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Retrofit remains the future

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Paul Finch’s letter from London: Retrofit: an architectural hot-spot in a cold work climate

As the construction sector contemplates downturns in many sectors, there is one that will inevitably grow hugely in the next few decades – retrofit. There are three reasons why.

First, because of political, legal and practical imperatives which go beyond what our European counterparts are committed to, for example the Climate Change Act. Second, because the appetite for new construction in both public and private sectors is likely to be lower in the next decade compared with the last. And finally because there are, potentially, significant savings to be made by going down the retrofit route.

Those savings are not inevitable. The condition of an existing building may make it unsuitable for future use and it would be better to put it out of its misery. On the other hand, if the building is structurally sound and has a geometry that will work, such as a good slab-to-slab height, there are strong arguments for re-use. The number of such projects in this year’s RIBA Awards is noticeable in this regard.

These points were brought home forcibly at an AJ event last week, held courtesy of the Building Centre Trust. Peter Fisher from Bennetts Associates and Ian Harrison of Davis Langdon presented the retrofit of an ugly old slab office block in Winchester, Hampshire County Council’s Elizabeth II Court. The project was won in competition with Bennetts’ proposal being the only one that kept the original building. The retrofitted building housed almost twice as many staff, other council leases could be disposed of elsewhere in the city, and massive embodied and operational energy and carbon savings were made. As a result, Bennetts had a very happy client.

One other advantage of the retrofit approach is that it removes the risk from planning. Although a permission may still be necessary in respect of new facades or roof treatments, there will be no argument about the basic size and mass. Sometimes only building control will be involved.

This also makes a huge potential saving in terms of time: not only do you get a quick start on site, but you will generally avoid going into the ground, with all the time and cost that can entail. This can transform the budget for the project and is another example of taking out risk.

On energy, keeping the existing structure could save up to half of the embodied energy in the existing building. This is a factor that is likely to become increasingly important as energy regulation inevitably tightens.

So the upside for contractors and specialist subcontractors, as well as the design team, is more work because it is more economical to build using the existing; faster starts on site once a retrofit solution is adopted; and faster builds because below ground work is already done.

The downsides are chiefly the complications that arise from dealing with the unknown. There may be more survey work required to establish what exactly is in the building and stripping back to the structure may reveal the unexpected. In Winchester the team found asbestos that appeared to have been used for fire resistance in relation to one area of concrete slab cast thinner than the others. A tricky removal job took 12 months rather than the anticipated 12 weeks.

But this is nothing really to frighten the horses. In general it is necessary to have an even higher degree of collaboration between designers and builders than for a conventional job because there may be more one-off decisions to make about points of detail where being robust, rather than precious, is essential.

For architects who have completed a retrofit job in the past 18 months, don’t forget to enter the ‘Refurb, Rethink, Retrofit’ Awards, supported by AJ and our sister titles, Construction News and New Civil Engineer. The closing date is 8 July (www.3rawards.com). The results of good projects of this sort, even if they can’t easily be seen from the outside, deserve to be acknowledged and celebrated.

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