Thermal Efficiency of Buildings
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Date
2014
Authors
Motaz H. Othman
Mohammad S. Humaidi
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Abstract
Hence, we must think over on what things can be controlled on an individual level to reduce electrical consumption in HVAC through: 1- The appropriate Selection of the exterior colors for residential building.2- The direction of the building and distribution of the holes and the area.3- Insulation the walls and roofs that exposed to an atmosphere and the external climatic conditions.4- Selecting windows and doors that thermally insulated. Thermal insulation of the building is used to reduce heat leakage from outside to inside the building in summer and from the inside to the outside in winter. The heat loss in and out of the building and it is supposed disposal of them using air conditioning; to keep the temperature as much as 25 degrees Celsius. The heat loss can be divided into three types: 1- Heat that leaks through walls and ceilings.2- Heat that leaks through the windows. 3- Heat transfer through ventilation holes. The heat that leaks through walls and ceilings in summer days represent the maximum heat that would to be removed with air conditioning which its rate estimated about 60% -70%, and in study on one of the building founded that 66% of the electrical energy consumed in the summer to cool the building .Methods of heat transfer: thermal conduction and convection and thermal radiation, heat transfer is mainly happens in the walls of the building by conduction; the amount of heat transfer depends on the following factors:1- The difference in temperature between the wall surfaces.2- Wall thickness.3- An area of surfaces exposed to heat.4- The period time of the thermal route. 5- The Average of thermal conductivity of the material.Convection and thermal radiation are the most important ways in the heat transfer through building materials. The best choice for thermal insulationMany kinds of thermal insulation material Present in local markets but they vary from material to other relative to heat transfer coefficient, where some of the materials deal with the required purpose of thermal insulation and others do not reach the minimum.Therefore, it is necessary to take the opinions of engineering Advisory designer offices. And advised when used into take certain characteristics into computation1- To be with high efficiency isolation for long time 2- Resistance to humidity and deposition. 3-Resistance to fret.4-Little ability to stretch and shrink. The advantages of using thermal insulation:1- Reduces the consumption of electric power2- Keeping the building with appropriate temperature for a long time.3- Increases the level of comfort to residents of the building.4- Protects building materials used in the constructions of the impact of the change in temperature.5- Protects the furniture inside the building.6- Limiting environmental pollution and greenhouse gas emissions. Insulating materials divides mainly to two types:1-Insulation of walls and ceilings, floors.2-Insulation Doors and windowsThe shapes that insulating material exist by is a powder or granules flowing normally between walls or any closed vacuum. Or in the shape of rolls fixing usually with nails such as glass wool and rock wool and aluminum foil or a plate such as polyurethane or poly styrene or in liquid poured or sprayed on/ or at the desired location