Best options for home temperature/humidity monitoring

Continuing the discussion from Thermal Imaging - as a tool for retrofit evaluation:

Some great discussion has been started here by @zapaman and @Peter_Mumford about home environment monitoring with temperature and humidity sensors. @Matt from Carbon Co-op has also been looking at this and I believe is also running some trials in the field with members. This could be a good place to discuss the best approach to monitoring!


I use the inexpensive Xiaomi Temperature and humidity Zigbee sensors with my Smartthings hub.
Also just started using the sonoff zigbee sensor as well, as they are sometimes slightly cheaper.

Could be integrated into the HEMS with a Zigbee dongle


Following on from Oscar’s post, I use the same sensors with a Raspbee dongle running HA.

1 Like

Sorry - where’s an explainer for what HEMS is?:smiley:

1 Like

HEMS - home energy management system that powershaper send out, basically a raspberry pi running home assistant.

Research ??? @matt @lloydham - I have a humidity monitor in my loft which is currently reading 99%. Condensation is all over the surface of my roof liner. Worrying!!! - for any homeowner who had just spent a small fortune insulating!!
Thankfully I received some great advice from within our community and I am tracking the moisture and the airflow.
It turns out we have stack effect !! - the cavity wall between the bathroom and the bedroom which is open from above in the loft. This cavity is full of super heated air which has been clashing with the cold air in the loft. The boiler pipes and radiator pipes reside in this cavity. Today I stuffed it from above with sheepwool insulation, then sealed it at the top with a piece of PIR board and insulating foam.
We have a number of other possible problems too.
A hole through to next doors loft who have a bubbling hot water tank which I am not sure whether it has a cover or not.
A void between the bathroom ceiling and plasterboard in the loft - both ceiling are full of possible air leaks via spot lights, speakers and holes for wires above in the loft
An exposed steel - boxed in with plasterboard in the bedroom below - we’ve pushed as much insulation around this as possible.
My loft has been sent to test me . I am sure of it!! It has made me probably the grumpiest housewife in Manchester this week. I can’t help but feel it has so many problems, that it would be ashame not to get some learning or research done for our members.
I will keep sharing. And anyone who wants to take a look is welcome.
I cannot deny that these problems are worrying, yet as I have started to learn the solutions - it’s fascinating too!
I hope my problems here can help others too x Carla


For those of you not on twitter:
Here is how I routinely track our household temperature together with how our energy use relates to this - giving a fairly rapid analysis of the thermal efficiency we are currently achieving.

I know that @Paul_Hadfield is looking into fitting around 10 humidity and temperature sensors, and is possibly following this thread as well! Just flagging this in case he wants to add his findings into the mix at some point too.

@Peter_Mumford apologies for missing this previously, and I’m sure you’ve since had a full explanation but this is the guide on the PowerShaper microsite- just in case you hadn’t been pointed to this before. Hope it helps, and happy to discuss further or field questions PowerShaper - HEMS User Guide | Carbon Co-op

1 Like

Thanks Polly. Yes, my key requirement is for ten or so inexpensive wired sensors to be sealed under my floorboards and to be functional for several/ many years (preferably for ever after - i.e. without needing batteries to be changed). Both the power supply and their signal outputs could I suppose ideally be carried by the wires - telephone cable? - if such sensors exist and are relatively inexpensive. I never want to have to lift my floorboards again just to get at them. I gather that these sensors need to be linked (by their wires I hope) to a hub/microcontroller of some sort in the room above, and as I have a Home Energy Management System (HEMS) under the Coop’s PowerShaper project it would be ideal if the microcontroller could in turn be wirelessly linked to feed the temperature and humidity data on in turn to that. Any thoughts greatly appreciated. They don’t need fancy cases, as they will never be seen again. I hope too that a switch could be incorporated in the system, so that it will automatically switch on a mains-powered fan to blow warm room air down there below the floor when/if necessary (I am bringing the underfloor space into the thermal envelope of the house, so am planning to close off the air bricks and insulate/air -seal the external perimeter, hence the requirement to monitor the humidity in particular).

1 Like

Hmm, similar problem here but not too bad as far as I can see. I put a load of extra insulation in my roof as I thought it sensible, so we’ve gone up from 3-4 inches by adding an other 200mm. Most of the roof has old (1980s) roofing felt and I’m now seeing some condensation on that. One area where we had an extension built in 2019 has breathable membrane, that’s fine plus area around it.

Worst area seems to be behind our solar panels. Next step - get some monitors up there so I can track temp and humidity on my Homeassistant. Xaiomi and Sonoff seem to be most used. Any recommendations?

@Matt-S and @zapaman will have some ideas on this, no doubt!

Thanks @polly. Yes Xaiomi or Sonoff sensors are very common and affordable.
In terms of just temperature a single EmonTH from OpenEnergyMon plus a daisy chain of multiple DS18B20 temperature sensors might be a good option. The EmonTH could be located somewhere accessible (for changing batteries)) and the DSB18820 probes could be inserted into the sub floor or loft areas where you need multiple temperature readings. These would not give you humidity but at least you would know if the temperature was getting low enough to cause concern about condensation.

1 Like

Thanks so much @zapaman @Paul_Hadfield here’s your starter for ten (sensors) :slight_smile:

Wasn’t sure where to post this, feel free to move somewhere more appropriate @mattfranklin.
I started off with two emonTh temperature and humidity sensors, and moved them around the house every few months. I still have both of those, plus another 7 connected to HA, including the latest pair in utility room and hall. So my house is pretty well covered :slightly_smiling_face:.
I’ve been watching the temperatures in different parts of the house, it’s like a yoyo in the loft and decidely cool in the hall. And my bedroom is nicely in between. A bit like the three bears?
But my daughter came to visit last weekend and complained the hall was ‘smelly’. So I started watching the humidity readings. I know there’s an inverse relationship between temperature and humidity, but can anyone interpret this graph? My utility room and hall have an original 1920’s clay drain running alongside them, which had some repairs done a couple of years ago. Wondering whether it needs more attention. 75%+ humidity is quite a bit outside the 40-60% healthy range!

1 Like

Hi, I have a variety of cheap manual monitors around the house and started recording before and during the work so we have a good idea of what is average normal in the house during and after plastering etc. 75% humidity is very high and occurs in the bathroom after the shower has been used but falls back to normal <55% within an hour. We detected a leak in the roof with sustained high readings over a couple of days after rain from a temperature and humidity monitor in the roof space (To check that work was done properly and fully effective we monitored everything). Our porch had high humidity and a smell- The internal ground level was found to be lower than outside, hence when it rained the ground underneath the porch accumulated water and created prolonged high humidity in the porch and hallway. Your graph shows high humidity 75% in the afternoon at 1.30pm in June. I am not aware of the orientation of the hallway- warming by sunlight or recent rainfall but this is shower room condition post use and it is higher than your bathroom! I would say it needs attention and probably a damp meter to check walls and skirting etc.

1 Like

Using this dew point calculator indicates that if any of the walls in the hallway dip below / around 13C then you will get condensation on those surfaces based on the values shown by the cursor on this sample of data. The values indicate a relatively high likelihood of condensation later on in the year. I guess there are a few ways of tackling this: dehumidifier, a more active ventilation strategy, some heating to raise the minimum temperature in the hallway etc.


I have today, just installed an indoor air quality monitor (M. Fawcett) in my kitchen, and these are my first impressions.

My kitchen is south facing and is used to propagate plants. I am currently working from home on a computer with two monitors and have had toast and a couple of cups of tea. It is 12.30pm and I have switched the air monitor unit on, and the initial readings are below. My partner entered the room not long after and comments that the air is a little stuffy, so I open one window a little and look at the monitor 15 minutes later- results below.

Foobot Initial Window open 15minutes 4.15 pm
Particulates µg/m3 16.8 26 37
VOC (ppb) 295 137 205
CO2 1067 467 740
Humidity (%) 74 47.6 48.9
Temp ℃ 24 23.3 22.6
Air Quality score (X/100) 28 29 36

I have been in the room since 8 am and noticed it was warm, but it was indeed “a bit stuffy” with high humidity and CO2 (see numbers). Venting the room through one of 4 windows for 15 minutes has significantly changed the composition with a small temperature drop but a huge reduction in humidity and CO2 and volatile organic compounds (VOC). The negative is the increase in particulates (dust, pollen, pollution?) above Global pollution index. I have sneezed a couple of times so pollen is a part of the increase in particulates (should have considered MVHR). I can feel the change in the room.

Initial verdict- very informative, I have seen an increase in particulates as rush hour has started 3.30pm (early as the football is on), I would love to see a rudimentary separation of the particulates. I am interested to see what happens when we start splashing the bleach about the house!!?


The hall floor is above ground level but there is a crawl space underneath the whole of the ground floor. Air bricks on all sides, so the crawl space should be well ventilated. The hall and utility room are east facing. The utility room has a lot of gaps at floor level, so has plenty of ‘natural ventilation’ up from the crawl space. But the hall doesn’t have any big gaps, has no windows and a double glazed porch beyond the front door. Temperatures went back up yesterday, so windows and internal doors were open well into the evening. Downstairs humidities went down, but the hall (orange) is still over 60%.

Haven’t got round to checking the humidity of the walls, but it’s on my list.