Computational Steering for Thermal Comfort Simulations
| Project team leader | Dr.rer.nat. Ralf-Peter Mundani Prof. Dr. rer.nat. Ernst Rank |
| PhD students | Dipl.-Ing. Jérôme Frisch |
Project Description
Indoor climate predictions in office buildings gained increasing importance in the past. The aim of reducing the energy consumption of buildings, and maintaining reasonable indoor temperatures for the occupants at the same time, can be accomplished using simulation tools in the early design stages of the design phase.
In a first study, a ‘virtual climate chamber’ was designed, which makes use of a human thermoregulation model according to D. Fiala. Occupants can be situated in a rectangular enclosure with well-defined boundary conditions, such as room and surface temperatures, relative humidity, air velocity and metabolic rate. The latter quantities can be changed during an ongoing simulation using the so-called 'computational steering' concept.
It is subject to the current work to couple the numerical thermal manikin with a previously developed interactive CFD steering environment ‘iFluids’. After a series of iterations of the CFD solver, the current boundary conditions at the surface of the manikin shall be delivered to the thermoregulation interface. The existing interface provides the thermal state of the manikin in terms of the resultant surface temperatures and heat fluxes, which may act as new boundary conditions of the manikin in the next CFD step. Using these resulting surface temperatures, a local comfort vote can be calculated using a 7 point ASHRAE scale, for example, indicating the comfort state of the manikin. Coupling CFD with the numerical manikin offers the possibility to predict the indoor thermal comfort situation in detail, such as assessing the draught risk, etc.
The interface further provides means to couple the manikin model with a zonal model according to J. Clarke. The resolution of the zonal approach is, however, much coarser than the CFD model. Starting with the evaluation of the annual thermal performance of a building, it is possible to determine the amount of hours in a first place, where the internal temperatures in the building may exceed a threshold, as given in standards like the EN ISO Standard 7730, for example. After refining the model, in a coupled manner (zonal model - manikin), detailed information can be obtained with the manikin model in an online simulation.
