The Crop Growth Research Chamber (CGRC), which is being developed under the Controlled Ecological Life Support System program at NASA Ames Research Center, will be operated to support research on the growth dynamics of crops of higher plants within a closed, precisely controlled environment. The CGRC is the first in a series of instruments which will be incorporated into bioregenerative life support systems for space habitats. The dynamic processes of the thermal and fluid portions of the CGRC are profoundly coupled with those of the plants and there is strong reason to believe that consideration of these interactions is necessary in order to design a CGRC which will support sound research.In this paper we describe the modeling system which we have developed for the thermal and fluid dynamics of the CGRC. The bases of the modeling system are symbolic representations of the individual processes which are included in the representation. The system includes the plant growth chamber, the associated control system components and the control devices. An example of the derivation of the dynamic equations of the system from the symbolic modeling system is presented.