At Telemark University College, Faculty of Technology, on-going work deals with energy efficiency of heating residential buildings. The work ranges from modeling to control of such buildings. Of particular interest in this study is the possibility to “harvest” solar energy via a solar collector, and use this energy to heat the building. Such heating must be combined with auxiliary heating, e.g. electric heating. Lie et al. (2014) discuss basic models for the complete system, with model parameters and operating conditions.
For control, the following question is of interest: if it is possible to predict solar irradiation, can this be used to improve the efficiency of energy use in the building? In other words: if we know that tomorrow will by sunny, can we then reduce electric heating during the night based on the knowledge that tomorrow’s sun will re-heat the stored water? Or vice versa: if we know that tomorrow will be cloudy, can we use this fact to heat the stored water in the night when the electricity is cheap? This problem is studied in Beyer et al. (2014).
In the discussion of Lie et al. (2014), the model is too simplistic and needs some refinement. The following improvements are needed, in order of importance:
1. Heat integration during ventilation should be included. Currently, the major heat loss is via ventilation.
2. The water storage model should be improved to include the effect of stratification in the tank (the tank is not well mixed) – either by some plug flow model or by dividing the storage tank into 2-3 compartments.
3. The Under Floor Heating (UFH) model is too simple.
4. Heat transfer should be computed from correlation models instead of using fixed numbers.
5. The solar collector model can be improved.
In this first improvement of the model, the two first points will be addressed. Thus, the model will be modified to include heat integration. Next, an improved water storage model will be developed to better capture the observed fact that hot water in water storage tanks have a temperature typically at 90C. The resulting improved model will be compared to the model of Lie et al. (2014).
References
Lie, B., Pfeiffer, C., Skeie, N.-O., Beyer, H.-G. (2014). “Models for Solar Heating of Buildings”. Proceedings, 55th International Conference of Scandinavian Simulation Society (SIMS 2014), October 21-22 2014, Aalborg University, Denmark.
Beyer, H.-G., Lie, B., Pfeiffer, C., Arachchige, D.D. (2014). “Using history based probabilistic irradiance forecasts for supporting the predictive control of solar thermal systems”. Proceedings, EuroSun 2014, September 16– 9, Aix-les-Bains, France.
Building model; Dynamics; Simulation; Water storage model; Ventilation heat integration
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