Civil Engineering Reference
In-Depth Information
Louvers and venetian blinds with special shapes
Innovative shading systems use louvers with a complex geometry, allowing for effective
control of solar radiation, but redirecting natural light deep into the indoor spaces. This is
achieved either through a particular shape of the louver, or incising the surface of the lou-
ver itself with an asymmetrical pattern. In both cases, the louvers, whose shape is always
location-specific, are designed to stop most of the direct solar radiation when the sun is
high (summer), while still reflecting some indirect light. With the low winter sun, more
radiation is allowed to enter the building.
These systems may be fixed or integrated in adjustable blinds (venetian blinds) allow-
ing for a degree of regulation from the users.
Glazing-integrated shading
While external shading devices are the most effective for the control of solar gains (heat is
stopped before entering the building), it may be advisable to protect them from wind, rain
etc. for maintenance reasons.
Louver systems may be placed in glass cavities, where they remain protected from
dust, water and shocks, while preserving the innovative concepts about shading and light
reflection that were discussed above.
Vertical angle-selective façade for solar control
The idea behind an angle-selective façade (Frontini and Kuhn
2009
) is to exploit the
thickness and optical properties of glass (different refraction index between glass and air)
to control the amount of solar radiation entering the building and the glare conditions,
while still allowing views outside and indirect natural lighting. This is obtained by print-
ing, or applying, thin opaque strips on two faces of a laminated glass pane. The system
does not include any movable parts and requires the same maintenance as a standard win-
dow or glazed façade. Thin, opaque strips are printed, or applied, between the two panes
of a laminated glass and on the inner surface of the façade, their height limited (6 mm
max) to avoid them distracting from the views out. The gap between the strips should be
designed on a case-by-case basis, according to the sun path of the location and the amount
of solar energy allowed to enter the building. Additional solar and glare control can be
obtained if strips are printed on both sides of a double-glazed cavity.
The glazing system can also produce energy if the strips are made with photovoltaic
thin film.
Prismatic glass
Prismatic glass consists of rolled glass, 3.2-6.4 mm thick, with one face shaped in par-
allel prisms that refract the transmitted light, thereby changing the direction of the light
rays. Under certain conditions of incision and sun height, the rays can also be reflected,
thus making prismatic glass a shading element that still allows a certain amount of diffuse
radiation to penetrate into the building.
Prismatic glass can be used as a fixed solar control device, especially when placed in a
glass cavity, or as adjustable louvers that also allow views out. It does not allow views out
because of its light diffracting properties.
Light tubes
Light tubes, or light pipes, are used for transporting or distributing natural or artificial
light. A tube lined with highly reflective material leads the light rays through a building,
starting from an entrance-point located on its roof or one of its outer walls. The entrance
point usually comprises a dome, which has the function of collecting and reflecting as
much sunlight as possible into the tube. Many units also have a directional “collectors”,
“reflectors” or even Fresnel lens devices that assist in collecting additional directional
light down the tube.
