PREDICTING THE CONCENTRATIONS OF AIR POLLUTANTS INSIDE MUSEUM BUILDINGS: A WEB-BASED SOFTWARE TOOL DEVELOPED BY THE EC IMPACT PROJECT

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PREDICTING THE CONCENTRATIONS OF AIR POLLUTANTS
INSIDE MUSEUM BUILDINGS A WEB-BASED SOFTWARE
TOOL DEVELOPED BY THE EC IMPACT PROJECT Declan
Kruppa, Nigel Blades and May Cassar, Centre for
Sustainable Heritage, University College London,
UK
The IMPACT Project The work presented here is
part of a European Commission funded project
entitled Innovative Modelling of Museum
Pollutants and Conservation Thresholds (IMPACT).
IMPACT is an interdisciplinary research project
involving universities (UCL UEA) a research
institute (NILU) with expertise in the study of
air pollution a manufacturer of pollution
control equipment (EMCEL) a museum (MNK) and as
a sub-contractor an architecture practice (AP)
specializing in heritage projects, to give an
end-user perspective to the research. It is
developing a tool for estimating the levels of
air pollution inside museum buildings and
providing advice to museum managers on how to
protect their collections. As well as developing
the software tool described below, the IMPACT
project includes a programme of laboratory
measurements in order to further understanding of
the interaction of atmospheric pollutants with
materials.
Treating a building as a single zone, the
concentration of a particular gas inside it is
related to the outdoor concentration by the
following equation I / O ach / ( Vdep (S/V)
ach) where I Indoor concentration O
Outdoor concentration ach air exchange rate
(hr-1) S/V interior surface area
(m2)/volume (m3) Vdep deposition velocity
(m/hr)
The applet user interface. Data are input by the
user on the left-hand panel and the pollutant I/O
ratio calculated. The output is displayed
numerically and graphically, as a function of air
exchange rate on the right-hand panel. The I/O
ratio can be converted to a concentration if the
user has access to external pollution data,
often available on national and regional
websites.
Multi-Zone Model A version of the web programme
which can model the concentration of air
pollutants in multi-zone buildings is currently
under development. The programme interface is a
drawing page where users can sketch the layout of
their building specify the interior surface
finishes of the different rooms the number of
windows, doors and other air leakage paths and
the typical external wind speed conditions. The
model will calculate the airflow pattern in the
building and the pollutant load from the user
inputs.
Introduction The reactive gases nitrogen dioxide
(NO2), sulphur dioxide (SO2) and ozone (O3)
damage artefacts in museums. Their
concentrations need to be monitored and
controlled. Many museums cannot afford to monitor
routinely these gases. These air pollutants are
generated outdoors and indoor concentrations are
generally lower the gases deposit on the
internal surfaces of the building and are removed
from the air. This process can be quantified by
the deposition velocity Vdep of a gas. This is
a measure of the rate at which a gas is deposited
on a particular material. The graph below shows
the variation of Vdep for NO2 to some common
interior finishes. Materials such as cement and
brick have a high deposition velocity whereas
glass has a low deposition velocity.
The Sainsbury Centre for Visual Arts, Norwich,
UK. A museum of modern design with a large
open-plan interior (i.e. low surface area to
volume ratio) and with large areas of glass and
painted metal. The model predicts that this
building fabric will be a poor absorber of
harmful air pollutants.
Single Zone Model The equation has been
incorporated into a computer model which
calculates the concentration of air pollutants in
museum buildings. The programme is written as a
Java applet that runs via an internet browser on
any computer system. The applet will be part of
a website providing information for the user on
interpreting results produced by the applet. The
software tool is designed to encourage users to
experiment with the input parameters and get a
feel for their relative importance in determining
the air pollution levels inside museum buildings.
Interim Results As work progresses, further
information on the software tool will be posted
on the UCL Centre for Sustainable Heritage
website (www.ucl.ac.uk/sustainableheritage) which
will also host the final freely accessible
software and associated website. For further
information contact Declan Kruppa
d.kruppa_at_ucl.ac.uk We would like to acknowledge
the support of the EC 5th Framework Programme Key
Action 4 City of Tomorrow and Cultural Heritage
for funding the IMPACT Project (Contract no.
EVK4-CT-2000-0031 IMPACT ).
The Pollution Model To calculate the air
concentration of a pollutant in a room the
sources and sinks for the pollutant must be
summed up in a mass balance equation. For
external air pollutants the source is a function
of the air exchange with the outdoor air. The
pollutant sinks are the surface finishes in the
room, characterised by their surface area and the
deposition velocity of the particular gas.
The IMPACT applet running on a laptop at the
Petrie Museum, UK.
University College London (UCL) Centre for
Sustainable Heritage
Norwegian Institute for Air Research (NILU)
University of East Anglia (UEA) School of
Environmental Sciences
Emcel Filters Ltd (EMCEL)
National Museum of Krakow (MNK)