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When it comes to making the shift to renewable energy, the heating and cooling sectors are laggards.

REN21's annual Renewables Global Status Report released last month said globally, the heating and cooling sectors lag “far behind” the power sector when it comes to renewable energy sources.

A record 70 per cent of net additions to global power generation capacity in 2017 were renewable, but when it comes to heating and cooling its a case of “slow progress.”

Why is this such a big problem? Because energy use for heating and cooling accounts for nearly half of global total energy consumption, split roughly equally between heat for industrial processes and heat for use in buildings.

Demand for space cooling – supplied mostly by electricity via air conditioners – accounts for about 2% of Total Final Energy Consumption (TFEC) but is growing rapidly, especially in emerging economies.

Renewable energy can contribute to the heating and cooling sector in three ways: through the direct combustion of biomass (both modern and traditional), through direct use of geothermal and solar thermal energy, and by contributing to the electricity supply when it is used for heating or cooling.

District heating systems supply about 11 per cent of the world’s space and water heating needs, but most are fuelled by either coal or natural gas, with the share of renewables ranging from 1 per cent in China to 42 per cent in Denmark to 90 per cent in Sweden.

The top renewable fuel for district heating systems worldwide is bioenergy, accounting for 95 per cent.

Overall, modern renewables supplied just 10.3 per cent of total global energy consumption for heat in 2017, the report found, while another 16.4 per cent was supplied by traditional biomass, predominantly in the developing world.

While additional bio, geothermal and solar thermal heating capacities were added, growth in these sectors were slow.

REN21 said this is because heat markets are complex and fragmented, which makes policy-making a challenge. Moreover, multiple barriers have slowed down the uptake of renewable heat. For example, fossil fuel-based heating systems can have lower capital costs, which when combined with low fuel prices can discourage a shift to renewables.

While policy options exist to address many of these barriers, the report noted that policymakers have devoted much less attention to renewable heat than to renewable electricity. At the end of 2017, 48 countries had targets in place for renewable heat compared to 146 for electricity.

REN21 said policies aligning renewables and energy efficiency – which often encourage the use of renewables for heating and cooling – are common in the buildings sector, but not in industry.

By the end of 2017, at least 145 countries had energy efficiency policies in place, and at least 157 countries had energy efficiency targets. Over 60 countries have mandatory and/or voluntary energy codes for buildings.

By comparison, policy mechanisms aimed at increasing the use of renewables for industrial processes are not common, the report said, although countries including Mexico and Tunisia launched new support mechanisms last year.

Although not as widely adopted as district heating, district cooling is attracting growing interest and can be fuelled entirely or in part by renewables.

District cooling networks (such as those in Paris and Helsinki) generally produce chilled water in centralised energy plants, which is then distributed via underground pipes to provide air conditioning to buildings.

Renewables thus far have played a small role in providing cooling services in general (aside from their overall role in electricity supply), yet great potential exists.

Locations with high cooling demand often also have good solar availability, creating the possibility for cooling using either solar PV systems or direct options such as solar absorption chilling.

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