17 Feb 2020 - The moon in Infra red
While doing a thermal imaging infra-red survey of a home recently, in the early morning, the moon was brilliant in the sky.
So we took a thermal image of it.
Now, we are no experts in astronomical thermal imaging, but still with the camera on full zoom the image was as we say in these part, a bit of craic!
original full image - moon waning
smoothed out, zoomed in thermogram (thermal image) of moon waning
Note that we did not alter the camera settings for this image
10 Feb 2020 - Airtightness of Blockwork - Part 4
Back in 2013 we had a little series about the airtightness, or not, of concrete blocks. Over the years we have had reason to talk to quite a few people about this. (See previous blog entry from 2013 here).
Today was the first time in a while where we have had to explicitly show a site supervisor why doing a pretest on a building with completed membrane, but incomplete plaster layer on blockwork does not make a lot of sense.
Of course, we did a test as requested, no surprise that the result is over 10 m3/hr.m2, but to be fair that should improve massively once the plaster layer is complete.
|Example of condition of building during test - membrane complete, window taping complete, no plaster on walls||Example of a leak at a mortar joint - one of very many||Example of leakage through the block itself|
The story in the 3 images above is this:
- the left image shows the condition of the wall in overview - well done, tidy blockwork.
- The middle pic shows a typical kind of 'mortar joint' leak as is very common in blockwork.
If we could have counted these in this house, there may have been thousands.
- The right hand pic shows a segment of only block taped off loosely. This means there is no mortar joint there, and yet still air leakage.
We could have a bit of fun with numbers and just pretend for fun that the hole size here at the tape is 2cm2.
If so, then the air volume through this 1/2 block in test conditions is 0.01 m3/hr, so the whole block could be 0.02 m3/hr.
If there are about 10 blocks per square meter, and the wall area in this house is 260 m2, allowing even 15% of that to be mortar (a bit high), say we have 220 m2 of blockwork, so that is ca 2200 blocks, which is then about 2200 * 0.02 = 44 m3/hr.
To be fair, the vastly greater proportion of leakages through unplastered blockwork is through the mortar joints - this leakage here directly through the block grain on a very rough sum is only about 1% of the observed leakage rate (but it still counts!)