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Thermal imaging camera case study – St Julian’s Church

Background information

St Julian’s Church was built in the 1950s, well before energy saving measures such as double glazing and loft insulation were introduced. Since then they have improved the energy efficiency of buildings with roof insulation and new boilers and radiators.

The entrance area and kitchen are recently built to modern standards.

What they wanted to know:

  • Is heat escaping and where?
  • Do the new curtains and blinds help?
  • Is the roof well insulated?
  • What needs fixing?

What and When:

  • February 2019
  • Photos were taken late afternoon
  • The whole building had been in use and heated all day


Understanding the pictures: The temperature shown at the top of each picture is that at the centre of the cross hairs. The scale on the right hand side gives the temperature range.

Window blinds

From looking at figures 1 and 2, it is clear that there is a significant reduction in heat loss when the blinds are closed.

Figure 1: Photo taken from inside the church with the blinds closed.

Figure 2: Photo taken from inside the church with the blinds open (note, heating pipe on the right – yellow).


The two images below (figures 3 and 4) demonstrate that closing curtains or blinds can have a similar effect to double glazing.

Figure 3: Photo taken from outside of the main hall, single glazed windows with curtains drawn.

Figure 4: Photo taken from outside the back of the kitchen, double glazed window with no blinds.


The dark blue roof shown in figure 5 indicates that the roof of the church is very well insulated.

Figure 5: Photo of church roof taken from outside.

Other findings

Figure 6: Photo taken from inside the church of the main doors, showing that the seal on the bottom of the door needs replacing.

Figure 7: Photo taken from inside the windows demonstrates that although double glazing is very effective, the metal window frames conduct cold air.

Improvements made in light of the findings

Partly as a result of using the Sustainable St Albans thermal imaging camera, St Julian’s has installed replacement curtains in their hall, as well as new blinds in the church.

Andy Sharp said in his article for The Parish Magazine in May 2019:

“I’ve looked at the gas bills – and we only use gas for heating. Gas consumption in the three months from 1 December 2017 – 28 February 2018 was roundly 16,200 kwh. For the three months 1 December 2018 – 28 February 2019, it was roundly 13,500 kwh. That’s a 15% reduction.

While the more recent December and February figures were lower than the previous year, the more recent January one was not.

This, I think, highlights the fact that:

  • the weather might have been different in the two years (and no, the Beast from the East was at the end of March!)
  • the pattern of bookings might have been different (because we heat the hall only when it’s about to be used – no bookings, no heat).

Because we pay monthly by direct debit, the financial impact may take a while to feed through completely. That said, we paid 20% less in January 2019 than in January 2018.

Caveats apart, it’s both interesting and heartening from a financial and environmental point of view. And it says to me that we do need to keep [the curtains and blinds] closed/drawn when possible!”

He also commented: “One other useful thing which emerged from use of the camera – a myth was dispelled. Our windows are separated by brick piers, and someone had once told us that these brick piers ‘wicked up’ the heat – so blinds or double-glazing wouldn’t help to insulate the building. The thermal images flatly contradict this. We are now actively considering double glazing.”

Use our thermal imaging camera

Our thermal imaging cameras are available to borrow. To find out more about how you can use one on your home or buildings, visit our thermal imaging camera page.


Acknowledgements – We would like to thank Mike Gibbs and Andy Sharp for providing the photos in this case study, and for providing insight into the improvements that the church is making to reduce their heat loss from the building.

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