How do HVAC efficiency and lighting efficiency contribute to energy demand management in buildings?

• A. Efficient HVAC reduces heating/cooling loads; efficient lighting lowers electricity demand; together they significantly reduce building energy use.
• B. They only affect industrial plants, not buildings.
• C. They increase energy use due to higher initial costs.
• D. They only influence peak demand in winter.

Answer: (A)

In buildings, HVAC and lighting are major energy drivers. When HVAC efficiency improves, heating and cooling loads shrink, so the system runs less and consumes less energy. Efficient lighting uses fewer watts for the same amount of light, reducing the building’s electricity demand. Put together, these improvements significantly lower overall energy use and also help manage demand by smoothing and reducing peak loads, which is a central part of how buildings participate in energy demand management. The other statements don’t fit because efficiency benefits apply to buildings (not only industrial plants), initial costs don’t make energy use rise in the long run (operating costs go down), and improvements influence peak demand beyond winter since cooling and daytime lighting affect peak periods in hot or sunny conditions as well.