27 Oct 2021 - Solar Power testing
Back in 2014 we noted that we did our first 'solar powered test'.
We have done a few more since then with a similar set up - where the home or building being tested had sufficient solar PV output to run the test fan.
However, it was ad-hoc, and depended on the site.
Recently, we have taken matters into our own hands and put together a little mobile solar generating station with battery, with which we have tested over a dozen homes already.
Ok, the output is low so it only works on our smallest fan - the Retrotec 300, but it is very cool to be doing solar powered tests.
As winter comes in, the solar tests will ease off again, but we look forward to spring.
On this site in early October, the panels were feeding the battery with about 130W for a few hours, while the fan used 75-150W in operation, all from the battery
Example of the small mobile solar generating system powering an airtightness test
The three best results are all from the same timber frame supplier. The best we tested that was not from them was q50 of 0.74 m3/hr.m2 on a 2 storey mid terrace house.
1 Aug 2021 - Blowerproof, Aerosana, Vara Fluid, and the likes: liquid airtightness membranes
Airtightness membranes were sheets of materials. Now they are also paint on or spray on liquids. But are they any good?
Well, like so much in life, it depends.
We have tested buildings to really good airtightness levels, including at least one that comes to mind that was at Passive House level for a newbuild, where they depended on one of these liquid membranes to provide the main wall airtightness. So they work.
But they also don't work, like any other airtightness material, if used in the wrong context or applied poorly.
The lesson has to be: use carefully, ensure the substrate have no really big gaps in them, and you may need more than just a couple of coats.
A section of wall coated with Blowerproof. The Siga membrane over it was checking if leakages were coming through. in case case, they were not. the traditional type membrane stayed flat on the wall
In this example, the mortar joint recesses into the blockwork a bit, revealing the grey of the block grain. The liquid membrane, even this one with extra fibres, was not able to fill the gap. Additional coat(s) were required to get the airtightness of this new home to the levels required.
01 April 2021 - Some infra red musings
We don't post many items on this blog regarding infra red - partly because there is the danger that the buildings in question would be identifiable.
But just for the crack, here are 2 sorts of things we come across from time to time:
- Internal walls plainly visible from the outside
- Double (triple) glazing not working as it should
A couple of examples below:
The vertical warmer (here: blue) lines in this image show the location of where inner walls are tied into the external walls. This is an older, solid walled house, so the effect is much more pronounced than it typically is with a cavity.
This example of a large glazing unit is typical of double glazed units that are failing - the heat loss in the centre of the pane is evidently more than the edges. Care has to be taken with the surface temperature readings noted, as they may be partly due to reflections, but rthe pattern of cold centre is the same whatever angle this type of window is viewed from.