Low – Ex – Technologies
The keyword “LowEx” is formed by a German research initiative, which was founded in the year 2005 in order to bring people together who work on innovations in terms heating and cooling technologies. Exergy –the useful part of energy – allows differing between high quality energies (like current) and low quality energies (like heat). The aim is to reduce “high quality” energy consumption and to use energies more effectively. In building, all controllable technologies generating a “not necessary use” of energy and all technologies using local heat sources have to be counted towards LowEx.
To lower the heating and cooling demands of the surPLUShome the shading influences the solar heat gains of the building. There are two different types of shading systems with different kind of advantages. An exterior louver system (fc-factor = 0.02) integrating the photovoltaic modules of the facade to produce extra energy. The second type is the jalousie-system (fc-factor = 0.08) which is integrated in-between the glass layers to provide accessible openings as for the case of emergency. Both systems are integrated in the building automation and can be set according to the interior needs as well as to external influences (e.g. the sun angle).
Every material is capable to accumulate thermal energy and to deliver it again. A phase change material (PCM) is a substance with a high heat of fusion. Thermal energy is absorbed or released when the material changes from solid to liquid and vice versa.
The surPLUShome activates the heat of fusion by using phase change materials and in the cooling ceiling (salt-hydrate). The PCM system has a day-mode, when the interior air circulates through the ceiling and decreases it´s temperature and a night mode, when the cool exterior air blows through the ceiling and discharges the PCM. The PCM can be regulated as a result of being separated from the interior room and controlled by the built in fans. Ventilation flaps allow operating the system with either interior or exterior air. The capacity of the system is equivalent to the energy demand for one day of cooling. We calculated a coefficient of performance of 9 to 15 regarding the ambient temperature.
Heat pump with Heat Recovery and Water tank
Due to the German Passive House standard and the resulting small loads the conditioning of the surPLUShome operates by air only. The center of our HVAC is a reversible heat pump which is able to heat and cool the space as one unit. The air source heat pump integrates ventilation compliance, a heat recovery with a coefficient of more than 80%, dehumidification in cooling case and a two layer hot water tank with a volume of 180l. In case of air cooling the as well produced heat is stored in the the hot water tank if possible to increase the exergetic value of operation. The tank also has an electrical immersion heater, whether the capacity of the heat pump is not high enough.
Flow of energy
This diagram is useful to get to know the overall building services of the surPLUShome. The diagram shows first of all the demands and requirements towards the surPLUShome and on the other hand the technical solutions.