Using a Infrared Thermal Imaging camera to assess the quality of my insulation
13 Jan 2010
A building physicist from the building industry came around to look at how well my walls are resisting heat gain/loss (keeping the heat in/out). He is conducting a study on retro-fitted insulation study for BRANZ. Polystyrene beads is one of the solutions he's looked at. (In fact he tested polystyrene bead insulation on his own house.)
He was particularly interested to see if there was any evidence of slumping of the polysyrene beads since Jan 2007.
When they came the temperature was 20 degrees Centigrade inside and 13 degrees Centigrade outside (we're near the end of a cold southerly snap).
They bought their FLIR P620 infrared camera which produced these images.
That's him in the center in white, and his reflection in the middle window. Then on the left is me standing behind the camera photographing the screen. His elbow is measuring 24 degrees.
The reason the left window is a different colour from the middle and right side windows is it's a retrofitted double glazed unit (bought from Ultraglass in Seaview). The middle windows are standard single pane glass, and the right hand window has 3M plastic "double glazing" over it. (IR cameras do not reflect clear plastic so it doesn't see any difference.)
He thinks my real double glazed unit may also have a low-E coating - which enhances the IR reflection. This would be nice - I didn't choose the low-E option when I was buying because it was going to increase the price too much.
This is the corner of the lounge, just above the back french doors.
Here's what I see:
- the windows are black - that means cold
- the pelmet and curtains are yellow - which means warm, that's good
- above the pelmet you can see warm wall with faint colder vertical sections - that's the wooden studs conducting cold
- the column above the left side seems to have a section at the top that I didn't fill properly. I wonder if there's a hole in the left side stud and beads have fallen thru to the bottom of the next column?
- to the left of the french doors there is a whole ceiling-to-floor column of cold - that's a section I left empty because there is a power socket down near the floor. The column beside it - in the corner does have insulation.
- at the top of the picture is the ceiling - all warm - that's my double layer of Batts doing a good job
- along the edge of the wall and roof it's black - meaning cold. In well-constructed modern super-insulated houses the builders and architects play particular attention to this area.
- on the left side wall it look's like my insulation is a bit light. This was the first column of insulation I ever filled (with the hair dryer). It may be that the vacuum cleaner blower I used later, with it's greater velocity, does a better job at packing in the polystyrene beads than the hair dryer. Also the left side is the south wall which you'd expect would be colder (in New Zealand).
We spent 1.5 hours doing the whole house and found a diagonal bracing beam that caused me to leave some gaps.
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Other things I learned:
- He used a (Ryobi Blower Vac 2200 leaf blower (search TradeMe) with the blower bit cut off and the machine acting as a vacuum rather than a blower
- He used 16mm holes on the interior walls (he experiments with a range of hole sizes to find the smallest size that would still allow the beads to flow well. This means a lot less effort drilling the holes and filling than my 35mm holes.
- He used a good stud finder to find the studs and dwangs in his house. I used a stick and a plumb line to find diagonals. From the IR pictures it now appears that I missed several diagonals with my technique.
- Then he used the infrared thermal camera to check his work. This is a very good quality checking system. In New Zealand there are companies who will do this for you. When I asked in 2009 they quoted $300 to do my house.
- I got the impression from him that the problem of polystyrene beads reacting with electrical wiring was less clear than some commentators state. The research he had seen made the assumption that the interactions would continue at a constant rate over the years. An alternate theory is that the reaction rate starts out high and decays over time. That doesn't mean it's "safe", just that it may be less unsafe than previously stated. Make of that what to will. I'm probably not going to go back and fill in the sections of wall that have wires - but I'll be less worried. (He didn't put polystyrene in with wiring in his own house.)
He sent me a follow up email:
And later he sent:
[Note: the greyish looking circle near the top where the beads are being blown in is the very fine powdery polystyrene that you get with recycled polystyrene beads. It shoots out of the nozzle and sticks to the perspex. Initially I thought it was an empty spot. Paul]
See also: CompressedAirTransferSystem for out latest experiments - May 2011