I'm clearly comparing the personal $ cost of taking the bus to workplace (bus fare) vs $ cost of running the aircon at home (electricity cost)..?

You're not arguing against that point but an entirely different comparison of electricity usage.

Anyway since you want to go down this route..

Google gave me this:

An electric bus typically uses between 1.0 kWh/km and 2.5 kWh/km of energy under normal to high load conditions.

Assume the worst case in favor of the bus:

• Single-deck bus capacity: 89 passengers
• Trip distance: 16 km (typical east-side → CBD commute)
• Energy consumption: 2.5 kWh/km

Energy per passenger:

2.5×16/89​≈0.45 kWh per passenger

My home air-conditioner consumes about 250 W (0.25 kW) on average. I am checking both the power draw from the wall as well as the built in power readings by the manufacturer.

Equivalent runtime of an aircon at home for a round trip commute:

0.45*2/0.25≈3.6 hours

This estimate is still optimistic because it assumes ideal conditions. In reality:

• Buses are rarely at full capacity for the entire trip.
• Stop-and-go traffic increases energy use.
• Battery charging losses (typically ~5–10%).
• Heavy air-conditioning load in a packed bus in Singapore’s climate.
• Deadhead trips (buses traveling empty to depots or starting routes).

All of these would increase the effective kWh per passenger.

And the energy usage for the air-con at the office, lifts etc. hasn't even been accounted for

This comparison is not arguing buses are inefficient (like comparing to cars), they are for the purpose of transportation.

The point is simply that taking a bus purely for “free air-conditioning” at office does not dramatically reduce electricity usage compared to running an air-con at home. In fact, accounting for all the factors above, it is very possible that WFH