Pool covers are a water and energy efficiency measure in EDGE, particularly relevant for hotels with swimming pools. The EDGE User Guide outlines their benefits: "Pool covers reduce water demand by minimizing evaporation and energy demand by reducing the need for heating, as they retain heat in the pool. In EDGE, the use of pool covers is recognized for its dual impact on reducing both water and energy consumption" (EDGE User Guide, Section 5.3: Additional Water Efficiency Measures). Option B, reduce both water and energy demand, directly aligns with this description. Option A (increase solar control and comfort) is incorrect, as pool covers are not recognized in EDGE for solar control or occupant comfort but for resource savings. Option C (require less maintenance and work from employees) and Option D (reduce chemical consumption and that of cleaning products) are potential secondary benefits but are not quantified or recognized in EDGE calculations, as confirmed by: "EDGE focuses on measurable water and energy savings from pool covers, not on maintenance or chemical use reductions" (EDGE Methodology Report Version 2.0, Section 4.3: Water Efficiency Calculations). Thus, Option B is the correct answer.