AbstractOften, large modern buildings such as high-rise office towers are enclosed by lightweight facades made up of prefabricated, aluminium-framed panels. Worldwide, the mass of metal required to build these unitised curtain wall systems is in excess of two million tonnes annually, and is increasing. Much energy is required to release metallic aluminium from its naturally-occurring oxides, and therefore, if these walls can be built with less metal, humanity will benefit not just because urban development will be less costly, but also because it will be environmentally more benign.
This thesis, in which previously unpublished research findings are presented alongside peer-reviewed journal papers, identifies strategies that can be employed -- by architects, facade engineers and the authors of structural codes -- to minimise the use of aluminium. These guidelines are abstracted from the results of research carried out in various ways.
Well-optimised extrusion shapes are found numerically, for tens of thousands of different facade layouts, using a genetic algorithm linked to a parametrically-controlled geometric model. The technique reveals that better optimisation can reduce, typically by 20% or more, the amount of aluminium in real buildings' bespoke curtain walls. Also, in common facade configurations, adjusting the design criteria and locations of attachment brackets can bring further savings of 40% or more, without affecting the wall's appearance or structural performance.
Existing structural analysis procedures are examined, errors and anomalies in the literature are pointed out, laboratory tests expose substantial shortcomings in the accepted idealisations, and new algebraic descriptions are proposed then validated.
National governments recognise the importance of, and are keen to enhance, the thermal performance of facades. However, this research demonstrates that much greater energy savings could be achieved, in buildings with curtain walls, simply by providing design professionals with knowledge of the methods needed to make efficient use of aluminium.
|Date of Award
|22 Jul 2020
|Paul Shepherd (Supervisor), Mark Evernden (Supervisor) & David Metcalfe (Supervisor)
- curtain wall
- aluminium extrusion
- structural optimisation
- genetic algorithm