Page 163 - AGC_EN_iBook

163
SOLaR PROteCtION
The solar protection devices on the external facades are adjustable (swivel-mounted), while on the internal facades they are both adjustable and retractable.
The control system for the external solar protection system enables:
– centralized control by wing;
– control by facade;
– local exceptions for each Venetian blind belonging to the internal facades.
The centralized control by wing provides protection against the wind, as well as the ability to reset the whole system and to block its use during maintenance work.
Control of the various systems involves the following:
–The retractable and adjustable Venetian blinds on the internal facades are retracted when total sunlight (direct and diffuse) on the facade is < 150 W/m2.They are fully lowered and set at right angles to the sun when total sunlight reaches or exceeds 150 W/m2. however, in the latter case, the blinds are kept horizontal when direct sunlight on the facade is < 25 W/m2.The blinds on the south facade are lowered for 1158 hours/year, with an average tilt of 44° to the horizontal, whereas the ones on the north facade are low- ered for 870 hours/year with an average tilt of 57°. A blind’s light re ectance is measured at 19%. Using this solar control system, the average g value4 is 0.13.
– The swivel-mounted horizontal louvres on the north and
south facades are positioned horizontally when total sunlight is
< 150 W/m2.They are set at right angles to the sun when total sunlight reaches or exceeds 150 W/m2. however, in the latter case, the louvres are kept horizontal when direct sunlight on the facade is < 25 W/m2. A louvre’s light re ectance is calculated at 41%, while its light transmittance is calculated at 11%. Using this solar protec- tion control system, the mean g value is 0.17. Glare is controlled
by manually operated indoor textile blinds.
– The swivel-mounted vertical louvres on the east and west facades are set at right angles to the facade when total sunlight (direct and indirect) on the facade is < 150 W/m2.They are set at right angles
to the sun when total sunlight reaches or exceeds 150 W/m2 and when the sun’s azimuth is between the south and the direction perpendicular to the facade. however, in the latter case, the blinds are kept at right angles to the facade when direct sunlight on the facade is < 25 W/m2.They are set parallel to the facade when total sunlight on the facade reaches or exceeds 150 W/m2 and when the sun’s azimuth is between the direction perpendicular to the facade and the north.The light re ectance and the solar factor of the ver- tical louvres are the same as the horizontal ones. Glare is again controlled by manually operated indoor textile blinds.
aNtI-GLaRe PROteCtION
The screens of visual display terminals (VDTs) are liable to be impaired by light re ections due to the environment and ambient lighting. Under certain conditions, re ections can cause annoyance to the user, negatively impacting his comfort and performance
in the execution of his tasks.The objective of part 7 of standard NBN EN ISO 9241 (Ergonomic requirements for of ce work with visual display terminals (VDTs) – Part 7: Display requirements with re ections) is to maintain an acceptable and ergonomic display quality under lighting conditions likely to generate re ections
on the screen.
To reduce the risk of impairment through light re ections, the luminance of the glazed surfaces is limited to a maximum value
of ten times that of a VDT screen (i.e., the mean luminance of the glazed surfaces = 1500 cd/m2 for a screen luminance of 150 cd/m2). Indoor blinds are used to limit luminance.