_Applied_  
_sciences_  
_Article_  
**Energy Balance, Cost and Architectural Design**  
**Features of 24 Building Integrated Photovoltaic**  
**Projects Using a Modelling Approach**  
**[PERSON] 1,2,3,4,5, [PERSON] 2, [PERSON] 2,6 and [PERSON] 1,3**  
Footnote 1: [[http://www.mpi.com/journal/applsci](http://www.mpi.com/journal/applsci)]([http://www.mpi.com/journal/applsci](http://www.mpi.com/journal/applsci))  
Received: 22 October 2020; Accepted: 7 December 2020; Published: 10 December 2020  
Within the EU, the average residential energy demand of regular homes is currently estimated at 180 kWh/m\({}^{2}\)-year, and 250 kWh/m\({}^{2}\)-year for non-residential buildings [8]. Because of their annual electricity yield, which is in the range of 800 kWh/kW\({}_{\text{P}}\).year for Northern European countries and up to 1800 kWh/kW\({}_{\text{P}}\).year in Mediterranean countries [9], photovoltaic (PV) systems can significantly contribute to the realisation of NZEBs [10; 11]. A specific category of PV systems is building-integrated PV (BIPV). BIPV is defined as the essential elements in the building envelope that contain at least one additional construction material function besides generating electricity (e.g., insulation, sound barrier, shading, etc.). While currently replacing conventional building materials, BIPV could play an essential role in generating the local energy demands of buildings [12]. BIPV may improve comfort and energy resilience, providing extra insulation, even preheating, such as reported in [13], which is a remarkable addition while aiming for NZEB. Compared with an ordinary roof-mounted installation (standoff systems), which is placed on top of a conventional roof, part of the basic concept of a true BIPV installation is to share the cost of the building envelope because the installation has a double function [14]. Building integrated PV modules can be treated as an envelope or as a finishing layer of the envelope and therefore they provide thermal, acoustic, wind, and humidity insulation, and sometimes fire and security protection, while producing electric energy and in some cases also thermal energy [15]. Despite an estimate annual growth rate of 18.7% of the global BIPV market between 2009 and 2019 [16], the use and application of BIPV has remained relatively limited. With average costs of BIPV of 600 EUR/m\({}^{2}\), a figure that is even lower compared to certain insulation materials [17], BIPV's market share in the EU's PV sector is only 2% [18]. Numerous commercially available PV technologies offer various design features, as defined in [19]. Beyond energy balance and costs, integrating photovoltaic systems into the building envelope strongly affects the appearance of buildings, but also the appearance of urban structures. Architectural design features of BIPV can be considered from two points of view: in terms of the shape of the building, i.e., the geometry of surfaces on which the PV modules are placed, and in terms of the required aesthetic expression, which all together influences the appearance of the building envelope [12; 20]. The design decisions regarding the architectural design features of BIPV such as; appearance (dimension, form [21], colour [15], transparency [22]), inclination, location, not only reflect on the visual experience, but can also affect the energy efficiency and the energy label of the building. Among non-residential buildings, offices have a tendency to generally promote a greener and futuristic image with distinguishable BIPV systems. Nevertheless, historical buildings, i.e., buildings under protection or heritage buildings, require unique design features and distinct regulations. As the requirements diverged, the buildings in this study were clustered into three separate categories: residential, office and historical.