Trade Secrets: Back to School

Updated: Jun 4, 2019

Trinity Road is a classic example of an adaptive re-use project: taking an old school building and re-purposing it to accommodate 9 commercially rented apartments. Whilst award winners such as the Studio for Juergen Teller and the Levring House grab headlines, the bulk of Harris Calnan's work is made up of more pragmatic projects that have modest budgets, tight programmes and which require us to provide workable solutions to unexpected problems thrown up by buildings that often do their best not to co-operate!

As works to Trinity Road draw to a close, we took the opportunity to speak to project architect Hannah Davies at reForm Architects, about the unique challenges and risks associated with these kinds of projects and what tactics or strategies were used to deal with them:

With much of the existing building to be retained on a very confined site, did this factor into your design decisions or affect the building methodologies that you ultimately chose?

The project is particularly challenging because it comprises both re-use and new-build components, both of which required very different design methodologies that need to be reconciled to the same cramped site.

For the existing buildings the challenge was to squeeze as much usable space as possible from the existing structures and this was done primarily by making use of the huge amounts of space in the roof once the structures had been suitably adapted. The rest of the design work revolved around trying to optimise the layouts so that the retained walls and levels contributed to, rather than fought against, an efficient layout that minimised circulation space and maximised usable space for the high value, habitable areas such as bedrooms and living rooms.

Due to the constrained nature of the site and its awkward logistical location along a TfL red route, a wholly traditional approach to the construction provided the best economies of scale and organisational simplicity for the construction phase.

For these kinds of projects, the building regulations require that the retained buildings must be improved so that their performance matches that of new buildings. Did you work with any specialist consultants and how did this inform your design approach?

We worked closely with a specialist energy and sustainability consultant from EB7 to develop a strategy to achieve a 19% reduction in CO2 emissions which was required by the planners. The initial strategy involved a very advanced and high tech air source heat pump unit and PV panels on the new extension roof.

However, after tendering the project it became clear that this approach was too expensive and so we developed a more low tech strategy through changes and tweaks to the glazing, insulation and services specifications that were none the less able to achieve the same reduction in CO2 emissions, but for a much lower cost. Whilst these changes did mean that there were trade-offs in terms of longer term benefits, it meant that the project could go ahead within budget.

With existing buildings, particular older ones such as this, there is always the risk of hidden surprises emerging when work starts and material is stripped away. What was your approach to managing risks such as these during the design phase of the project and did it pay off?

In an ideal world we would always want to have perfect knowledge of any building or structure that we are going to work on. But whilst exhaustive surveys and opening up works can help to eliminate risk, they can be expensive and time consuming and so a balance has to be struck between managing risk and controlling the costs.

In the case of Trinity Road, we undertook an number of opening up works as part of the design process so that we could establish the existing roof structure, the adaptation of which was a critical part of our design approach.

But despite these investigations, when demolitions commenced at the start of the contract stage, they revealed an array of piecemeal modifications and alterations to the structure, particularly the original roof that was to be retained, that could not have been reasonably expected.

The scale of these discoveries was so great that we had to completely re-think parts of our design and it was only by working in concert with the contractor and structural engineer that we were able to minimise both the cost and time implications on the project.

Even in hindsight we would not have changed the way we approached the project. Yes, we could have carried out greater investigations but the result would probably have been much the same and the additional time and expense incurred may have even been greater than was ultimately the case. Our experience on this project showed that whilst you cannot anticipate every problem, by choosing collaborators that are capable and keen to solve problems, you are often providing yourself with a far better means of dealing with the unexpected.

Unlike new-build projects that begin with a clean slate, adaptive re-use and refurbishment projects require the design and construction teams to negotiate far more risk. But the "disaster behind the plaster" doesn't have to be catastrophic. As our experience with Trinity Road shows, with good lines of communication and a problem solving approach, it is possible to manage the risks of these complex projects and ensure that a positive outcome is not left to chance.

#technical #reFormArchitects #adaptivereuse #refurbishment #extension #Linked

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