A comfortable temperature is quite a balancing act, and a good thermostat is key. This is not even touching individual preferences … think how many arguments at home start with one person shivering while the other one sweats bullets ? 🙂
Old-school Pneumatic thermostats were widely installed in buildings over 30 years old. Pneumatics use the energy in compressed gases to make things move or work. Despite the fact that more and more projects have a centralized building automation systems, many buildings still rely on pneumatic thermostats to control individual heating, ventilation and air conditioning (HVAC) for individual zones to address the occupants’ comfort.
With energy efficiency standards continuing to improve and facility management requirements getting more detailed, pneumatic thermostats could not meet the demand.
Disadvantages of pneumatic thermostats:
- It’s hard to adjust the setpoint on the spot … you need a special tool
- And it’s also hard to adjust remotely
- Temperature cannot be monitored remotely
- Pressure cannot not be controlled remotely
- No schedule control for individual area
- Thermostat needs frequent calibration to be accurate
It is not easy to convert a pneumatic controlled room to Direct Digital Control (DDC). It’s expensive and it’s disruptive to the people working in the area. In the last few years, wireless pneumatic thermostats emerged on the market and are a good solution for old buildings. They save installation time and cost.
For those interested in the nuts and bolts tech side, Wireless Pneumatic Thermostats (WPT) include an electric temperature sensor and convert the electrical signal to a pneumatic transducer. All signals are relayed to BAS via wireless router. With WPT, facility managers and building operators are able to know the details on how the rooms and floors are operating. Furthermore, energy optimization could be put in place with all these inputs.
Typical energy optimization includes:
- Schedule control.
- Each zone could change the different setpoint based on the schedule.
- VAV damper can be fully closed or supply the minimum flow in unoccupied mode.
- Reheat valve can be fully shutoff when the space condition is satisfied.
- Setpoint adjustment
BAS could now adjust the setpoint based on the condition of the occupancy.
- AHU duct static pressure setpoint reset.
With the information of room temp, setpoint and pneumatic pressure, duct static pressure reset can be implemented in the AHU control. Duct static pressure setpoint could increase when more rooms are calling for cooling.
- AHU supply air temp setpoint reset.
- With the information of room temp, setpoint and pneumatic pressure, AHU supply air temperature reset can be implemented in the AHU control.
And that should keep everyone more comfortable.