Low-Cost Thermoelectric Module Attic Ventilation

This paper investigates the performance of a new attic ventilation concept using low-cost thermoelectric (TE) modules. Incident solar radiation heats up roof tiles thus creating a temperature difference between tiles and attic. By making use of this temperature difference, laboratory made low-cost thermoelectric modules, assimilated as roof tiles, could produce an electric current to drive a fan for attic ventilation. First, a low-cost TE module consisting of 7 couples of N and P type Bi-Sb-Te materials was fabricated on a 2x2 cm² aluminium substrate. Electrical performance was measured in the laboratory for various temperature differences of roof tiles obtained from field measurement. Then a TE tile of 0.1656 m² surface area was designed based on the laboratory made TE module. In total 414 modules were used. Two TE tiles were considered sufficient to generate a 5 V electrical current to drive two small DC fans. Heat gain reduction due to the induced TE attic ventilation was estimated using the TRNSYS program for a regular house in Thailand. It was found that the TE tiles could induce an air ventilation rate of about 100-250 m³/h. The average daily percentage of total rate of heat gain reduction through the ceiling during 9 – 17 h was about 14-18%. The proposed concept, using low-cost TE modules, offers a new interesting alternative as it uses the heat accumulated in roof tiles to generate electricity for ventilation.