tool was introduced by the authorities for potential owners of buildings to facilitate the improvement of energy efficiency of their buildings . However , compliance is on a voluntary basis and it is not currently compulsory for owners of buildings to apply for the Green Building Index . The other issues related to ACMV include the environmental stewardship of the refrigerant used , noise pollution and safety issues during the construction phase .
Design Guidelines and Best Practices
In Malaysia , due to the hot and humid tropical climate , air-conditioning system design is critical in ensuring thermal comfort and providing indoor air quality for the occupants . To achieve this , a reasonably accurate estimation of the cooling load is of paramount importance in ensuring thermal comfort to occupants and maintaining environmental stewardship . To deal with the aforementioned design issues , the ACMV design methodology , equipment selection and specifications have to be in line with good engineering practice , and give due regard to the following criteria :
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Simplicity of design and installation .
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Ease of operation and maintenance .
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Energy efficiency and impact on the environment .
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System flexibility and adaptability .
The following standards and guidelines are generally applicable in the design of an ACMV system :
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American Society for Heating , Refrigerating , and Air Conditioning Engineers ( ASHRAE ) Standards [ 3 ].
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Malaysia Standard MS 1525:2014 [ 4 ].
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JKR ’ s Guideline on Air Conditioning System Design [ 2 ].
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Uniform Building By-Laws .
Malaysia Standard MS 1525:2014 recommends acceptable indoor conditions for comfort cooling to be designed as follows :
( i ) Recommended dry bulb temperature = 24 ° C ― 26 ° C . ( ASHRAE Standard : 20 ° C ― 24 ° C )
( ii ) Recommended relative humidity = 50 % ― 70 %. ( ASHRAE Standard : 40 % ― 60 %)
( iii ) Recommended air movement = 0.15 m / s ― 0.50m / s . ( ASHRAE Standard : same )
The recommended outdoor air condition is 33.3 ° C DB and 27.2 ° C WB as stated in MS 1525:2014 .
According to the Jabatan Kerja Raya ( JKR ) Guidelines for Air Conditioning System Design , engineers have to propose an air-conditioning system according to the cooling load required to serve the peak load of the building . The type of a suitable air-conditioning system should be selected according to Table 1 . If a different type of system is selected , it must be justified .
Two common practices for cooling load estimation are :
1 . Estimation of cooling load using computer software such as the Carrier E20 programme [ 5 ] with detailed inputs . This approach is commonly applied in large scale projects , in some cases after a client ’ s request . Many M & E consultants use their self-developed cooling load spreadsheet which is very similar to E20 but very practical and user friendly .
2 . Estimation of cooling load using check figures and rule of thumb [ 6 ] for common buildings and structures . It is often used for the purpose of design verification .
The check figures and rule of thumb approach provides a practical and time-efficient method for industry players . The check figures are especially helpful when it comes to verifying the design of an ACMV system for existing and common buildings and structures . Compliance with the check figures is important in order to avoid over sizing .
When engineers are required to design something that is not listed in the check figures table they need a detailed input from the E20 programme to estimate the cooling load . The check figures are not accurate enough unless the engineers run the E20 programme in detail . The cooling load calculation is based on cooling load temperature difference ( CLTD ) method . The five
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