the air we breathe is related to many health problems. Pollution, allergens and other particles found outside cause illnesses or the development of hypersensitivity to allergens in many people. One way to limit the entry of these harmful particles is to have control over the inside air quality. The trend in residential construction is to build the dwellings as insulated as possible to prevent pollution and damp entering. In general, a well thermally-insulate dwelling will always cost less to heat and cool, with corresponding repercussions on energy bills and, at the same time, aid in preserving the environment. Several studies have shown that the annual savings can be around 10% to 45%. (CFA) Moreover in-situ reinforced concrete dwellings can be reinforced with additional insulating materials, such as expanded polystyrene or fibre glass, which can be installed on either side of the wall or even inside it.

 
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