ADAPTING AIR-CONDITIONING SYSTEM IN THE BUILDING THRU’ BUILDING’S HEAT GAIN.

The Issue

Human beings are born into a hostile environment, but the degree of hostility varies with the changes climate of the year and geographical environment. Jones (1985) reports that air conditioning is necessary for human comfort, especially on the rising of industrialized social structures and standard of living. Heat gains from sunlight, especially on hot days, and electric lighting may affect repulsively high temperatures in rooms. If window opened, it will cause unnecessary draughts from the wind speed and will worsen the upper floor of the subjected building. It will also attract noise and dirt to the building. Roger, G. (2003) reports that for buildings with human occupancy, the design specification is likely to include an internal air temperature of 19-23 ْ C.

Definition

Fan Wang (2004) has described that air conditioning system is a control mechanism of an environment in terms of providing comfort for human beings in occupied spaces or for the efficient performance of a process in an industrial or scientific setting.

Air conditioning is achieved by developing the principles of moving air in ducted ventilation systems to include a number of physical and scientific processes that will enhance the air quality. The objective is to provide and maintain internal air conditions at a predetermined state, regardless of the time of year, the weather and the external atmospheric environment. It controls the air temperature, room saturation, ventilation rates and air cleanliness by cooling, humidification and dehumidification.

There are several types of air-conditioning systems that can be applied for the building namely Centralized or Plant System, Packaged Systems, Split Systems and Window Systems. Each of the systems has its own characteristics and specification to meet the building requirements for healthy environment and human comfort. So, it is very important to consider all aspects of air conditioning design, such as load assessment, relative humidity, and wind aspects, location of the building, weather analysis, temperature and many more.

Heat gain in the building

Heat gain in a building can be achieved by numerous types of sources. Heat gain occurred when there are sources of heat expand and build up in the certain spaces or location which had fewer openings, as an example a room.

Heat gain can be contributed by the sources of:

(a) Electrical appliances (refrigerators, computers, electronic devices, television, heater, etc).

(b) Human respiration (Human exhales Carbon Dioxide which provide heat towards the environment).

(c) Solar radiation (which penetrates into building materials and transmit heat to the internal space).

(d) Lighting system (Luminance from lights inside the building can provide heat)

(e) Activity in the building (Cooking, exercising and working provide high level of heat)

These heat gains from several sources will affect thermal comfort of these spaces and increase occupants’ body temperature in time. The needs to adapt air-conditioning system in the room are necessary to control the environment and the temperature of the room.

From the early era of construction, a building was significant to give a reliable place of social and functional identity whilst creating the humanised space to carry out daily tasks and functions in ‘comfort’. The term of ‘comfort’ must reflects from the needs for commodity (comfortable environment conditions), which can be achieved by adapating air-conditioning system in the building thru’ building’s heat gain.

The interior of buildings are ventilated in order to provide comfort environmental condition. In the UK, the Chartered Institution of Building Services Engineers (CIBSE) guide suggests that the quantity of fresh air needed can vary from 8 litres per person/second in fairly smoke free environments. Whilst in the Malaysia, the Uniform Building By-Laws (1984), the fresh air needed in rooms are 28 nos of air changes rate/hour. Thus, there are need to provide natural air inlet, natural air outlet and mechanical inlet and outlet as well (CIBSE, Guide B2, 1998). Ventilating, cooling and general treatment of the building’s interior thermal and atmospheric condition is a multidimensioned task. Air conditioning in building can be defined as the cooling of interior air, which include filtering out of dust and odours, freshening with outdoor air, adjustment of temperature and relative humidity (James E. Ambrose, 1991).

Air-Conditioning systems generally include the cooling system, an air-handling system, a control system for hand adjusting and automatic monitoring of the system operation. In Malaysia and other tropical countries, designing the air-conditioning system for a building requires a balance temperature within the comfort natural environment outside in a range 17-22ºC. A wide range of air-conditioning system can be installed to supply fresh air and extract heat. A centralised unit of air-conditioning system is essential to allocate into a suspended ceiling in providing thermal comfort to the occupants. This system is suitable for large building (commercial, offices or shopping complexes) which need high volume of fresh air. The suspended ceiling helps to provide space for fresh air distribution from the central air handling unit. Other than that, the most popular option in the nation reflects to split system. This system is more economic and easy to install. Moreover, the needs to adapt air-conditioning system are generally reflects to one’s budget and the needs to achieve comfortability especially on decreasing heat gain in the building.

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