Is the kidney responsible for water loss from body on a hot day?

The answer is No, the kidney is not responsible for water loss from the body on a hot day.

Evaporation from the lungs and skin plays a primary role in eliminating bodily heat and managing body temperature. Sweating also aids in this process, while urination does not contribute significantly to fluid loss on a hot day. Conversely, urine output might decrease as sweating increases to prevent excessive fluid loss