A modular, open system for testing ventilation and cooling strategies in extremely low energy lecture rooms

Lecture rooms with their high, quickly fluctuating internal gains, e.g. changing from no occupation to full occupation within some minutes, are quite challenging when good indoor air-quality and thermal comfort is required in an extremely low energy building context.
One essential aspect is the perfect control of air flow and temperature based on reliable, continuous measurement in all relevant parts of the ventilation system.
This paper describes a case study that combines real building operation on a university campus with an advanced, modular test platform covering all aspects of the real operational performance of extremely low energy lecture rooms.
A full-scale Passive House test facility was constructed at Technology Campus Gent, KU Leuven, Belgium. The building is part of the campus and has two lecture rooms for 80 students each. Designed and certified according to the Passive House standard, the new facility consists of two levels, constructed on top of an existing building (ground-floor only).
Thermal insulation was placed also in-between the two lecture rooms and in the internal walls towards the staircase. This results in a layout with two identical, box-shaped volumes with different thermal mass (one with a timber-frame structure, one with brick-walls).
The facility includes a high performance AHU, with frequency controlled fans and two sets of VAV-boxes, providing ventilation, heating and cooling, a wood pellet boiler, motor-controlled exterior sun-shading and windows and high performance lighting fixtures with daylight control.
A key feature is the integrated system for monitoring and control based on open standards: BACnet for communication with the AHU, KNX, DALI and EtherCAT to link decentralized IO-units with the Building controller. This PLC based, distributed PC environment provides detailed control of the building equipment and real-time, long-term monitoring of all building parameters and the outdoor climate.
It provides also a very flexible and powerful platform for the implementation and testing of new strategies for model based predictive control (MPC) and fault detection and diagnosis (FDD). The Modelica language is used for building simulation during operation.
A detailed Building Information Model (BIM) was created and all relevant elements of the equipment and the BMS will be added. The BIM will be used to manage measured data and provide integration between simulation and measurement.
Results from detailed air flow measurements at different fan speeds are provided. These initial measurements show good general agreement and provide deeper insight in the dynamic behaviour of the ventilation system. Beside the air flow sensors of the AHU and the VAV boxes, Venturi tubes are integrated in the supply- and return-air duct of each lecture room. The modular monitoring system provides the possibility of easy integration of additional sensors (e.g. thermo-anemometers for temporary measurement of velocities and calculation of the air flow based on the Log-Chebychev method)..