Designers of buildings and government authorities need to pay closer attention to the importance of air distribution products, says Adrian Pais, manager of the Khalid Manufacturing Company of Qatar, a major regional manufacturer of these products.
"Air conditioning is a necessity in this part of the world, and yet designers give very little importance to air distribution, with economy often given higher priority over human health," says Pais.
"It is very important to remember that air movement cannot be seen, therefore the damage caused is slow but sure, yet can be prevented if technically correct products are used."
Pais highlights a recent study by Dr Elsyed Mohammed Bilasy, director of the preventive medicine department of Abu Dhabi which probes the causes of Sick Building Syndrome (SBS).
Dr Bilasy's study shows that inadequate ventilation and insufficient air distribution inside a building are some of the causes of poor indoor air quality which lead to SBS, according to Pais.
"The UAE has learned by making mistakes, as highlighted by Dr Bilasy, which I am sure we in Qatar can avoid," says Pais.
He says the notion that most designers have is that any product appearing to be similar in appearance can be installed and it will perform.
"They are absolutely wrong. Similar products will allow air to flow into an enclosed space, but caution is required when dealing with cold air," he says. "Cold air being heavier will drop to the floor faster than hot or warm air, causing discomfort and health problems.
"Catalogued performance data therefore becomes very important and reliable if tested and rated to the correct technical standards," he says.
Pais points out, however that the public must be made aware of the fact that a number of air distribution product manufacturers are misleading authorities by using seals such as ETL-Listed mark designed primarily for safety product certification. He states that Intertek Testing Services (ITS) has confirmed that "ITS does not have a certification programme for air distribution devices such as ceiling grilles, registers or diffusers. However, ITS does conduct performance testing on these types of devices and will issue a test report stating the test results. The ETL Listed mark is not a permitted use for these types of products."
Another aspect he draws attention to is that performance data of most manufacturers of such products in the UAE and other GCC countries are based on isothermal air. "Isothermal means that supply air temperature entering the room through the device is the same as the room temperature. Data based on this criteria are not reliable for cooling system applications. Therefore these products are very attractively priced."
Pais says economic consideration coupled with ignorance and vested interests have encouraged the use of these products on private projects. This trend has now crept into government projects as well, he adds.
"Humans occupy these buildings, be it in the government or private sector. The use of technically incorrect products creates health hazards," he says. "A cooling system requires that the supply air temperature entering the room should be at least 11 deg C (20 deg F) less than the temperature to be maintained in the room. Therefore catalogued information based on actual tests conducted under these conditions is very reliable, accurate and essential.
"Designers should assert their authority while selecting and locating air distribution devices and not leave it to the architects who are only interested in the aesthetics and not the technical performance of the product. How large an area an air distribution device can satisfactorily serve may be answered as follows: 'The throw required to meet the air quantity per sq ft (cfm/sq ft) criteria for thermal comfort". This will ensure proper and uniform air distribution.
"Authorities should take necessary steps to ensure that technically correct air distribution products are used in order to prevent Sick Building Syndrome."
