Experiments

The hypothesis for some of the experiments that will be performed with the fan coil installation is that the operation of HVAC control systems can be improved by:

• using real time data from a distributed sensor network deployed throughout the building,
• commissioning,
• real time communication between occupant and building control and facility management system,
• combining feed-forward control with feedback control, and
• providing higher spatial resolution of zonal temperature, humidity and air quality

Therefore, the research objectives are:

• to design and test occupant interface for comfort and energy efficient
• to develop methods for combining feedback control and feed forward model based control
• to examine the use of models in testing and improving control strategies
• to assess the possible benefits of an increased number of sensors in thermal and IAQ control

Various control strategies will be implemented and evaluated to control the:

• installation of fan coil units in individual rooms
• supply water to the fan coil units
• ventilation air damper at the fan coil units.

A "comfort" reference variable will be adopted to replace air temperature.

Below are some of the initial control strategies that will be experimented with:

Fan Coil Unit (FCU) Fan and Valve Control

Control Strategy 1

• In this strategy the fan and valve in the fan coil units are controlled using a feedback algorithm.

Control Strategy 2

• Here, the fan and valve are controlled using an algorithm that combines feedback and feedforward control. 

Control Strategy 3

• In this strategy the principle of a thermostatic valve is used with an aim to minimize water flow.

Control Strategy 4

• In this strategy the valve and fan are controlled in sequence. The valve is actuated first while the fan speed is kept at a minimum. If comfort conditions are not met after a specified time, then the fan speed is increased. This strategy provides acoustic advantages.

 

Supply Water Pressure and Temperature Control

Water Pressure (Control of Variable Speed Pump)

Control Strategy 1

• The water pressure is determined based on the fan coil unit specifications for water flow rate

Control Strategy 2

• In this strategy the water pressure is determined based on maintaining the average position of all the valves in the space at 50% thus providing the greatest adjustability of temperature at individual rooms. Possible limitations exist for this strategy include non-linear operation and hysteresis of the valve.

 Water Temperature (Control of 3 Way Mixing Valve)

Control Strategy 1

• In this strategy the supply water temperature is determined as a function of measured outdoor air temperature providing a level of feed forward control.

Control Strategy 2

• In this strategy the water temperature is set based on keeping fan speeds of all FCUs in the space at minimum providing an acoustic advantage.

 

Ventilation Air Damper Control

• The control of this damper is based on real time measurements of carbon dioxide, volatile compounds and carbon monoxide compared to established standards for these parameters.