In cold weather and climates, appropriate insulation takes on a key role in the heat storage of buildings . In modern living concepts, this includes achieving the best possible gains from solar energy. Architecture aligned to the maximization of solar gains in connection with a highly insulated outer shell can – especially in summer or high heat periods – lead to overshooting of the ambient temperature and increased problems associated with overheating. This challenge is best met by active solar prevention measures and optimizing the design of heat-storing building masses.
Not every building achieves the necessary thermal mass and storage capacity with its building material alone. Due to their construction, buildings constructed of light-weight materials lack necessary thermal storage mass. Internal loads and sun exposure lead to, particularly in summer, large variations in temperature, loss of comfort and intensified need for air conditioning inside of the building. Solid building materials that possess the necessary thermal storage capacity are particularly slow-acting. They take up warmth slowly and release it just as slowly.
This is where Micronal® PCM provides an effective solution. Micronal® PCM, Microtek's formaldehyde-free, microencapsulated latent heat storage material, makes it possible to combine the advantages of modern architecture with the benefits and compensatory effect of thermal storage compatibility for a pleasant room climate. As a component of modern architectural solutions in new buildings and redevelopment, Micronal® PCM offers a new, high-efficient way of buffering energy load peaks within a defined temperature range. These load peaks usually occur during the day when it’s warmer with a time-delayed delivery of the stored energy at night and during cooler periods. Integrated into various types of building materials and structural systems, Micronal® PCM contributes effectively to improved room climate, increased comfort and better energy efficiency through the use of intelligent temperature management.
Micronal® PCM is a microencapsulated phase change material that phases from solid to liquid within the ambient temperatures and comfort ranges of humans (Approximately 21°C, 23°C or 26°C). Micronal® PCM can absorb and store very large quantities of heat that would otherwise lead to a super-elevated interior temperature.
This principle of latent heat storage is comparable with an ice cube, which keeps a beverage constant at 0°C during the melting process. Micronal® PCM uses this simple physical effect in order to stabilize the indoor temperature. The core of the microcapsule (size of approx. 5 thousandth millimeter) contains a latent heat storage material made from a special wax mixture. The wax mixture absorbs the surplus heat energy when the temperature rises above a defined threshold (21°C, 23°C or 26°). This thermal energy is stored in the liquid wax and is released again when the temperature drops below the temperature threshold.
While the loading of the storage material takes place passively, with the heat transfer and storage during the day, unloading of the stored heat can take place via natural ventilation, mechanical ventilation and renewable or conventional cooling concepts. Using Micronal® PCM latent heat storage as a component of a functional building concept results in passive overheating protection, stabilization of the ambient temperatures and efficient use of surface cooling systems.
Microtek’s PCMs with the brand name Micronal® are microencapsulated, formaldehyde-free latent heat storge systems made from high purity waxes. The temperature range of the products was tailored particularly to its employment in buildings. The melting range of the Micronal® PCM products is defined in the range for human comfort (A temperature between 21°C- border of the chill feeling, and 26°C-border of the hot feeling).
Microencapsulation makes fast heat exchange possible representing a "just in time heat buffer” - with a very high surface-to-volume relationship. The heat conductivity is defined by the surrounding building material matrix. With their small size of 2-20µm and highly elastic, sealed plastic shells, the Micronal® PCM caps are virtually mechanically indestructible.
With their small volume and space requirements they are ideally suited for combination with, or for direct integration into building materials. This brings advantages in handling, being building materials can be processed like conventional construction materials. At the same time additional expenditure is avoided by the direct integration of the PCM into the building material or the system. Phase changes and variation in volume of the PCM take place invisibly and exclusively inside the capsule wall. The volume of the building material remains completely stable because the variation in volume of the microscopically small capsules takes place solely in the natural pores of the building materials. Contrary to other PCM systems, the melting process of the Micronal® PCM products cycles and maintains its performance and function over decades of time. This has been proven by the RAL quality community for PCM registration in comprehensive cycle and load tests with 10,000 cycles.
Solid building materials have a high thermal mass but they are slow to release stored heat. The most important criteria regarding the principle of latent heat storage are: the speed in which the PCM reacts to temperature fluctuations and, most importantly, close binding to room surfaces. Close proximity to room surfaces is best achieved by directly integrating the Micronal® PCM into interior building materials. From this integration, a best solution for thermal management can be created- a carrier building material with good thermal conduction, combined with enormous surface to volume ratio and the high storage capacity of PCM in microcapsules.
The microencapsulation of phase change materials is the only key technology to date which allows for the integration of PCM’s into large-scale production building materials. This makes a new class of intelligent building materials possible with minimal additional effort.
Additional advantages of microencapsulation come with the processing of the Micronal® PCM. Due to the microscopically small size, with correct processing conditions, it is nearly impossible to damage the capsules. Contrary to macroencapsulated material, the microcapsules survive the mechanical treatment of the building material (e.g. drilling, cutting etc.) completely without damage. Even during daily phase changes, wax does not leak through the dense and highly elastic microcapsule wall. In building materials, integrated microencapsulated phase change materials offer you the possibility of providing thermal mass selectively in the desired temperature range, self-activated passive thermal regulation, and light weight, low volume contribution. These characteristics of the microencapsulated PCM easily incorporate into, and enhance the advantages of modern, light-weight architecture.
Micronal® PCM can be integrated in different forms into building materials. For applications in which an aqueous liquid form can be used, Microtek offers Micronal® PCM dispersions as an aqueous slurry. For applications of building materials that utilize dry finished mixtures (For example, gypsum or cement mortars) Microtek offers Micronal® PCM as a dispersible dry powder.
According to the criteria of the RAL quality community PCM registered association, 10,000 phase changes were examined and passed. This corresponds to an average product life cycle of approximately 30 years. In the test no losses of efficiency were determined. Due to these results it is to be assumed that the caps will keep their function over decades, over the entire life cycle of a building. The exact test criteria can be found under http://www.pcm-ral.de/ .
Due to the microscopically small cap size of 5-20 µm, the Micronal® PCM caps are virtually indestructible and are displaced by drilling as opposed to being damaged.
Weber.mur clima® machine-applied plaster from Saint-Gobain Weber: Weber.mur clima is a PCM machine-applied plaster for making single-layer interior plaster with a temperature regulating effect. Through varying the thickness of the layer, the quantity of Micronal® PCM available for latent heat storage can be controlled according to requirements. Maxit clima® is available fully formulated (for direct processing on the construction site) as a dry mortar.
Ilkazell Isoliertechnik GmbH's Ilkatherm® System (http://www.ilkazell.de/) Derived from sandwich technology (metal surface, PUR rigid foam core, metal surface), highly efficient radiant ceiling panels with Micronal® PCM were developed. These panels can be linked to existing cooling water circuits via a simple Plug and Play process. Water cooling is achieved through capillary tube mats, which are located on the reverse of the PCM layer facing into the room. This system solution makes renewable cooling and buffering of peak loads possible.
Further product developments available on request