# Passive and Active Solar Systems in Eco-Architecture and Eco-Urban Planning
## 3 Research: Passive and Active Solar Systems in Eco-Architecture and Eco-Cities
### Multi-Scale Model of Passive and Active Solar Systems  
Contemporary ideas for ecological solutions in cities and housing complexes allow for a combination of various passive solar urban-planning solutions with active methods of using renewable energy in connection with municipal energy networks (Figures 3 and 4). This is favored by those with an interest in energy-saving solutions and the development of sustainable architecture and urban planning [16]. The diagrams below present solutions concerning active and passive solar and shading systems at two scales: the building scale (micro) and the residential complex scale (macro). In the diagrams, active solutions for insolation are supported by passive solutions; the macroscale (that of the residential complex) is the framework for the urban design of energy-sustainable cities and sets the stage for other energy-saving investments on an architectural building scale.  
Historical analyses carried out for the purposes of this article show that passive solutions on a macroscale, including the optimal location of buildings, regulating the intensity of development, and modeling building height, dimensions and shape, have proven themselves in many cities, right back to antiquity. They have also turned out to be energy-efficient enough that they have found their continuation in modern eco-cities, such as Masdar in the UAE.  
Using modern construction materials and research on energy-saving design methods, we can model the degree of permeability of buildings in relation to the sun's rays (e.g., using glass) or determine the optimal energy-saving type of urban development (e.g., quarter, linear or quarter-linear systems of buildings, etc.). Modern technological achievements allow us to supplement passive macroscale energy systems with active solutions, such as heliostats transmitting reflected sun rays, or intelligent mobile architecture using optimal sunlight conditions. These solutions are supported by the modern way of designing buildings, taking into account the use of active microsystems (such as light chimneys and solar towers) and passive microsystems (such as the glazing of southern facades, regulating the size and number of windows or the use of accumulation walls).  
Figure 4: Multi-scale systems of passive and active shading on micro- and macroscales (authors).  
Figure 3: Multi-scale systems of passive and active insolation on micro- and macroscales (authors).  
In view of the constant warming of the climate, an important problem is how we can protect cities against excessive overheating, evaporation and the effect of the urban heat island. This is where multiscale passive and active shading solutions can help. Applications depend on the scale of a residential complex, e.g., intelligent roofing systems for streets and squares, the use of irregularly shaped roofs regulating sunlight, the use of functionally intelligent mobile architecture working together on the scale of the building, and the use of greenery combined with architecture, shutters, semi-permeable walls and other features.