Cwmdu Sustainable Energy Group

helping the community to a sustainable future

Energy: Insulation

Thermal Imaging Insulation Audits: Infrared Camera Project

The aim of the project was to evaluate the use of an infrared camera to find out if it would help to identify where most heat was being lost from buildings. These areas could then be targeted.

Camera Used

Following research through magazine articles and on the internet, a suitable camera was identified and a quotation for a weeks hire obtained. A grant from the Sustainable Development Fund of Brecon Beacons National Park was obtained with match funding from voluntary labour to experiment in using the camera and interpreting the results.

It was planned to use a FLIR i5 with a sensitivity of +/- 2 °C. This would have cost £1,750+vat to purchase. Due to confusion with the supplier the camera used was a FLIR B40 which had additional features and a sensitivity of +/- 1°C. This camera would cost about £4000 to purchase. The supplier though the original camera would not have been sensitive enough for our purposes but his colleague thought the original camera would have met our needs.

Ease of Use

The camera was very easy to use. It had a display screen which showed an infra red image of what the camera was pointed at. The camera was auto ranging, and squeezing the trigger saved the image on screen. So the camera worked by pointing and clicking. There were a few functions available including an infra red image surrounded by a visual image, only showing temperatures above or below a set temperature and black and white images rather than multicoloured ones.

We found the multicoloured images the most useful. In the centre of the image was a circle and the temperature of the image in that circle was displayed on screen. You could also adjust the focus for close up images, but we did not find this very useful as we were usually sufficiently distant from the buildings we were surveying that focusing was not necessary.

Buildings Surveyed

We surveyed 17 buildings in the Cwmdu area with 3 of these in Crickhowell. The buildings age ranged from being built about 1650 to the CRIC Resource centre built in the 2000s. We took images of walls made of a variety of materials, windows and doors and roofs. As we got used to using the camera started to evaluate the results we got more sophisticated in the way we used the camera. We started to take images of the same object from both inside and outside so that the temperature drop through it could be identified and the heat loss calculated. We built up a collection of images which were downloaded into a PC. If viewed through normal photographic software you could just view the image. However when viewed using the software supplied with the camera you could manipulated the image, change the range of colours, turn the image to black and white which made identification of the building much easier and move the circle anywhere on the image which then gave you the temperature at that point.

How well did the camera work?

The manufactures claim you could use the camera to identify the following

Detect hidden problems

Using the camera on an under floor heating circuit you could clearly see where it was not working properly

The red is where hot water is heating the floor and the blue is where there is no heat. This was due to very restricted flow due to a blocked mixer vale

The picture below shows a correctly working electric under floor heating in a toilet and shower

Assess damages
Survey moisture and leaks
Identify energy losses

Using the camera to take images of both the inside and outside of a property you could calculate the heat loss through the material, as you would have the temperature on both sides of the material. With other information i.e. room temperature and outside temperature are able to get an accurate indication of the heat being lost through surfaces in the buildings
Find electrical faults

When taking an image of a house wall, the thermostat showed it was clearly hotter than the surrounding wall. It is represented as white.

Find overheating

In the image below of a prefabricated bungalow you can clearly see the construction of the building, from the lines of the wooden frames inside the building wall.

Issues identified when using the camera

When taking images you needed to record the image number that showed on the camera so you knew which building the image related to.

You could only effectively use the camera during the heating season for obvious reasons.

It was easy to have an infrared reflection of your body heat when recording images. See the two reflections below with hot faces!

The use of the camera was restricted to late evenings or at night as materials would heat up during sunny weather. We used the camera during a sunny week and you could easily see the solar gain from the prolonged sunshine. See the image of Cwmdu village hall where the path is as hot as the walls of the building due to the solar heating whereas the grass is 6 °C cooler.

The camera was meant to be able to identify heat loss from draughts but we could not identify this effect even on a badly fitting door. You were meant to see swirly effects of the draught.

The camera self adjusted what the colours represented in the thermal image which could be confusing. In the picture of the wood burning stove red represents about 130 C.

Whereas in the much cooler image it represents 15 C.

The equipment is relatively expensive

We planned to trial a £2000 model but were sent a £4000 one!

Conclusions

Positives

The camera was easy to use
Produced clear infra red images of buildings
Self adjusted to the temperature range of the building and surroundings
Images when viewed within the software supplied were easy to interpret
Very good at detecting faults, in effect seeing into walls and floors
With experience of using the camera could get clear images

Negatives

Being self ranging made it hard to compare images as one colour could represented different temperatures in the image
Often the camera was telling you information you could work out without it
Restricted times could use during the year as needed heating on, and it not to be a sunny day
The model used was very expensive

Recommendation

As the infra red camera gave good thermal Images which were excellent at finding faults, and with practice and experience, the green valleys should consider purchasing the cheaper model for use by the local sustainable energy groups. The more expensive model does not offer value for money.