Theoretical and experimental development of cooling load temperature difference factors to calculate cooling loads for buildings in warm climates

Abstract

In Mexico, electricity consumption is highest during the summer due to the usage of air conditioning systems. Considering that half of Mexico has warm climatic conditions and more than 30% households are equipped with some kind of air conditioning equipment, accurate cooling load calculations would directly affect energy efficiency, indoor thermal comfort and suitable heating, ventilation, and air conditioning design. The cooling load temperature difference/solar cooling load/cooling load factor (CLTD/SCL/CLF) method provides a reasonably accurate estimation of total heat gains through a building envelope; however, it is restricted to climatic conditions in the United States and a small number of construction materials. This study aims to determine the CLTD values for flat roofs and walls of buildings for different climatic zones in Mexico, such as Monterrey, Veracruz, and Mexicali, and for different construction materials that typically used in Mexico. We used the complex finite Fourier transform to solve the one-dimensional transient heat transfer model. We ran experimental setup in Monterrey to validate the mathematical model developed in this work. Additionally, we verified the theoretical model with the previously reported studies and compared them with CLTD values calculated using the correction factor proposed by the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) methodology. From these results, we can conclude that applying the CLTD method with the correction factor overestimates cooling loads through walls and roofs for typical buildings and Mexican climatic conditions. The average difference between ASHRAE-derived values and the obtained CLTD values was 10 °C.