It is rumoured that some of the EU-leaders who signed up to the renewables directive last year – the famous 20% of all energy to come from renewables by 2020 – did not quite understand what they were agreeing to. First, as a directive, this has legal implications and is no longer just a target or an aspiration. Second, it covers all energy, not just electricity but heating and cooling, and transport as well. 

Transport will be the most difficult sector to get significant penetration by renewables, and is likely to fall short of its 20% share. This shortfall will have to be made up across the other sectors.

While the plans for renewable electricity are relatively clear, the scope for this to make up much of the difference is likely to be limited. Plans in the heating and cooling sector are much less well worked out. Comparatively little research has been done on this historically, and the extensive scenario studies in the electricity sector (and to some extent the transport sector) are not as common in the heating and cooling sector. However, as the recent ESTEC conference heard, there are now a number of comprehensive studies looking at how the heating and cooling sector can not only meet its own 20% target, but also start to make up some of the likely shortfall from the transport sector. (For instance, Sven Teske from Greenpeace outlined some of the implications for the thermal sector from www.energyblueprint.info)  

It was Werner Weiss from AEE in Austria (and, incidentally, editor of our book Solar Heating for Houses) who pointed out some of the other consequences. A number of the uses of thermal energy, particularly higher-temperature ones used in industry, are not very amenable to renewable technologies. There is likely to be a growing demand for air conditioning, which will probably offset some of the gains that can be made using renewable technologies in commercial buildings. To make significant inroads, therefore, not only must much of the water heating in Europe come from solar energy, but much of the space heating should as well. As consumers will not accept separate heating and hot water systems, meeting these targets should see a rapid increase in demand for solar combi-systems, those capable of delivering both heat and hot water. These are currently something of a neglected technology, but the logic seems impeccable. If we are going to get close to those targets, we will need an awful lot more of them between now and 2020!