Reducing the envelope load involves minimizing the heat that enters or escapes through a building's envelope (walls, windows, roof, etc.). Summer solar shading is an effective strategy to block direct sunlight during warmer months, decreasing the cooling load on the HVAC system. This method helps reduce solar heat gain, which lowers energy usage for cooling. Other options like maximizing daylighting (B) increase natural light but may also increase heat gain, and decreasing the opaque wall area (C) can actually increase energy loss.
Economizers (D) are HVAC strategies and don't directly reduce the envelope load.