Confirmation Bias and Malaysia’s OTTV

Confirmation Bias and Malaysia’s OTTV

Confirmation bias refers to the tendency to seek out, interpret, and recall information in ways that affirm our preexisting beliefs or values. This unconscious cognitive bias can skew how we gather and process evidence, causing us to overlook or minimize contradictory information and prioritize data that supports our viewpoints. Even when we think we’re being objective, these biases often shape our decisions because they simplify complex thinking processes.

To reduce the influence of confirmation bias, it’s important to actively seek information that challenges our views, consider opposing perspectives, and remain open to changing our stance based on new evidence.

In the context of Southeast Asia's building industry, I’ve witnessed firsthand how confirmation bias has influenced decision-making, particularly regarding the development of Malaysia’s OTTV (Overall Thermal Transmission Value).

The Origins of OTTV in Malaysia

The first iteration of OTTV in Malaysia was created by Lawrence Berkeley Lab in the late 1980s as part of a USAID program for Southeast Asia. At the time, OTTV was a hand-based calculation method designed to estimate the amount of heat gained through a building’s fa?ade. This approach was necessary due to the limited access to computers in the 1980s. The OTTV constants were then derived from building energy simulations of various buildings, with best-fit curves applied to the results.

When the OTTV was initially developed, internal plug loads in buildings were minimal. Personal computers and printers were rare, with most offices using typewriters. However, by the mid-1990s, the widespread adoption of personal computers drastically increased plug load density, making buildings significantly hotter. This raised questions about the relevance of the original OTTV formulations from the 1980s.

Revisiting OTTV in the 2000s

In the early 2000s, we had the opportunity to revisit OTTV calculations under a DANIDA (Danish International Assistance) program in Malaysia. Thanks to Professor Kannan, we accessed Lawrence Berkeley Lab’s original report, which revealed that in the 1980s, Kuala Lumpur did not have a comprehensive set of weather data. The lab requested for weather measurements to be taken at Universiti Sains Malaysia (USM) in Penang. If I recollected correctly, only a few weeks data were collected.

By the turn of the century, Universiti Teknologi MARA (UiTM) had made available a Test Reference Year (TRY) weather dataset for Kuala Lumpur, based on 21 years of actual monthly data. This data was far superior to the limited measurements used in the 1980s and allowed us to develop more accurate Solar Correction Factors for each orientation used in OTTV calculations.

The West vs. East Solar Radiation Misconception

One surprising result from our analysis of the TRY data was that the solar correction factor for west-facing fa?ades was significantly lower than what was shown by the 1980s OTTV formulation. The TRY data showed that the west received 20% less solar radiation than the east, contradicting the common belief that the afternoon sun is hotter than the morning sun.

We revisited the USM data from the Lawrence Berkeley Lab report and found an even greater difference: the east fa?ade received far more solar radiation than the west. The differences were greater than the TRY. This discrepancy led us to investigate further. We discovered that cloud cover in Malaysia is typically heavier in the afternoon than in the morning, which explains why the west fa?ade receives less solar radiation over the course of a year. This is further collaborated with our experience living in Malaysia, where the rain occurs far more frequently in the evening hours than in the morning hours.

Convincing the industry to adjust the OTTV formulation based on this data took time, but the evidence was clear. The experts from Lawrence Berkeley Lab had overlooked the measured data from USM in favor of their own assumptions, likely due to confirmation bias and the limited time and data they had available.

OTTV as an Energy Efficiency Tool

It’s important to remember that OTTV is a building energy efficiency tool. It is not a tool for sizing air-conditioning peak cooling loads. While air-conditioning systems should be designed for peak load conditions—such as a hot, clear afternoon with direct sunlight on the west fa?ade—OTTV is focused on annual heat gain through a building’s envelope. Properly understanding this distinction can lead to more energy-efficient designs, such as placing unconditioned spaces like lift cores on the east side of buildings to reduce overall energy consumption. Wrong understanding of the data will cause wrong design to be implemented, causing higher energy consumption. ?

The Broader Implications of Confirmation Bias

As far as we know, Malaysia is the only country in the region that accounts for the east fa?ade receiving 20% more solar radiation than the west. We haven’t analyzed weather data from neighboring countries, but we wonder if confirmation bias has affected their building codes as well. For instance, Singapore’s ETTV calculations assign higher solar factors to the west than the east—a reversal of our findings, despite similar weather patterns, including more frequent evening rains.

Admitting that we were wrong does take courage, and even more courage is required to correct it publicly. Till today, I am still constantly learning to listen more to opposing views and to work harder to overcome my own biases. Putting aside our egos, we can learn more from each other and create a better, more sustainable world together. So do tell me if I am wrong. Correcting my misconceptions is far more important. Plus, I am training my ego to take the blows.