diff --git a/drivers/place/demo/hvac.cr b/drivers/place/demo/hvac.cr
new file mode 100644
index 00000000000..1c73731cd24
--- /dev/null
+++ b/drivers/place/demo/hvac.cr
@@ -0,0 +1,222 @@
+require "placeos-driver"
+require "placeos-driver/interface/powerable"
+
+# Simulated HVAC unit for demos: no hardware and no transport.
+# The temperature eases toward the setpoint, and an unoccupied room widens the
+# target by `setback_offset` (occupancy setback).
+class Place::Demo::HVAC < PlaceOS::Driver
+  include Interface::Powerable
+
+  descriptive_name "PlaceOS Demo HVAC"
+  generic_name :HVAC
+  description %(simulates an HVAC unit: temperature eases toward the setpoint \
+with noise, exposes mode/fan/humidity/CO2/power, and applies occupancy setback. \
+Accepts control commands. For demos. No hardware.)
+
+  enum Mode
+    Off
+    Heat
+    Cool
+    Auto
+  end
+
+  enum Fan
+    Auto
+    Low
+    Medium
+    High
+  end
+
+  default_settings({
+    initial_temperature: 22.5, # deg C
+    setpoint:            21.5, # deg C
+    mode:                "cool",
+    fan:                 "auto",
+    ambient_temperature: 28.0, # deg C the room drifts toward when not conditioning
+    humidity:            50.0, # % relative humidity at start
+    deadband:            0.4,  # deg C either side of the target
+    tick_interval:       5,    # seconds between simulated samples
+    occupancy_setback:   true,
+    setback_offset:      3.0, # deg C
+    occupied:            true,
+  })
+
+  @temperature : Float64 = 22.5
+  @setpoint : Float64 = 21.5
+  @ambient : Float64 = 28.0
+  @humidity : Float64 = 50.0
+  @co2 : Int32 = 500
+  @deadband : Float64 = 0.4
+  @mode : Mode = Mode::Cool
+  @last_on_mode : Mode = Mode::Cool
+  @fan : Fan = Fan::Auto
+  @occupied : Bool = true
+  @occupancy_setback : Bool = true
+  @setback_offset : Float64 = 3.0
+  @tick : Int32 = 5
+
+  MIN_SETPOINT = 16.0
+  MAX_SETPOINT = 30.0
+  MIN_TEMP     = 10.0
+  MAX_TEMP     = 40.0
+  MIN_CO2      =  420
+  MAX_CO2      = 1400
+
+  # on_update is not called at startup when on_load is defined
+  def on_load
+    apply_settings
+    @temperature = setting?(Float64, :initial_temperature) || @setpoint
+    @occupied = setting?(Bool, :occupied) != false
+    publish_state
+    schedule.every(@tick.seconds) { simulate }
+  end
+
+  # Keeps the simulated temperature; only the tunables are re-read
+  def on_update
+    previous_tick = @tick
+    apply_settings
+    if previous_tick != @tick
+      schedule.clear
+      schedule.every(@tick.seconds) { simulate }
+    end
+    publish_state
+  end
+
+  private def apply_settings
+    @setpoint = (setting?(Float64, :setpoint) || @setpoint).clamp(MIN_SETPOINT, MAX_SETPOINT)
+    @ambient = setting?(Float64, :ambient_temperature) || @ambient
+    @humidity = setting?(Float64, :humidity) || @humidity
+    @deadband = setting?(Float64, :deadband) || @deadband
+    @mode = Mode.parse(setting?(String, :mode) || @mode.to_s)
+    @last_on_mode = @mode unless @mode.off?
+    @fan = Fan.parse(setting?(String, :fan) || @fan.to_s)
+    @occupancy_setback = setting?(Bool, :occupancy_setback) != false
+    @setback_offset = setting?(Float64, :setback_offset) || @setback_offset
+    @tick = setting?(Int32, :tick_interval) || @tick
+  end
+
+  # Returns the target temperature for this tick and whether setback applies.
+  # Heating targets move down when empty, cooling targets move up.
+  private def effective_target : {Float64, Bool}
+    return {@ambient, false} if @mode.off?
+    setback = @occupancy_setback && !@occupied
+    return {@setpoint, false} unless setback
+    if @mode.heat?
+      {(@setpoint - @setback_offset).clamp(MIN_SETPOINT - 5, MAX_SETPOINT), true}
+    else
+      {(@setpoint + @setback_offset).clamp(MIN_SETPOINT, MAX_SETPOINT + 5), true}
+    end
+  end
+
+  private def simulate
+    target, setback = effective_target
+
+    heating = !@mode.off? && !@mode.cool? && @temperature < target - @deadband
+    cooling = !@mode.off? && !@mode.heat? && @temperature > target + @deadband
+    conditioning = heating || cooling
+
+    rate = conditioning ? 0.22 : 0.04
+    noise = (rand - 0.5) * 0.2
+    drift_target = conditioning ? target : @ambient
+    @temperature = (@temperature + (drift_target - @temperature) * rate + noise).clamp(MIN_TEMP, MAX_TEMP)
+
+    hnoise = (rand - 0.5) * 1.5
+    hnoise -= 0.4 if cooling
+    @humidity = (@humidity + hnoise).clamp(30.0, 70.0)
+
+    if @occupied
+      @co2 = (@co2 + 12 + rand(8)).clamp(MIN_CO2, MAX_CO2)
+    else
+      @co2 = (@co2 - 20).clamp(MIN_CO2, MAX_CO2)
+    end
+
+    publish_state(heating, cooling, setback)
+  end
+
+  # 0 = off, 1 = low, 2 = medium, 3 = high
+  private def running_fan_level(conditioning : Bool) : Int32
+    return 0 if @mode.off?
+    return @fan.value if @fan != Fan::Auto
+    return 1 unless conditioning
+    diff = (@setpoint - @temperature).abs
+    diff < 1.0 ? 2 : 3
+  end
+
+  # Watts
+  private def power_draw(heating : Bool, cooling : Bool, fan_level : Int32) : Int32
+    watts = fan_level * 120
+    watts += 2800 if cooling
+    watts += 2400 if heating
+    watts
+  end
+
+  private def publish_state(heating : Bool = false, cooling : Bool = false, setback : Bool = false)
+    fan_level = running_fan_level(heating || cooling)
+    self[:temperature] = @temperature.round(1)
+    self[:setpoint] = @setpoint.round(1)
+    self[:mode] = @mode.to_s.downcase
+    self[:fan] = @fan.to_s.downcase
+    self[:fan_level] = fan_level
+    self[:fan_running] = fan_level > 0
+    self[:humidity] = @humidity.round(0).to_i
+    self[:co2] = @co2
+    self[:occupied] = @occupied
+    self[:heating] = heating
+    self[:cooling] = cooling
+    self[:setback_active] = setback
+    self[:power_draw] = power_draw(heating, cooling, fan_level)
+    self[:power] = !@mode.off?
+    self[:connected] = true
+    self[:last_updated] = Time.utc.to_unix
+  end
+
+  # On restores the last mode other than off
+  @[Security(Level::Support)]
+  def power(state : Bool)
+    @mode = state ? @last_on_mode : Mode::Off
+    simulate
+    state
+  end
+
+  @[Security(Level::Support)]
+  def set_temperature(value : Float64)
+    @setpoint = value.clamp(MIN_SETPOINT, MAX_SETPOINT)
+    simulate
+    @setpoint
+  end
+
+  @[Security(Level::Support)]
+  def set_mode(mode : Mode)
+    @mode = mode
+    @last_on_mode = mode unless mode.off?
+    simulate
+    @mode.to_s.downcase
+  end
+
+  @[Security(Level::Support)]
+  def set_fan(speed : Fan)
+    @fan = speed
+    simulate
+    @fan.to_s.downcase
+  end
+
+  @[Security(Level::Support)]
+  def set_occupied(state : Bool)
+    @occupied = state
+    simulate
+    @occupied
+  end
+
+  def state
+    {
+      temperature:    @temperature.round(1),
+      setpoint:       @setpoint.round(1),
+      mode:           @mode.to_s.downcase,
+      fan:            @fan.to_s.downcase,
+      humidity:       @humidity.round(0).to_i,
+      co2:            @co2,
+      occupied:       @occupied,
+      setback_active: @occupancy_setback && !@occupied && !@mode.off?,
+    }
+  end
+end
diff --git a/drivers/place/demo/hvac_spec.cr b/drivers/place/demo/hvac_spec.cr
new file mode 100644
index 00000000000..bb3f6567197
--- /dev/null
+++ b/drivers/place/demo/hvac_spec.cr
@@ -0,0 +1,51 @@
+require "placeos-driver/spec"
+
+DriverSpecs.mock_driver "Place::Demo::HVAC" do
+  # on_load has published an initial frame
+  status[:mode].should eq("cool")
+  status[:connected].should eq(true)
+  status[:power].should eq(true)
+  status[:temperature].as_f.should be_a(Float64)
+  status[:occupied].should eq(true)
+
+  # setpoint control + clamping
+  exec(:set_temperature, 19.0).get
+  status[:setpoint].as_f.should eq(19.0)
+  exec(:set_temperature, 99.0).get
+  status[:setpoint].as_f.should eq(30.0) # MAX_SETPOINT
+
+  # mode control (string arg deserialises into the Mode enum)
+  exec(:set_mode, "heat").get
+  status[:mode].should eq("heat")
+  exec(:set_mode, "off").get
+  status[:mode].should eq("off")
+  status[:power].should eq(false)
+  status[:heating].should eq(false)
+  status[:cooling].should eq(false)
+
+  # fan control
+  exec(:set_mode, "cool").get
+  exec(:set_fan, "high").get
+  status[:fan].should eq("high")
+  status[:fan_level].as_i.should eq(3)
+
+  # occupancy setback: emptying the room activates setback and widens the
+  # cooling target above the comfort setpoint
+  exec(:set_temperature, 21.0).get
+  exec(:set_occupied, false).get
+  status[:occupied].should eq(false)
+  status[:setback_active].should eq(true)
+
+  # re-occupying clears setback
+  exec(:set_occupied, true).get
+  status[:setback_active].should eq(false)
+
+  # power off then on restores the previous mode
+  exec(:set_mode, "heat").get
+  exec(:power, false).get
+  status[:power].should eq(false)
+  status[:mode].should eq("off")
+  exec(:power, true).get
+  status[:power].should eq(true)
+  status[:mode].should eq("heat")
+end