## 2 Method Applied to BIPV Project Evaluations
### Architectural Design Features  
Integration of PV into buildings challenges architects and construct designers. While some of them are afraid of the possible \"solar look\" of their designed buildings, others respond to the challenge with innovative, advanced architectural solutions. The architects and PV professionals nowadays need to understand the need for the integration of PV systems, and to predict its architectural design implications. It is very important for contemporary architects to be informed of exceptional examples of BIPV around the world. A significant contribution for BIPV promotion comes from the most renowned architects, awarded the Pritzker prize for architecture, who applied BIPV on their recent designs (for example, Taiwan National Stadium, Table 1).  
For BIPV, different performance data can be required regarding location possibilities, function possibilities, dimensions and forms, colour and appearance of modules, light permeability and  
Figure 1: Summary of the modelling steps, data analysis, and evaluation of the projects.  
construction possibilities [12; 21]. As for the location on the building, BIPV can be applied on facades and roofs, fences, skylights, and canopies. In the end, the system yield is strongly influenced by the orientation and inclination of PV modules.  
With regard to the geometry of the surfaces on which the BIPV modules are placed, there are flat, saw tooth, accordion, stepped, and curved surfaces and their combinations, called free forms, which can be placed as vertical, horizontal and inclined planes (angle \(<90^{\circ}\)) [18].  
Various light permeability and interesting light effects inside a building can be produced through the use of light-permeable solar cells or the variation of the arrangements and distances between the cells. In general, building surfaces with BIPV can be \"opaque\" or \"semi-transparent\", and lately, thanks to new technologies, also transparent. The appearance of the facade and roof with BIPV is influenced by the PV module's colour, which depends on the material of solar cells and antireflection coating. Using double-layer antireflection coatings, a broad range of colours of PV modules can be obtained [20] (gold, steel blue, dark blue, pink, green), allowing architects flexibility for the integration of PV cells into building facades and providing a good match to the environment. Regarding construction possibilities, photovoltaic facades usually represent a type of glazed, suspended facade, while roof integrated PV systems can appear as integral roof modules (appear as a glazed structure) and roofing tiles and shingles (appear as a roof) [19].  
The mentioned architectural design features of BIPV indicate that the integration of PV into the building envelope affects its structure, requiring solving the necessary installations, although in terms of the application of PV modules, the mainly available technologies for constructing the final layers of facades and roofs are represented.  
Design features such as glazing, transparency, module or cell dimensions and spacing, and colours could be taken into account during the modelling in BIMsolar(r) to modify the design features to express them more easily [50; 52]. The software could cover the impacts of those aspects on energy generation, by creating modules and cells with their own characteristics and technology, respecting manufacturers' details and the 3D surroundings, including frames. The position, the data input and the electricity generation details are mentioned in Section 2.4. Simulating the integration of specific PV systems in chosen buildings, it was essential not to impact their basic geometry and external appearance. This was especially important with historic and landmark buildings.