When it comes to indoor air quality (IAQ), one should not just focus on temperature control. In fact, there are other factors affecting the thermal comfort such as humidity, air distribution, draft, radiant temperature, etc. This is the view of Shaher Rajha, lead mechanical engineer at Lacasa Architects & Engineering Consultants.
He adds: “Inadequate installation and maintenance of the HVAC systems can result in bad IAQ and human thermal discomfort.” He says that cleaning and disinfection of duct work and filters should be considered as a necessity. “Building operators need to be educated about the health concerns associated with the lack of cleaning and disinfection of HVAC systems. Moreover, building operators are very frequently facing cost pressures. However, cost should not be the driving factor in this regard,” he says.
Rajha says that for HVAC systems to be optimised so as to strike the balance between good IAQ and managing energy costs, all stakeholders should choose the right equipment during the design stage.
He says: “Contractors have a significant role to play by installing the system according to the manufacturer’s guidelines. The facilities manager or building operator plays a significant role in this matter by ensuring the operation of the HVAC systems are aligned with the design intent and most importantly with the manufacturer’s guidelines. Moreover, the facilities manager should ensure that adequate maintenance schemes are implemented so that the HVAC system performs as intended by the designer and manufacturer.”
At design stage
HVAC systems should be designed such that the potential post-occupancy operation aspects are identified and addressed during the design stage itself. In addition, Rajha says: “Due consideration should be given to the compliance of the green building practices and regulations for design, construction, and operation stages.
“The right choice of the system plays a critical role in lowering energy costs and easing maintenance. A system that is ideal for one application may fail to deliver the same results for another application or condition. Solutions that are specific to each case is the right step towards optimising energy consumption and facilitating proper maintenance.”
Rajha says that “the cost of the system takes greater attention at the expense of IAQ, which is considered as a burden”. Stakeholders might be aware of the significance of IAQ. He adds: “People should be educated that IAQ is not independent of but interrelated to cost. Poor IAQ may negatively impact the cost by adversely affecting the building reputation, and hence, the Return On Investment (ROI) in the long run.”
Good indoor environmental quality (IEQ), which also includes IAQ aspects, is well recognised to be a crucial factor in increasing the productivity and wellbeing of employees, Rajha says. He adds: “Enhancing IAQ and tackling Sick Building Syndrome (SBS) can be achieved by adopting increased ventilation rates, enhanced air filtration, natural light, use of low volatile organic compounds (VOC) materials, good air distribution, proper humidity, and temperature control.”
By providing the employees with individual control of temperature, air flow, etc., one can increase the thermal comfort and reduce general and localised discomfort. Rajha explains a bit further with examples: “In residential applications this means providing individual rooms with individual thermostats. This is far more challenging in open office plans. However, this might be tackled by the use of adjustable flow diffusers where the employees are in control of the air flow if they are not in control of temperature.
“In healthcare facilities, the IAQ concerns are more related to the cleanliness of the air and the control of air movement between adjacent spaces that not only may affect the patients but also the employees. This can be achieved by improved filtration, enhanced ventilation rates, proper maintenance, and proper design that can help maintain the right pressure regime among adjacent spaces. Such measures would enhance the thermal comfort and IAQ, and reduce the risk of nosocomial infections.”
The best and the worst
Outlining some of the best and the worst practices when it comes to IAQ in the Middle East, Rajha says: “Adopting state-of-the-art technology, balancing cost and IAQ, having good maintenance regimes, installing systems properly, etc., are among the best practices.”
When it comes to the worst practices, designing the air conditioning system without the right consideration to human thermal comfort can result in poor IAQ. He says, “A design that does not consider the Air Diffusion Performance Index (ADPI) for air distribution would compromise the comfort level.
“Additionally, non-ducted return [air] is commonly adopted due to cost considerations. While this is considered an acceptable practice from a cost point of view, it would have an adverse effect on the quality of air due to the fact that it would introduce particles into the air stream.
It is also a common practice to discharge the ventilation air at the back of the fan coil unit. Again, while this is driven by cost considerations, it would adversely affect the quality of air. Moreover, ventilation air when delivered in this way may not make it to the occupied zone if the fan coil unit is turned off, which further exacerbates the IAQ.”
Given the seriousness of having good IAQ, it goes without saying that all stakeholders should come together and make IAQ mandatory in their business plan.