As an example ofapplication ofexperimental researches carried out by means ofscale models under artificial sky and sun, a specific case-study, concerning the assessment of environmental performances ofsimple shading devices, is presented. Tested shades were conceived and designed to be applied to educational buildings located in Turin. To analyse daylighting conditions inside high-school classrooms, a scale model was achieved so as to reproduce a sample classroom, representative oftypical real environments with regard to sizes, exposure, optical and chromatic internal surface properties and daylighting system typologies (unilateral side-lighting through vertical windows). For artificial sky and sun experimental activities purpose, the achieved model was 1:10 scale, featuring (figure 2):

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sizes: reproduced classroom is 9 m long, 6 m wide and 3 m height, determined according architectural design handbook. These sizes are representative of typical real classrooms

• 2 windows in the south wall, each of them 3 m wide and 2 m height, sill being 0.9 m from floor level; the openings have a clear 6 mm glass and a grey frame similar to the one characterising some real classrooms

• internal surface colours and luminous reflectance values (rl): the ceiling is white painted (n = 0.72), walls have a lower part light blue painted (rl = 0.48) and an upper part with an ivory-coloured finish (rl = 0.61), while the floor is made of red brick (rl = 0.33)

• internal surface optical properties: all materials were assumed as Lambert diffusers. Among all possible solutions, shading devices chosen forthe south-oriented glazed wall consisted of both external and internal screens. Tested configurations are described in table 1. In particular, the performance ofa simple overhang was compared to the one of otherfixed screens (like external light-shelf, internal light-shelf, external-internal light-shelf and horizontal fins). The goal of improving daylight penetration in the rear part of unilateral side-lighted classroom was one ofthe criteria used to define the tested configurations. For this reason, the upper part of internal light shelves, different finishing were tested (matt, semispecular and specular). The same was applied to one of the horizontal fin (finished in both a matt and a semispecular material).

Screens’ size and position were determined in order to assure a comparable shading effect. Forthis reason, assumed configuration were characterised calculating the Shading

Factor value24 (SF) and the final geometry was set so as to have similar SF values (table 1 and figure 3) and an efficient shading effect with respect to Sun’s position during the year. The SF values were determined both for the summer time (referring to June, 21st) and for wintertime (referring to December, 21st), based on monthly average irradiance data measured for the town of Turin25.

As far as experimental activity is concerned, two sets of measurement were carried out for each shading configuration.

The former involved the use of the artificial sky, aimed at quantitatively assessing the illuminance and Daylight Factors values in correspondence of 16 points on the classroom’s work plane (positioned at a height of 0,8 m from the floor).

Measurements were repeated referring to different sky conditions and different daylight availability: both a CIE Clear Sky and a CIE Overcast Sky were assumed as reference standard sky conditions, while to take daylight variation during the year into account both a winter condition (identified in December, 21st, at noon) and a summer condition (June, 21st, at noon) were simulated.

The latter experimental set involved the use of the artificial sun, aimed at qualitatively evaluating the dynamic penetration ofthe Sun into the classroom fordifferent periods of the year and within a single day. The analysis was carried out for two “extreme” sun-light conditions: a winter day (December, 21st) and a summer day (June, 21st), respectively characterised by lowest and highest Sun’s elevation angles with respect to the annual solar dynamic behaviour. For both days, sun-light penetration was assessed at different hours: 9 a. m., noon and 4 p. m.