Preliminary results on a novel photo-bio-screen as a shading system in a kindergarten: Visible transmittance, visual comfort and energy demand for lighting

A study on a novel photo-bio screen (PBS) used as a shading system in a real building is presented. The green microalgal culture (Scenedesmus obliquus) of the PBS allows a screening of the direct sunlight and a production of biomass containing bioactive compounds. The PBS was tested in a kindergarten classroom at Saint Marcel (Aosta Valley, north-west of Italy) and monitored for 3 weeks (June-July 2016). The visible transmittance Tv of PBS was determined through in situ illuminance measurements, while the daylight amount in the room and the energy demand for lighting EDl were calculated through Diva-for-Rhino simulations (using the median measured Tv as input). The analysis was split in two phases: (i) the real room (with south-facing windows and external obstructions); (ii) the same room without obstructions, analyzed parametrically by changing the site (Turin, Östersund, Athens, and Abu Dhabi) and the orientation (south, west, north, and east). For both phases, the results for PBSs were compared to what obtained applying a traditional venetian blind VB of comparable light transmission to the window. From the monitoring campaign, the Tv of the PBS was found to have a quite high variation as a function of the dynamic boundary conditions, so an median value of 0.75 was identified as the reference Tv. From simulations, it was found that the daylight amount and the EDl for PBS and the VB were comparable, with slightly better results for the PBS in Turin and Athens and slightly better results for the VB in Östersund and Abu Dhabi.