Tightly sealed (air-tight) buildings are often highly energy-efficient, particularly important in hot, humid climates like the tropics, where air conditioning demand is high. However, these airtight designs can limit fresh air exchange and potentially reduce indoor air quality (IAQ) unless carefully managed.

This sets up a trade-off scenario:

EA Credit: Optimize Energy Performance encourages tightly controlled environments to reduce energy consumption (especially from HVAC systems).

IEQ Credit: Enhanced Indoor Air Quality Strategies promotes fresh air circulation, filtration, and contaminant control to maintain health and comfort.

From LEED v4 BD+C Reference:

"Achieving high energy efficiency through airtightness must be balanced with adequate ventilation and IAQ strategies to ensure occupant health and comfort."

Therefore:

Option B is correct, representing this trade-off.

Option A (metering and construction IAQ) doesn’t reflect the trade-off in building operation.

Option C includes demand response, which is about energy grid participation, not IAQ.

Option D (heat island and thermal comfort) relates to exterior design and comfort, not air-tightness vs IAQ.