Sweet Home’s Windows

The love affair that the high tech school of architecture has with glass and steel shows no signs of abating. As the frontiers of performance are challenged the gauntlet to find solutions is being taken up by structural, façade and M&E engineers.

The Renzo Piano Building Workshop designed ‘Shard’ building currently under construction in the pool of London’s regeneration area is a case in point. When construction is completed in 2012 the 72 storey ‘Shard’ will be a little over thee hundred meters tall, which will enable it to lay claim to be the tallest building in the European Union.

The building has been designed for ‘mixed’ use, in that the first 28 floors with the widest floor plates have been designated for office use, the next few floors have been set aside for restaurants and viewing galleries, followed by 12 floors allocated for an hotel. The floors above which, as the floor plate narrows further, are to be residential. This particular building, designed by an internationally respected architect, will almost certainly become one of the icons in the London skyline.

The ‘Shard’ will have a triple glass façade to improve the buildings energy efficiency. The façade will contain a computer controlled Venetian blind system which will shield occupants from the sun and reduce the need for air conditioning. The heat gains in the office areas, from the likes of computers, will be recycled to help heat the floors higher up.

The challenges it has presented to the professional teams responsible for the various design details have no doubt often been unique and equally the solutions they have had to use have had to be innovative. Yet it could be argued that to an extent this is true for all new buildings irrespective of their size or intended use. Ultimately all buildings should meet the design criteria of the functions for which they were intended.

It is the responsibility of the professionals involved to provide the correct solution to the challenge their particular discipline is faced with. For the façade engineers and designers their decisions and choices will have to work in conjunction with the choices and decisions of a variety of the other professional disciplines involved in the project.

For example the choice of fenestration incorporated into the façade will have an impact not only on the appearance and configuration of the building but also in the areas of smoke evacuation, the heating and ventilation strategy, the size of the floor plate in terms of room dimensions, the energy consumption, thermal efficiency, acoustic properties, night cooling, virtually every aspect across the board. Increasing the glazing area of a building can have a positive effect on the reduction of energy consumption for heating and lighting but may have a negative impact on the energy use for cooling.

The façade design has to balance these needs while at the same time take into consideration a variety of climatic conditions, summer and winter. The issues of wind speed, pressure, air flow and buoyancy will vary greatly from the ground floor to the fiftieth. Yet the need for thermal comfort and indoor air quality for the occupants will remain the same. Fortunately for the professionals involved in the design process increasing sophisticated programmes for computer modelling are available to help them make the correct choices.

Extensive design development work can be conducted at a pre-planning stage with computerized thermal modelling to show the probable energy and CO_² ratings of the proposed building.

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Text by Ken Evans, Securistyle National Specifications Manager,images by Securistyle