Building Integrated Solar Thermal Systems. Design and Applications Handbook

COST Action TU1205 – Building Integrated Solar Thermal Systems (BISTS), Soteris Kalogirou

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The Renewable Energy Framework Directive sets a target of 20% for renewables by 2020. Buildings
account for 40% of the total primary energy requirements in the EU and are responsible for 30% of
greenhouse gas emissions. Therefore, developing effective energy alternatives for buildings is
imperative. Energy in buildings is used primarily for heating and cooling and for the provision of hot
water. One way to reduce the dependence on fossil fuels is by the use of renewable energy sources and
systems. The benefits of solar thermal systems are well known but one area of concern has been their
integration. Most solar collecting components are mounted on building roofs with no attempt to
incorporate them into the building envelope. In many instances they are actually seen as a foreign
element of the building. Many architects, irrespective of the potential benefits, object to this use of
renewable energy systems (RES) due to this fact alone. It is therefore necessary to develop techniques
that better integrate solar collectors within the building envelope and/or structures which should be
done in a way that blends into the aesthetic appearance and form of the building architecture in the
most cost effective way.
The Energy Performance of Buildings Directive (EPBD) requires that RES are actively promoted in
offsetting conventional fossil fuel use in buildings. A better appreciation of solar thermal system (STS)
integration will directly support this objective, leading to an increased uptake in the application of
renewables in buildings. This uptake of RES in buildings is expected to rise dramatically in the next few
years. This is further augmented by a recast of the Directive which specifies that the buildings in the EU
should be nearly zero energy consumption (residential and commercial buildings by the year 2020 and
public buildings by 2018, respectively). Meeting building thermal loads will be primarily achieved
through an extensive use of renewables, following standard building energy saving measures, such as
good insulation or advanced glazing systems. Solar thermal systems are expected to take a leading role
in providing the thermal energy needs, as they can contribute directly to the building heating, cooling
and domestic hot water requirements.
A solar thermal system (STS) is considered to be building integrated, if a component (in most cases the
collector) is a prerequisite for the integrity of the building’s functionality. If the building integrated STS is
dismounted, dismounting includes or affects the adjacent building component which will have to be
replaced partly or totally by a conventional/appropriate building component. This applies mostly to the
case of structurally bonded modules but applies as well to other cases, such as replacing with BISTS one
of the walls in a double wall façade.
The scope of this document is to present a review of current STS state of the art technological
developments published in the area and the most suitable options for building integration RES
applications. The aim of the document is to determine the work carried out in the area of building
integration of STS. This will enable an understanding of how this integration is applied so far, which will
help to identify new ways that this integration will be investigated subsequently. For architects, the
application of PV and STC (solar thermal collector) systems in buildings must form part of a holistic
approach. A high-quality solar system can provide a substantial part of the building’s energy needs if the
building has been designed in the right way. Through a holistic approach, integrating these systems does
not only mean replacing a conventional building material, but also aesthetically integrating it into the
design, which is called architectural integration. The integration then takes over other functions of the
building’s skin. Mounted on a sloped roof for instance, profiled systems mean that PV or STC modules
can be part of the watertight skin. A distinction can be made between literal integration of these
systems in the building skin as cladding elements or integrated into the roof or as building components
like awnings, shading devices etc. (Reijenga and Kaan, 2011). The aim of architectural and building
integration of these systems into buildings is to reduce the requirement for land and the costs, in
addition to aesthetics that is generated by the process. This could be the cost of a support structure and
the cost of building elements, such as tiles and cladding elements. It is evident that PV and STC systems
integrated into buildings give a more elegant look, and it is more efficient to integrate these systems
when constructing the building, rather than mounting them afterwards. For example they may provide a
high degree of solar shading for the building itself; this is particularly relevant in warm climates. Usually
there are three zones for integrating the systems into buildings. These are the roofs, façades and
building components like balcony railings, sunshades and sunscreens (Reijenga and Kaan, 2011).
Both PV and STC systems can be incorporated into buildings by either superimposition - where the
system is attached over the existing building envelope, or integration - where the system forms a part of
the building envelope (Fuentes, 2007).
Original languageEnglish
Place of PublicationCyprus University of Technology
PublisherEuropean Cooperation in Science and Technology
Number of pages449
ISBN (Print)978-9963-697-22-9
Publication statusPublished - Mar 2015

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