Engineer
Group shot taken with the team at the rooftop Air Handling Unit (AHU) during the Mechanical Systems Design (ME3103) project that work on the optimisation of the heating, ventilation, and air-conditioning (HVAC) system.
In retrospect, I have found great beauty in pursuing mechanical engineering, one of the oldest and broadest disciplines in engineering, that solidifies my appreciation and understanding of the role engineers play in transforming our lives. Engineering is the crucible in which science, built upon strong scientific foundation, mathematics, design, and technology come together to develop a solution that advances the world. At its core, engineers are responsible for opening up new vistas of innovation through science and technology. Yet, the role of an engineer, while largely logical, fact-based, technical, and sophisticated, cannot be fully accomplished without the accompanying spirit of entrepreneurship, and without the virtue and ethics that continuously guides the work of an engineer on the ethical path.
For engineers, in fulfilling the engineering duty and obligation towards those who call upon their service, providing top quality product or services that satisfy customer’s requirement or ameliorate their problems is the fundamental calling of the engineering profession. Yet, as engineers engage in dealings with their customer, issues of conflict of interests, or situation that becomes an ethical dilemma would sometimes cloud the judgement of the engineers. Even as a student, I had a glimpse into the potential ethical dilemma that could call upon us to exercise our virtue and ethics while maintaining that vigour and spirit of innovation for the customer, albeit within the sheltered confines of NUS.
This is the air handling unit that serves the 1st floor office in PepsiCo. Air from outside (red ink) is drawn into the AHU, mixed with the recycled air (blue ink), passing through the chilled water supply (CHWS) that cools down the air, which is subsequently blown into the room to cool down the room temperature. Majority of the cool air would be recycled, while the excess would be expelled through the exhaust air duct to maintain a stable internal room temperature. As outside fresh air is hot and humid, the air presents a larger heat load, which would translate to more energy used to cool down the mixed air, and correspondingly, greater energy cost.
In the Mechanical Systems Design (ME3103) module, one of the “capstone” engineering modules, we were required to put theory into practical use and work with an industry partner on their problem statement. We were tasked to help PepsiCo reduce their electricity consumption for the heating, ventilation, and air-conditioning (HVAC) system—comprising of the centrifugal chiller, cooling tower, and 17 air handling units (AHUs) serving different location of the industrial plants—by at 10% at the end of 13 weeks. Without delving too much into the intricacies, one of the components that we began our optimisation work was the AHU, one at a time.
In simple terms, the trick here is to reduce the outside air damper, which would essentially cut down on the hot and humid fresh air intake. This would circulate more recycled air that is much cooler and dry relative to the fresh air. In doing so, we essentially reduce the heat load, corresponding to lower electricity consumption required to maintain the indoor thermal comfort. Perhaps, one of the fastest ways to reduce electricity consumption was simply to completely switch off the outside air damper, drawing a negligible amount of fresh air. However, this comes at a cost of increased carbon dioxide level (CO2) within the indoor environment. Even though the Building and Construction Authority (BCA) in Singapore has set forth guidelines for the indoor CO2 level to be less than 1000ppm, indoor CO2 levels going as high as 2000 –3000 ppm is still within the tolerable limit for human beings.
In this case, without accounting for the indoor air quality, we found the fastest way and most effective way to obtain the desired objectives for PepsiCo. At the same time, the manufacturing nature of PepsiCo meant that indoor human traffic will not fluctuate widely and that CO2 level would not be a great concern.
It then dawned on me that, in a situation where the stakes are much higher, and when the reward-to-risk ratio is attractive, it is easy to be misguided by our own selective bias. This is a state where we look for evidence or reason ourselves into believing that our actions are ethical and justifiable so that we feel more comfortable doing things that serve the client or our own interests at the expense of others. In this case, the reward can be intuitively understood as cost saving for PepsiCo, and the completion of a project that generates results for the key stakeholders. What about risk? Can the risk here be intuitively understood? How then do we begin to quantify the risk to make an assessment of what constitutes an acceptable risk?
Class lecture note from Quantifying Nuclear Risk (UQF2101G), where we learnt the scientific definition of risk and the individual perception of risk.
Class lecture note from Quantifying Nuclear Risk (UQF2101G), where we learnt how to quantify risk through the scientific approach.
Final assignment for Quantifying Nuclear Risk (UQF2101G), where I applied the scientic approach to quantify the risk of nuclear power by analysing nuclear power plant.
I connected the need to quantify the risk involved in one of the earlier class called Quantifying Nuclear Risk (UQF2101G) I had at the start of my university career. This module was taught by professor Philippe Raynal whom, through the scientific lens, taught us how to quantify risk, i.e. risk = probability x cost. In a sense, the scientific approach from the expert point of view tried to remove, or if it is not possible to remove, tries to reduce, the subjective element in quantifying the risk involved. Removing the subjective element is important as similar events can be perceived to have different risk because of the value judgment people attach to the event based on their prior personal experience, the media influence, or their limited knowledge.
In trying to apply the scientific approach, based upon objective facts, to quantify the risk involved in the PepsiCo project, by doing a quick google search, I found that lower 1000–3000 ppm for the indoor CO2 may lead to sleepiness, headache, poor concentration or loss of attention. If the production rate is unaffected and that the probability of damage to human health is extremely small at such CO2 concentration levels, and assuming we attach a healthcare cost to the equation above, the risks involved still seemed very minute relative to the cost-saving (approximately amounting to an extra thousands of dollar per annum) from closing out the outside air damper completely.
While it is possible for me to apply the scientific approach here to understand the risk involved, it then also raises the question of how much risk is considered acceptable? Should engineers have the sole discretion to make this kind of value judgement? In the name of providing the best solution and cost savings, how far should we go to exercise our the spirit of innovation when it comes at the expense of increasing risk?