Planning the future today: a STO obligation helps in gradually preparing the building stock for the post-oil and gas era, since buildings are planned with an investment horizon of some decades.

Saving energy...and saving environment: if Europe covered 50% of its hot water consumption with solar, the savings would be roughly 12 Mtoe per year, equivalent to the total consumption for space and water heating of almost 10 millions households.

Being on time: it is most convenient to include solar at an early stage of planning in new buildings or when a new heating system is being installed in existing buildings. A STO makes sure that these convenient opportunities are not missed.

Owners build, tenants save: a STO makes sure that renewables are used also when the energy bill is paid by tenants, who cannot decide on structural investments.

Promoting solar thermal: by creating a stable market in part of the building stock, STOs trigger investments in the whole supply chain, leading to economies of scale and higher use of solar energy. STOs also encourage the voluntary use of solar energy beyond the amounts required by law, and in buildings not subject to the obligation.

No public money needed: promoting renewable heating through financial incentives taken from the public budget becomes more and more difficult as the market volumes increase; STOs show very limited impact on public budgets, since the main costs are carried by the building developers or owners, which will be able to pass the costs on the building users, who also benefit from the reduced energy bill thanks to the solar system.