Using the thermal imaging camera was really helpful. We've found a few areas that require some minor work. Generally, we've been very pleased with the insulation work we've done. The colours aren't always that important – it depends on what you're targeting on. 

@editor Which Flir model was it you used ? I've been thinking about getting the 'cheap' one Flir One Gen 3 with resolution of 60 x 80. 

@heat-pump-newbie, we used this model (FLIR ONE iOS) and it was excellent – a tad pricy, but very, very helpful:

https://amzn.to/4gkv08Q

@editor 

I use my companies Flir camera - I think it's E40, or something like that.  It was pricey (£5k), but that was ages ago, they're all much cheaper now.  It's best when it's dark and cloudy and cold - the sun heats objects up, and the night sky is very cold so things unevenly cool down if they can "see" it.  When it's cold you get better contrast.  I think the more expensive cameras have manual focus, bigger aperture, so lower noise, the work one is 50fps - not needed for my "non work activities"!  

I tend to let the camera autorange first, then "lock it off", fixing the Tmin and Tmax of the display, so as I walk around the colours don't change their meaning.  I like the colour bar on the side for easy reference later.

Here's a pic I took of a friends house recently.  I've labelled the walls a(left gable), b(above campervan), c(right hand side):

a) cavity wall insulated

b) rendered cavity wall.  Don't think they filled the cavity, hence glowing.

c) wooden slats over cavity wall.  Don't think they filled cavity.  It looks like it is ok - but cold air will be circulating behind the cladding, so the pic "lies".

@robl I have an Fluke IR thermometer which is great unless the scanned surface is shiny, like a copper pipe... Would the Flir have trouble giving a meaningful thermal picture of shiny pipes etc, eg foil covered lagging ? I'm hoping to get a good idea of how well the lagging is performing.

@heat-pump-newbie 

Yes, just as you say it’s terrible with metal surfaces.  You can sometimes program in the emissivity, I think ‘mine’ defaults to 0.95.  An emissivity 0.95 means 95% of the reading will be of the surface, and 5% is a reflection.  Reprogramming the units 0.95 value just changes how the camera interprets the amount of 10um radiation hitting it,  it won’t alter the picture itself.   If it’s a shiny surface, like a window, you’ll still see images in the reflections, and you won’t see through it or walls, not like in the movies!.  I think clean metal is so low emissivity as to be pointless - stick anything on it and it will be ok - pvc tape, paper, paint, dirt.

To update the thermal imaging thread, we were recently sent the world’s smallest thermal imaging camera. I’ve just finished reviewing the Thermal Master P2 Pro, and with Picture-in-Picture mode, multi-point monitoring and sharp thermal imaging, it’s pretty awesome. Plus, no extra batteries to charge - it’s powered directly by your phone!

Watch the full review to see how it compares to the FLIR One and why it’s a must-have for your home:

If you want to buy it, use code RHHP2Pro for a Christmas discount: https://bit.ly/rhh-p2