Greenhouse climate screen for any site
Daily light integral, vapour pressure deficit, heating and cooling degree-hours, frost and extreme-heat hours from an hourly weather file. Compare sites for a new greenhouse, size heating and supplemental lighting, or check a season before planting.
Screen a site → Free. Upload an EPW or make one for any location.
Sample result: eleven sites
Actual year 2023 at each site. Daily light integral (DLI, outdoor, mol/m² a day) as the annual mean and the darkest month; share of hours with vapour pressure deficit in the 0.4 to 1.2 kPa range most crops prefer; heating degree-hours below 10 °C; hours below 0 °C and above 38 °C.
| Site | DLI mean | DLI darkest month | VPD in range | Heating °C·h | Frost h | Above 38 °C h |
|---|---|---|---|---|---|---|
| Amsterdam | 23 | 4 | 23 % | 14k | 146 | 0 |
| London | 22 | 4 | 26 % | 12k | 182 | 0 |
| Toronto | 28 | 6 | 30 % | 36k | 1,255 | 0 |
| Chicago | 30 | 8 | 34 % | 29k | 894 | 0 |
| Denver | 37 | 16 | 33 % | 39k | 1,747 | 0 |
| Madrid | 38 | 16 | 29 % | 13k | 345 | 70 |
| Phoenix | 44 | 23 | 20 % | 1,210 | 0 | 1,034 |
| Nairobi | 42 | 26 | 39 % | 0 | 0 | 0 |
| Riyadh | 42 | 20 | 17 % | 178 | 0 | 1,329 |
| Tokyo | 34 | 21 | 59 % | 5,380 | 18 | 0 |
| Melbourne | 32 | 16 | 38 % | 3,619 | 0 | 4 |
In their darkest month Amsterdam and London get about a seventh of the light Nairobi gets, which is why Dutch growers light and heat while East African growers shade; Riyadh and Phoenix have no frost but more than a thousand hours above 38 °C.
What you get
Monthly and annual DLI; VPD statistics and hours in the optimal range; crop degree-hours for heating (base 10 °C) and cooling (base 27 °C); frost hours and extreme-heat hours. It runs on any EnergyPlus weather file (EPW), so the same screen works for a past year, a typical year or a 2050 future-climate file, and the same file can drive an energy model of the greenhouse in EnergyPlus.
Frequently asked questions
Where does the weather come from?
From an EPW weather file: one you already have, or one generated by EPW.tools for any coordinates and any year since 1990, a typical year or a future climate year.
How is the daily light integral estimated?
Photosynthetically active radiation is taken as 45 % of global horizontal irradiance and converted at 4.6 µmol per joule. These are the standard fixed-fraction approximations; the result is outdoor light, before glazing and screens.
Does the VPD account for the leaf temperature?
No. Air dry bulb stands in for leaf temperature, so it is a screening value for comparing sites and seasons, not a crop-control setpoint.
Can I see how a site changes by 2050?
Yes. Make a future-climate weather file for the site and run the same screen on it, then compare the two.
Screen a greenhouse site
Free. Upload an EPW, or make one for any coordinates first.
Screen a greenhouse site →