Payback
time
Evidence suggests that many school
iStock
refurbishments do not deliver on energy
efficiency. Dan Lash pinpoints key
an understanding of exactly where and when energy is
being consumed. The revised CIBSE TM39 can assist
measures that can help to achieve in devising a metering strategy. The measured data and
savings and return on investment
analysis should be compared with benchmark data to
establish where effort should be concentrated. Benchmark
data can be found in CIBSE Guide F, CIBSE TM46, and in
he zero-carbon agenda has been gathering numerous publications from the Carbon Trust.
T
pace nationally, with a recent plethora of policy A full energy audit of the building should be undertaken,
documents and consultations. One policy using the principles described in CIBSE Guide F. The
target that has been in place for some time is Carbon Trust Schools Sector Walk Around Checklist (CTL067)
for all new schools to be ‘zero carbon’ from 2016. But the can also be used, as well as the recommendations from
evidence for refurbished schools suggests that this may the DEC advisory report that will exist for every school
prove difficult to achieve, as it seems that energy saving with a floor area above 1000sq m. From these sources,
measures do not necessarily manifest themselves in more a strategy to reduce energy consumption should be
efficient buildings. devised, with appropriate targets, following the hierarchy
A recent analysis of results from the first year of Display of first addressing user behaviour, and then improving
Energy Certificates (DECs) by research body BRE stated: the efficiency of both the building fabric and the installed
‘DEC ratings for some schools recently refurbished to services.
higher energy efficiency standards under Building Schools Only once these have been addressed, should more costly
for the Future and the Primary Capital Programme renewable energy solutions be pursued, though clearly in
appeared to be no better than average’ (see www.bre.co.uk/ the longer term all strategies including renewable energy
newsdetails.jsp?id=606). will be required to meet the testing emission reduction
Analysis by consultancy AECOM of schools that have targets that are necessary.
been refurbished has shown that refurbishment typically
reduces carbon emissions by about 5 to 20 per cent (see Efficiency measures
chart). This study, carried out for the Department for Estimates of energy savings can be made using information
Children, Schools and Families Zero Carbon Task Force, from sources such as Annex 36 (the international retrofit
is due to be published soon (see http://www.dcsf.gov.uk/ project – see Web links, left) and the Carbon Trust (including
pns/DisplayPN.cgi?pn_id=2008_0113). the new ‘How to implement’ series of publications which
It would seem likely therefore that in practice, some contain worked examples for numerous technology
carbon savings are being achieved through refurbishment, options). Having refined the efficiency options, installers
Web links
though these savings are not as high as they need to be to should be contacted to discuss specific technical issues for
www.cibse.org
meet our national carbon targets. So how can we as an the project, and to establish prices.
industry improve on this situation? The following efficiency measures have been adapted
www.bre.co.uk
from some of the above sources, though clearly actual
www.annex36.com
Energy strategy costs, savings and payback periods are specific to site and
www.carbontrust.co.uk At the outset of a project, there are many competing envisaged usage.
www.partnershipsforschools.org.
potential solutions that may be confusing for a client. • Space heating: This can account for 60 per cent of energy
uk/about/aboutbsf.jsp Possible consequences of this are relatively expensive use in an existing school. It is important that heating set-
www.partnershipsforschools.org.
renewable technologies plastered onto poorly managed or point temperatures are set correctly (18C in classrooms,
uk/programme/primaries.jsp inherently inefficient buildings. It is important therefore 15C in corridors) to avoid energy penalties. Whilst boiler
www.aecom.com
that a sensible and consistent approach is taken to reduce replacements often have relatively long payback periods
emissions from existing buildings. in energy terms, the additional cost of specifying a more
www.dcsf.gov.uk
The first step should be to measure consumption using efficient boiler at the time of replacement will have a low
www.usablebuildings.co.uk
metered data, preferably at half-hour intervals, to build up payback period. Boiler sequencing controls, electric heater
30 CIBSE Journal February 2010 www.cibsejournal.com
CIBSEfeb10_School_pp30-31_refurb.indd 30 22/1/10 11:09:37
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