Optimal Design of multi-functional and ventilated facades

• Research unit: EU RFP
• Project number: 97.0143

Key words (English)

Multi-functional facades; ventilated facades; transparent insulation; solar wall heating; solar collectors

Alternative project number (English)

EU project number: JOR3-CT97-0190

Research programs (English)

EU-programme: 4. Frame Research Programme - 5.1 Nonnuclear energies

Short description (English)

See abstract

Partners and International Organizations (English)

Universidad Politechnica de Cataluña UCP (E), Teulades i Façanes Multifunctionales TFM (E), Robertson Española S.A. (E), Fraunhofer Institute for Solar Energy Systems ISE (D), Caparol GmbH & Co. (D), Technical Research Centre of Finland, Building Technology VTT.BT (FIN)

Abstract (English)

The main activities of the final project phase in 2000 were the validation of the numerical models of the software tool AGLA and the successive parameter studies for further theoretical optimisation. For the validation task the temperatures measured in the facade module prototypes at the outdoor test site at Fraunhofer ISE in Freiburg i.B. were compared with results from the numerical simulations.
As an overall outcome of the validation it can be concluded that the simulation model in its current state is limited to moderate temperatures in the ventilation cavity. Thus, for moderate solar radiation levels and natural ventilation the simulation model fits the reality sufficiently well (module M5). However, for high solar radiation and high absorber temperatures (module M7) the differences between the measured behaviour and the calculated results is rather high.
The reason for this limitation is the pronounced temperature stratification in the ventilation cavity at higher temperature levels. As this stratification is not linear the 1-dimensional model is not valid anymore. As a consequence, closed cavities in the heating mode of the solar wall can not be modelled with AGLA at all.
Due to this limitation that is most prominent for the TI model the scope of the parameter study was reduced to find relative trends for optimisation instead of predictive values.
The results of this extensive study led to the conclusion that the optimal solution of the facade module depends on the type of mass wall combined with it. The use of phase change material (PCM) does not lead to a significant improvement of the energy gains. However, PCM attached to the mass wall can limit the maximum temperatures for constructions with medium weight mass walls (e.g. from brick) to thus avoid problems in solar wall heating systems for renovation applications.

References in databases (English)

Swiss Database: Euro-DB of the
State Secretariat for Education and Research
Hallwylstrasse 4
CH-3003 Berne, Switzerland
Tel. [phone]
Swiss Project-Number: 97.0143