LIGHT AND THERMAL PERFORMANCE

A sunscreen is an external solar protection distributedalong a generally vertical glazed partition. This type of solar protection contributes to making conditionspleasanter in the building as regards:- light - temperature These two factors not only enhance the well-being of the user, but also reduce energy costs:1) less artificial light (electric light)2) less or no expenditure on building air conditioning in summer Indeed, the increasingly large areas of glass used in façades lead to increased use of air conditioning to avoid the over- heating caused by excessive absorption of sunlight; a solution both expensive and controversial, due to its damaging effectson the environment (emission of building greenhouse gases).Sunscreens reflect or absorb a proportion of the sunshine; in this way, they limit the transmission of solar energy into the building. The energy not transmitted does not even reach theglazing, which therefore does not heat up due to a "localgreenhouse effect" (a disadvantage of interior solar protec- tions, such as blinds furniture). A small proportion of the energy not transmitted directlynevertheless is relayed into the interior of the building, inan "intelligent" manner: - reflection of the rays off the horizontal surfaces of the solar protection enable the room to be illuminated in greater depth. - only half of the energy absorbed by the material is re-emit-ted towards the interior; the terracotta sunscreen thus signi-ficantly reduces the solar factor of the glazed unit. Sunscreens make it possible to favour large building window areas: - in which the light is filtered and better diffused in all directionsby sunscreens oriented horizontally - where "free" solar supplements, in contrast, are best exploit-ed in winter: as the sun is down nearer the horizon, the pro-portion of its rays that passes between the horizontally ori- ented sunscreens is greater: reduced heating needs. - where "free" solar supplements, in contrast, are best exploit-ed in winter: as the sun is down nearer the horizon, the pro- portion of its rays that passes between the horizontally ori-ented sunscreens is greater: reduced heating needs. The terracotta sunscreen is an automatic regulator of ener-gy and sunshine filtering. Summer: bright sun, high above the horizon Winter: weak sun, low above the horizon

Reference standards

Thermal regulations: > Th-C rules for calculating the energy needs of the buildingin winter (with free solarcontributions taken into account inRT 2005)> Th-E rules for calculating interior temperature in summerwithout air conditioning.> Th-S rules for calculating the solar factor of the building (= the proportion of solar radiation transmitted directly orindirectly to the interior of the building)

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