Paolo Beccarelli

An Evaluation of Thermal and Lighting Performance Within an ETFE Structure

This paper reports on a study into the thermal and lighting environment of an enclosed ethylene tetrafluoroethylene (ETFE) foil-covered structure. This is based on the on-site monitoring over set periods of time in summer 2014 and winter 2015. ETFE foil is a relatively new highly-translucent construction material that has been used in some high profile projects around the world. In a unique development, this project looked at a new building product that makes use of ETFE film and tensioned it over aluminium frames to create a modular ETFE-covered panel that can look similar to and can be installed as a replacement for glazing. This opens up new markets for the use of ETFE film, such as agriculture and horticulture, and allows for possibilities such as urban and vertical farming or the retrofitting of existing commercial and residential greenhouses. A test structure was constructed from the ETFE-covered panels. This paper will report on the impacts of solar radiation on the thermal environment as well as the relative humidity within this enclosure so that a more holistic understanding of the thermal comfort can be obtained. The second section will explore the internal daylighting environment including analysis of the daylight factor within the structure and luminance mapping to examine brightness and visual performance and its effect on the perception of space and objects within. The paper will conclude that the temperature within the enclosed ETFE structure can become too high during the summer months and may require heating when occupied during the winter months. The research also finds that the daylight levels can be too bright if the internal space were to be used regularly by occupants, although this may be beneficial for plants. In both cases, overheating and solar gain issues can be resolved through appropriate shading and ventilation.

Designing with Membranes

This contribution offers an introduction to membrane structures and the experimental approach which has characterised this building system since its origins. In particular, the chapter offers an overview of the design approach currently adopted for tensioned membrane roofs.

Textile shelters for archaeological or heritage areas: design references

The paper gives a short summary of the properties of tensile surface structures made out of technical textiles. Tensile surface coverings can protect archaeological or heritage areas against deterioration and revalue these sites for visitors. Covering systems have to combine several preservation requirements like protection from environmental and pollution load, low maintenance, compatibility of new materials, reversibility, ease of disassembly, reusability, adaptability and flexibility. Textile lightweight structures present a great number of advantages like easy mounting, natural aeration, elegant design and filtered natural day lighting. Building on archaeological or heritage areas is a delicate task. Architects have to compare alternative approaches and find solutions appropriate for the situation under consideration. The discussion on built shelters, presented together with the underlying concepts, the performance, the used primary structure and the chosen coated fabric can support design decisions in future. A recent research activity has been started in Sardinia (Italy). The aim is to analyse technical aspects and to clarify which solutions really serve to protect while others contribute to further damage. Prototypes have been built in order to evaluate the behaviour of some innovative textile materials in comparison with traditional ones.

Recent Applications and Potentialities

This chapter presents two recent examples of biaxial tests for advanced applications such as strain controlled tests and flexible solar cells. The example of a strain-controlled biaxial test aims to investigate the potential offered by new testing equipment and the controlling software in order to reproduce strain histories assigned to the central zone of the cruciform specimen. The example of a biaxial procedure applied to laminated lightweight, thin-film, organic solar cells and ETFE foils offers a groundbreaking example of the future applications for biaxial tests due to the increase of lightweight and flexible building products.

Brief Review of the Membrane Structure Context

This chapter offers a brief introduction to tensioned membrane structures and describes the recent developments in their design. The most relevant international associations operating in this field are presented together with the most significant research projects funded in the last decades in order to promote the use of membrane structures. The current design codes and testing standards are described in detail with a focus on the structural design and the mechanical performance of architectural fabrics and foils.

Biaxial Testing Apparatuses and Procedures

This chapter describes the mechanical data required during the realisation of architectural tensioned covers, the main testing procedures and the testing equipment currently in use for biaxial testing. In addition, the chapter presents the first inter-laboratory study between four research centres which repeated the same biaxial test originally designed for the Juventus Stadium in Turin. The study includes the description of the testing procedure and apparatuses, the overall behaviour of the biaxial machines and the level repeatability of the tests according to the values required by the designer of the membrane roof.

The Development of Biaxial Testing Devices and Procedures for Architectural Fabrics

This chapter analyses the technical requirements for the development of biaxial testing devices and procedures for architectural fabrics. The description includes the overall shape and stiffness of the frame, the sample shape and dimensions, the clamping system, the stroke of the actuators, the loading profile, the transducers for force, strain and displacement, the temperature and humidity conditions, the control system and the calibration. Finally, the chapter describes the aspects which should be considered in the development of a testing protocol.

The Design, Analysis and Construction of Tensile Fabric Structures

Coated fabrics and foils, used for architectural applications, are presented in the first part of this chapter. The current fibres and coatings available on the market are described in detail according to their performance, the advantages/disadvantages and current applications in architecture. The second part is focused on the most common typologies of tension structures, the design process and the comparison with conventional roofing forms. The main physical and digital techniques for form-finding, static and dynamic analysis, patterning and manufacturing are described in detail.