2012 Annual Report - Jesus College - University of Cambridge

CHAPEL COURT I Jesus College Annual Report 2012 15
so that the specific detail of the different buildings is respected. How the alterations of
the twenty-first century should “read” is therefore a major issue. When spaces are
subdivided in new ways, how should the new insertions be expressed? One extreme
would be to replicate the style of the two buildings concerned, but of course nineteenth
and early twenty-first century college rooms did not have all the small bathrooms we
now demand, so the proportions of the rooms were different, and rigidly “period”
detailing would look curious. The other extreme would be to treat new insertions as
entirely distinct: plastic “service pods”, for example. In common with most architects
engaged in such work, BGS have aimed to steer a middle course: the insertions will be
clear to anyone who seeks to discover these things, but unobtrusive enough not to
announce themselves unnecessarily to the majority who do not. The staircases will be
practically unaltered, so that superficially it will seem as if more than £11 million has had
little noticeable effect.
Less obvious still are the efforts the design team have gone to in order to minimise
carbon emissions. Spurred on both by the City of Cambridge’s planning requirements
and by the college itself, the services consultants, Hoare Lea, assessed the various
options. Those areas of the south-facing roof that are sufficiently shielded from view not
to upset the Conservation Officer have had solar panels placed on them, which pre-heat
hot water for showers. An alternative would have been photovoltaic cells and the cost
benefits of the two systems are finely balanced; both feed-in tarrifs and manufacturing
costs have changed since the choice was made but the solar-thermal solution is still
reckoned to make a greater contribution to carbon reduction, with a 15-year pay-back
period. In addition, ground-source heat pump technology has been employed. Its
contribution to carbon saving is considerably more than solar-thermal installation, but
the pay-back period is longer because of the capital cost of sinking 16 bore holes to a
depth of 150 metres – about 20 years. GSHPs are most effective at producing low-grade
Eric Gill’s sculpture over the Angel Gate