Possibilities of application of facade solar collectors in the urban environment can be shown for typical cases. To imagine how the urban environment can influence annual solar irradiation on facades of buildings three different types of urban structure in Prague have been chosen. Considered estates differ in time of construction and density of buildings.

The oldest case is housing estate in quarter Vinohrady typical for central part of Prague (see Fig. 4, left). Housing estate is formed by five floor tenement houses with central courts each placed very close to others (distances between houses is 15 to 20 m). Although the application of solar facade collectors at houses with certain historical value is problematic, the case has been chosen as an example of dense structure and its influence on solar gains.

Housing estate Chodov from 70’s of 20 century has very heterogeneous structure (different heights and orientation of buildings, see Fig. 4, right) with free areas among prevailing row buildings with 8 to 12 floors. Ground plan of the building site is very irregular.

Housing estate case Barrandov is a quite young structure in Prague built in 1988. Case with sparse building structure is formed by tower fabric buildings with 4 to 8 floors (see Fig. 5). South orientation of building gables with large available areas is advantageous for facade integration of solar collectors.

Shading analysis for given three cases has been performed using ESP-r simulation tool. Annual solar irradiation level for south building fagades in the individual cases obtained from simulations are shown in Fig. 6 to 8. Designation of buildings in the ground plans is identical with model views. Each building is described with its height and annual solar irradiation value in kWh/m2.

While shading by surrounding urban environment in the central part of Prague (case Vinohrady) leads to reduction of incident solar irradiation by 10 to 20 %, housing estates in suburban areas show the reduction significantly lower about 1 % (case Barrandov) with maximum 5 % (case Chodov).

2. Conclusion

Sensitivity of south building fagade to shading by surrounding objects has been investigated with respect to basic geometry parameters (height of considered shaded building, distance from shading object and height of shading object) for two principally different building types (row building, tower building). The simulation analysis resulted in parametric curves for solar irradiation reduction factor. Practical use of such graphs is in easy and fast outlook on required geometry parameters and relationships to maintain sufficient annual solar irradiation values on fagades or for prediction of possible fagade shading problems for given urban environment geometry.

Influence of fagade shading has been further analysed in three case studies with different urban environment structure. While old urban structure in the city centre shows considerable reduction of solar irradiation up to 20 %, for the newer housing estates the reduction ranges within several percents and offer the application potential for solar systems with fagade-integrated collectors without excessive shading problems.

References

[1] G. Rockendorf, S. Janssen, Facade integrated solar collectors, Proceedings of the ISES Solar World Congress 1999, Jerusalem, Israel.

[2] I. Bergmann, W. Weiss, Fassadenintegration von thermischen Sonnenkollektoren ohne Hinterluftung, AEE Intec, Final report, Gleisdorf 2002.

[3] W. Weiss et al., Solar Heating Systems for Houses: A Design Handbook for Solar Combisystems. Earthscan Publications Ltd. (June 2004), ISBN 978-1902916460

[4] T. Matuska, B. Sourek, Facade Solar Collectors, Solar Energy, vol. 80, pp. 1443-1452, 2006.

[5] T. Matuska, B. Sourek, Solar systems with fagade-integrated collectors. Proceedings of ISES 2005 Solar World Congress. Orlando (Florida, USA) 2005.

[6] T. Matuska, B. Sourek, Aspects of solar collector integration into building fagade. Proceedings of ISES Eurosun 2006. Glasgow 2006.