This document discusses a study that aims to reduce energy consumption in buildings by optimizing the thermal mass capacity of concrete structures through the integration of phase change materials (PCMs). The study tests two concrete panel samples, a regular concrete mix and a PCM concrete mix containing microencapsulated paraffin, and measures their heat storage, natural drainage, and drainage with forced cooling via pipes. The results show that the PCM concrete achieved higher thermal storage but was slower to release heat, necessitating forced cooling through pipes to sufficiently cool the panel overnight and allow it to absorb heat the next day, improving indoor thermal comfort.

1. Heat discharge through forced cooling of phase change materials
in concrete
Kristin Kuckelkorn
Abstract
Currently, research is concentrated on renewable energy due to a worldwide shortage of
energy resources. A priority of the construction industry is the reduction of energy
consumption, as 40% of the total global energy consumption worldwide is used in buildings.
It is necessary to generate renewable and natural energy sources for heating and cooling in
buildings. Solar energy is the main renewable energy source and is already used in passive
buildings applications.
The current study aims to reduce energy consumption by optimizing the thermal mass
capacity of concrete structures in buildings. This will have the added benefit of improving
indoor thermal comfort. The study investigates two samples of concrete panels, one regular
concrete mix and one phase change material concrete mix. The integration of phase change
materials into the concrete panel optimizes the thermal mass capacity of the concrete.
Concrete has a good thermal mass capacity which is described through a high specific
heat capacity, a high density, good thermal conductivity, and thus the ability to store heat.
Phase change materials provide a high latent heat storage capacity and a low thermal mass
conductivity with a low density. Here, micro-encapsulated paraffin, with a melting temperature
of between 20 and 24o
C, is incorporated into a fresh concrete mixture with a ratio of ~5% of
the weight of the concrete. The microcapsules are added to the cement paste during the mixing
process.
The research focuses on heat drainage along the concrete panels. This is done through a
cast-in copper pipe with a length of 2300 mm for each panel. After the concrete is cured for 28
days, the panels are heated to ~30°C in a controlled environment. The installed thermocouples
measure the heat storage, natural heat drainage, and heat drainage with forced cooling though
the passage of cooled water in the copper pipes. The results show that the phase change material
concrete panel achieved higher thermal storage capacity compared to the reference panel. But
it was also slower to release heat, thereby necessitating the provision of cooling pipes so that
the panel is sufficiently cooled overnight to be able to absorb heat the following day, thus
ensuring a more comfortable ambient environment in the building..