It has been said that Malaysia is endowed with ‘ four seasons ’ — the hot and humid season , the rainy season , the haze season and the durian season ! All these four seasons have direct bearing on the HVAC engineer .
It has been said that Malaysia is endowed with ‘ four seasons ’ — the hot and humid season , the rainy season , the haze season and the durian season ! All these four seasons have direct bearing on the HVAC engineer .
even find the operating point on your pump curve during this season . And you probably forgot to commission the by-pass valve to open to maintain minimum flow across the evaporator . The flow in your HEX ( Heat Exchanger ) might be laminar by now . To make things worse , all VSDs have been running at 20Hz since day one . Things look gloomy . People don ’ t call this the rainy season for no reason . Guess the remedy for this season is just good old words of wisdom : Sediakan payung sebelum hujan — design with part load in mind .
This brings us to the third season . Haze season is problematic because the bad air makes worse the headache the designer already has , trying to find haze season design guidelines from ASHRAE handbooks . Haze season can be defined as when fresh air is no longer “ fresh ”. Thanks to energy savings initiatives today CO 2 sensors are widely installed for demand control ventilation . Let ’ s not go into the debate of whether CO 2 is a good indicator of whether the occupant is getting enough oxygen . But the underlying assumption in such a set-up is that the CO 2 level outside is always lower than that indoors and higher indoor CO 2 levels means higher occupancy . That is why the dampers will open when the indoor
CO 2 reaches a certain set point to bring in more outside air and will modulate to close to a preset minimum when the setpoint is reached . But it is highly likely ( although CO 2 is not an indicator parameter for Air Pollutant Index ) during the haze season the outdoor CO 2 level is higher than the indoor setpoint . So if your fresh air damper is 100 % opened during the haze season , you know the contractor has installed everything according to your specification . But before you crack your head or omit the CO 2 monitoring system , the solution might be as easy as installing an outdoor air CO 2 sensor to be used as a reference . The rest you can figure out yourself .
Next , before you rush to install HEPA filters and think you have done a good job which would eventually clog in no time , it is good to know that there is more than meets the eyes for the haze package . Not only dust and fog particles , the haze also brings high levels of gaseous chemicals such as Sulfur Dioxide ( SO 2
) and Nitrogen Dioxide ( NO 2
) if you remember your chemistry well . These don ’ t go away with the normal particulate pre-filters installed at the air intake . Googling terms like “ activated carbon ” “ potassium permanganate ” and “ gas phase filtration ” will prove to be useful . You will be surprised to find out that this stuff is already in the “ air purifier ” you recently bought at the electrical appliances shop for your house . I leave to your judgment on how to do justice to the season ( and your client ).
Lastly the durian season we love ! This is a season where delays in issuing drawings can be tolerated because you left office early yesterday to join the durian buffet and fell sick the next three days . It is a season to celebrate and embrace the king of fruits because we have worked too hard for the last three seasons . One word of caution though . Try avoid conducting the Indoor Air Quality test during this season . Otherwise you might have a hard time finding an explanation for the high VOC levels !
Don ’ t you just love being a Malaysian HVAC engineer and agree with me that all the four seasons in Malaysia are equally important ?
57