The art of humidity control€¦ · Outside the building, estates with orangeries and orchard rooms...
Transcript of The art of humidity control€¦ · Outside the building, estates with orangeries and orchard rooms...
MUSEUMS AND GALLERIES MUSEUMS AND GALLERIES
42 November 2018 www.acr-news.com
The majority of indoor environments are able to
tolerate small variations in humidity and temperature
with no ill eff ects for the occupants – for example,
a relative humidity (RH) range of 40-60% is acceptable for
most workplaces.
This is not the case, however, for spaces that house
delicate objects such as those typically found in museums
and galleries. There are also a number of other objects that
may not be considered delicate, but require a controlled
environment to prevent deterioration.
A case in point is vintage vehicles and, indeed, newer
vehicles that are being stored for extended periods. Vehicles
are particularly vulnerable to damage to bodywork and
interior fabrics due to high humidity. High moisture levels
can accelerate corrosion of metallic surfaces, and a build-up
of moisture in fabrics accelerates degradation and may even
lead to mould growth.
Historically, the approach in these applications has been to
use heating to ensure the air doesn’t fall below a particular
temperature. However, experience shows that controlling
humidity through dehumidifi cation, rather than by simply
heating the space, is far more eff ective at protecting the
vehicles, whilst also optimising energy effi ciency.
How this achieved is largely determined by the size of the
space. In a large storage space, desiccant dehumidifi ers are
the ideal solution. Models range from free-standing mobile
units to larger bespoke designs, with drying capacities from
0.6 kg/hour to 162 kg/hour and air volumes up to 24,000
m³/hour. These also provide a low level of heating that
supports the dehumidifi cation process and helps to gently dry
vehicles that have been garaged whilst still wet from rain.
For smaller spaces, refrigerant dehumidifi ers are usually a
more cost-eff ective option for preventing the degradation of
vehicles.
There are many other situations that may not be typically
considered as ‘close control’ applications, but will benefi t
from maintaining RH within a relatively narrow range.
For example, several top hotels in London have fi tted
humidity control systems to their wine cellars to prevent the
corks from drying out, as well as in their humidors to keep
cigars in perfect condition. Similar principles apply to the
houses and apartments of the well-to-do - to protect their
furs, works of art and antique furniture.
And if they happen to be rock superstars they may well
require humidity control to protect guitars, harpsichords
and other sensitive stringed instruments. Considerably less
common was a recent request to control humidity in a space
where natural coral was on display, to maintain its natural
colours.
Outside the building, estates with orangeries and
orchard rooms require not just the very best glasshouse
technology but also very precise humidity control to simulate
Mediterranean conditions and enable their exotic plants to
fl ourish.
Arts and antiquities
The art of humidity controlWhile eff ective humidity control is important for any indoor environment, it has particular signifi cance for spaces housing fragile or historic items – as well as some items that aren’t typically considered as delicate. John Barker of Humidity Solutions explains
MUSEUMS AND GALLERIES
www.acr-news.com November 2018 43
Heron Hill
As well as the less obvious examples cited above,
there are many applications with a clear need for
close control of RH.
Arts, antiquities and other delicate objects
are particularly vulnerable to damage resulting
from fluctuations in the indoor environment –
especially any wide swings in temperature and
humidity. Wood, for example, is particularly prone
to expansion or shrinkage if it is not stored in
a humidity-controlled environment. Any such
movement of the wood may cause cracking,
separation of different wood layers and will
also destabilise any paint or other finishes that
have been applied to the wood. Additionally,
the finishes themselves may be subject to
deterioration when exposed to low or high
humidity.
High humidity may also lead to condensation
on metallic, stone or other objects with cold
surfaces, potentially causing significant damage.
Stabilising the relative humidity in any such
storage areas will help to prevent any defamation
or cracks and ensure they maintain the same
dimensions. In doing so, in compliance with
BS5454, the RH should be maintained in the
range 40-65% (+/-5%), with temperatures in
the range 16-19°C (+/-1°C). As well as ensuring
protection of the objects, compliance with this
standard will help to meet the requirements of
insurance companies or benefactors loaning works
of art.
Staying in controlThe UK climate dictates that most problems
relating to humidity are due to low RH, creating
a requirement for humidification – though some
projects will require both humidification and
dehumidification and different times of the year.
The important thing is to fully understand each
project’s requirements – there are no ‘off the
shelf’ solutions for these types of applications.
For instance, if the space is open to the public
there will be considerable variation in line
with fluctuating visitor numbers. Each person
contributes moisture to the air in their exhaled
breath, and if it’s been raining they may also be
evaporating water into the air from their clothes.
In parallel, their body temperature will contribute
to an increase in room air temperature.
Consequently, systems serving areas with
variable occupancy – or subjected to non-
tempered air from outside for ventilation – will
need to incorporate continuous monitoring by
humidity sensors and be able to respond quickly
to changes in RH. However, many such venues
do not have staff experienced in humidity
control, so there is growing demand for remote
monitoring, where system operation can be
monitored, via the ‘cloud’, by humidity control
specialists. Not only does this ensure a quick
response to any deviation from acceptable
environmental parameters, it also helps to inform
a cost-effective planned maintenance regime
based on actual plant usage.
As well as the usage of the space, the best
solution for each project will also be influenced
by factors such as budgets, lifecycle costs, the
client’s attitude to sustainability/carbon reduction
and the nature of the building itself. For instance,
we were required to devise very different
solutions for the Tate Modern (housed in a former
power station), Tate Liverpool (a converted
warehouse) and Tate Britain, which was designed
as a gallery from the start.
Demanding humidity control applications
demand a combination of specialist expertise and
experience of a range of different project types.
For that reason, it makes sense to call on support
from a supplier that has no ties to a particular
manufacturer and can offer a tailored solution
using the most appropriate products.
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