Wednesday, February 8, 2012

Thermographic images

8 Feb 2012: At this time of cold weather, it is an ideal time to get out with a Thermographic camera - forms the image from infrared radiation. This is a FLIR T400 which I have borrowed from my Faculty at the University of Nottingham. It's chinese made, and very easy to use, and copying the images to computer is like copying from a memory stick! There are a few things to learn, but it only takes a few experimental pictures to get the balance right. After more experience, there are deeper subtleties one can employ. But the initial results are very good, and I had the coldest night of the entire winter, ensuring maximum contrast between interior and exterior temperatures.
My first picture, the car parked just after driving it a couple of miles.
Front wall of the house, revealing conduction at window heads
Window of my home-office, revealing the thermal bridge of the lintel
SW corner, including the Surya Sunbox, showing that there is a warm zone
below the Sunbox. The temperature inside the sun box is almost always warmer than
the surroundings, even at night, so I am not surprised to see the brickwork being warmer,
and warmth leaking out at the edges.
Interior ceiling corner of my home-office. There is a cold bridge where
the blockwork goes up into the Loft. There are also faint lines revealing the
location of the rafters which transmit heat faster than the loft insulation.
This could be useful for the West Bridgford Ecohouses group, to check if their insulation has been done effectively, especially at junctions and corners.

Postscript: I did do a few more, for the Ecohouses group, and we were lucky, because this week was the only truly cold week of 2012.

2 comments:

  1. like this DNC!

    I am interested in seeing more pictures of the sunboxes though - perhaps from the field looking straight on.... I guess one of the only problems with photographing the boxes is that you are likely to be seeing reflections of the night sky rather than the temperature inside.... though its still worth investigating. I see from your picture that there is warmth above the windows and below the boxes, and then a warm spot at the top corner. Perhaps this is more to do with heat from the thermal bridge of the lintel, which then tracks along the aluminium frame of the sunbox. At the top corner this localised warmth could be due to the fixing, which anchors the box to the wall. i.e. tracking the heat from the internal to the external. This can be a significant effect and metal penetrations are something that we try to avoid in a passivhaus for this reason.
    Chris

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  2. Hi Chris. Due to the greenhouse effect (I presume) and also to the fact that in a sheltered enclosure, some heat loss from the house can build up, the air in the boxes is always a few degrees higher than outside, even at this time late at night. I think this is leaking out through the vents along the soffit of the box. The sides have been sealed. The upper part of the box is next to the loft, so there is negligible heat transfer up there. We are doing OK in this weather still, with the heat pump staying below 30kWh a day and the house below 40kWh.

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