Posted on 02/01/12
It is 2005, BB101 has been launched and we are looking forward
to a new era of education. School buildings will be built which are
wonderful learning environments, which provide appropriate amounts
of fresh air, which keep occupants comfortable temperature-wise and
which ensure that the buildings are energy efficient.
It is now 2011 and how have we done? Well, a mixed bag of
results is probably the correct judgement. In terms of temperature
regulation, there are still examples of buildings which overheat in
summer. Sometimes this is because the buildings ended up having
more heat load than was originally intended. In other cases it is
because the ventilation rates provided were just not enough. It is
really important that the industry provides the right amount of
ventilation area if the building is naturally ventilated. Larger
vent areas do cost more because there is more physical equipment or
more opening window area - but unless we do what the models ask us
to, we'll end up with buildings which overheat. At Breathing
Buildings we launched the online design tool a
year ago to help designers ensure they get the areas right for
summer - it has been heartening to see so many people using it. The
comments we get from end-users are positive.
However, it is not just the summertime conditions which can
provide designers and users with problems - the wintertime
conditions can also be problematic. In fact, our experience is that
the winter conditions can be the ones that hurt us most when a
design is flawed. Firstly, if there is inadequate automation and
control, classrooms will be under-ventilated. I was horrified to
learn only last month that one system which has been used in 24
schools was found to remain in the closed position for 80% of the
time in winter! The "system" clearly is not providing the minimum
ventilation needed for winter. Needless to say, it is not a
Breathing Buildings system which was being highlighted. The
observation made by one of the delegates at the CIBSE Natural
Ventilation Group meeting on 4 Oct in London where the research was
presented was that if the high level dampers had been opened, then
occupants may have been subjected to cold draughts.
So, the second problem lies with pre-heating of fresh air in
winter. Martin Liddament gave a great talk at the same CIBSE
meeting explaining that from a heating perspective and energy
balance, classrooms should basically run for free for external
temperatures above ~6C. I agree - there is typically enough heat
generated by the people, lights and IT to eliminate the need for
heating until external temperatures fall below 6C.
The ventilation guidelines for schools are being revised right
now. Fortunately, it looks as though the new guidelines will
mandate that ventilation systems need to be provided which not only
ensure minimum rates of ventilation are provided in winter, but
that they are designed to do so without causing cold draughts. The
guidelines will also state that pre-heating of air needs to be done
in an energy efficient way. This means that there will be more
thought about just when heating will actually be used, which of
course in turn should result in lower energy schools.
So, as we enter 2012, perhaps now we should all live the dream…
school buildings will be built which are wonderful learning
environments, which provide appropriate amounts of fresh air, which
keep occupants comfortable temperature-wise and which ensure that
the buildings are energy efficient. I look forward to more
buildings adopting the Breathing Buildings e-stack mixing
ventilation approach for winter, to help move us towards low energy
schools, and of course working with us to size the overall
ventilation system properly with so that we have lovely cool summer
conditions too.