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planning:calculating_energy_efficiency:dynamic_simulation [2020/08/05 12:27] – [References] wfeistplanning:calculating_energy_efficiency:dynamic_simulation [2020/08/07 23:26] (current) – [Dynamic Simulation using DYNBIL] wfeist
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 ====== Dynamic simulation of a building's thermal performance ====== ====== Dynamic simulation of a building's thermal performance ======
  
-\\+==== Dynamic Simulation using DYNBIL ==== 
 |{{:picopen:network_eng_s.png|}}| |{{:picopen:network_eng_s.png|}}|
 |Fig. 1 A typical room model used in instationary simulation of a buildings \\ thermal performance; this is the model-type used \\ in the program DYNBIL [Feist 1994]| |Fig. 1 A typical room model used in instationary simulation of a buildings \\ thermal performance; this is the model-type used \\ in the program DYNBIL [Feist 1994]|
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-==== Models used for Simulation ====+Dynbil is a multizone dynamic thermal building simulation program developed at the Passive House Institute. Dynbil also takes into account moisture storage and moisture transport processes. The room model works with one air node and one radiation node, which are clearly separated from each other. Heat transmitted to interior surfaces is calculated depending on the location in the room and the actual temperature difference; for exterior surfaces, the complete solar and infrared radiation balance and the influence of wind speed are taken into account. Heat transfer (radiative and convective/conductive) and g-values are calculated for windows depending on the current temperature and solar radiation in each period of time (nonlinear). The wall model uses not transfer functions but uses a forward difference method, thereby fulfilling the conservation of energy principle even over long periods of time. The program was first validated under Central and North European climatic conditions with a number of construction projects measured in detail. 
 + 
 +A single room ("zone") will be modelled by DYNBIL as shown in fig. 1. 
 + 
 +In the meantime, additional features have been added such as simulations of moisture transport and ventilation models. 
 +Although DYNBIL models the building components very accurately (see e.g. comparison of simulated and measured temperatures within the wall), the focus is the whole building perspective (fig. 2). The entire building  defines the system boundary. All energy fluxes are part of the model, including all electric appliances. This makes it possible to simulate the internal heat gains. General assumptions on heat gains may be tolerable for energy inefficient buildings, but lead to high differences in the calculated demand as soon as heating and/or cooling demands are very low. 
 +Another aspect of the whole building approach is the integration of all system components including the consideration of thermal comfort, ventilation, air quality, noise protection, user friendliness, building protection. 
 + 
 +|{{:picopen:Dynbil_multizonal.png|}}| 
 +|Fig. 2 Several zones will be connected to a building model with air flows between the zones as well as components connecting the different zones.| 
 + 
 +Dynbil has been validated with the detailed measurements in the first Passive House (located in Darmstadt Kranichstein; see fif. 3). It had been possible to predict the energy consumptions, as well as to test several variations of the model itself. DYNBIL is also the basis for the development of stationary tools. 
 + 
 +|{{:picopen:compare_meas_Dynbil.png|}}| 
 +|Fig. 3 Comparison of measured temperatur developments and the simulation with the DYNBIL model for room air temperature and temperatures at the surface and inside the west facing well.| 
 + 
 + 
 +==== General Considerations on Models used for Simulation ====
 The actual task in dealing with the questions of indoor climate and energy balance results from the high level of complexity which the "house and heating" system exhibits in combination with the respective physical theories of the subsystems. The actual task in dealing with the questions of indoor climate and energy balance results from the high level of complexity which the "house and heating" system exhibits in combination with the respective physical theories of the subsystems.
  
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 Quite often, therefore, even with computer supported simulation models, the "detour" via an abstractly defined mathematical model is no longer described, rather the model is formulated directly as a program. In the first place, too, this is not a fundamental deviation from the path of virtue in scientific theories - after all, not every model has to be a mathematical one and, in addition, computer algorithms are also mathematical models. However, there are some dangers in this shortened procedure: Quite often, therefore, even with computer supported simulation models, the "detour" via an abstractly defined mathematical model is no longer described, rather the model is formulated directly as a program. In the first place, too, this is not a fundamental deviation from the path of virtue in scientific theories - after all, not every model has to be a mathematical one and, in addition, computer algorithms are also mathematical models. However, there are some dangers in this shortened procedure:
  
-  * Unordered List ItemAs a rule, the digital algorithm itself lacks direct clarity (it is mastered by discretion). Therefore, even experienced users often find it difficult to read simple facts that can be generalized from EDP models.+  * As a rule, the digital algorithm itself lacks direct clarity (it is mastered by discretion). Therefore, even experienced users often find it difficult to read simple facts that can be generalized from EDP models.
  
 Example: Example:
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 From the considerations so far it follows quite clearly: From the considerations so far it follows quite clearly:
  
-The method of choice for answering typical questions of structural influences on the indoor climate and heating energy consumption is the use of thermal computer aided building models. - On the other hand, validation of such models thus becomes one of the most urgent tasks of research.+|**The method of choice for answering typical questions of structural influences on the indoor climate and heating energy consumption is the use of thermal computer aided building models. - On the other hand, validation of such models thus becomes one of the most urgent tasks of research.**|
  
      
-In practice, this finding has long since become established: Computer-aided thermal-technical building simulation is a widely used instrument. Of course, this does not say much about the suitability and accuracy of such procedures.+In practice, this finding has long since become established: Computer-aided thermal-technical building simulation is a widely used instrument. Of course, this does not say much about the suitability and accuracy of such procedures. A big part of the validation work has been done in recent research projects especially involving passive houses [Johnston 2020].
  
  
-===== References =====+==== References ====
  
 **[Blomsterberg 1990]** Blomsterberg, Å.: Ventilation and airtightness in lowrise residential buildings; Byggforskningsrådet, Stockholm D10:1990 \\ **[Blomsterberg 1990]** Blomsterberg, Å.: Ventilation and airtightness in lowrise residential buildings; Byggforskningsrådet, Stockholm D10:1990 \\
  
 **[Feist 1994]** Thermische Gebäudesimulation; 1. Auflage, 366 Seiten, 1994   **[Feist 1994]** Thermische Gebäudesimulation; 1. Auflage, 366 Seiten, 1994  
-Thermal building simulation, first edition,1994 \\+Thermal building simulation, first edition,1994 (in German)\\
  
 **[Fredlund 1989]** Fredlund, B.: Blocks of flats with glazed verandas, Taberg; Swedish Coun¬cil for Building Research, Stockholm D3:1989 \\ **[Fredlund 1989]** Fredlund, B.: Blocks of flats with glazed verandas, Taberg; Swedish Coun¬cil for Building Research, Stockholm D3:1989 \\
 +
 +**[Johnston 2020]** Johnston, D. et al: Are the energy savings of the passive house standard reliable? A review of the as-built thermal and space heating performance of passive house dwellings from 1990 to 2018. March 2020, Energy Efficiency, DOI: 10.1007/s12053-020-09855-7
  
 **[Lange 1990]** Lange, E.: Radhus i Valdemarsro, Malmö - En energi- och innklimatanalys, Byggforskningsrådet. Stockholm R1:1990 \\ **[Lange 1990]** Lange, E.: Radhus i Valdemarsro, Malmö - En energi- och innklimatanalys, Byggforskningsrådet. Stockholm R1:1990 \\
planning/calculating_energy_efficiency/dynamic_simulation.1596623275.txt.gz · Last modified: 2020/08/05 12:27 by wfeist