The energy-saving benefits of refurbishing

Helping to make possible the upgrading of the 1970s Tricorn House into modern office accommodation is the incorporation of underfloor air conditioning and cabling into a 175 mm-deep floor void and a 78 mm-deep ceiling void.
Upgrading existing buildings rather than demolishing them avoids the loss of embodied energy — making a valuable contribution to avoiding carbon emissions. One problem to solve is how to squeeze services into restricted slab-to-slab heights — as GLAN BLAKE THOMAS explains.With global warming contributing to increasingly warmer summers, older office buildings require air conditioning to offer comfortable working conditions. However, many of these buildings do not have sufficiently high ceilings to easily retrofit traditional air conditioning, resulting in either major structural changes or, if this is impossible, demolishing it and building a new one. Embodied energy Both options generate high carbon emissions at a time when the UK is struggling to meet its reduced carbon output. It is important to remember that 10 to 20% of the energy used in buildings over their lifetime is in the form of embodied energy incorporated into materials and in the process of building itself. Instead of demolishing a building and starting again, it is far more environmentally considerate to recycle buildings. However, reduced ceiling heights in older office buildings remain a problem for many developers when faced with refurbishing older offices. Retrofitting a typical fan-coil, VAV or split-system air-conditioning into a ceiling on such a project usually requires the creation of a false ceiling, often around 450 mm deep. This is not generally practical, so consigning the building to a second-class existence or demolition. However, installing air conditioning under the floor can provide a solution. One example is AET’s Hiross Flexible Space System, where the floor void can easily be used as a plenum to distribute conditioned air to office space instead of installing fan coils in the ceilings. Using a raised access floor instead of a false ceiling for air-conditioning, ventilation, cable and power distribution services brings a net height saving per floor of about 450 mm, since there is no longer a need for 600 mm above the ceiling for ductwork to service the air conditioning. Tricorn House, an iconic landmark of the Birmingham skyline since the 1970s, is a good example of an office building which was originally marked for demolition until the alternative solution of using underfloor air conditioning with shallow air diffusers was discovered. Iconic Tricorn House is a multi-let, 12-storey office building with a total lettable area of 14 000 m2. Commercial Estates Group (CEG) has completely refurbished it and constructed a new undercroft reception/breakout facility with café. To transform Tricorn House from an outdated 1970s office building into modern, premium-rent office space with an easily reconfigurable working environment, CEG used the Hiross Flexible Space System from AET to maximise space, comfort, potential lettability and rental income. Andrew Wilkes, from consulting engineers Andrew Wilkes Management, was the workplace engineering consultant brought in by CEG before they bought the building. He explains: ‘If I could come up with a modern, quality internal workplace that added value, CEG would buy the building. Basically, the AET concept allowed a building that might not otherwise be retained and reused to be refurbished with an excellent internal environment.’ Tricorn House was initially designed and constructed to high standards for its day. However, the perimeter fan-coil units had reached the end of their life and their position restricted flexible layouts. Raised floor To upgrade the building using traditional means, a cable-management system would have required a raised access floor of perhaps 150 mm, while retrofitting ordinary air conditioning typically requires a new false ceiling 600 mm or more deep. The Flexible Space System solved this problem. Andrew Wilkes explains: ‘I devised a concept that allowed the whole of the floors to be let with air delivered via the floor void —a very shallow void of just 175 mm! The ceiling void I wanted was only 78 mm, and I obtained a very shallow recessed luminaire.’ The duct-free air-conditioning and ventilation system plus all cabling and power distribution services are located in the floor void. This approach eliminates the need for a ceiling void of any substantial depth, saving about 450 mm per floor compared to ordinary air-conditioning solutions. Andrew Wilkes further explains: ‘Without underfloor air conditioning there is no doubt that the building would have reached the end of its useful life and that eventually it would have been demolished to make way for a new structure. This solution is truly sustainable with embodied energy of the building being retained.’ Another older office building which has used underfloor air conditioning to maximise the floor to ceiling height and provide a flexible air-conditioned environment is No.1 Cavendish Place in London. The underfloor air conditioning allowed O&H Properties to deliver the high levels of air conditioned comfort demanded by modern commercial tenants while preserving the architectural integrity of the project.
— In central London, No. 1 Cavendish Place has been brought up to modern standards with the help of underfloor air conditioning. Note the oak panels for the raised access floor.
‘We wanted to move away from the traditional office space to differentiate this building from others on the market. The ability to maximise the floor to ceiling height for a truly comprehensive look was fundamental to the interior concept,’ explains Alison Allen, project manager at O&H. Specified and procured by Surrey-based project consultancy, PSM Project Services + Management, AET’s system covers over 1500 m2 on four floors of the building. Alison Allenadds: ‘AET were able to source and supply distinctive oak panels for the raised access floor. The overall effect is visually stunning, while its potential for flexibility will deliver significant cost advantages over the life of the building.’ Sustainable options Whole-life costs and embodied energy will become increasingly important in construction as the environmental movement escalates its pace to reduce carbon emissions. Developers are already aware of the direction the market is going and have begun to offer sustainable options in their projects. Recycling buildings rather than starting from scratch is a key way to keep a building’s carbon footprint low, but high-specification demands also need to be met to provide office accommodation that is demanded by the market. With the increase in summer temperatures, air conditioning is part of the specification that developers cannot afford to ignore, so alternative solutions to traditional cooling systems now need to be considered. Glan Blake Thomas is managing director of Advanced Ergonomic Technologies.
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