A good real-estate agency (Nest Property Management at Louth) gave me a pamphlet about mustiness. I failed to find an Internet version. Similar webpages are WWW.FNREM.com.Au/pages/real-estate/blog/4526/the-menace-of-mould-and-how-to-manage-it and WWW.PropertyTribes.com/down-in-the-damps-t-2084.html and HTTPS://CEP.org.UK/landlords/damp-condensation-and-mould-advice-for-landlords and WWW.ClydeWindows.com/blog/windows/internal-window-condensation/?srsltid=AfmBOoqcZ_pLawhwSvMLowDgwFgEhKB3CHnemvmvGaeNgW-XnmkBepGX and WWW.DIYdata.com/problem/condensation/condensation-overcoming.php and WWW.Netmums.com/coffeehouse/home-garden-194/cleaning-14/110656-condensation.html etc.
A different good real-estate agency (Anthony-Byrne Property Services at the same town) gave me a booklet from a Viking town. That booklet about mustiness is like the document which is hyperlinked to by this sentence, which is available in many languages.
I bought a dehumidifier (during 2008) and 2 hygrometers at Portugal. A dehumidifier significantly reduces a house’s humidity. A hygrometer also showed me that open doors and open windows during non-night times much more significantly reduce a house’s humidity than a dehumidifier accomplishes. WWW.Netmums.com/coffeehouse/home-garden-194/cleaning-14/110656-condensation.html alleges that a "a positive pressure unit" is better than a dehumidifier.
The 2nd Republic of Portugal robbed a hygrometer etc. of mine. “I keep my expectations low.” said an advocate about regaining my properties that Portugal robbed on 5th July 2023.
“indoor humidity of 80% or higher
[. . .]
•In winter, you still need to open windows on a daily basis (wait till the warmest time of day)
[. . .]
•[. . .] opening blinds during the day”
says First National Real Estate Maitland at Australia. Cf. WWW.PropertyTribes.com/down-in-the-damps-t-2084.html and HTTPS://CEP.org.UK/landlords/damp-condensation-and-mould-advice-for-landlords and WWW.DIYdata.com/problem/condensation/condensation.php etc.
Clyde Windows and Construction Limited says: "During the winter months, condensation will be seen on the inside of the window. Condensation will present itself on the outside of the window during the summer months." Moisture on opened and closed windows here was on their outsides, not insides, on 18th August 2025 (i.e. a warm day during a warm month) shortly after 6a.m. o'clock.
"I bought a wardrobe and chest of drawers for my lo and the backs of them have gone mouldy I keep wiping down but it returns. As I said before the windows are so wet in the morning and I never leave windows closed fully plus we have a few wall air vents in every room." says a person who reports worse dampness than I ever lived with.
Mother owns a printout of a document. That document seems to be a webpage of a newspaper. It recommends to avoid fustiness by never opening curtains. That document does not convince me. Cars’ windows do not have curtains. Cars’ windows gain moisture before 6a.m. o’clock. I keep a subset of this house’s curtains opened and different subsets closed and opened for different amounts of times. I do not detect an overwhelming difference of moisture between any of these windows.
Italy is too humid. Many persons attempt to dry clothes outside at Italy during nights. An educated gentleman at Italy said that that is normal and bad because nighttimes humidities are against drying. He said that many persons at Italy do not know that that is a bad technique.
My hygrometers at Portugal have digital displays. My hygrometer here is analogue with its display graduated only by multiples of 5%, so my estimated readings thereof lack precision.
I quote numbers by HTTPS://WWW.Met.Ie/ga - that website declares that it is copyrighted. (More about copyright.)
My analogue non-electric hygrometer here professed circa 75% relative humidity on 23/08/2025 at 10:22a.m.
These graphs show measured (not predicted) humidity at a weather station which is located near where I reside. Their minimum is 54% relative humidity. Their maximum is 99% relative humidity. It was least humid at circa 2p.m. or 4p.m. and circa 80% or worse before circa 10a.m. and after circa 6p.m.
Many days during September 2025 here were humid. E.g. a prediction for a less (sic!) humid day here (i.e. for 29th September 2025 predicted also on 29th September 2025) by HTTPS://WWW.Met.Ie/ga was 79.3% and 74.6% and 75.9% for 2p.m. and 3p.m. and 4p.m. and that day's all other hours' values being at least 80.6% (5p.m.) and at most 94.4% (10p.m.).
My analogue non-electric hygrometer here professed circa 61% relative humidity on 23/09/2025 at 1:07p.m. when HTTPS://WWW.Met.Ie/ga predicted 66.0% humidity for here for 2p.m. on the same day.
It professed circa 65% relative humidity on 23/09/2025 at 9:17p.m. when HTTPS://WWW.Met.Ie/ga predicted 82.3% humidity for here for 10p.m. on the same day.
My analogue hygrometer reported circa 67% at 10:05a.m. and 65% at 11:35 on 24/09/2025 when HTTPS://WWW.Met.Ie/ga predicted 81.5% and 78% for 11a.m. and noon respectively when all windows and external doors were closed since circa 8:10p.m. the previous night (except 1 door for a few seconds at 11:07a.m. to collect mail). My analogue hygrometer reported circa 69% at 6:05p.m. when HTTPS://WWW.Met.Ie/ga predicted 88.9% for 7p.m. when all our windows and external doors remained closed since 11:07a.m. except for a few seconds to exit once and to enter once. Shortly before 3p.m. on the same day HTTPS://WWW.Met.Ie/ga predicted 82.2% and 88.2% (instead: i.e. not 88.9%) for 6p.m. and 7p.m. respectively.
Predictions for 1st October 2025 here predicted also on 1st October 2025 by HTTPS://WWW.Met.Ie/ga were at least 87.0% or 89.1% (for 4p.m.) and e.g. 93.1% or 89.5% (for noon) and 92.3% or 91.6% (for 10p.m.).
Furthermore Met.Ie warns that it shows data which are not checked (and data which are checked), which I republish for this webpage.
gnuplot
set datafile separator comma
set terminal png
set ylabel "Relative humidity"
set title "humidity here"
set xlabel "when"
set xdata time
set timefmt "%Y-%m-%d"
set format x "%A\n%d\n%B\n%Y"
set output 'some_name.csv.png' #Based on HTTPS://StackOverflow.com/questions/14047061/how-to-call-gnuplot-from-cli-and-save-the-output-graph-to-the-image-file
plot "some_name.csv" using 1:2 #"If time/date information is to be plotted from a file, the using option must be used on the plot or splot command." says HTTPS://GNUPlot.SourceForge.net/docs_5.4/gnuplot.pdf
cat san_aice_umam_tableView_September2025.csv | sed -e 's/.*T//' | sed -e 's/+.*,/,/' > san_aice_umam_tableView_September2025_moments.csv
gnuplot
set datafile separator comma
set terminal png
set ylabel "Relative humidity"
set title "humidity here"
set xlabel "when"
set xdata time
set timefmt "%H:%M:%S"
set format x "%l%p" #This incorrectly shows noon as "12pm" and and midnight as "12am". Cf. HTTPS://WWW.EnglishClub.com/efl/articles/vocabulary/12am-12pm-whats-the-difference and HTTPS://WWW.RMG.co.UK/stories/time/noon-12-am-or-12-pm
set output 'san_aice_umam_tableView_September2025_moments.csv.png' #Based on HTTPS://StackOverflow.com/questions/14047061/how-to-call-gnuplot-from-cli-and-save-the-output-graph-to-the-image-file
plot "san_aice_umam_tableView_September2025_moments.csv" using 1:2 #"If time/date information is to be plotted from a file, the using option must be used on the plot or splot command." says HTTPS://GNUPlot.SourceForge.net/docs_5.4/gnuplot.pdf