Double envelopes, also known as double facades, are building facades with multiple layers or skins. They are used to maximize daylighting while controlling solar gain and temperature. There are four main types of double envelope configurations: box windows, corridor facades, multi-story facades, and shaft boxes. Double envelopes provide benefits like increased insulation, natural ventilation, and shading/sun control. Their performance must be considered in the context of a specific building and climate. Case studies demonstrate how double envelopes allow interior control of light and views while providing energy benefits.

1. Design Envelopes An Overview Dana al-Hasan - Dalal al-Shatti Design IV - Dr. Yasser Mahgoub

2. Building and facade orientation Double envelopes: Are multiple leaf wall assemblies used in the transparent or largely transparent portions of a building façade Outer leaf Intermediate space Inner facade

4. aesthetic Relationship of glazing to overall facade The glass wrapped facade used the glass panels as shingles on the building exterior. Glazed balconies in Venice, Italy

5. Thermal insulation Relationship of glazing to overall facade Outer glazing covers the entire surface of the façade at the Arup offices in London A “double skin glazed thermal buffer” curtain wall addresses solar heat gain as the project’s critical factor. Simply put, a shading device within the double skin absorbs solar gain and re-radiates it as heat trapped in the cavity

6. climate control Performance goals at the transparencies most double envelopes are designed to maximize daylight while controlling solar gain – a condition typical of office buildings dominated by internal heat gain . The interstitial space is used as a protected enclosure for operable shading devices that might otherwise suffer from wind damage and weather exposure.

7. active heating and cooling Performance goals at the transparencies Double envelope mitigate the surface temperature of the interior glass, reducing the mechanical intervention required to provide comfortable conditions under both and cooling modes The double envelope facade of Bayerische Vereinsbank Building in Germany has operable leaf glass louvers

8. Configurations: 4 main types Construction Strategies Box window Corridor facade Multi-story facade Shaft-box

9. Box windows Pre-fabricated curtain wall system Construction Strategies Kofmehl Building (Switzerland) Architect: SSM Architekten’s

10. Corridor facade Construction Strategies City Gate (Dusseldorf) Architect: Petzinka, Pink & Partners Pre-fabricated curtain wall system

11. Effective with regard to ventilation Incorporate service walkways of metal grating Construction Strategies Corridor Multi-story Victoria Ensemble (Koln) Architect: Thomas Van Den Valentyn

12. Shaft box Construction Strategies ARAG Turm, Dusseldorf Architect: Norman Foster

13. LEED Rating Energy and Atmosphere (35 points) Fundamental Commissioning of Building Energy Systems Minimum Energy Performance Fundamental Refrigerant Management Indoor Environmental Quality (15 points) Minimum Indoor Air Quality Performance Environmental Tobacco Smoke (ETS) Control Innovation and Design Process (6 points) Construction Strategies

14. Utilization Maintenance Requirements Efficiency of the façade can only be assessed in the context of the climate conditions of the site Each double façade must be tailored to the occupant’s function

15. Europe: Operable inner glazing leaf Control over outdoor air in the workspace North America: Interior hinge plate glass “ exhaust window” Maintenance Requirements

17. Case Study Herz Jesu Church, Munich

19. Case Study

20. Any Questions? If you are interested in this strategy you might want to consider the following literature: On the Typology, Costs, Energy Performance, Environmental Quality and Operational Characteristics of Double Skin Facades in European Buildings. Available: http://www.earthscan.co.uk/Portals/0/Files/Sample%20Chapters/9781844073894.pdf Double Skin Facades, Maria Wall Available: http://www2.ebd.lth.se/ebdhome/avd_ebd/main/personal/Harris/main/Double%20Skin %20Facades.htm Case Studies: Double FaçadeAvailable: http://www.architecture.uwaterloo.ca/ faculty_projects/terri/sustain_casestudies/ut4.pdf Case Studies: Double Facades in Germany Available: http://www.bbri.be/activefacad es/new/index.cfm?cat=5_example_building&sub=8_germany