Barcelona is the first European city to have a Solar Thermal Ordinance making it compulsory to use solar energy to supply 60% of running hot water in all new buildings, renovated buildings, or buildings changing their use. It applies to both private and public buildings.

What is it?

Europe’s first solar ordinance — requiring residential and commercial buildings to generate 60% of hot water requirements from solar.

How does it work?

Barcelona drafted its Solar Thermal Ordinance (STO) in 1998. It was approved by the city council in 1999 and, following a one-year moratorium to allow for adjustments, took effect in August 2000. It was then strengthened in 2006. The program is designed to harness Barcelona’s 28,000 average hours of annual sunshine.

The Ordinance is managed by the newly established Barcelona Energy Agency — the agency funds two full time staff, provides training, information and media.

First stage

The ordinance first required that new buildings, and those undergoing major refurbishment, using more than 0.8 MW per day for hot water production, meet at least 60% of their demand with solar thermal collectors. All commercial buildings, and residential buildings with more than 16 apartments, were subject to the regulation. The ordinance also subsidized SHW for those buildings too small to be subject to compliance, and required that 100% of energy to heat swimming pools be generated from SHW.


In 2006, Barcelona upgraded the existing ordinance, eliminating the 0.8 MW per day minimum requirement. Consequently, the STO now applies to all new buildings and those undergoing renovation, regardless of their size or intended use.
Nationally, 30-70% of hot water energy needs must now be met with SHW, depending on the level of consumption, the availability of back-up fuel, and the climatic zone in which the building is located.

Applies to

  • new buildings or constructions
  • complete renovation of buildings or constructions
  • change in the use of the whole building or construction
  • residential
  • health
  • sports
  • commercial
  • industrial (if hot water is needed for the industrial process or if showers are to be installed for the staff)
  • any other use that entails the presence of dining rooms, kitchens or collective laundries.

It is managed by Barcelona Energy Agency, a consortium made up of a number of local institutions directly involved in sustainable energy and environmental management. The BEA ensures adherence to the STO by requiring approval of the building design simultaneous with the approval of the construction permit. Building inspectors are then responsible for ensuring that construction meets the stipulated criteria. The BEA reports satisfactory levels of adherence.


Buildings that satisfy their demand through co-generation, as well as those that are shaded, may be exempt from the updated ordinance.

Energy efficiency

  • Over 25,000 MWh/year are saved
  • The energy produced is equal to the domestic hot water demand of a population of 45,000, or the needs of some 20 health care centres with 1,400 beds.
  • Barcelona has increased by over 20 times the surface of solar thermal square metres in the city from 1.1 sqm per 1,000 inhabitants in 2000 to 19 sqm/1,000 inhabitants in March 2005.
  • Licenses requested for the installation of solar panels increased from 1,650 sqm in 2000 to 31,000 sqm in 2005.
  • 20% of the total solar thermal capacity area approved for buildings had been installed and is operational.
  • The Barcelona Energy Improvement Plan (PMEB) is ahead is estimated to go beyond its 2010 target of 96,300 m² of solar collectors installed in the city – to beyond 100,000.


The key to the success of this project has been ensuring that people are educated on the use and maintenance of their solar panels. The BEA says solar panels need to be treated like elevators — they need to work and be maintained. BEA runs a successful education campaign — known as Porta Porta (Door to Door) — they work with the Neighbourhood Association and body corporates of buildings to ensure that tenants/public measure their energy savings and check to ensure that the solar installations are working. The BEA also has an information centre open 6 days a week, where people can get information on solar use and maintenance.

On the national level, Barcelona’s 2006 STO inspired a piece of national legislation requiring minimum levels of SHW and photovoltaic (PV) in new construction and renovation projects.

Some cities, including Seville, Madrid, Burgos and Pamplona have followed Barcelona’s lead and instituted regulation more stringent than that imposed by the federal government.

As the first regulation of this type to be adopted in a large European city, it has been presented to autonomous bodies, local administrations, networks of cities and institutions.

  • 39 municipalities in Catalonia and 26 in the rest of Spain have followed Barcelona's example and have now adopted solar ordinances.
  • The Ordinance was prepared and approved thanks to the political will of the local administration to promote solar thermal energy in Barcelona.
  • A communications program was crucial in order to encourage adoption of the Solar Thermal Ordinance by contractors.
  • Barcelona City Council also has a Plan for Energy Improvement in Barcelona (2002-2010) which is designed to increase the use of renewable energy (especially solar energy), reduce the use of non-renewable energy sources and lower the emissions produced by energy consumption in order to meet Barcelona City Council's international protection commitments.

This integrated plan includes a quantification of the energy used and emissions produced in the city and provide scope for municipal action to promote the solar programs and other environmentally sustainable initiatives that reduce air pollution and the consumption of fossil fuels in the process.