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insulated internally (to avoid changes in the appearance of the façade) and the back façade
can be insulated externally. (IEA 2010)
To ensure the functioning of mixed insulation, thermal bridges need to be minimised. The
places where wall insulated from outside meets a wall insulated from the inside should also
have overlapping insulation (both internal and external insulation). (IEA 2010)
3.7.2 Internal insulation + Cavity insulation
In some cases, when the façade of a building may not be altered, but a highly efficient
additional thermal insulation is needed, combining cavity insulation with internal insulation
might be a viable option. By insulating the cavity, the insulation thickness of the inner
insulation layer can be reduced. However, this method is not commonly used. (EST2005)
3.7.3 External insulation + Cavity insulation
Combining external insulation with cavity insulation may be used in some cases. When cavity
is insulated and thermal insulation is applied also externally, the thickness of external
insulation layer can be reduced to gain the same U-value. (EST 2005)
On the other hand, a thin external insulation layer can be added to enhance the insulating
capability of cavity insulation, and to protect the outer wall from rain penetration problems.
(EST 2005)
3.8 Advanced refurbishment technologies
This chapter will discuss advanced refurbishment technologies. Some of these technologies
are already commercially available, but they haven’t been adopted to wider use. On the other
hand, some technologies are still in development phase and some are only discussed at a
theoretical level.
3.8.1 Phase-changing materials (PCM’s)
Phase change materials, or PCM’s help to utilize the so-called latent heat. The latent heat is
energy which released or absorbed during the phase change of a substance. Latent heat can
be absorbed or released, for example, when a substance changes phase from solid to liquid
form. (Knaack et al. 2007)
One example of a PCM is a material by BASF. The Micronal PCM is a microencapsulated
latent heat storer, which can be used with many existing construction materials, such as
gypsum, plaster and concrete. The following image shows how the PCM microcapsules are
integrated in a construction material.
The latent heat of PCM’s can be used for two purposes in building applications. These are:
use for heat control and use as heat or cold storage.