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INSULATING GLASS PANELS with METAL INTERLAYER and OTHER GLASS FACADES Des Moins Public Library DAVID CHIPPERFIELD

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

1. General characteristics of the material 2. Technical characteristic of the material 3. Other examples of usage of the material 4. Insulating glass system 5. Comparison and evaluation

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

GENERAL INFO ABOUT THE LIBRARY SITE PLAN

NAME: DES MOINS PUBLIC LIBRARY ARCHITECT: David Chipperfield DATE: 2006 PLACE: Des Moins, Iowa, USA •

located in the eastern part of the park acting as a bridge between urban and landscape areas

•

the unusual shape of the library allows for a varying degree of privacy inside the library

•

the library includes education facilities, children´s areas and a conference wing with a cafeteria

• • •

2-storey concrete structure above underground car parking entirely wrapped in a composite glass-metal skin

about 60% of the facade is covered with Okatech units



• the remaining areas, which occur mainly in the administrative parts, are not transparent but rather are clad with insulation and aluminum fascia • a green roof provides store water management

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

GENERAL INFO ABOUT THE LIBRARY SECTION

FLOOR PLANS

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

GENERAL CHARACTERISTIC OF THE MATERIAL

The triple-glazed panels incorporate a sheet of expanded copper mesh which reduces glare and solar gain and provides shade.

The structural silicone jointed panels are 1.2m wide by 4m high. The entire facade appears to hover on a 400mm ‘plinth’ of precast concrete cladding panels.

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

GENERAL CHARACTERISTIC OF THE MATERIAL

The triple- glazed panels incorporate a sheet of expanded copper mesh between the outer panels. The three. dimensional quality of the copper mesh reduces glare and solar gain, providing all the shading from the sun that is necessary.

From the outside, the skin appears opaque, the view to the inside is blocked by the combined effects of the reflection and glare from the copper mesh and the triple llayers of glass. From the interior, the mesh dematerializes to reveal a fully glazed building offering generous views out in all directions.

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

GENERAL CHARACTERISTIC OF THE MATERIAL

At night the effect is reversed: imbalance between levels of illumination in the brightly lit interior causes most of the facade to appear transparent from the outside.

The mesh also mitigates the intesity of the sunlight, reducing the need for artificial light to balance disparities in levels of interior and exterior illumnination. It functions as a directional natural light system. This is due to the numerous, asymmetrically configured metal perforations.

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

TECHNICAL CHARACTERISTIC OF THE MATERIAL MATERIAL LAYERS

SPECTRAL PROPERTIES 1. direct irradiation from high and medium solar altitude • thermal solar control with total solar energy transmittance values of as low, in particular secondary heat transfer without solar radiation transmission • glare protection 2. direct irradiation from low solar altitude • partial transmission of the direct sunlight • solar yields on south-facing façades Light transmission

Tv = 19 - 36 %

for angle of incidence = 0°-60°

g-value = 19 - 22 % 1. Outermost sheet of glass 8 mm thick, low iron 2. 2 mm of copper interlayer 3. Air cavity 4. Mid-glass sheet 8 mm thick with a low e-coating 5. High performance solar and thermal protection layer 6. 16 mm air cavity 7. 2x 5 mm laminated glass sheets

for angle of incidence = 0°-60°

LIGHT TRANSMISSION AND TOTAL SOLAR ENERGY TRANSMITTANCE DEPEND ON THE ANGLE OF INCIDENCE

PHYSICAL PROPERTIES Thermal insulation Thermal transmittance

Ug = 1.0-1.2-1.5 W/(m2K)

lower values are possible by adding aditional cavity between the panes

Sound insulation Depends on the glass assembly

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

EXAMPLES OF LIGHT DISTRIBUTION FOR INCIDENCE SUN ANGLE 25°



clear glass

Okatech

normal view outwards

Okatech

normal view outwards

Okatech

normal view outwards

OF LIGHT DISTRIBUTION FOR INCIDENCE SUN ANGLE 50°



clear glass

OF LIGHT DISTRIBUTION FOR INCIDENCE SUN ANGLE 75°



clear glass

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová

GLASS BREAKAGE - NIKEL SULFIDE INCLUSIONS • after 21 months, in February 2008 at least 31 tempered glass panels in their nearly 38,000 ft2 (3,500 m2) curtain wall had shattered due to nickel sulfide inclusions • the tempered glass was not heat-soak tested in the process of manufacturing •



the panels cost approximately $8,000 each to replace

NIKEL SULFIDE INCLUSIONS OF TEMPERED GLASS •

in the glass production process are microscopic imperfections in the glass - INCLUSIONS

•

nickel sulfide (NiS) inclusions have been shown to cause disastrous failure of tempered glass

•

when the glass is rapidly cooled to achieve the properties of tempered glass, the NiS remains in a high-temperature form

• over several years, the NiS will return to its low-temperature state, and in the process will increase in volume •

when these windows break, they shatter into thousands of pieces which can fall from panes and cause injury to inhabitants of the building or pedestrians around it

HEAT - SOAK TESTING • it consists of reheating tempered glass panels for a third time, maintaining it at an elevated temperature that is still below the phase transfer temperature of NiS for a set time, and then allowing it to cool •

it is still the only method the industry has to eliminate a large portion of nickel sulfide inclusions

Politecnico di Milano | Material for Buildigs | Professor: Sara Goidanich

Students: Viktória Zacharová | Simona Čabanová