In daily practice, the experts involved in the design and engineering of the thermal insulating joinery curtain walls face the demands for more and sometimes confusing requirements for the various types of projects. Moreover, complex technical regulations, specific terms designating the innovative concepts, tasks to be performed to ensure compliance often appear. The technical staff of a company in the industry struggles daily with terms like: threshold values of heat transfer coefficient, g factor, radiation transmittance, the European rules for trading of building materials, safety in use, accessibility, carbon footprint, universal design, temperature factors, linear thermal transmittance values, passive house standards, sustainability, environmental declaration of conformity and the list goes on. It is interesting to know to what extent a person to whom it is addressed the myriad of laws, indices and principles effectively uses these tools and if a common technician has the ability to comply with all such restrictions. A half a century before, there was sufficient to follow simple design rules and standards, promoting the relatively ordinary products, including glazing consisting of a single sheet of glass. At that time, the rules were limited to no more than one page which referred to 20 criteria of quality and there existed a uniform barcode system to verify the compliance and ensure the continuity of mass production. Although the simplicity of this process constitutes an advantage, however, the quality of finished products accurately reflects the limited number of special requirements. Also, things got exponentially complicated once the customers had special requests of size, geometry and technical equipment of the windows. In such cases, a product clearly deviated from the provisions stipulated in the standards of design, and it was almost impossible to evaluate and certify the compatibility with those legislative requirements.