11.20.12 retractable louver presentation.pdf

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    Feasibility Study of Retractable Louver

    System on Museum TowerNovember 20, 2012

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    A Review of our Work on Retractable Louvers

    as a Potential SolutionMuseum Towers technical team has undertaken the task ofstudying a retractable louver system as suggested by theNasher. To date our activities include:

    o Discussions with Clauss Markisen (manufacturer of the

    proposed louver system) representatives.

    o Review of engineering drawings.

    o Review of wind tunnel tests specifications.

    o Employed DEC (engineers for Museum Tower curtain wall) toperform structural calculations.

    o Study of the NOAA National Weather Service wind records forDallas.

    o Consulted with insurance underwriters and consultants.

    o Consulted with legal experts to evaluate the potential liabilitiesthat might arise from owners to the public if there werecatastrophic failures of the louvers.

    o Participated in many technical meetings.

    o Visited a recent louver clad project by Clauss Markisen inSingen, Germany.

    museum tower louver feasibility study

    Hegau Tower

    Singen, GermanyOctober 17, 2012

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    museum tower louver feasibility study

    Critical Issues Reviewed

    and Conclusions

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    o Wind Tunnel Test data from the manufacturer indicates

    that the louver system is approved for applications with amaximum wind speed of 53 mph.

    o In 2011, the National Weather Service recorded 29 dayswith wind speeds that reached between 50 and 80 mph.

    o Additionally, wind speeds increase dramatically aroundhigh-rise towers.

    museum tower louver feasibility study

    museum tower louver feasibility study

    Wind Related Issues

    Ext reme Winds

    at 42 s to r ies

    29 days in 2011with wind gusts

    over 50 mph(at ground level)

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    CONCLUSIONS:

    o Retractable louvers have not been proven reliable for gustywinds in Dallas, TX. The inability to guarantee that thelouvers will stay attached to Museum Tower during windyconditions could be potentially hazardous to the public and

    neighboring buildings.

    o Windy conditions can cause the louvers to vibrate, makenoise and potentially detach from the building.

    o Insurance underwriters have identified wind is a significantrisk factor.

    o Louvers will not descend in windy conditions, and aretherefore, not a 100% solution to reflected light.

    museum tower louver feasibility study

    Ext reme Winds

    at 42 s to r ies

    29 days in 2011with wind gusts

    over 50 mph(at ground level)

    Wind Related Issues

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    Louvers Not Designed to Mitigate

    Reflected Light

    museum tower louver feasibility study

    o According to Clauss Markisen, retractable louvers weredesigned to decrease the amount of solar heat enteringthe building and limit incoming ambient light.

    o This louver system reflects sunlight.

    o According to the manufacturer, this would be the firstproposed application for a louver system to mitigatereflection. No test data, modeling or engineering reportsexists for this new application.

    o Current louver system is manufactured from reflective

    stainless steel. Louvers with low reflectance qualities arecurrently unavailable in the marketplace.

    o Clauss Markisen has attempted to fabricate darkenedstainless steel (to reduce reflectivity) louvers, but ran intofabrication problems.

    .

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    Louvers Not Designed to Mitigate

    Reflected Light

    museum tower louver feasibility study

    o Clauss Markisen has an aluminum louver fabric system indevelopment, but the aluminum would not be as strong ordurable as stainless steel, and there are currently no windtunnel tests or engineering reports for this new product

    available for study.

    o Control of the louver system will require the developmentof a customized computer program. The manufacturerwill not warrant a program developed by another vendor.

    CONCLUSION: This stainless steel louvered systemreflects light. It is not designed to mitigate reflected sunlight.No computer control system exists to address the uniquerequirements for a louver system on Museum Tower.

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    Other Technical Implementation Concerns -

    Waterproofing

    museum tower louver feasibility study

    o Retrofitting a louver system for a 42-story tower willcreate more than 20,000 holes in the current water-tightexterior glass wall system.

    o Insurance underwriters have expressed concern that this

    presents risk for chronic water seal problems and on-going moisture damage issues.

    CONCLUSION: The attachment of retrofitted louver systempresents significant risk of exposure to moisture and water

    damage, and ongoing maintenance problems, making itextremely costly and practically impossible to obtaininsurance coverage.

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    Insurability

    museum tower louver feasibility study

    The insurance applicant (Museum Tower) will have theburden of proof regarding the safety of a unique andrelatively untested system. Underwriters will need tobe absolutely convinced that the louvers will not createincreased risk exposures.

    Insurers typically err on the conservative side bydeclining to provide coverage if any doubt exists regarding

    the engineering efficacy of an unusual or complex systemwith little or no modeling or prior real world data. Moreover,underwriters may decline coverage simply because theeffort to evaluate and understand a unique and complexengineering solution is too costly or beyond the insurersinternal engineering capabilities.

    I am certain that we would encounter significantunderwriting obstacles. I believe that there is a strongpossibility that we will be unable to procure Propertyand General Liability coverage if you proceed with thelouver retrofit.

    Alec T. Biele, Area Senior Vice PresidentArthur J. Gallagher Risk Management Services, Inc.

    November 14, 2012

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    Maintenance

    o Observations from the Hegau Tower show that thehousing headers (rectangular boxes) protruding fromcurtain wall surface and the louvers themselves requirefrequent cleaning for dirt, debris, bird nests anddroppings. The headers attract birds as a roosting site.

    o Louver headers and tracks may interfere with currentwindow washing equipment and may requiremodification.

    o Louver interior surface can only be cleaned by removingthe louvers.

    CONCLUSION: Louver system will require a continuous,expensive, laborious effort to clean and repair to prevent itfrom becoming a visual eyesore for owners as well as thosein the Arts District.

    museum tower louver feasibility study

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    Appearance and Impaired View

    SELLING A WORLD-CLASS LUXURY RESIDENTIALPROPERTY

    o Louver system requires a substantial (9x12)architectural head (rectangular box) that protrudes

    from the existing curtain wall and obscures the glassshingle system as designed.

    o Vertical louver tracks on two sides of each panel willprotrude from mullions, modifying the current flat walldesign to a deep wall design.

    o Louvers alter visibility and lighting levels withinresidences.

    o Louvers minimize interior views down (to the landscapebelow) and up (to the sky).

    museum tower louver feasibility study

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    Appearance and Impaired View

    CONCLUSION:

    Museum Tower was specifically designed as world-classarchitecture complementing the Dallas Arts District.

    The unattractive appearance of the louvers on the building,the impaired views for homeowners make the louversystem an aesthetically unpleasant treatment for both theArts District and the owners of Museum Tower.

    The louver solution is not acceptable to home buyers.

    museum tower louver feasibility study

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    museum tower louver feasibility study

    From the manufacturers representative:

    Clauss Markisen has confirmedthat they have not installed the

    system on a building as tall as theMuseum Tower.

    Clauss Markisen haveundertaken quite a large numberof retrofit projects but not on any

    tall buildings.

    Hegau TowerSingen, GermanyOctober 17, 2012

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    From the manufacturers representative:

    museum tower louver feasibility study

    I am not aware of any

    projects where the specificintention of the system was todeal with reflection.

    All the projects that I know of

    are ones where the system isused for solar and lightcontrol.

    Hegau TowerSingen, GermanyOctober 17, 2012

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    Hegau TowerSingen, GermanyOctober 17, 2012

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    Hegau TowerSingen, GermanyOctober 17, 2012

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    Hegau TowerSingen, GermanyOctober 17, 2012

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    Hegau TowerSingen, GermanyOctober 17, 2012

    Dirt and stains visibleon louvers

    Hegau TowerSingen, Germany

    October 17, 2012

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    Glare from the

    Louvers

    Hegau TowerSingen, Germany

    October 17, 2012

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    According to our research, retractable louvers have many technical and engineeringchallenges, most notably, the inability to insure that the louvers will remain attached toMuseum Tower under gusty wind conditions that may exceed the louver manufacturers

    maximum wind speed tolerance.

    Insurance underwriters appear unwilling to insure the building because of 1) the ongoingproblems of waterproofing 20,000 holes in Museum Towers faade to attach the louvers,and 2) the risk of louvers detaching from Museum Tower, and the possibility of damage tosurrounding buildings and people in the Arts District.

    Museum Tower has invested significant resources into the research of other options.

    Summary:

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