Tensile Structures as Microclimate Modifiers. TS3 Tensile Structures as Microclimatic Modifiers

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1 Tensile Structures as Microclimate Modifiers

2 What Materials are used in Tensile Structures? A tensile structure is a construction of elements carrying only tension and no compression or bending. Fabric for clothing was the first material used in tensile structures. Modern manifestations include other forms of fibrous material such as Fiberglass, Polyesters and Polymers such as ETFE. Such structures are classified as thin-shell structures since there s only a thin layer of material separating indoors from outdoors

3 Thermal Flows On Thin- Shell Structures Thermal flows are important to any architectural design and have been for centuries. As an inhabited structure a Thin-Shell Structure must be a comfortable environment However, whilst the structural design can be approached with almost total confidence, the environmental performance of the spaces they enclose is still relatively poorly understood.

4 Thermal Flows On Thin- Shell Structures

5 Thermal Flows On Thin- Shell Structures The thickness of the fabric membrane, typically around 1mm permits the skin to function as a passive filter, capable of modifying both thermal and light levels within the enclosed space to minimise reliance on conventional energy sources to control the internal environment. Selection of materials with appropriate optical properties offers a means of creating spaces where daylight levels are accentuated or creating more protected shaded spaces.

6 Use of Materials and Topology to Manipulate the Internal Environment Tensile structures can be used as microclimate modifiers in a number of different ways Selection of materials with reflective properties and strategically defined openings offer a means of creating spaces where heat can be retained, or dissipated within the enclosure.

7 Example: Khan Satyr - Astana, Kazakhstan Temperatures in Astana can drop to -35 degrees Celsius in winter and climb as high as +35 degrees in summer.

8 Example: Khan Satyr - Astana, Kazakhstan Temperatures in Astana can drop to -35 degrees Celsius in winter and climb as high as +35 degrees in summer. The three-layer ETFE envelope is designed to shelter the enclosed accommodation from weather extremes and to allow daylight to wash the interiors.

9 Khan Satyr - Astana, Kazakhstan Temperatures in Astana can drop to -35 degrees Celsius in winter and climb as high as +35 degrees in summer. The three-layer ETFE envelope is designed to shelter the enclosed accommodation from weather extremes and to allow daylight to wash the interiors. A unique ventilation system utilizes buoyancy forces to drive hot air out of the structure in summer months, whilst retaining heat in winter months.

10 Example: Denver International Airport, USA Temperatures in Denver can drop to -8 degrees Celsius in winter and climb as high as +30 degrees in summer. The two layer fiberglass envelope is designed to shelter the enclosed accommodation from weather extremes. The internal surface is highly reflective to prevent re-radiation of heat absorbed in the daytime to the night sky. A clever ventilation mechanism utilizes natural stack effect to effectively remove heat build up over warm periods

11 Rules of Thumb to Microclimatic Modifiers in Thin-Shell Structures Every enclosed structure needs adequate levels of fresh air to ensure a healthy and comfortable environment Use low level openings on multiple orientations, combined with high level openings Use the natural form to drive ventilation airflow via natural means i.e. stack ventilation Select the reflectivity and transmissivity properties of the tension material carefully, based on the local climate/microclimate Warmer climates should have large openings at high level combined with low reflectivity materials, to flush the heat out. Colder climates should have smaller openings at high level combined with highly reflective materials, to keep the heat in.

12 THANK YOU! Ioannis Rizos / AA Tutor