Combined simulation of the building, primary and secondary plant of a typical office building

Office buildings are very often equipped with complex HVAC systems made of primary,
secondary and control sub-systems. The interaction between those elements is complex and requires specific analysis tools. In the context of the IEA-ECBCS Annex 48 and IEE-HarmonAC projects, a typical office building of the Walloon region was deeply analyzed through both monitoring and simulation work.
The main objective of the work was, starting from the existing status of the building, to assess
the performance of a number of changes in the building envelope, HVAC system and control
system. In particular, the performance of different reversible (air coupled, ground coupled) heat pumps was calculated and compared to a reference situation (separate production for heating and cooling).
To achieve this objective, different simulation tools were used. This paper will relate the development, calibration and use of a detailed TRNSYS application integrating a multi-zone
(10 per floor) modeling of the building envelope, a detailed representation of the secondary plant (including the simulation of a customized VAV system), a modeling of the different configurations of the primary plant (with and without heat pump) as well as a realistic consideration of the main elements of the control system.
The paper will present successively the architecture of the simulation application, the
selection of the Types required to perform the task, the calibration of some of them using measurements carried out in the building and the results obtained by running a number of configurations of the system.
The paper will specifically focus on the problems generated by the interaction between the primary and secondary plant as well as with the specific issues related to the simulation of the control system.