Psychrometric state and crop verdicts.

What the page answers

One outdoor air state — a dry-bulb temperature and a relative humidity — graded against a crop's published climate recipe: the full psychrometric state, the day and night verdicts in the engine's own words, and, per requested technology tier, the indoor state that tier can hold. A withheld figure says so, an absent figure says so, and nothing is filled in.

The three published crops, at the Riyadh July day state: TOM-TOV, CUC-LONG, LET-BUTTER.

Worked examples

Riyadh — July

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

Tiers	Day °C	Night °C	24 h mean °C	Grade	Class	Next rung	Link
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.

Tiers	Day °C	Night °C	24 h mean °C	Grade	Class	Next rung	Link
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.

Tiers	Day °C	Night °C	24 h mean °C	Grade	Class	Next rung	Link
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.

Tiers	Day °C	Night °C	24 h mean °C	Grade	Class	Next rung	Link
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.