Product design question

Design a smart building.

Practice this question out loud. An AI interviewer asks it, follows up like a real interviewer would, and scores your answer. Type or speak.

What this question tests

Tests systems design thinking applied to IoT and building management: balancing efficiency, occupant experience, and integration complexity.

Define the users: building occupants who want comfort and convenience, and facility managers who want efficiency and cost control.
Identify core smart systems: occupancy sensing, adaptive climate and lighting control, and predictive maintenance for building equipment.
Propose the core loop: sensors feed real time occupancy and environment data, the system adjusts climate and lighting automatically to optimize comfort and energy use.
Address integration complexity: many existing buildings have legacy HVAC and electrical systems requiring retrofit sensors rather than full replacement.
Define success: energy cost reduction per square foot and occupant comfort satisfaction scores.
Confirm with the interviewer whether this is new construction or a retrofit of an existing building.

Grounds the design in a measurable trade off, occupancy based climate control cutting energy waste in unused spaces while maintaining comfort in occupied ones.
Addresses the retrofit reality explicitly, proposing lightweight sensor add ons compatible with legacy HVAC systems rather than assuming a greenfield build.
Adds predictive maintenance using equipment sensor data to catch failures before they cause costly downtime or occupant discomfort.
Sets a measurable goal, for example a stated percentage reduction in energy cost per square foot within the first year of deployment.

Assuming new construction and ignoring the far more common retrofit scenario for most existing buildings.
Focusing only on flashy IoT features without a clear energy or cost efficiency metric tied to facility manager goals.

How would you retrofit this into an older building with legacy electrical systems?
What would you prioritize first, energy savings or occupant comfort, if they conflicted?