The psychrometric chart

20 kJ/kg40 kJ/kg60 kJ/kg80 kJ/kg100 kJ/kg20 %40 %60 %80 %0.0000.0050.0100.0150.0200.0250.03001020304050Dry-bulb temperature (°C)Humidity ratio (kg/kg)day: unknown · night: unknownNo published day band — the night recipe temperature is not published.No published night band — the night recipe temperature is not published.
Queried stateSaturation and relative-humidity curvesEnthalpy lines

The queried state

Dry-bulb 43 °C at 12 % relative humidity.

Dry-bulb 43.0 °C
Relative humidity 12.0 %
Humidity ratio 0.0064 kg/kg
Dew point 7.5 °C
Enthalpy 59871 J/kg
Air VPD 7611 Pa
Release to grade this state.

Set the state

Technology tiers, toggled by link — each one the grammar's own spelling of the changed state:

The hour

No hour selected — day and night read side by side.

Hours 6 to 17 read the day context; 18 to 5, wrapping midnight, read the night — an even split, this page's own convention, not a solar model.

The scrubber steps an index between two verdicts this page already computed — it runs no simulation. The engine's measured basis: a fogged 8760-hour year is 194 ms in-process, so per-hour series analysis belongs to a batch surface, where the ladder runs per month, not per hour. This page requests no series at all.

The air state

Dry-bulb temperature43.0 °C
Relative humidity12.0 %
Humidity ratio0.0064 kg/kg
Vapour pressure1038 Pa
Dew point7.5 °C
Wet bulb20.9 °C
Specific enthalpy59871 J/kg
Air vapour-pressure deficit7611 Pa
Density1.112 kg/m³
Pressure101325 Pa

The crop recipe — LET-OAK-R

Day climate

Temperature21.85 °C (range 21–22.7)
Relative humidity70 % (range 60–80)
Vapour-pressure deficit0.7861953886352817 kPa (range 0.5241302590901875–1.0482605181803755)
Daily light integral12.35 mol/m²/d (range 11.5–13.2)
PhotoperiodNo published value. The crop record states none. (h)
CO₂1000–1100 ppm
Root-zone temperatureNo published value. The crop record states none. (°C)

Night climate

TemperatureHeld for engineering review — not published. (°C)
Relative humidityHeld for engineering review — not published. (%)
Vapour-pressure deficitHeld for engineering review — not published. (kPa)
Daily light integralHeld for engineering review — not published. (mol/m²/d)
PhotoperiodHeld for engineering review — not published. (h)
CO₂Held for engineering review — not published. (ppm)
Root-zone temperatureHeld for engineering review — not published. (°C)

Stress limits

Hard low temperatureHeld for engineering review — not published. (°C)
Hard high temperatureHeld for engineering review — not published. (°C)
VPD alertHeld for engineering review — not published. (kPa)
Disease humidity alertHeld for engineering review — not published. (%)
Dew-point marginHeld for engineering review — not published. (°C)
High-DLI alertHeld for engineering review — not published. (mol/m²/d)

Irrigation

Irrigation pH5.5–6 pH
Irrigation EC1.6–1.8 mS/cm
Drain fractionNo published value. The crop record states none. (%)
Dosing capacityNo published value. The crop record states none. (L/m²/h)
Daily water useNo published value. The crop record states none. (L/m²/d)

Transpiration

Mature leaf-area indexHeld for engineering review — not published. (m²/m²)
Light extinction coefficientHeld for engineering review — not published. (-)
Minimum stomatal resistanceHeld for engineering review — not published. (s/m)
Daily transpirationHeld for engineering review — not published. (kg/m²/d)
Peak transpirationHeld for engineering review — not published. (kg/m²/h)

Verdicts

Day — graded at full light, 200 W/m², the engine's own day threshold provisional

Temperature — The night recipe temperature is absent from the crop record. No effective band forms at this radiation level, so the state carries no temperature grade.

Vapour-pressure deficit — The night recipe vapour-pressure deficit band is absent from the crop record. No effective band forms at this radiation level, so the state carries no transpiration grade.

Condensation margin — comfort (comfortable). The coldest plant surface stays clear of the dew point of its air. Water stays off the crop at this state.

Night — graded with no sun

Temperature — The night recipe temperature is absent from the crop record. No effective band forms at this radiation level, so the state carries no temperature grade.

Vapour-pressure deficit — The night recipe vapour-pressure deficit band is absent from the crop record. No effective band forms at this radiation level, so the state carries no transpiration grade.

Condensation margin — comfort (comfortable). The coldest plant surface stays clear of the dew point of its air. Water stays off the crop at this state.

The strategy ladder

semiClosedRung: design.setpoint_c is required for this crop. The mechanical setpoint defaults to the midpoint of the crop's blended recipe band, and no band forms here — the blend reports night_recipe_temperature. A setpoint invented out of an absent recipe is a fabricated answer, so this rung asks for one rather than manufacturing it.

Worked examples

Riyadh — July

Outdoor: 43 °C at 12 % by day, 31 °C at 22 % by night; day length 13.6 h.

TiersDay °CNight °C24 h mean °CGradeClassNext rungLink
vent, fog 23.9 19.8 22.16 inside comfort none open
Air temperature sits outside the recipe band and within the grading envelope. The envelope is about as wide as the leaf model resolves, so the state reads as comfort rather than as a departure from target.
vent 43.0 31.0 37.80 above risk fog open
Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. Fog cools by evaporating water into the air the crop stands in, so the temperature falls and the humidity rises together, down to the margin that keeps water off the crop.
baseline 76.7 31.0 56.91 above risk fog open
Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. Fog cools by evaporating water into the air the crop stands in, so the temperature falls and the humidity rises together, down to the margin that keeps water off the crop.

Dubai — August

Outdoor: 41 °C at 45 % by day, 33 °C at 70 % by night; day length 13.4 h.

TiersDay °CNight °C24 h mean °CGradeClassNext rungLink
vent, fog 32.9 31.2 32.17 above stress semi_closed open
Air temperature has passed the tolerance limit the crop record states and stays within the stress margin beyond it. The crop survives; yield and quality carry a direct penalty for as long as the state holds. A semi-closed greenhouse holds a setpoint mechanically rather than evaporatively, and dries the air by controlled condensation to the margin the crop record states, keeping enriched air where the crop is.
semi_closed 21.0 18.5 19.90 inside comfort none open
Air temperature sits inside the blended recipe band for this radiation level. The crop holds its target temperature.
baseline 72.8 33.0 55.20 above risk semi_closed open
Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. A semi-closed greenhouse holds a setpoint mechanically rather than evaporatively, and dries the air by controlled condensation to the margin the crop record states, keeping enriched air where the crop is.

Beja — July

Outdoor: 36 °C at 25 % by day, 18 °C at 60 % by night; day length 14.6 h.

TiersDay °CNight °C24 h mean °CGradeClassNext rungLink
vent, fog 23.9 16.4 20.97 inside comfort none open
Air temperature sits inside the blended recipe band for this radiation level. The crop holds its target temperature.
baseline 67.8 18.0 48.27 above risk fog open
Air temperature lies beyond the tolerance limit the crop record states by more than the stress margin. Tissue damage and loss of the crop follow while the state holds. Fog cools by evaporating water into the air the crop stands in, so the temperature falls and the humidity rises together, down to the margin that keeps water off the crop.

Naaldwijk — July

Outdoor: 22 °C at 70 % by day, 15 °C at 85 % by night; day length 16.3 h.

TiersDay °CNight °C24 h mean °CGradeClassNext rungLink
vent 25.0 15.0 21.79 inside comfort none open
Air temperature sits inside the blended recipe band for this radiation level. The crop holds its target temperature.
baseline 42.9 15.0 33.96 above stress vent open
Air temperature has passed the tolerance limit the crop record states and stays within the stress margin beyond it. The crop survives; yield and quality carry a direct penalty for as long as the state holds. Ventilation moves the greenhouse toward the outdoor air, which is as far as opening the vents can take it.

Provenance

Computed by the DGH Climate Engine, version 0.2.0.

Two layers, stated separately: the psychrometric-core layer is validated; the greenhouse-model layer is design-stage.

Licence: Apache-2.0, covering software-implementation.

Attribution: DutchGreenhouses® — DGH Climate Engine

Citation: DutchGreenhouses B.V. (2026). DGH Climate Engine v0.2.0. Apache-2.0.

Sources: plant_empowerment, bakker_1995, ashrae_2017, dgh_crop_model_db.

Methodology · Canonical link for this view

Indicative, design-stage. Engineering confirms.