Zones
Overview
This chapter provides the details for modeling zones and their associated sensors and setpoints. See the Spaces chapter for an introduction to how zones are modeled as a subtype of space.
Occupancy
Determining and controlling occupancy is one of the most critical aspects of building automation. Haystack defines several occupancy related point specs:
- OccupiedSp: setpoint true when occupied, false when unoccupied
- OccupiedSensor: boolean sensor true when occupied, false when unoccupied
- OccupancySensor: people counter that measures number of occupants
- occ: marker tag is used on points for occupancy modes
- unocc: marker tag is used on points for occupancy modes
- occupants: the people who occupy a space
In most cases, the occupied setpoint is a schedule that determines occupancy based on the time of day and day of the week. We might also use a sensor like a motion sensor to determine occupancy. More sophisticated sensors can actually count the number of people in a space using OccupancySensor.
The occ and unocc tags are used in cases when we need to distinguish
modes. For example, if we have two different temperature setpoints based
on the occupancy mode, then we distinguish them as occ temp sp
and unocc temp sp.
HVAC
The HvacZoneSpace conjunct models an HVAC zone for the conditioning of space comfort and air quality.
The sensor and setpoints associated with temperature control include:
- hvacMode sp: current mode such as "cooling" or "heating"
- temp sensor: actual sensed temperature of the space
- temp occ cooling sp: cooling setpoint when occupied
- temp occ heating sp: heating setpoint when occupied
- temp unocc cooling sp: cooling setpoint when unoccupied
- temp unocc heating sp: heating setpoint when unoccupied
- temp standby cooling sp: cooling setpoint when in standby mode
- temp standby heating sp: heating setpoint when in standby mode
- temp effective sp: current setpoint we are controlling to taking into account cooling/heating mode and occ/unocc/standby mode
Whenever possible, there should be one effective temperature setpoint
that takes all the various modes into account. This provides the simplest
model to perform analysis of HVAC operations. However in some cases
a thermostat will provide two effective setpoints - one for cooling
and one for heating. In this case, there must also be a hvacMode point
to determine which one is the true effective setpoint. That setup should
look like this:
In addition, we might also find the following points:
- pressure sensor: measured static pressure of the space
- pressure sp: static pressure setpoint (commonly used for lab situations)
- humidity sensor: measured relative humidity of the space
- humidity sp: setpoint for relative humidity
- dewPoint sensor: measured dew point temperature of the space
- dewPoint sp: setpoint for dew point temperature
- enthalpy sensor: measured heat content of the space
All the points above must also be tagged with zone, air, and point.
Air Quality
It is also common in an HVAC zone to also measure and control air quality using a ZoneMonitor. Typical air quality points include:
- Ch2oConcentration sensor: measured formaldehyde (CH₂O)
- CoConcentration sensor: measured carbon monoxide (CO)
- Co2Concentration sensor: measured carbon dioxide (CO₂)
- Co2Concentration sp: configured max carbon dioxide (CO₂)
- Nh3Concentration sensor: measured ammonia (NH₃)
- No2Concentration sensor: measured nitrogen dioxide (NO₂)
- O3Concentration sensor: measured ozone (O₃)
- Pm01Concentration sensor: measured particulate matter 0.1
- Pm25Concentration sensor: measured particulate matter 2.5
- Pm10Concentration sensor: measured particulate matter 10
- TvocConcentration sensor: measured total volatile organic compounds
All the points above must also be tagged with zone, air, and point.
Lighting
The LightingZoneSpace conjuct models lighting zones. Typical points used for lighting measurement and control include:
- LightLevel sensor: brightness level status as percentage
- LightLevel sp: brightness level setpoint as percentage
- light illuminance sensor: lux, footcandle, or phot
- light LuminousFlux sensor: luminous flux in lumens