Solar chimney combined with earth to-air heat exchanger for passive cooling of residential buildings in hot areas

In this study, a novel interrelationship between the ventilation rate and the solar chimney design parameters, EAHE geometrical specifications, pressure drop, and climatic conditions in the hot arid area was presented based on experimental and numerical comprehensive investigations. This new correlation simplified designing and optimizing of the passive cooling/heating and ventilation system. Moreover, this correlation was used in a case study of passive cooling/heating and ventilation of a two-stories residential building in Egypt by TRNSYS simulation. The indoor operative air temperatures, heating and cooling loads, thermal comfort conditions, energy consumptions/savings, and CO2 emission savings were calculated and analyzed. Two cases were simulated and compared with the basic-case. In case 1, the basic-case combined with the solar chimney and EAHE. Case 2 had a hybrid passive and active ventilation, which included case 1 equipped with electrical fans that continued operating for 24 h. Finally, an economic study was conducted to calculate the payback period and discount payback period for the construction of such a system using the local Egyptian market equipment. The basic case results show that the zonal temperature was more than the ambient temperature yearly, and in summer, the indoor temperature exceeded the surrounding temperature by 5-6 degrees C. Using the proposed system in case 1 and case 2 attained a zonal temperature around 5 degrees C and 9 degrees C less than the ambient temperature in the summer season, respectively. However, the total annual electrical energy and CO2 emission savings were 42.9 kWh/m(2)/year and 4.545 tons/year, respectively, in case 2. Finally, the simple payback period was 5.4 years, and the discount payback period was 6.8 years.