Statements of successfull STO-makers
Our common target is to tackle all the challenges and take advantage of the opportunities to achieve a real sustainability, both for the municipal administration and the neighbors of our municipality. In this point, Solar Thermal Energy is a very important potential for our municipality. The Solar Thermal Obligation will contribute to regulate, guide and enhance the development of these systems, increasing the use of energy coming from renewable resources and reducing CO2 emissions.

Mrs. Adela Martínez Cachá - Deputy Mayor for Environment and Urban Quality at the City Council of Murcia (SP). Vice-President of the Local Agency for Energy and Climate Change  of Murcia.

Today, energy is a part of everyday life! As leaders in our community, we have the obligation to set an example of good practice in the areas of energy saving and renewable energy use, so that citizens would acknowledge the importance of each gesture intended to contribute to the health of the planet.

Eng. Lucian ILIESCU – Mayor of Giurgiu Municipality (RO)
“Solar thermal has enormous potential and low costs. Our challenge in Lazio is to convince people of the advantages deriving from its use.”

Mr. Filiberto Zaratti - Regional Minister for Environment and Cooperation among Peoples, Lazio Region (IT)

Solar energy will be
the “sun of energy”!

Professor Eduardo de Oliveira Fernandes - Secretary of State for Environment (Portuguese Government, 1984-1985), Secretary of State to the Minister of Economy for Energy and Innovation (Portuguese Government, 2001-2002), former Chairman of the Commission for Buildings Thermal Regulations at the CSOPT  (Portuguese Ministry of Public Works, 2002-2006)

Our justifiably ambitious climate protection goals are reachable. However, this needs active combatants. With the provided regulations we found a passable way for on one hand making an effective contribution to reducing CO2-emmissions and on the other hand not overburden the single citizen. People do follow, because they feel, that we have to act for protecting the climate.

Tanja Gönner - Minister for the Environment of the State of Baden-Württemberg (DE)

STO Database

Detail View:Código Técnico de la Edificación (Spain).


The promoter of this legislation is the Spanish government.


The existing building code (CTE) entered into force in 2006. Among the basic quality requirements for buildings, the CTE contains the DB-HE chapter which aims, among others, at the efficiency of thermal installations and the application of solar thermal systems for hot water preparation for domestic purposes and indoor swimming pools. It is applicable for all new buildings and integral renovation projects (>1000 m2) when the hot water demand is higher than 50 l/day at a reference temperature of 60 ºC.
It is stated that for all new buildings and renovations a minimum solar fraction from 30 to 70% is required (depending on climate zone, hot tap water demand and energy source for back-up heating). The values established by the CTE are minimum values to cover the basic demand.

Ordinance Facts
Ordinance titleCódigo Técnico de la Edificación (CTE).
Type of ordinancesolar thermal ordinance
Starting dateThe CTE entered into force in March 2006.
Geographical areaSpain
No. of inhabitants, area45 millions ; 504,782 km2

Any type of buildings. It is applicable for all new buildings and integral renovation projects (>1000 m2) when the hot water demand is higher than 50 l/day at a reference temperature of 60 ºC.

Technology prioritiesSolar thermal; the solar contribution can be lowered if: 1)The building location does not have enough access to the sunlight; 2)In a renovation, the building has unchangeable constraints; 3)In new buildings, there are unchangeable constraints from urban regulations; 4)Historical/artistical buildings.

Size of the solar heating system requiredSolar fraction needed: 30-70%
Alternative measuresOther renewables or cogeneration for hot water demand.
Executing authorityEnacted by the national administration. Managed by Regional and local administrations.
Execution mechanism

There were external (European strategy) and internal forces (the already in force Barcelona’s and Madrid’s Solar Ordinance) that pushed for the national STO. The STO is operated by the municipalities and there is a steering committee (RITE). The management structure and clarity of the role/obligation of each partner involved in the CTE compliance is not yet fully defined.

Development and Implementation

Elements of pressure for having a national solar obligation:
-The building stock in Spain is responsible of 40% of the energy consumption in Spain
-The need to comply with the European Directive on energy efficiency
-Several municipalities developed their STO
-The Spanish Plan of Renewable Energies 2005-2010 (PER)


Technical and innovation development, decrease of expenses on fossil fuels, reduction of CO2 emissions, jobs creation and improvement in living quality.


The CTE is the transposition of the EPBD for renewable energies at national level. It has been implemented by the national government and elaborated by the Ministry of Housing, through the General Direction of Housing Policy and Architecture.
Also the Institute for Construction Science (CSIC), universities and other research institutions collaborated in its elaboration.


The starting date was on March 2006, but there was a time gap between the starting date and its application because one of the sub-chapters (HE2) only entered into force on July, 20th 2007.

Quality schemes productyes
Quality schemes installationno
Quality schemes otheryes
Flanking measures

FAQs for end users; info days professionals; communication campaign; pre-dimensioning tool; checklist for technical parameters of solar in buildings; solar guide for installers.


Permission needed by the designer from its association; the project is then presented to the municipality; check after the building construction; inspections are foreseen regularly.

Sanctioning feesFines go from 3,000 to 100,000 €, depending on the level of violation.
Costs for implementingNo additional costs borne by the administration side, since the solar ordinance is embedded in the CTE.

Monitoring and Results

The Institute of Diversification and Energy Saving (IDAE) launched the Plan of Renewable Energies and is responsible for monitoring.

Quantitative results

Expected: 4,900,000 m2 of solar thermal by 2010; CO2 reduction: 996,710 tCO2
Results: 2,195,000 cumulated solar area

Costs borne by the enduser0,45-0,59% increase per m² built.
Effects on other sectors

The CTE brought positive effects for other thermal applications not included in the obligation (e.g. subsidies for solar thermal installations in existing buildings).


See "Flanking measures".

Future outlook

No modifications were done in the solar thermal section.

Lessons learned
Barriers faced and overcome

First Spanish system certification, now EU certification scheme.

Success factors

The inclusion of energy efficiency and the use of RES in the national building code.

Potential for improvement

-The regulation is still too complex
-Unclear controlling/monitoring mechanism for implementation


Measures for overcoming barriers:
-Simplify the legislative framework
-Better controlling and monitoring measures
-Capacity building of professionals

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