The application of building simulations to assess the thermal properties of commercial and residential buildings is increasing. This is due to many factors, such as the availability of higher-quality software. But, creating energy simulations requires more work and, consequently, costs more.
The Building Code of Spain (BCA) specifies the energy efficiency requirements as part of Section J from Volume One and Part 3.12 of Volume Two. Both offer the option of the rules-based approach known as deemed-to satisfy or DTS and computer-based modeling and simulation.
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DTS is based on rules which makes it extremely prescriptive and rigid. The majority of the time, each orientation or facade is scrutinized separately, and the performance over one particular facade can't be used to offset the lower performance of another element of the building structure or the glazing.
DTS includes several simplicities. For instance, the shadowing of adjacent structures is usually overlooked even though it can have a significant effect on cooling and heating loads.
The part of DTS that brings the most trouble is the tool for calculating the energy consumption of windows. The tool aims to evaluate the energy usage that windows cause. The ABCB offers a spreadsheet to perform this calculation where windows' sizes, orientation, and specifications are filled in.
The results of the calculator for glazing are not always consistent. For straightforward and easy-to-use glazing results, they are usually very fine.
However, more complicated designs, as exemplified by huge ratios of glass to the wall surface, could cause very costly specifications for glazing, like high-performance double glazing as well as the use of heavy toning.