To cut greenhouse gas emissions and tackle the climate crisis, we need to rapidly change how we produce and consume energy. Using energy more efficiently and sourcing energy through renewables (rather than fossil fuels) can play a massive role in reducing global emissions.

But as the world warms, cooling services will also be needed more and more. And with that, the demand for energy-intensive technologies such as air conditioners will grow, thereby exacerbating the sector’s impact on the climate.

Rooftop solar energy is a versatile solution for buildings and cities and probably the sustainable local energy source with the largest potential globally. In cities with a warm climate, energy efficient and passive cooling solutions are one of the major sources of “negawatts” – energy that we don’t have to produce or use.

The combination of both solutions can ensure we can keep our homes, businesses and cities cool without contributing to global warming. WWF is working to drive this change through our ‘Cool & Solar’ initiative.

There is a huge potential for rooftop solar photovoltaics (PV), but we aren’t taking nearly enough advantage of this clean power source. Solar PV on existing buildings has the potential to provide a high share of a country’s total electricity consumption (e.g. 40% in the US and over 40% in Switzerland).

Solar PV can also be deployed very quickly (a few days to a few weeks for a new installation), compared to fossil or nuclear solutions which take years, and can be integrated in existing structures, without the need for new land. In recent years, solar PV prices have become much more competitive, and will often be cheaper than any other electricity producing technology.

While cooling is essential to meet sustainable development goals, it also presents a very significant threat for the climate. Nearly 20% of the total electricity used in buildings across the globe is spent on cooling technology like air conditioners and electric fans. Over the next three decades, the demand for cooling is expected to become one of the top drivers of increased energy demand.

It doesn’t need to be like this – cooling can be much more efficient and demand less energy. This can be done by reducing our need for cooling through improved ‘passive’ cooling solutions (such as better building insulation, optimised shading solutions and cool roofs), implementing robust standards for cooling appliances, and installing more rooftop solar to meet the growing electricity demand.

Both solutions create the perfect pair. The hotter the sun, the higher the solar production and the greater the need for cooling. Solar energy can directly provide energy to cooling systems, thereby reducing the need for electricity from large power stations far away, and alleviating pressure on the power lines.