One solution for reducing carbon footprints – and household bills – is increased energy efficiency. With infrared imaging, inventor Brian Harper is helping people to see exactly how.

Brian Harper is not happy with the state of my house. As he pulls up the corner of my bathroom carpet, he cries out when he sees what is beneath: a section of missing floorboard. On a tablet showing live thermal image video, the resulting cold patch is dark violet. Harper is assessing the energy efficiency of my home. And apparently, it is sub-par.

Cutting the energy we use in our homes is vital if societies are going to reduce global emissions from fossil fuels. Technological advances in renewable sources will help, but they still are unlikely to provide all the answers. Which explains why Harper, who helped develop early thermal imaging tech for the military almost 50 years ago, is poking about behind the lavatory of my semi-detached Victorian home in Bristol. His reaction to my missing floorboard and seeing the heat loss on screen underscores the potential connections between my chilly, poorly insulated room and our large gas bills.

The ability to take thermal images dates back to 1929 when Hungarian physicist Kalman Tihanyi invented the first infrared-sensitive camera. Infrared is a form of electromagnetic radiation that humans can’t see but can feel as heat. The hotter an object, the more infrared radiation it gives off.

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Early German night vision technology used infrared light sources to illuminate targets at the end of World War Two. The first systems that generated images based on reflected light from the Moon, stars and sky were developed during the 1960s.

British scientists played a leading role in the development of modern thermal imaging technologies, mostly those working at the Royal Radar Establishment (RRE) in Worcestershire, where Harper started as a student apprentice in 1967.

Harper’s headteacher had told his mother that the teenager – who spent long hours in his garden shed making and inventing things – was not university material. But the RRE assessors were more than happy to take the 15-year-old.

In the early 1970s, the sensors used in infrared cameras had to be cooled to close to -200C (-328F), usually with liquid nitrogen, making them bulky and expensive. Harper became part of a small team working on lower resolution, but more portable, uncooled systems.

The group adapted television camera technology that produced broadcast signals from a beam of electrons scanning over an image in a vacuum tube. By replacing the light-sensing layer with elements made of triglycine sulphate – a crystalline material capable of turning temperature change into a change in voltage – they developed a portable thermal camera. This would later be adopted by firefighters to see through smoke on military ships, including during the Falklands War.

After leaving the military in 1980, Harper developed a portable, uncooled thermal imaging camera, called Starsight, that measured temperature. It was used in a wide range of applications: detecting damage to electrical equipment, production line quality control, medical diagnosis and even catching drug smugglers. Nasa ordered a version capable of making normally invisible burning hydrogen visible for the 1988 space shuttle launch – the first since the Challenger disaster two years earlier.

By the late 1990s, Harper had become interested in something else: the idea of building homes partially underground to reduce energy use. He used his own home in the hills of Worcestershire for his first experiment.

Today, he still lives and works long hours in what is surely the archetypal eccentric inventor’s lair. Under his home are six underground workshops stacked high with lathes, plasma cutters, theodolites, 3D printers, spray cans, dozens of spools of wire and stacks of scientific journals. When I pay a visit, the largest room, which he calls Middle Earth, contains three large gas street lamps. Two assistants are bent over electronics circuit boards, hard at work with soldering irons. Next door is another workshop mostly filled by a small red boat called Jemima.

Harper became aware of the energy efficiency potential of thermal imaging when working with a scheme to construct experimental, low-energy houses during the 1970s. While building his underground workshops, Harper became increasingly interested in green building and other efforts to reduce humanity’s carbon footprint.

Harper carried out early thermal imaging-based energy efficiency surveys in Devon and in Malvern. The assessment on my own home is part of part of the Cold Homes Energy Efficiency Survey Experts (Cheese) pilot project. The brainchild of Harper and others who heard about his work, including former television producer Mike Andrews and software engineer Jeremy Birch, the project has cut the cost of the equipment needed to carry out thermal imaging surveys. It also draws on research suggesting that when you show homeowners pictures of wasted energy escaping from their houses, they are five times more likely to take action.

Their first move was to develop Heatview, an interactive map of Bristol that adapts Google Street View to give users thermal images of the front of their homes and those of their neighbours. The group adapted capabilities of Harper’s camera to a cheaper system, including software they developed themselves and a camera that could be clipped onto an iPhone. This brought the cost of the equipment needed for a thermal imaging survey down to about £350 from more than £5,000.

“People find the concept of energy quite difficult to visualise and understand,” says the project’s general manager Andrews. (He has previously worked on BBC natural history and science documentaries). “My original instinct – that seeing is believing is especially true in this case – was subsequently shown to be correct by independent research.”

While the Cheese project was being set up, Plymouth University psychologists were investigating the same question. Their 2014 study showed that householders who received internal thermal images of their homes were 4.9 times more likely to install draught proofing in their homes than those just presented with an energy use audit.

Seeing green

In the first phase of the Cheese pilot, in the winter of 2015-16, Bristol residents were asked to heat their homes overnight. During their surveys, the air inside them was blown out of their front doors with a giant fan to increase the in-flow of cold air through gaps. Issues such as roof insulation gaps, poorly fitted windows and underfloor heating problems were highlighted on a tablet the occupants looked at as as they accompanied the surveyor around the house. According to follow-up calls, 73% of the occupants take some action within three months, and 94% say they plan to carry out further work.

The Cheese project has not been the only effort to encourage householders to make energy-efficient changes. But many government-led schemes have failed to live up to expectations.

In 2013, the UK government launched the Green Deal, which offered loans for energy efficiency changes which could be repaid through energy bills, and the Green Deal Communities fund for local authorities to offer further incentives. Both were scrapped two years later amid low take-up and widespread criticism. Bristol City Council, for example, had to step in to help people who signed up for energy efficiency work on their homes after the company contracted to deliver the work closed down.

So far, the volunteer-run Cheese pilot has carried out around 110 surveys over two winters. The group has had initial discussions with groups in other cities interested in running similar projects, such as the city of Vancouver.

“Within five years I hope we’ll have 10 to 20 cities carrying out internal thermal surveys,” says Harper. “Within a decade, if we do this right, we could be having a major impact on energy efficiency.”

It certainly has an effect on me. As well as the missing floorboard, the survey of my house revealed ill-fitting sash windows, a draughty ventilation fan, inefficient lightbulbs, gaps around piping and cabling, and holes in roof insulation. A few weeks later, I receive a call from a Cheese co-ordinator, asking whether I’ve done anything to reduce my energy consumption.

I confess that many of the jobs are still on the to-do list – but we have filled some gaps in floorboards and decided to lay imitation plastic tiling in the hall rather than have bare floorboards. The electricity meter Harper left behind showing the real-time cost of electricity use has made me turn off unneeded lights. And I’ve replaced the environmentally-criminal missing floorboard.

“Lecturing to people from above about what they have to do to save the planet isn’t going to work,” says Harper. “You have to educate people at a community level about reducing their costs and improve their comfort, so that thinking about energy becomes second nature. As a result you end up with enlightened people with significantly reduced carbon footprints.”

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