Infrared Thermal Imaging

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.

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:

[I used a] $100 Ryobi Blower Vac 2200 with the blower bit cut off and the machine actually acting as a vacuum rather than a blower
In the loose-fill insulation industry this is classified as a thru-blower as opposed to the bypass-blower type where the insulation is fed into the output stream of the blower rather than into the suction end. Ironically the blowers used in many of the small commercial bypass units are actually the motor and blower units from domestic central vacuum systems. I think they call them blowers to avoid calling them suckers!
The bead goes in at 70 litres/min.
You can just see the small 16mm injection holes in both the thermal image and the picture. The holes made for the other materials are typically 25-50mm
The gap at the top of one of the cavities was deliberate to demonstrate what happens if an installer doesnít determine the frame location correctly and the injection hole ends up being at the bottom of a cavity and not near the top. The blower is still able to push the bead up 600mm but it was not done in this case.
For comparison there is a video on the Johns Manville:
Despite the technical literature indicating a fill rate of about 70 litres/min the reality in that video is that it takes him 5 minutes and the withdrawal of the injection tube is particular tedious. This translates to a fill rate of about 11 litres/min or 1/6th of what we can achieve with the EPS bead.
I notice on the U.K. websites of EPS bead injectors that they are all claiming that the material is %100 recyclable but they donít say how they intend to do that when it is adhesively bonded. Sucking the loose bead back out is not an issue and the insulation industry already has equipment for doing this with cellulose.
There are still a number of issues still to be resolved with recycled EPS bead and one that I came across recently is the concerns about the environmental prevalence of the fire retardant chemical (HBCD) that is unique to polystyrene. It looks like there is a need to separate the dust and fine particles from the beads during the processing stage. PolyPalace apparently has plans to do it at some point.
Advantages of recycled EPS as opposed to cellulose, rockwool and glasswool:
* Can only be blown at one density Ė canít be overblown
* Very little settling compared with new bead or low density fibres
* Much better at fill behind objects like pipes and diagonal bracing.
* Packs easily with relatively light pressure compared with risks of structural damage when dense packing fibrous materials
* No variation in pressure during installation so constant flow rate and packed density
* Much smaller infection hole so much quicker and easier to patch. Less risk to damage to the building associated with exterior injection. Less mess.
* Placement of injection hole is much less critical
* Easy to control installation when dealing with open top plates by using injection hole lower down the wall or reducing airflow/pressure
* No need to use a filler tube
* Cheaper, small, lighter quieter, less invasive equipment so much more opportunity to install from inside.
* Obvious from the back pressure when the cavity if full
* Material does not need expanding before installation so much easier to use material inventory to check that installation is complete.
* Equipment could include quantitative flow rate measurement.
* Only need to check the tops of each cavity with a thermal imaging camera and not the edges as well.
* Much easier to thermal image than low density fibrous because of uniform density and low conductivity.
* Can easily be removed and re-installed or recycled
* VERY FAST: so effort can be directed at the quality and completeness and not on doing it even faster.
* CHEAP: so effort can be directed at the quality and completeness and not on the process of using as little material as possible.
Canít think of many negatives!

And later he sent:

The video shows recycled EPS bead being installed using a commercial grade compressor and a hand held vacuum-blower. The bead is going in at about 35 litres (compacted) per minute.

[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]

Vac-u-Gun (And here's a similar unit: Hand-E-Vac)
We have been using the Vac-U-Gun in the field with a cheap $250 2.5 HP compressor from Bunnings running at about 80 psi.
It is noticeably slower than with the commercial compressor and small compressors are very noisy but it is far easier and simpler than using a centrifugal blower and the compressor can be left outside. The blower is then light and easy to handle and quiet Ė no mechanical parts to stuff-up. Also very controllable in terms of flow rate and start & stop is instantaneous.
Now that PolyPalace is supplying the beads in smaller bags it is a simple task to just shove the end of the hose into the bag. No double handling of bead and associated mess and it is easy to clear the nozzle and hose when it blocks.
A 5 HP compressor would be needed to enable a continuous duty cycle on the air. For DIY I would recommend drilling all the holes and then hiring a compressor as it would then only take about half a day for two people using two vacuum-blower guns to insulate the walls of a typical house.
The compressed air vacuum-blower creates much less of a static charge issue than the mechanical thru-blower method. As an added bonus is that if needed there are simple/cheap anti-static air ionizing systems designed to work in conjunction with compressed air blowers.

See also: CompressedAirTransferSystem for out latest experiments - May 2011

Cheers, Paul

Page last modified on 14 May 2011 at 04:09 PM