LUCE estratti LUCE 319_Frascarolo_Basilica di San Francesco | Page 8

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in which the space is subdivided.
The two Basilicas share the same lighting
principle: diffused light with soft chiaroscuro
effects so that it is easy to view the
architecture and the frescoes, avoiding
oblique lighting which would emphasize
the irregularities in the surfaces of the
frescoes, specially in the Upper Basilica
which was damaged in the dramatic
earthquake that struck Assisi in 1997.
In the initial stage, the existing system was
analysed and the design concept was developed.
This was followed by a scrupulous optimization of
the lighting technological system, with the intent
of harmonising the presence of the same,
as far as possible, in the complex volumes
of the Basilica, and suitably distributing the
luminous flux produced by over 600 units, whose
photometry and pointing effects were studied
individually in the simulation phase.
For this purpose, tests were carried out on
the equipment designed for this application
both in the laboratory and on site.
In particular, the Lower Basilica, presented
a very challenging project design: to illuminate
the full spaces of the vertical walls without
invading the empty spaces created by the arches,
thus avoiding the phenomena of direct glare
and imprecise distribution of the luminous flux
on the frescoes painted on the walls.
Elliptical lenses for COB (Chip on Board) modules,
a solution that did not exist in the market, were
designed and produced in order to conciliate
visual comfort with regard to the risk of direct
glare which characterizes COB solutions, with
the performance of elliptical-type lenses
previously used for single LED units only, that are
closer to the concept of a punctiform source
of light , and therefore easier to manage with
regard to the optics. The aperture of the beam
of light (65° x 21°) obtained as described above,
was determining in order to “shape” the
geometry of the walls painted with frescoes more
precisely, with a consequent 30% decrease
in the flux, i.e. in the absorbed power, with
equal levels of light on the surfaces, which
is added to the saving obtained as a result of the
efficiency of the state of the art LEDs, the quality
of the electronics and modulation of the flux
in the different lighted scenarios, which allows
approximately 75% average energy saving (with
an equal amount of installed luminous flux).
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1 | Nuova illuminazione della Cripta / New lighting in the Crypt
2 | Basilica Superiore: vista dei nuovi lampadari / Upper Basilica: view of the new lighting system
3 | Prove di illuminazione su una parete affrescata della Basilica Inferiore con fasci luminosi ellittici /
Testing the lighting of a fresco on a wall of the Lower Basilica with elliptical beams of light
70 LUCE 319 / PROGETTARE LA LUCE
The first test that was carried out with the
prototype lenses confirmed their efficacy in terms
of precision. This, together with the possibility
of pointing each light individually, enabled the
realization of an extremely uniform illumination.
In the Upper Basilica a complex challenge was
to harmonize the permanent lighting system
and the temporary lighting system, used once a
year when broadcasting the traditional Christmas
concert on the television network, besides
developing control logics to integrate the natural
light. This result was obtained by using very solid
linear equipment, provided with equally stable
attachment and pointing systems.
In the Crypt, the principal aim was the
technological optimization of a solution for
the distribution of the luminous flux which was
already satisfactory, and to concentrate mainly
on energy-saving and a decrease in maintenance
costs. Particular attention was paid to the
containment of the visual impact of the
equipment. The positions for installation
of the equipment were studied; it was positioned
further back compared to the visibility angle
in the Upper Basilica, and guaranteed a cut-off
effect in the Lower Basilica.
The lighting in the Basilica in Assisi is, in order
of time and importance, a “beacon” project
which will also “light up” other sites that are
not as well-known and other more important
ones, creating a new and precious course across
the territory for pilgrimages, or to visit places
of cultural interest in our country, an invitation
to get to know and re-discover these marvellous
places of Christianity and art.
The initiative “Jubilee of light ”, promoted
by ANCI (The Italian National Association of Town
Councils) will promote these projects on a
national scale. Among its founding elements,
based on the agreement with the Ministry for the
Environment and Protection of the Territory and
the Sea, are a greater efficiency of the lighting
system and enhancement of the Italian artistic
heritage. The “Jubilee of light ” was presented to
the press and to the public in October 2016,
completion of the project design is estimated by
the end of the year, and realization of the same
in the first semester of 2017. This “new” course,
also of light, will leave a mark in the territory that
will continue to be appreciated well beyond
the period of the Jubilee.