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Klimatförändringarnas inverkan på mögel- och rötangrepp

Jeppsson, Hans LU and Lindahl, Karl LU (2011) In TVBK VBK920 20102
Civil Engineering
Division of Structural Engingeering
Abstract
The purpose of this Master’s Thesis is to investigate how the risk of onset of mould and decay
will change due to a changing climate. The research encompasses the time period 1960-2099
in open fields near the cities Göteborg, Lund, Stockholm and Östersund for the emission
scenarios A1B, A2 and B1. The risk of onset of mould and decay is studied on wood in
outdoor climate as well as the risk of onset of mould for an exterior wall.

In order to calculate the risk of onset of mould a dose-response model was used. For the risk
of decay another dose-response model was used. Both models depend on the daily mean
values of the temperature and relative humidity. The decay model also depends on the daily
precipitation. The outdoor... (More)
The purpose of this Master’s Thesis is to investigate how the risk of onset of mould and decay
will change due to a changing climate. The research encompasses the time period 1960-2099
in open fields near the cities Göteborg, Lund, Stockholm and Östersund for the emission
scenarios A1B, A2 and B1. The risk of onset of mould and decay is studied on wood in
outdoor climate as well as the risk of onset of mould for an exterior wall.

In order to calculate the risk of onset of mould a dose-response model was used. For the risk
of decay another dose-response model was used. Both models depend on the daily mean
values of the temperature and relative humidity. The decay model also depends on the daily
precipitation. The outdoor climate was modelled by the global climate model ECHAM5 and
the results were downscaled using the regional climate model RCA3 to take the Nordic
topology into account. This was done for all three scenarios by Rossby Centre at the Swedish
Meteorological and Hydrological Institute. The specific humidity, radiation and wind from the
climate models had to be transformed so they could be used in the mould and decay models
and the computer program WUFI.

The computer program WUFI was used together with the modelled outdoor climate to model
the climate in the exterior wall. The exterior wall was assumed to be a wood stud wall with a
wooden facade. The climate in the exterior wall was modelled for three ten-year time periods
and this was done for all the cities and scenarios. The observation point was located on the
boundary between the air gap and the outer insulation.

The values for both the relative mould and decay doses for wood in outdoor climate were
higher for the modelled climate than compared to the observed one during the years of 1961-
1990. Since there was a major difference in the relative humidity between the modelled
climate and the observed one (but no difference for the temperature or precipitation) it was
concluded that the humidity was the main reason for high values of relative mould and decay
doses. For Östersund the relative mould dose was much higher for the modelled climate than
the observed one. Since Östersund had considerably more days with high relative humidity,
above 97 %, whilst the temperature was above 0.1°C it was concluded that this was the
reason behind the high relative mould values for Östersund. The results for both the mould
and the decay onset indicate that the values for both mould and decay start to rise after the
year 2040. This was concluded to happen because it was around this year the temperature
started to increase continuously whilst the relative humidity didn’t have any significant
changes.

The relative mould dose for the modelled climate in the exterior wall is much lower than for
the modelled outdoor climate. The difference was concluded to depend on the increased
temperature due to the heat flow from the indoor climate. The temperature change lead to a
lower relative humidity, but the moisture transport in the wall meant that this change was not
as large as the temperature increase first suggests. Between the two last ten-year periods the
relative mould dose increases significantly. As mentioned before the temperature rises during
these years are the main reason for the increase in relative mould dose. (Less)
Please use this url to cite or link to this publication:
author
Jeppsson, Hans LU and Lindahl, Karl LU
supervisor
organization
course
VBK920 20102
year
type
H3 - Professional qualifications (4 Years - )
subject
keywords
climate change, mould, decay, exterior wall
publication/series
TVBK
report number
TVBK - 5193
ISSN
0349-4969
language
Swedish
id
3358495
date added to LUP
2013-01-10 13:08:58
date last changed
2013-01-10 13:08:58
@misc{3358495,
  abstract     = {The purpose of this Master’s Thesis is to investigate how the risk of onset of mould and decay 
will change due to a changing climate. The research encompasses the time period 1960-2099 
in open fields near the cities Göteborg, Lund, Stockholm and Östersund for the emission 
scenarios A1B, A2 and B1. The risk of onset of mould and decay is studied on wood in 
outdoor climate as well as the risk of onset of mould for an exterior wall. 
 
In order to calculate the risk of onset of mould a dose-response model was used. For the risk 
of decay another dose-response model was used. Both models depend on the daily mean 
values of the temperature and relative humidity. The decay model also depends on the daily 
precipitation. The outdoor climate was modelled by the global climate model ECHAM5 and 
the results were downscaled using the regional climate model RCA3 to take the Nordic 
topology into account. This was done for all three scenarios by Rossby Centre at the Swedish 
Meteorological and Hydrological Institute. The specific humidity, radiation and wind from the 
climate models had to be transformed so they could be used in the mould and decay models 
and the computer program WUFI. 
 
The computer program WUFI was used together with the modelled outdoor climate to model 
the climate in the exterior wall. The exterior wall was assumed to be a wood stud wall with a 
wooden facade. The climate in the exterior wall was modelled for three ten-year time periods 
and this was done for all the cities and scenarios. The observation point was located on the 
boundary between the air gap and the outer insulation. 
 
The values for both the relative mould and decay doses for wood in outdoor climate were 
higher for the modelled climate than compared to the observed one during the years of 1961-
1990. Since there was a major difference in the relative humidity between the modelled 
climate and the observed one (but no difference for the temperature or precipitation) it was 
concluded that the humidity was the main reason for high values of relative mould and decay 
doses. For Östersund the relative mould dose was much higher for the modelled climate than 
the observed one. Since Östersund had considerably more days with high relative humidity, 
above 97 %, whilst the temperature was above 0.1°C it was concluded that this was the 
reason behind the high relative mould values for Östersund. The results for both the mould 
and the decay onset indicate that the values for both mould and decay start to rise after the 
year 2040. This was concluded to happen because it was around this year the temperature 
started to increase continuously whilst the relative humidity didn’t have any significant 
changes. 
 
The relative mould dose for the modelled climate in the exterior wall is much lower than for 
the modelled outdoor climate. The difference was concluded to depend on the increased 
temperature due to the heat flow from the indoor climate. The temperature change lead to a 
lower relative humidity, but the moisture transport in the wall meant that this change was not 
as large as the temperature increase first suggests. Between the two last ten-year periods the 
relative mould dose increases significantly. As mentioned before the temperature rises during 
these years are the main reason for the increase in relative mould dose.},
  author       = {Jeppsson, Hans and Lindahl, Karl},
  issn         = {0349-4969},
  keyword      = {climate change,mould,decay,exterior wall},
  language     = {swe},
  note         = {Student Paper},
  series       = {TVBK},
  title        = {Klimatförändringarnas inverkan på mögel- och rötangrepp},
  year         = {2011},
}