The proposed project aims to develop adequate rules of thumb for Palestine. These rules will help in estimating the required heating and cooling loads for a specific application without complexity and hours of detailed calculations, considering good accuracy and reliability.
The previous experimental approach resulted with models of multiple linear type with three variants, which was a first indicator that the load is a function of multiple parameters and not only a single parameter as contractors assume. The reliability of the model was uncertain because it depended on presumed rooms and results were obtained only from the HAP, the variability of combinations was huge, so it was hard to refer to manual calculations, so the model was missing a real reference, in addition ,some parameters were kept constant regarding its effect on the load. All these precautions led us to think of a more applicable model that deals with real cases.
To do so, different rooms with different applications were chosen for the study. First Detailed calculations were applied to each room depending on the load parameters such as: walls, partitions, windows, roofs, ceilings, floors, doors, applications, occupancy, fresh air requirements, lighting, and electrical loads. Then mathematical model s were developed and compared to the true values of the heating and cooling loads. Further simplifications were applied and the final results were simple charts that depend mainly on the number of occupants and area of the given space .Results were compared to the true values and to the contractor’s scenarios, our model showed high accuracy comparing to contractors who relate the load linearly to the area of space, while the true relation is much more complex and depends on other factors rather than only the area of space. Average error was 5.3% for heating load and 13.4% for cooling load.
Finally after confirming the feasibility of the new model, the previous model was applied to each room and results were compared to that obtained from new model in order to determine the conflicts. The results were very close in rooms containing the same level of occupancy assumed in the model, but deviations appeared in rooms with large occupancy which leads to the important outcome of the huge effect of ventilation on the load that was neglected previously.