Topographical optimisation of single-storey non-domestic steel framed buildings using photovoltaic panels for net-zero carbon impact

A methodology is presented that combines a multi-objective evolutionary algorithm and artificial neural networks to optimise single-storey steel commercial buildings for net-zero carbon impact. Both symmetric and asymmetric geometries are considered in conjunction with regulated, unregulated and embodied carbon. Offsetting is achieved through photovoltaic (PV) panels integrated into the roof. Asymmetric geometries can increase the south facing surface area and consequently allow for improved PV energy production. An exemplar carbon and energy breakdown of a retail unit located in Belfast UK with a south facing PV roof is considered. It was found in most cases that regulated energy offsetting can be achieved with symmetric geometries. However, asymmetric geometries were necessary to account for the unregulated and embodied carbon. For buildings where the volume is large due to high eaves, carbon offsetting became increasingly more difficult, and not possible in certain cases. The use of asymmetric geometries was found to allow for lower embodied energy structures with similar carbon performance to symmetrical structures.

The 'Belfast' timber roof truss - is it sustainable and relevant today?

In the early 19th century the requirement for clear span industrial buildings brought about the development of a variety of timber truss types. The Belfast truss was introduced circa 1860 to meet the demand for efficient wide span industrial buildings. It has essentially a bow-string configuration with a curved top chord, straight horizontal bottom chord and close-spaced lattice web. Several thousand still exist in Ireland, many in buildings of historic significance. This paper sets out to demonstrate the efficiency of the Belfast truss and to show that, by modern structural design criteria, the concept, member sizes and joint details were well chosen. Trusses in historic buildings can be replicated almost exactly as originally fabricated. Results of a theoretical study are compared with the experimental behaviour of two full-scale trusses: one a replacement truss, tested in the laboratory; the other an 80-year-old truss tested on site. In addition, experimental results from a manufacturers archive material of full-scale truss tests carried out about 100 years ago are compared with theoretical models. As well as considering their significance in building conservation the paper proposes that Belfast trusses are an attractive sustainable alternative to other roof structures. The analysis, design, fabrication and testing of trusses have resulted in a better understanding of their behaviour which is not only of historic interest and fundamental to the repair/restoration of existing trusses, but also relevant to the design of modern timber trusses and the promotion of a sustainable form of roof construction.