Thermal imaging cameras can help reduce running and maintenance costs by quickly detecting energy loss.  FLIR Systems explain the benefits of bringing thermography in-house.

It’s so much easier to conserve energy if you can sense it.  For example, when lights and heating are left on in a high-rise, largely unattended office block that wastage is easily perceived.  What we don’t see however, at least not to the naked eye, is energy loss through building defects. Thermography has evolved into one of the most valuable methods of seeing this energy loss.

The commercialization of the technology has allowed it to be applied economically to an exceptionally broad range of tasks in this field.  Predictive maintenance of heating systems for example is a well established application.  But with the development of cameras dedicated to the specific needs of the building and construction industry the technology is now widely used to spot construction failures and insulation defects.

The New Harmood Estate in the London Borough of Camden is a typical public housing development that uses thermography in a traditional predictive maintenance role.  Built in the 1980s, the site comprises more than 200 dwellings that receive communal hot water and heating via a vast network of pipes.  This ageing system connects the properties to a remote, central boiler house.  

It was on this estate that Mechanical Services Manager for the Housing Department, John Stow, decided to test-drive his thermal imaging camera.  Readings from the pressurisation unit water meter in the boiler house had told him the New Harmood system was leaking substantial volumes of water. Without the benefit of site construction plans and in advance of thermography training, he scanned the estate and within half an hour had found the problem.

“I didn’t trust it at first,” John explained.  “I thought I might have simply discovered a buried, unlagged pipe. But when the contractor started digging, the major leak was evident.  I couldn’t believe it had been so simple to find.”  

Thermal imaging is certainly not a new technology to the Camden Council.   To ensure a high level of service to its tenants as well as to reduce running and maintenance costs, thermal imaging surveys have been regularly out-sourced.  However, whilst this service has been effective at pinpointing problem hotspots, it is not readily available.  

With the cost of a thermal imaging camera now very much reduced by comparison with prices prevailing in the mid-nineties, John Stow sought Council funding to bring the service in-house.  It was a move that made a lot financial sense as the Council is responsible for no less than 35,000 properties including 200 district heating systems that serve from 10 to 400+ properties ranging from bed sits to five bedroom properties.

There is no doubt that the problem on the New Harmood Estate could have taken up to a week to resolve if thermal imaging had only been available as an out-sourced service.  In the event, speedy diagnosis resulted in the residents being without a full service for just 18 hours.

Whilst good service delivery to its residents is clearly an important commitment for the London Borough of Camden, so too is the reduction in green house gasses and making sure that best value is achieved from investment. Reducing energy loss is therefore another key reason for purchasing the thermal imaging camera.

A typical district heating boiler house comprises three or four boilers and associated plant including a pressurisation unit.  If there is a leak anywhere in the piping network on an estate, this unit will continue to pump-in a corresponding top-up to maintain the required pressure.  This in-fill is metered making it immediately obvious there is a leak.

If left unchecked, the continual top-up of raw water promotes scale build-up in the boiler, plate heat exchangers and calorifiers. This scale build up not only leads to increased energy consumption but may result in premature failure of key plant.  As a result more energy has to be used to maintain the temperature.  Finding leaks fast is therefore of critical importance in cutting these costs and the fundamental reason why the Council purchased a thermal imaging camera.

Visualising air leaks

Air tightness testing is a field in which thermal imaging is increasingly being used to provide tangible evidence of non-visible air leakage paths.  Indeed the air leakage test is required by Building Regulations AD L1 2006 on all new buildings and many regularly fail to meet their target.

Failure makes it necessary to carry out diagnostics and a smoke pencil or smoke generator is often used to detect these air leakage paths.  These are fairly basic tools and to a degree effective but whilst they indicate the presence of a leak they don’t show its extent.

This is where an infrared camera is a boon as, provided there are a few degrees of thermal difference between the inside and outside of a building, it will visualize the air flow.  Swift remedial action can therefore be taken to seal the leak, not by trial and error but by using the visual information provided.

Ian Mawditt is an expert in building physics and has been using this technology for air leakage applications.  His company, Living Space Sciences is based in Oxford providing a consultancy service in building code compliance and accredited mid- and post construction site testing services.

Whilst he uses thermal imaging predominantly for evaluating insulation continuity and thermal bridges, for which it has evolved as the ideal method, Ian often takes his camera to an air tightness test.  “If I need to visualize the air leakage to a client there is no better way than to capture infrared images,” he explains. “And although the greater the temperature difference the better, I can still get a good image on my camera with a temperature difference from as low as 5°C.”

Checking for insulation defects is an ideal IR application and is made simple by the inclusion of an insulation alarm.  All that is required is for a temperature measurement of the outside face of a wall to be taken and a critical surface temperature factor applied.  When the temperature is then taken of the inside face of the same wall the new feature will calculate which areas are inadequately insulated and highlight them in an ‘alarm’ colour on the infrared image.

What else can I inspect?

Facilities management is just as much about maintaining the efficient running of tangible assets, power supplies and heating systems as it is about identifying problems in building fabric and minimizing energy loss.  Infrared inspection is the ideal tool for a broad range of electro-mechanical, electrical and HVAC predictive maintenance tasks that combine to ensure a rapid return on investment for the camera.

Infrared cameras are widely used for electrical inspections.  They can detect hot spots due to excess load, loose connections, faulty equipment or other problems that manifest themselves thermally.  A major benefit in facilities management is their ability to scan a wide area in one pass to highlight potential reliability problems.  All kinds of problems show up thermally for further investigation.

Thermography should focus primarily on equipment that is considered critical — vital to the operation or representative of the biggest safety concern in the facility.  Equipment that could blow up or catch on fire is clearly something that should be added to an infrared inspection route and inspected at regular intervals.

In addition to their predefined route, the most effective thermographers have an innate curiosity as to how something would look thermally and why.  Frequently, the people that install and repair equipment are well-suited to becoming thermographers because once they learn the basics of infrared, they can visualize how the system they are observing with infrared is built.  This can be extremely valuable for infrared targets that are covered or far enough away as to be difficult to resolve with the naked eye.  

There are numerous applications that are suited to infrared. A thermographer at a semiconductor plant described how during his normal inspection route he observed a pipe that was extremely hot.  The pipe ran to the drain, which seemed unusual to the thermographer.  When he followed the pipe back to it source he discovered that purified heated water was literally connected directly to the drain.  An improper piping installation was corrected and an estimated £60,000 a year saved.  The company had owned its infrared camera for just a month and it had paid for itself several times over, all because the thermographer asked “What else can I inspect?”


FLIR Systems Ltd
2 Kings Hill Avenue
West Malling
Kent
ME19 4AQ

Tel: + 44 (0) 1732 220 011
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Web site: www.flir.uk.com