Esegui ricerca
16 March 2012

Saving 80 to 90 % of conventional energy in office buildings

Aumenta dimensioni testoDiminuisci dimensioni testo

In Spain, the building sector generates over 33% of conventional energy consumption. Reducing it is a need shared with the European Union.

In 2006 the Technical Building Code (CTE) has come into force in Spain. The Code provides for a reduction of energy demand of buildings from architectural design and a reduction of conventional energy consumption through the use of solar thermal water to produce heating and photovoltaic panels to generate electricity.

The PSE-ARFRISOL project on Bioclimatic Architecture and Solar Cooling (2005-2012) co-ordinated by the Research Centre for Energy, Environment and Technology (CIEMAT, part of the Spanish Ministry of Science and Innovation, MICINN) is a step forward on the CTE as it seeks to use the hot water produced in the solar collectors not only for domestic hot water production but also for thermal conditioning (heating, cooling) of buildings.

Five public office buildings located in different areas of the country's climate (Almería, warm temperate and desert climate, Madrid, continental climate, Soria, extreme continental climate and Asturias, northern climate), both new and for rehabilitation, are being analyzed and evaluated in actual use conditions with the objective of being able to save 80 to 90% of conventional energy thanks to architectural design, solar energy and biomass.

In addition to CIEMAT, the project involves the universities of Almería and Oviedo and the largest Spanish construction companies (e.g. Action) and technological ones (e.g. GRUPO UNISOLAR). Maria del Rosario Heras, Chief of the R & D on Energy Efficiency in Building at CIEMAT, is the co-ordinator of the project.

How did the project start?
The project began to take shape in 2004 when the Ministry of Education and Science (now Science and Innovation) asked me to write a technical memory of what should be the line of research of a project on bioclimatic architecture that could show Spanish society the relevance of the energy saving of such buildings.
The design of the technical memory matches up with what we are doing now, that is helping architects so that their designs are as energy efficient as possible from the standpoint of passive solar energy, help installers integrating their active solar energy equipment and conventional energies designing their conventional installations. Once you have the building project, the idea is to build and then measure and evalute the buildings’ behaviour in the actual conditions of use from an energy point of view, which is what we have been doing for 25 years at CIEMAT with already constructed and designed buildings. When the design of the project was done, the Ministry asked me where such a project could be carried out and I suggested taking a few different climates in Spain. Since almost all the buildings we had measured in CIEMAT were public housing and we know how to save energy in homes, we opted for offices. According to the data of energy consumption in buildings, offices are the places where most energy is consumed after residential houses. Since the CIEMAT is a public research organization we chose public office buildings. Of the five testing laboratories (called C-DdI, container-demonstrator for research) four are of new construction (Center for Solar Energy Research at the University of Almería, Almería’s Solar Platform-CIEMAT, the research center in Biomedicine of CIEMAT in Madrid and the Barredo Foundation in Asturias) while Soria’s Centre for Renewable Energy Development (CEDER) is the rehabilitation of an existing building. In 2005 we started the project in the five buildings at once.

How do you do it to save 80 to 90 percent of conventional energy?
It is easy. First of all we know that architectural design (that is what separates the exterior of the building from the interior) is where you save the most in terms of energy efficiency.

Does this also apply in the case of a rehabilitation?
In the case of a new building what you do is to make an architectural project from scratch, that is deciding the distribution of walls, windows and the orientation of the building. In the case of Soria’s building, which already existed, what we did was to improve the architectural project with a computer (theoretical simulation of the building) and then put it into play.

Going back to the previous question?
So, the architectural design, the passive solar elements (that is walls and windows) correspond to 50 to 60 percent energy savings. The remaining 20, 30 percent is saved thanks to active solar energy systems (solar collectors, piping, valves, cooling and space heating, photovoltaic modules). The building of Madrid, for example, has windows facing south and shadings that are integrated photovoltaic modules, which make shade in summer, while in winter, when the sun is lower, let solar energy in. The other 10, 20 percent is conventional energy (natural gas). In the buildings of Soria and Asturias this 10, 20 percent is biomass.

What stage of project are you at?
Since 2009 all the five buildings are built up. We are now acquiring and analyzing data to be able to say whether in actual use conditions these buildings behave like they should according to our goals.
The measuring consists in sensors we put inside and outside the building. Solar radiation, temperature, relative humidity and wind speed direction is what we measure outside while inside we put sensors according to what we consider interesting to measure, e.g. corridors, offices. In every building we are measuring in the order of 300 to 400 different points.

What is that you are seeing?
We are achieving our goals but we will be more precise in June 2012 when the project is over.

What difficulties are you finding in carrying out this adaptation of the bioclimatic architecture and solar energy in the different buildings?
Difficulties as such none, what we do see is that there are equipments (sensors, facilities for hot water etc) that could work better and we are making improvements to the facilities.

How much does it cost to to have an energy efficient building compared to having a conventional one?
Designing an energy efficient building costs the same as one that is not. The civil works construction (walls and windows) have an extra cost of 3 to 5 percent with respect to a conventional building while the facilities have a slightly higher cost. In total ARFRISOL buildings have an initial extra cost of between 15 and 20 percent compared to a conventional building but they produce an energy saving of 80, 90 percent up to 100 hundred percent in the case of Soria and Asturias. We still do not know exactly what the recovery period will be, we will be able to tell accurately when have the real data. The EU says this should not exceed 10 years, we'll see. I do not like to talk about this in a theoretical way but by evaluating the data measured.

Out of the nearly 21 million homes accounted for in Spain about 3 million are empty. What additional cost is necessary to rehabilitate a building in an energy efficient way compared to in a conventional one?
The increase in public works and facilities of Soria is at 17 percent, but being only one building it can not be generalized.

What materials are you using for the buildings?
We attempted to use local materials and ones that are as environmentally friendly as possible.

In your opinion, what is most innovative about the project?
Undoubtedly involving sectors as diverse as construction, engineering and research that go hand by hand from the start in such a big project that covers different geographical areas, something that was never done before in the country. In Spain we have many buildings that are called bioclimatic because the simulation in the project was done. In this project we do not want to have many bioclimatic buildings in theory but to actually measure and evaluate them.
Another important element is that all the solar thermal systems and photovoltaic manufacturing are prototypes the Ministry had already funded companies for and which in this project we can have in real conditions and are able to evaluate so they can be on the market.
Another very important part of the project is trying to make dissemination and outreach on the subject, i.e. through micro and mini guides, so that all the technical sectors can use everything we have done in the project.
The next important part is to transfer that knowledge to teachers and the media.
As a researcher I think the most important thing is to transfer research achievements  through all possible means and try to change the mentality of society at all levels.

Given the current Spanish situation in what time period do see it feasible for the bioclimatic architecture to become commonplace?
With the economic crisis and the ‘building break’ it is undoubtedly more complicated than it was three or four years ago.

What would it take to make it commonplace?
Especially changing the Spanish mentality concerning energy awareness in consumption in any building. It is necessary that the Spanish users know for instance that if there is sun on the street they should use natural light instead of electric light, or that if they live in a first floor they can walk down rather than use a lift. It is extremely important to try to avoid the energy waste that is taking place in Spain.

Do you believe this to be a peculiarity of Spain?
No, but here we have a very important feature which is our climate and we need to take advantage of it both in winter and in summer!

Related Articles provides its content to all media free of charge. We would appreciate if you could acknowledge as the source of the content.