Thermal imaging cameras are a brilliant invention.
Made to show up things that are warm or hot against a cool background, they have been used to find missing children, apprehend thieves who are hiding in the dark and film wild animals at night. But one of their most common applications these days is in showing up heat loss from buildings.
Edinburgh World Heritage used them in 2010 to demonstrate how much heat can be saved from single-glazed buildings by pulling the curtains or closing the shutters (loads, as it happens).
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If you took a thermal imaging camera around Scotland, it would show how office buildings glow in the dark and how heat flies out of uninsulated houses; in short, it would demonstrate how much heat we use - and waste - all the time. Reducing that loss and generating heat from low-carbon sources will be the next big step in trying to reduce carbon emissions.
Scotland is doing well when it comes to generating renewable electricity. The equivalent of more than 40 per cent came from renewables in 2012. That should rise to 50 per cent by 2015 and puts the target of 100 per cent by 2020 within reach.
But electricity accounted for only 21 per cent of Scotland's energy consumption in 2011. The single biggest cause of energy use is non-electrical heating, which accounts for more than 50 per cent of Scotland's total energy demand (the remainder is down to transport). About two-fifths of Scotland's heat use comes from domestic heating and three-fifths from industry and commerce, with fossil fuels accounting for a great deal of it. The Scottish Government has missed its own targets on greenhouse gas emission reductions three years in a row, partly because of this.
So something has to be done about Scotland's heat use. The Scottish Government currently has a target of generating 11 per cent of non-electrical heat requirements from renewables by 2020, up from less than three per cent in 2010. It also wants to reduce Scotland's total energy consumption by 12 per cent.
So how can it be done? There will have to be a major reduction in the overall demand for heat, through energy-efficiency measures, but the way we generate and distribute heat will also have to change. One way forward will be district heating, where many buildings are heated from one source. Even using fossil fuels to generate the heat, these systems can achieve reductions in both carbon emissions and fuel bills, but with biomass or geothermal heating they can be very low-carbon indeed.
This summer, the Scottish Government published a "heat map", highlighting areas of high heat demand and supply so that local authorities and developers can better plan district heating systems, but also identify ways they could recover heat (where it is being wasted by industry, for example) or install renewable energy generation. Scotland has thus far failed to make sufficient progress towards its much-trumpeted low carbon future, but with political will - and investment - measures such as this could help turn that aspiration into reality.