Dr Nigel Blades

UCL Centre for Sustainable Heritage

UCL CENTRE FOR SUSTAINABLE HERITAGE

Application of an Air Pollution Modelling Tool to Cultural Heritage Buildings

IMPACT pollution model - JAVA applet implementation of pollution mass balance

equation of Weschler et al. (1989)

• Model outputs:– Indoor pollutant concentration or

I/O ratio – Which surfaces absorb most

pollutant– Relation between I/O ratio and

ventilation rate

)/( VAvacr

acr

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Case study 1: Sainsbury Centre for Visual Arts, Norwich, UK

• Metal walls and ceiling• Glass end walls• Open plan display area• Mechanical ventilation but

not air conditioning• Close relation to outdoor

environment

Sainsbury Centre for Visual Arts

Table 1: Data on the SCVA used in the modelling

Internal surfaces Aream2

Other parameters

Metallic wall finish 2620 Room volume 42570 m3

Metallic ceiling finish 4585 Air change rate 1.5ach

Glass 528 Temperature 20°C

Carpeted floor 4257 Relative humidity 55%

Inner wall insulation 2064

IMPACT modelling of the SCVA

Model scenario Sulphur dioxide

Nitrogen dioxide

Ozone

(a) SCVA without interventions 0.89 0.87 0.88

How can pollution control be improved at the SCVA?

IMPACT modelling of the SCVA

Model scenario Sulphur dioxide

Nitrogen dioxide

Ozone

(a) SCVA without interventions 0.89 0.87 0.88

(b) Reduce ventilation rate to 0.3ach 0.76 0.78 0.78

(c) Introduce enhanced pollution absorbing paint

0.72 0.70 0.72

(b) and (c) combined 0.62 0.62 0.62

Case study 2: Factory building converted into an archive store

• Concrete walls and floors• Most glazing covered over• Naturally ventilated, but

building tightly sealedDoor to outside

Entrance lobby

Internal doors

Stair well

modelled zone

Data used to model the archive store

Surface Area m2

Other parameters

Concrete wall 582 Room volume 7972m3

Chipboard window covers 214 Air change rate 0.3 ach

Synthetic flooring 1355 Temperature 20°C

Concrete ceiling 1355 Relative humidity 55%

Exposed paper and book boards 6934

IMPACT modelling of nitrogen dioxide at the archive store

IMPACT modelling of the archive store – results for all gases

Pollutant Modelled I/O ratio

Nitrogen dioxide 0.46

Ozone 0.24

Sulphur dioxide 0.33

IMPACT modelling of the archive store – results for all gases

Pollutant Modelled I/O ratio

Nitrogen dioxide 0.46

Ozone 0.24

Sulphur dioxide 0.33

Is this good for conservation of the collection?

IMPACT modelling of the archive store – pollution effects on the collection

Pollutant Modelled I/O ratio(with collection)

Modelled I/O ratio(no collection)

Nitrogen dioxide 0.46 0.78

Ozone 0.24 0.73

Sulphur dioxide 0.33 0.60

IMPACT modelling of the archive store – comparison with measured data

Pollutant Modelled I/O ratio Measured I/O ratio

Nitrogen dioxide 0.46 0.24

Ozone 0.24 0.1

Sulphur dioxide 0.33 0.4

Reasons for discrepancy between measured and modelled data

• Amount of active surface area in the building has been underestimated

• Single zone model does not allow for air infiltration from other zones (rooms)

• Enhanced pollution deposition around cracks and crevices where air infiltrates

• Homogeneous chemistry?

Conclusions

• IMPACT model can quickly and easily estimate the contribution of outdoor pollution to indoor environment, using a simple deposition model

• Help understand relation between air pollution and buildings

• Teaching aid for conservators in UK and Malta, COST G8 Training School

• In use by heritage organisations, e.g. English Heritage

European project details

IMPACT, Contract No. EVK4-CT-2000-00031, ‘Innovative Modelling of Museum Pollution and Conservation Thresholds’ (2000-04)

http://www.ucl.ac.uk/sustainableheritage/impact