The basic and historic idea behind using screen walls for buildings is their constituting a lightweight
and transparent outer shell. The need for lightweight screen walls arose from the necessity to reduce the overall weight of the tower in order to minimize size and construction cost of the skeletal structure.
The need for transparence arose from the idea of using natural light to illuminate the spaces where people work or live.
From the above basic idea, curtain walls capable of dealing with wind, seismic, snow and heat loads, water and air permeation, and more, were designed and developed over the last 100 years.
But let us face the fact that life behind the curtain walls is intolerable. Why?
The transmission of heat from the outside to the inside through radiation, conduction and convection is unbearable; and if we have made it bearable, then we probably decreased the transmission of light to the inside in significant percentages, and we live in the dark.
The use of natural lighting in offices, improves work efficiency and employee satisfaction and their health. It is possible to explain the positive psychological effects of the unique qualities of natural light by its unique qualities: natural light consists of a full spectrum of radiation of different wavelengths and thus enables a better distinction in a wide range of colors.
Many studies show that the dynamics of natural light, manifested in slight changes of illumination intensity, spectrum and shading, creates a stimulating psychological effect.
Exposure to natural light allows tracking changes occurring in the external environment in accordance with the time of day, season and weather.
Natural lighting also has positive psychological effects on workers’ health: solar rays permit the drying, disinfection and the prevention of bacteria in space, processing and assimilation of vitamins and maintenance of the integrity of the daily biological cycles of the human body. In our mind, sunlight is related to clarity, joy, warmth and health. Natural light affects the mood and the perception of space in the office.
To everything said so far, we must add the fact that screen walls, due to their exposure to solar radiation and wind, can be a perfect platform for the production of energy by exploiting solar radiation and wind energy.
Out of all these, the Aluminum Construction Company developed the ALC 10,000 System which promotes comfort and an extraordinary living experience, and produces immense amounts of energy by utilizing sunlight and turning it into electricity
The ALC 10,000 System is a screen wall system built using the STICK or the UNITIZ method.
The system consists of 2 glass sheets about 200 mm apart, with the outer glass being a particularly
transparent glass transmitting about 92% of the light frequency spectrum; and the inner glass is
insulated glass 6-12-6 of the LOW E type having LOW EMISSIVITY.In the space between the glass, and next to the external glass sheet, extend Venetian blinds 25-50mm in width, performing automatic tracking of the sun’s movement, and in fact, reflecting the solar radiation that passes through the glass back to the outside, and thus heat transmission is avoided but light allowed that does not originate from direct solar radiation is allowed entry in especially large quantities, from 30-70 %.
In the space between the glass sheets, there is an air switching system which causes air warmed by solar radiation, and its impact on the Venetian blinds, to be deflected out and replaced by colder air, even though this air comes from the outside.
In SPANDRAL areas of the screen wall, prismatic photovoltaic cells that produce electricity from
solar radiation with 15-20 % efficiency are installed, and from this area photovoltaic shading winglets extend tracking the sun using the same tracking system which operates the Venetian blinds.
The ALC 10,000 System is a system unique in its kind in the world and has been tested in Company
labs in conformity with ASTM standards.
REDUCING HEAT TRANSMISSION FROM THE OUTSIDE TO THE INSIDE.
In the ALC 10,000 System a number of principles exist which together reduce heat transmission from the outside to the inside by about 50 %. As everyone knows, heat energy moves from place to place in three different ways:
A. Radiation, responsible for about 80% of heat transmission
B. Conduction, responsible for about 10% of heat transmission
C. Convection, responsible for about 10% of heat transmission
THE WAY THE ALC 10,000 SYSTEM DEALS WITH RADIATION, CONDUCTION AND
CONVECTION IS AS FOLLOWS:
A. Solar radiation penetrates the outer glass and hits an electronic Venetian blind that follows the position of the sun and is always at 90° to the sun. The radiation that hits the Venetian blind is reflected back through the transparent outer glass to the outside and thus direct radiation is prevented.
B. Heat conductivity occurs in the metallic parts that make up the ALC 10,000 System, but these are cut off from the interior by a “polyamide” type insulation system, and prevent heat conduction from the exterior to the interior.
C. Convection occurs when air molecules are trapped between the wall skins. To neutralize heat convection from the exterior to the interior, air switching is performed regularly whenever the air temperature between the system skins is higher than the outdoor temperature.
D. The heat resulting from heat radiation, conduction and convection which remains in the system is reflected outside by a coating of silver dioxide deposited on the inner glass. The property of silver dioxide is to reflect back to the outside the heat radiation frequency spectrum.
The ALC 10,000 System combines two systems for power generation inside screen walls. The first is a prismatic system inserted into insulating glass glazed in the SPANDRAL areas of the screen walls; the second is a winglet aluminum system with polycrystalline photovoltaic panels placed on the winglet, extending outward from screen walls for shading purposes.
ALC 10,000 SYSTEM – SPANDREL AREAS
As stated, in these areas, insulating glass is glazed, inside which photovoltaic cells are installed located on a glass prism or a PMMA prism (UV- resistant transparent plastic). These cells receive the solar rays regardless of the position of the sun as the property of the prism is to concentrate solar rays and bring them to the PV (photovoltaic) cell. The PV cell converts radiant energy into electricity.
The SPANDREL zone of the tower wrapped in screen walls is about 40% of the screen walls’ area.
The ALC 10,000 System PV Aluminum Winglets The winglets system is built from aluminum winglets upon which are installed mono or polycrystalline PV panels.
The winglet system tracks the sun along one or two axes and harnesses solar energy for electricity production and use up to 40 % more than a static system.
The winglet system is elegant and has a futuristic look, and also in itself contributes to the prevention of the entry of direct sunlight into the building.
The electricity generation system installed in the ALC 10,000 contains everything needed for full operation, including all the components required for converting electricity’s direct current to an alternate current.
The ALC 10,000 System allows for production of 100% of the electricity required to operate the electro-mechanical systems, air conditioning and lighting of the building throughout the year.