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Thermally Activated Building System TABS

 Thermally Activated Building System TABS

By combining building construction as a thermal energy storage in the sense of construction services, thermal construction systems (TABS) have proven to be economically viable for heating and cooling buildings. As I have already developed an integrated design approach and various control concepts in the past, in the present paper the impact of various aspects of TABS on the effectiveness of these systems is analyzed. Based on a case study of a Central European office simulation case, the following conclusions can be reached. The energy efficiency of TABS is greatly influenced by the hydronic circuit topology used. By separating the energy-saving power supply pipes to about 15-25 kW h / m2 a, or 20-30% of the heat and cooling requirement, it can be achieved, compared to local recovery pipes, where power losses occur due to mixing return water. A strong impact on energy efficiency can also be seen in the control strategy. Therefore, with the occasional operation of the system using pulse-wide fluctuations (PWM), the electricity demand for water pumps can be reduced by more than 50% compared to continuous operation. With regard to TABS refrigeration production, it is shown that free cooling with a cool wet tower works best, if the cold source is outdoor air. The range of machine-operated chiller displays 30-50% higher energy requirements for cold production and distribution, although their operating time is much shorter compared to the operating time of the cooling tower. In conclusion, the results show that significant energy savings can be achieved using modified system modifications and using appropriate TABS control solutions.The construction of thermal construction systems is discussed in REHVA and ISO 11855 section 4 [10, 11]. The standards state that dynamic calculations must be performed with the correct temperature and cooling capacity of the thermal construction system using the response factor series and the method of making a difference because the system has a certain high temperature. If the analysis of volatile conditions is not appropriate, the standards suggest the use of a powerful simulator of appropriate design.

Standards advise using a simplified diagram of an unstable condition analysis to determine the water supply temperature and the average cooling capacity of a thermal construction system. The simplified diagram can be used with daily estimates of the maximum temperature gain of each specific area and the operating hours of the thermal construction system. Using (1) and (2), the water temperature can be calculated by the shape of the building, the number of active areas, the thermal resistance of the pipes, and the thermal resistance of the concrete slide. Thereafter, the cooling power between the thermal construction system is determined by the daily heat gain and working hours (3):