COMPARISON OF CLTD AND TETD COOLING LOAD CALCULATION METHODS FOR DIFFERENT BUILDING ENVELOPES

The estimation of the cooling load through the building envelope is an essential task in the selection of proper HVAC system components that influences the building’s performance. For this task, ASHRAE has presented several methods to calculate the building cooling load due to heat gain, such as the total equivalent temperature difference method (TETD), the cooling load temperature difference method (CLTD), and the radiant time series method (RTS). The present study aims to explore the accuracies of those calculation methods in terms of energy efficiency. In this regard, an analytical solution method utilizing Complex Finite Fourier Transform Technique (CFFT) was developed for the calculation of cooling load due to heat gain to compare the temperature differences obtained from the TETD and CLTD methods. Then, a computer program was prepared in MATLAB to perform the calculations based on an analytical methodology. Besides, the estimated CLTD and TETD values by the CFFT were compared with those values presented in the Handbook of the ASHRAE. The calculation results revealed there is a good agreement between the analytical and presented results in the ASHRAE Manual for the selected building envelopes. However, several differences were found between the estimated TETD and CLTD cooling load values and those presented in the Handbook of ASHRAE.