The luminous environmental performances of tested shading devices were assessed by means of different quantitative and qualitative information elaborated from the data collected during the diffused and direct light simulations.

As far as diffused component of daylight is concerned, average Daylight Factor (DFav), average illuminances (Eav), uniformity of illuminance distribution U (determined as DFmin/DFav and Emin/Eav) and profiles over a cross section of the horizontal plane were calculated.

Obtained results are shown in tables 2, 3, 4 and figures 4, 5.

The following trends can be emphasised from result analysis:

— the average Daylight Factor measured for the CIE Overcast Sky condition is over the minimum value recommended by the Italian Standards for classrooms26 (DFav> 3%) only when the internal light shelves are used. All the other devices ensure a DFav within 2,45% and 2,96%, with a better performance for the horizontal fins and a worse for the overhang and the external+internal light-shelves;

— in clearsky conditions, the highest average illuminances are achieved with the internal light shelves, intermediate and similarvalues with the overhang and the horizontal fins and lowervalues respectivelywith the external light shelfand the external+internal light shelves;

— the uniformity of daylight distribution over the horizontal plane is quite similar for the external light shelf, the external+internal light shelves and the horizontal fins, while it is reduced if the overhang or the internal light shelf are used;

— the light penetration towards the rear part of the classroom and the uniformity of distribution along the cross section (assessed for each point along the section in terms of Daylight Factoror illuminance relative difference with respect to the overhang — tables 2,3,4 — and by observing the graphical representation offigures 4, 5) are higher for the horizontal fins and the external light shelf and respectively lower for the external+internal light shelves, the overhang and the internal light shelves.

code description Fs 0) summer, winter, June,21st Dec.,21st 1 0 overhang — matt diffusing reflectance = 0,7 — depth = 0,6 m 55 88 2 ELS external light-shelf — matt diffusing reflectance = 0,7 — positioned 0,55 m awayfrom window’s lintel — depth = 0,7 m 55 87 3 ILS1 internal light-shelf — matt diffusing reflectance = 0,7 — positioned 0,55 m awayfrom window’s lintel — depth = 0,55 m not applicable not applicable 4 ILS2 internal light-shelf — semispecular reflectance = 0,9 — positioned 0,55 m away from window’s lintel — depth = 0,55 m not applicable not applicable 5 ILS3 internal light-shelf — specular reflectance = 0,9 — positioned 0,55 m awayfrom window’s lintel — depth = 0,55 m not applicable not applicable 6 E+ILS1 external light-shelf+ matt internal light-shelf see cases ELS and ILS1 55 87 7 E+ILS2 external light-shelf+ semispecularinternal light-shelf see cases ELS and ILS2 55 87 8 E+ILS3 external light-shelf+ specular internal light-shelf see cases ELS and ILS3 55 87 9 HF1 horizontal fins — matt diffusing reflectance = 0,7 — fins’ spacing = 0,67 m — fins’ depth = 0,2 m 53 88 10 HF3 horizontal fins — matt diffusing + 1 semispecular reflectance = 0,7 / 0,9 — fins’ spacing = 0,67 m — fins’ depth = 0,2 m 53 88

Table 1 — Description of analysed shading system configurations

<1) Fs = Shading Factor, defined as24:

Fs, b • lb+Fs, d • Id + [a lb + Id + la

Fs, b = sun-light fraction of the window in presence of direct radiation [-]

Fd, b = skylight fraction of the window in presence of direct radiation [-]

lb, ld, la = direct irradiance, diffuse irradiance and irradiance reflected from the albedo incident onto the glazed surface [W/m2]

					matt / semispecular / specular
	cross section —ft—- ft—- ft—- ft —		cross section —&—- #—- #—- —		cross section —&—- Э*—- #—- —
	overhang	external light-shelf	internal light-shelf
	^iatt / semispecular / specular		^matt / semispecular
	cross section		cross section |—fc———- *——— «———
external-internal light-shelf	horizontal fins

Figure 3 — Geometry and position ofanalysed shading systems

SHAPE * MERGEFORMAT

Table 2 — Average Daylight Factor, uniformity of distribution overthe horizontal plane and CIE Overcast Sky О CO _l Ш CO CM CO -J CO CO J E+ILS1 E+ILS2 E+ILS3 Li. X CO Li. X DFav [%] 2,54 2,68 3,46 3,51 3,56 2,45 2,52 2,54 2,86 2,96 U = OFmin/DF, av 0,33 0,40 0,30 0,31 0,31 0,38 0,39 0,38 0,39 0,38 distance from window fm] DF relative difference (referred to the overhang) f%]<v 0,75 0,00 0,02 51,47 53,04 53,19 -3,39 -1,67 -1,34 2,11 4,39 2,25 0,00 16,78 29,29 32,36 34,51 4,26 7,30 9,82 28,89 32,81 3,75 0,00 6,44 9,06 12,55 15,20 -11,74 -8,46 -5,73 17,56 20,26 5,25 0,00 27,76 21,47 23,75 26,84 10,54 12,72 15,64 29,98 30,82

Table 3 — Average Illuminance, uniformity of distribution over the horizontal plane and relative difference of daylight quantity over the cross section (CIE clear sky — Dec. 21st). CIE Clear Sky December, 21st — noon О CO _l Ш CO J CM CO J CO CO J E+ILS1 E+ILS2 E+ILS3 Li. X CO Li. X Eav [lux] 4089 3883 4564 4625 4669 3535 3704 3752 3932 4023 U = E 0,54 0,62 0,54 0,52 0,53 0,59 0,57 0,58 0,60 0,59 distance from window fm] E relative difference (referred to the overhang )f%](1) 0,75 0,00 -11,06 13,36 14,89 15,09 -11,96 -10,18 -9,99 -12,90 -10,17 2,25 0,00 -3,99 13,37 15,76 17,23 -10,18 -8,04 -6,35 1,58 3,81 3,75 0,00 -8,22 1,96 3,71 5,57 -19,30 -17,53 -15,57 -3,02 -2,88 5,25 0,00 9,64 10,19 9,96 12,06 -4,78 -5,04 -2,94 7,84 8,26

Table 4 — Average Illuminance, uniformity of distribution over the horizontal plane and ^^^/edifference_^<daylight^ja^ity_over_t^3_cross_section(CIE_clear_sky_-_Jun^22st).i CIE Clear Sky June, 21st — noon О CO _l Ш CO J CM CO J CO CO J E+ILS1 E+ILS2 E+ILS3 Li. X CO Li. X Eav [lux] 1682 1637 2142 2174 2203 1472 1552 1571 1715 1748 U = Emin/Eav 0,43 0,50 0,38 0,39 0,39 0,49 0,48 0,48 0,48 0,48 distance from window fm] E relative difference (referred to the overhang) f%](v 0,75 0,00 -9,91 40,35 41,53 42,44 -14,08 -12,19 -11,78 -6,46 -4,62 2,25 0,00 2,79 17,50 20,07 21,73 -8,06 -3,92 -2,10 10,48 13,92 3,75 0,00 -2,31 4,47 6,07 8,06 -13,90 -12,01 -10,06 4,16 6,06 5,25 0,00 11,90 12,08 12,85 14,87 -1,22 -0,05 1,77 12,34 14,70 ™ Daylight Factor or illuminance relative difference with respect to the overhang are calculated through the formula: (DFi — DF0)/DF0; (Ei-E0)/E0 DFi; Ei = Daylight Factor; illuminance measured for each shading device DF0 ; E0 = Daylight Factor; illuminance measured with the overhang.

Figure 4 — Daylight Factor measured along the cross section (CIE Overcast Sky condition)

CIE Clear Sky (Dec. 21st — noon)

distance from the window [m]

Figure 5 — Illuminance measured along the cross section (CIE Clear Sky condition)

Even if similar trends of performance can be observed for the different sky conditions and period of the year, different absolute values emerge due to the different luminance distribution of the sky vault (tables 2,3,4 and figures 4,5).

As far as the direct component of daylight is concerned, digital pictures taken inside the model to analyse the visual perception ofthe produced luminous environment are the collected results. A sample of sun-light penetration produced by the different shading devices during the 21st of December at different hours of the day is presented in figure 6. With the exception of internal light shelves the tested shading devices provide an effective protection from direct sun light in summer period (June, 21st) (no direct sun-light observed inside the model).

The use of specular or semispecular finishing for the upper part of internal light shelves and horizontal fins seems to produce a general increase of illuminance on the horizontal plane inside the model (Tables 2,3,4). Furthermore they differently contribute to increase daylight penetration in the centre and rear part of the model, as shown in figure 8.

ELS

ILS2

HF3

Figure 6 — Example of direct sun-light penetration

Figure 7 — Effect ofdifferent finishing on ceiling light distribution

The effect of different finishing is also perceptible in the images taken during sun-light simulations (figure 7).