Thermal comfort is one of the essential indoor environmental factors that needs to be properly evaluated for an optimum user satisfaction in every building. In the hot dry climatic zone where the mean daily maximum dry bulb temperature during the dry season equals or exceeds 35oC and the relative humidity does not exceed 40%, harsh indoor conditions may arise. Studies have shown that this harshness can be counteracted or overcome by either using the mechanical means (active strategy) or natural (passive strategy) landscape elements such as trees, shrubs and grasses. This study focused on the effect of trees as a landscape element on enhancing the thermal condition of indoor spaces. This was carried out quasi-experimentally by taking both indoor and outdoor measurement of the parameters – air temperature, relative humidity, air velocity – that impact thermal comfort for two identical departmental buildings with different incidences of trees – Banking & Finance and Industrial Design – both on opposite locations in Modibbo Adama University of Technology campus, Yola. The results revealed indoor mean temperatures of 29.8 and 30.5oC in the building with more trees, and 29.7 and 29.8oC in the other; and mean cooling of 3.5oC and 4.1oC in the former, and 4.5oC and 5.0oC in the latter. Thus the effect of difference in incidence of trees around the buildings on the indoor temperatures of the spaces under study was not discernible. However, increase of 23.0 and 34.6% in indoor relative humidity in the building with more trees, and below 1.0% in the other were observed. Consequently, it was recommended that more trees should be planted on campus to foster serenity and conduciveness of the environment for learning.
Key Words: Thermal Comfort, Indoor Spaces, Trees, Air Temperature, Relative Humidity, Air Velocity