A performance model has been programmed for a solar thermal collector based on a linear parabolic trough reflector focused on a coated absorber tube enclosed in an evacuated transparent tube: a Parabolic Trough Solar Collector (PTSC). This steady state, single dimensional model is based on fundamental material and energy balances together with heat transfer correlations programmed in the Engineering Equation Solver (EES). The model considers the effects of solar intensity, incident angle, collector dimensions, material properties, fluid properties, ambient conditions, and operating conditions on the performance of the PTSC. The model has been used to size system devices, to choose proper operating conditions, and to detect possible operating problems for the solar cooling and heating system for the Intelligent Workplace (IW) at Carnegie Mellon University (CMU) in Pittsburgh. The IW installed 52 - square meter PTSCs coupled with a 16 kW absorption chiller for space cooling and heating in August of 2006. The tests on PTSC performance are now being carried out. After the model is validated by experimental data of the tests, it will be further used to improve PTSC design and to optimize system operation and control for the IW.