Passive solar buildings : development and evaluation of a model-based optimal controller through experimentation and simulation.

Different heating system controllers for passive solar buildings are compared on two different
buildings. The performance criterion combines energy performance and thermal comfort
using the "cost function" paradigm. The experimental facilities did not allow a direct
experimental comparison by using two identical buildings.
The controllers were implemented alternatively in one building and a performance
comparison was obtained in two ways: first by identifying short periods that have similar
driving variables (weather and building occupancy) and comparing the experimental obtained
in both cases. The second method mixes experiments and simulation using a well-tuned
model of the building and its occupants.
This paper discusses the results obtained using both methods and shows that both methods
give consistent estimates of the difference between controllers, while the second method
allows to extrapolate useful information from the limited data available. In a second
evaluation step the controller is applied to a multizone building, and a detailed model is used
for the HVAC system. The model-based control algorithm is not modified. It is based on a
simplified internal model.
It is shown that the optimal controller's performance varies strongly with the zone that is
considered and the reference zone that is used. However, it is never worse than the
performance of a reference controller. The global performance at the building level depends
on the selected reference zone and on the building sensitivity to overheating.