As a former engineer, I found Mr George Martin Jacobs’ suggestion on building climate controls well-intentioned but impractical (Buildings with central air-con should set temperature at 25 deg C, March 17).

First, all buildings are different. Cooling needs can vary tremendously by size, layout, materials and construction, which determine the amount of atmosphere to be cooled, and the levels of heat dissipation and solar irradiation the air-con system must work around.

Cooling capacity and power consumption also differ depending on the age and capabilities of the equipment. As a result, a setting of 25 deg C on the controls may not yield the same level of comfort and efficiency in every location.

Second, people are different. While Mr Jacobs may find many public spaces too cold, I have rarely found that to be the case. For example, one often sees cinemagoers dressed in singlets and shorts despite the low temperature in the halls. Individuals who are “too cold” have recourse to layered clothing, but those who are “too warm” have more limited options; it is logical that building owners would ensure occupant comfort by erring on the side of the former.

It is the professional practice for engineers in the heating, ventilation and air-conditioning fields to adjust the cooling systems for large buildings through careful study and calculation, ensuring optimal operation and results before handing over to the owners and tenants. These are results that an arbitrary, one-size-fits-all temperature standard cannot achieve.

Paul Chan Poh Hoi