Carnegie Mellon University Website Home Page


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.