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OLD HOUSE |
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CARE AND |
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CDAC
Conservation
Architects
www.oldhouse.info Householders
want to save on expensive fuel; governments and our consciences are
encouraging us to reduce ‘greenhouse gas’ emissions
to benefit the environment. As a result there is a lot of pressure to
cut domestic energy use and in particular to increase
home insulation. Applying
insulation to a building alters the way it
behaves. It is like the house wearing
more clothes - and many current building insulation measures work in the
same way as a warm coat, trapping pockets of warmed
air, stopping it from
drifting away and taking our hard-earned warmth. New
houses have been built with increasing amounts of roof and wall insulation for decades.
But old houses (unless they are already built from something naturally
insulating, like a thick-walled cottage with a thatched roof) would have
to have extra insulation applied in some way
to existing surfaces; this is intended to alter the environment within the building. Altering
the environment within the building can be fairly predictable
if
designing a new house from scratch. All the technical factors affecting
it (which include the balance between insulation, damp, ventilation,
materials, vapour-permeability, condensation, heating) can be predicted
in the design and building processes and
controlled using modern building technology, calculation and
the application of regulations. But an old house is already there, containing everything (known and unknown) that will interact with any new insulation: the opportunities to balance the whole are limited. Applying insulation can easily unbalance the way the fabric deals with damp, for example. If insulation is installed without understanding what will happen to damp afterwards, the danger is that damp could be retained when it was vented previously, perhaps retained within the new insulation (reducing its usefulness), perhaps held inside the building fabric (nourishing decay). Trapped damp is just as unwelcome for a house as a few days in that wetsuit would be for us. Which is why we think that if additional insulation is identified as a worthwhile energy-saving measure on all or part of an existing building, then it needs to be pursued with care: it is foolhardy to apply insulation to an old house as if it were a modern house. Our usual guidance when alterations to an old house are being considered is for specific on-site conservation-accredited professional advice - simply because every old house is different and will react differently. Unfortunately it is easy to foresee that, instead starting from informed analysis, one-size-fits-all insulation methods may be rolled out nationwide to meet short-term targets, with little thought given to the potential pitfalls and longer-term effects. Just slapping insulation onto old buildings
to
improve their performance, without
considering how they will
work
together, is probably as
recklessly naïve as expecting
an
ordinary car to run
better if
it had rocket fuel in its
tank. Any improvements might
be quite
temporary and ultimately costly – to the
owner and to the environment. Insulation
is often coupled with thorough draught-proofing. Old houses
which originally had open fires were
intended
to work with lots of permanent, benign minor draughts (to feed oxygen to
the fires that burned all year for cooking) that kept the house’s
structure dry. And
‘dry’ for an old house means survival – better to resist
rot,
woodworm and mould. But unlike those cements and paints, insulation does not even have to be impervious to risk trapping damp in an old house or cottage, simply mis-applied (in a way that inhibits adequate 'breathing'). It is a delicate balance that even affects more predictable modern buildings: the UK building regulations were amended late last century to address problems arising partly from inappropriate insulation placement as well as reduced ventilation in roofs, for example. There have also been similar moves to address condensation occurring within the walls of certain modern constructions. Arguably, our older building stock is generally even less well understood and less well protected. So far this article has only touched on the technical side of things; there is also the visual
side. How do you apply extra insulation to an attractive old house or
cottage without covering up or re-building some of the
authentic old
surfaces that are responsible for its visual appeal
- and which probably
also account for a great part of its financial
worth? You can’t just
whip off all the insulation when your friends pop round or when you want
to sell the place. Similar
arguments have been aired for years about the ugliness
of replacement double-glazed windows and doors manufactured in industrial materials, compared
with the characterful hand-made originals. There are other,
cost-effective, ways to insulate original doors
and windows on old houses while retaining their visual contribution to the value of
an old house or cottage intact. Well, a house that has lasted several hundred years is likely to have been originally built using largely locally-sourced sustainable materials and sustainable low-energy processes. That’s good in sustainability terms, and much better than we can manage now in mass house-building. And then there's the durability of those materials and the energy that was embodied in old houses, which may have lasted a century - or two, or three or more. This represents a really excellent environmental investment. Cottages up and down the country have already comfortably out-performed the design-lives often quoted for modern energy-efficient houses, many times over. Not only that, our oldest houses and cottages were designed to use wood as a fuel. Wood as a heat source is now frequently credited as being almost carbon-neutral. So that's good too, especially as few modern homes have an effective option to burn wood. So, if old houses are already so incredibly sustainable why do we need to tinker with them to make them...sustainable? The answer is that one critical element has changed from sustainable to unsustainable over the last hundred years. The occupants. Not only do people now tend to want to use old properties unsustainably - for example by heating every last inch of them beyond the necessities for health and comfort - those homes may also get redecorated in ways that also undermine the houses' health. And if all this damages the property, then we will be tying up more energy and materials in future repairs. That isn't energy-efficiency. Insulation is about conserving the energy we have just consumed, and it can usually be improved, but so can our attitudes to the energy before we use that. People can, and do, live in old houses without spending more on energy than their neighbours in modern houses. They do this by simple common-sense measures and a robust attitude to avoiding waste. This article is certainly not anti-insulation, it aims to add some perspective to a growing well-intentioned trend that is easily misapplied and which is feared to have the potential to harm old houses in the long term, and so cause energy and materials to be used up needlessly in the future mending them. At
oldhouse.info
we think that energy-efficiency is important and we understand
that people want to be as comfortable as their old houses can make
them (and that there will inevitably be two-way compromises between past
standards and modern expectations). To find out more about the general requirements of old houses and
cottages - and how they affect the insulation of
windows, doors, walls, floors and roofs – plus some ideas
to develop, starting with simple
and inexpensive measures that may be appropriate to improve
your own home's insulation – take a look (at
the green pages especially) inside these books…
...and please take a look at the rest of our site, and our other books and downloadable articles. HOME
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