Green Building Forum - Current Humidity Reading Tue, 19 Dec 2023 05:13:01 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197574#Comment_197574 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197574#Comment_197574 Tue, 04 Mar 2014 11:19:33 +0000 andyman99 Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197576#Comment_197576 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197576#Comment_197576 Tue, 04 Mar 2014 11:32:32 +0000 HalcyonRichard The humidity can vary quite a lot depending on wind/rain/rivers etc. So it would be difficult to give a local result that is meaningful for a large area. The one I have takes minutes to respond to any cooking in the kitchen. The highest reading I have ever seen is just over 70% so maybe it's not that accurate. I am not sure how to get a known humidity in a room so it can be calibrated/checked.

Richard]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197580#Comment_197580 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197580#Comment_197580 Tue, 04 Mar 2014 11:54:00 +0000 SteamyTea Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197581#Comment_197581 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197581#Comment_197581 Tue, 04 Mar 2014 11:58:48 +0000 Sprocket
Not convenient on the scale of a room but in a suitable container you can easily generate a known humidity above a saturated salt solution. I haven't tried it myself recently and I can't remember the details exactly but was able to google these examples/refs which look like the right kind of thing so they might help:-


http://ambientweather.wikispaces.com/Humidity+Calibration,+Saturated+Salt+Test

http://exoticpets.about.com/od/herpresources/ss/hygrometer.htm

http://www.omega.com/temperature/z/pdf/z103.pdf

(that last document looks particularly handy - I have saved myself a copy for 'lab' use)

However, you should know that cheap electronic hygrometers are pretty inaccurate near the extremes of the RH range so certainly don't expect accurate readings much below 20% or above 80%]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197593#Comment_197593 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197593#Comment_197593 Tue, 04 Mar 2014 14:33:36 +0000 PeterStarck
http://www.bbc.co.uk/weather/6695249]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197595#Comment_197595 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197595#Comment_197595 Tue, 04 Mar 2014 14:41:34 +0000 SteamyTea Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197596#Comment_197596 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197596#Comment_197596 Tue, 04 Mar 2014 14:43:02 +0000 PeterStarck Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197597#Comment_197597 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197597#Comment_197597 Tue, 04 Mar 2014 15:18:37 +0000 skyewright Posted By: SprocketHowever, you should know that cheap electronic hygrometers are pretty inaccurate near the extremes of the RH range so certainly don't expect accurate readings much below 20% or above 80%
Based on my experience with weather station equipment (Davis, Oregon & 1-wire) even within those limitations RH units seem to fail[1] sooner than temp sensors etc., especially so if regularly used in very humid conditions. I guess that's maybe inherent - after all you can't fully waterproof a humidity sensor!


[1] As in become even more unreliable.]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197610#Comment_197610 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197610#Comment_197610 Tue, 04 Mar 2014 18:02:23 +0000 barney
Regards

Barney]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197611#Comment_197611 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197611#Comment_197611 Tue, 04 Mar 2014 18:08:45 +0000 funcrusher
You don't state why you need to know RH. if it's protection of possessions eg furniture and clothes against damp/mould, you should be safe if RH is not above 70% for prolonged periods - say 5days +.

If you are trying to control RH in an enclosed space, a dehumidifier is by far cheaper than heating.]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197625#Comment_197625 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197625#Comment_197625 Tue, 04 Mar 2014 21:10:51 +0000 andyman99 Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197627#Comment_197627 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197627#Comment_197627 Tue, 04 Mar 2014 21:35:33 +0000 RobL
Measure the room temp, and the temp of the window on the edge of the dew - right where its starting to form. Wiki can convert the two numbers for you into a relative humidity:

http://en.wikipedia.org/wiki/Dew_point

This technique is what some pricey RH meters use- they point a laser at a peltier chilled mirror and the light back indicates the onset of the dew-point.]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197632#Comment_197632 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197632#Comment_197632 Tue, 04 Mar 2014 22:12:53 +0000 borpin http://www.maplin.co.uk/p/black-usb-wireless-touchscreen-weather-forecaster-n96gy give you indoor & Outdoor temp and hum (plus some other bits.

Only £50 and may get one as my wind and rain has stopped working.

Edit, if you want to get the data into a RPi use pywws.]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197634#Comment_197634 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197634#Comment_197634 Tue, 04 Mar 2014 22:14:32 +0000 Ed Davies
Clever. Only really works as the dew is forming - might be a bit misleading if the water's there but not yet evaporated as the window warms up or something.

Still, if you have an IR thermometer you ought to be able to use any old damp rag as a wet-bulb hygrometer:

https://en.wikipedia.org/wiki/Wet_bulb

Have to admit I'd have to read that carefully and do some head scratching with a psychrometric chart to work out what the humidity is.

https://en.wikipedia.org/wiki/Psychrometric_chart#Psychrometric_charts]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197656#Comment_197656 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197656#Comment_197656 Wed, 05 Mar 2014 09:30:08 +0000 car-mark
I bought 3 elcheapo items from ebay, usual month to deliver. Total cost £12
All read %humidity to within 1 digit of each other, all approach 90% plus in prolonged rainy conditions in outdoor conditions. all approach 95% in shower/wet-room until the fan has coped with it.
What gets interesting is the heated rooms and how low the humidity can go.

Yes I did use the wet bulb dry bulb calculations and these cheap beasts are still within 5 digits at the ends of scale

Yours Mark]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197659#Comment_197659 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197659#Comment_197659 Wed, 05 Mar 2014 10:23:38 +0000 skyewright Posted By: andyman99Essentially looking to understand humidity levels in various parts of the house before deciding how to control it.
At the risk of stating the obvious, if it's indoor humidity in your own house you're interested in then seeing other peoples figures, no matter how current, isn't going to help.]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197661#Comment_197661 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197661#Comment_197661 Wed, 05 Mar 2014 11:27:04 +0000 Ed Davies
With mobile broadband, the most accurate scheme would probably be to park near an airport and get the METAR for that. Without mobile broadband, get an accomplice to log the METARs as they're produced then compare afterwards. Here's Heathrow recently:

http://www.wunderground.com/Aviation/index.html?query=EGLL#METAR

METAR EGLL 051050Z 22005KT 190V260 CAVOK 10/03 Q1021 NOSIG

Lots of explanations around the net of the coding but the key bit is 10/03 meaning temperature 10 °C, dew point 3 °C.]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197707#Comment_197707 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197707#Comment_197707 Wed, 05 Mar 2014 20:20:47 +0000 andyman99
Mark are these he HTC-1 devices I have read about on other threads.

Thanks Andy]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197726#Comment_197726 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197726#Comment_197726 Thu, 06 Mar 2014 06:44:32 +0000 car-mark
Yes Andy the very same, very happy with the figures.

Warning it does take time to understand how the humidity changes with ventilation and heating.

yours Mark]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197733#Comment_197733 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197733#Comment_197733 Thu, 06 Mar 2014 08:49:48 +0000 funcrusher Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197759#Comment_197759 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197759#Comment_197759 Thu, 06 Mar 2014 13:01:54 +0000 dazdread
It reads as between 55 and 65% which I take it is within norms, could it be that the house interior is being kept warmer due to our three year old and 4 month old children which encourages condensation on the solid walls?

EWI is on the to do list when the money gods answer our prayers!]]> Current Humidity Reading http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197769#Comment_197769 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11828&Focus=197769#Comment_197769 Thu, 06 Mar 2014 14:24:40 +0000 djh Posted By: dazdreadIt reads as between 55 and 65% which I take it is within norms, could it be that the house interior is being kept warmer due to our three year old and 4 month old children which encourages condensation on the solid walls?
Yes, 55-65% is perfectly normal. What would be interesting to know is the temperature as well. Both of the room where you are measuring the humidity, and of the wall or wherever you're finding mould.

EWI is on the to do list when the money gods answer our prayers!

That's the best idea to minimise energy use but you might find that some of the thin internal insulation (insulated wallpaper type of stuff) is enough to lift the internal surface temperature of the walls enough to stop mould.]]>