 • Indoor temperature swings are 10 °F to 15 °F less in in-direct gain systems than in direct-gain systems.Since a less fluctuating temperature swing is more desirable for occupant senses and to maintain an average space temperature, Trombe walls perform better than any indirect-gain systems regarding this matter.• Among the passive solar heating strategies, Trombe walls can harmonize the relationship between humans and the natural environment and are widely used because of advantages such as simple configuration, high efficiency, zero running cost and so on.