T. Matuska* and V. Zmrhal

Czech Technical University in Prague, Dept. of Environmental Engineering, Faculty of Mechanical
Engineering, Technicka 4, Prague 6, Czech Republic

* Corresponding Author, tomas. matuska@fs. cvut. cz

Abstract

Paper is focused on potential shading problems of solar collectors integrated into building facades in the urban environment, especially in housing estates. Parametric shading analysis of facades for two basic types of buildings configuration (row buildings, tower buildings) has been performed. Case study of facades shading by surrounding objects has been evaluated for three different housing estates in Prague (Czech Republic) with different period of development and density of the buildings. While old dense housing estate case results in 20% annual decrease in solar irradiation incident on facade, the newer housing estates show just several percent decrease.

Keywords: building integration, facade collector, shading analysis, solar irradiation

1. Introduction

Solar domestic hot water (DHW) systems and solar combisystems for DHW and space heating in residential buildings have a high potential in central Europe. Solar thermal systems show a dramatically increasing trend being more and more applied in modern family houses. Number of solar systems applications for newly built and retrofitted blocks of flats especially in urban environment of larger cities is very low in Czech Republic but strong development is expected with respect to financial support in the frame of European Operational Programmes for use of renewable energy sources.

Placing the solar collectors on blocks of flats results in number of aspects that designer has to take into account. On the one side, there could be problems to bring a sufficient collector area on the roof of the building. There are often collisions with already installed building furnishings and devices (machine rooms for elevators, exhaust heads of ventilation systems, antennas cell operators or WiFi providers). However, the collector field placed above the roof affects the compact shape of the building, it can be visually disturbing and it can result in rejection of the whole solar system by the responsible architect.

On the other side, a large area for solar collector application is offered by building facades. The integration of solar collector into building facade envelope instead of separate installation on the flat roof represents a transition from the building envelope considered as an energy loss to envelope being a heat source (energy active envelope). Coupling the function of building envelope with solar thermal collector leads to a concept of multifunctional facade elements providing several functions (synergy effects). Trends focus in holistic approach supposing that solar collectors form an essential part of building facade constructions.

However, solar facade collectors are more sensitive for potential shading due to vertical position of surface receiving solar energy. This fact is problematic especially in the complex and dense housing estate structures in the urban environment.