Tue, 19 Dec 2023 05:08:57 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256700#Comment_256700 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256700#Comment_256700 Sun, 02 Apr 2017 21:54:05 +0100 nigelm
The roof build up from inside out is:-
20mm timber board
Vapour barrier
300mm timber I beam filled with mineral wool
20mm wood fibre sarkling board
Batterns and tiles.

We have a WUFI model that indicates all should be well but i wanted to fit sensors to compare real world against the model. I have some BME280 combined temperatute, RH and pressure semsors but wanted some advicde as where to install them.

The stone walls are to be imsulated as wel with 300mm Rockwool batts on the inside and will monitor those as well.

i]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256702#Comment_256702 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256702#Comment_256702 Sun, 02 Apr 2017 22:41:31 +0100 Nick Parsons
What did WUFI say about that? That sounds like a very cold wall!]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256704#Comment_256704 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256704#Comment_256704 Sun, 02 Apr 2017 23:31:57 +0100 djh
PS Those are interesting looking sensors. I wish they'd been around when I installed mine!]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256705#Comment_256705 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256705#Comment_256705 Mon, 03 Apr 2017 07:44:41 +0100 SteamyTea Posted By: djhPS Those are interesting looking sensors. I wish they'd been around when I installed mine!I have just got some (BME280), not got around to wiring any up yet. Got to work out how to get them to sit on the same I2C GPIO as the real time clock

Does WUFI show any areas of low temperature or high RH?
If it does, then fit the sensors there.

Alternatively, place them in random locations, then model from there. Or you could try and work out areas that may pose a problem i.e. junctions, interfaces, high and low airflow areas, north and south facing etc.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256707#Comment_256707 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256707#Comment_256707 Mon, 03 Apr 2017 08:36:07 +0100 nigelm We are however in France and the weather patterns are different here.

The sensors are working on an Pi I2C, only two addresses available but the PI zeroW are cheap enough to deploy. The sensors came direct from China at less than a euro each.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256711#Comment_256711 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256711#Comment_256711 Mon, 03 Apr 2017 09:43:41 +0100 SteamyTea https://stackoverflow.com/questions/17687132/multiple-sensors-on-raspberry-pi-gpio

http://www.robot-electronics.co.uk/i2c-tutorial]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256782#Comment_256782 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256782#Comment_256782 Tue, 04 Apr 2017 19:00:04 +0100 nigelm The adafruit I2C multiplexer looks interesting, 8 channels giving potential for 16 sensors.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256785#Comment_256785 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256785#Comment_256785 Tue, 04 Apr 2017 19:58:32 +0100 Ed Davies
That multiplexer looks neat but you could avoid the extra hardware by just bit banging other GPIO pins to give more I²C buses. High data rates are hardly critical to monitoring temperatures and humidities in walls.

Steamy's considering using SPI as it has a chip-select line which you could run off other GPIO pins. It occurred to me today that you could maybe actually use the SDO pin as a chip-select line for I²C. Ground it for the device you want to talk to then address that using the alternative address, leaving all the others on the bus at the default address. Assumes the SDO pin is dynamic - it doesn't just sense its address on startup then stick with it.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256794#Comment_256794 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256794#Comment_256794 Tue, 04 Apr 2017 21:38:30 +0100 SteamyTea http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256804#Comment_256804 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256804#Comment_256804 Tue, 04 Apr 2017 23:58:16 +0100 goodevans
I wager that so long as the vapour barrier is relatively intact that....
a) the absolute humidity of a sensor just outboard of the vapour barrier will closely track the outside absolute humidity and
b) the absolute humidity just inboard of the vapour barrier will closely track the internal absolute humidity (provided there is an air gap between the 20mm timber board and the VCL - and the 20mm board is not designed as an air barrier)

(derive absolute humidity from the RH and Temp - in any units you like (grams/M3 is my favourite it makes for easy calcs for the effect of ventilation)).]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256823#Comment_256823 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256823#Comment_256823 Wed, 05 Apr 2017 14:55:09 +0100 nigelm
Having checked thesensors there calibration looks good or at least consistent against each other.

What is the relevence of absolute and relative humidity in relation to the building fabric?]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256828#Comment_256828 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256828#Comment_256828 Wed, 05 Apr 2017 17:20:32 +0100 djh Posted By: nigelmWhat is the relevence of absolute and relative humidity in relation to the building fabric?
Absolute humidity is the density of water molecules in the air (or actually in the space that the nitrogen, oxygen etc also occupies). It has physical significance and has pretty strong conservation properties. In particular, if you take air from outside and bring it inside, it will still have the same absolute humidity, but its relative humidity is likely to be be quite different.

Relative humidity is to do with the relative rates of evaporation and condensation at a particular temperature and pressure. It's a much more nebulous concept and more complicated to deal with. But it is of great importance because it is largely relative humidity that matters to living things. How comfortable you feel, how well fungus grows (whether mushrooms or rot in wood), how comfortable mites feel, how well bacteria grow and spread all depend on what the relative humidity is. As does the moisture content of wood etc etc.

https://en.wikipedia.org/wiki/Humidity has some more info.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256959#Comment_256959 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256959#Comment_256959 Mon, 10 Apr 2017 00:58:10 +0100 goodevans http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256961#Comment_256961 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256961#Comment_256961 Mon, 10 Apr 2017 08:07:34 +0100 nigelm
I have been thinking about read frequency, I am guessing that once every 30 minutes would be sufficient.]]> http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256963#Comment_256963 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15026&Focus=256963#Comment_256963 Mon, 10 Apr 2017 08:40:04 +0100 SteamyTea