Tensile Structures as Microclimate Modifiers TS3 – Tensile Structures as Microclimatic Modifiers 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 TS3 – Tensile Structures as Microclimatic Modifiers 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. TS3 – Tensile Structures as Microclimatic Modifiers Thermal Flows On Thin- Shell Structures TS3 – Tensile Structures as Microclimatic Modifiers 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. TS3 – Tensile Structures as Microclimatic Modifiers 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. TS3 – Tensile Structures as Microclimatic Modifiers 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. TS3 – Tensile Structures as Microclimatic Modifiers 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. TS3 – Tensile Structures as Microclimatic Modifiers 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. TS3 – Tensile Structures as Microclimatic Modifiers 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 TS3 – Tensile Structures as Microclimatic Modifiers 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. TS3 – Tensile Structures as Microclimatic Modifiers THANK YOU ! Ioannis Rizos / AA Tutor .