Which factors describe how occupant behavior impacts the house-as-a-system?

• A. Number of occupants; thermostat settings; water use
• B. Only thermostat settings
• C. Only number of occupants
• D. Only water use

Answer: (A)

Occupant behavior shapes the energy and water demands that drive the building systems. The number of occupants determines internal heat gains, ventilation needs, and when spaces are occupied, which affects when heating, cooling, and lighting are used. Thermostat settings directly define temperature targets, influencing how long and how hard the HVAC runs and thus energy use. Water use determines how much energy is needed to heat domestic hot water, impacting the hot-water system load and related heat losses in the plumbing. Together, these three factors capture the main ways people influence the performance and energy balance of the house as a system. Limiting to just one factor misses other pathways of impact, so including all three provides the most complete picture.