Energy-saving potentials of some local trees

The energy-saving potentials of some common tropical trees are presented. The experimental setup consists of a tree and sixteen (16) 0.05 cm by 0.05 cm dry wood of height 3 m which served as a stake. Each of the dry woods has two 0.001-mm-thick galvanized steel plates (0.3 cm by 0.3 cm), which served as the heated surface, nailed at heights of 1.3 and 2.6 m from the ground level. The plates are insulated at the back side with plywood, thus leaving only one side exposed to the direct effect of solar heating. The woods were installed at equal distances from the tree trunk such that the uncovered sides of the plates face east, west, north, and south. Temperatures of the plate at 1-h intervals were recorded from 08:00 and 17:00 h and subsequently used to compute energy absorbed by each plate. Four trees, Dogon Yaro (Azadirachta indica.), mango (Mangifera indica), velvet tamarind (Dialium indum), and oil bean (Pentacletra macrophylla), were used for the study. Results obtained showed that a reduction in solar space heating by up to 79 % can be achieved, depending on the position of the tree relative to the building. This corresponds to a saving in energy of up to 1050 kWh/year or 22 % of the annual energy consumption in a typical average residential building in Nigeria. Thus, proper tree planting is recommended for reduced residential energy consumption.