# Energy Screens

> Part of: [Screening](/screening.md) · Provider: [DutchGreenhouses](/)

Energy screens are movable horizontal cloths installed above the crop, drawn closed at night and in cold periods to form an insulating buffer under the greenhouse roof. By trapping heat that would otherwise radiate away through the glass, they substantially cut a greenhouse’s heating energy use, with double-screen installations saving more than single screens.

## Facts
| Property | Value |
|---|---|
| Heat loss reduction | up to 47 % |
| Whether screen savings add up | No — a reduction factor applies to the second screen categorical |
| What a closed screen actually blocks at night | Radiant heat emission to the cold sky categorical |
| Moisture a single closed screen lets through | 35 g water/m² per hour |
| Closed fabric fraction to qualify as an energy screen | from 90 % closed |
| Maximum mesh opening to qualify | up to 2 mm² |
| Minimum diffuse transmission to qualify | from 10 % |

Screening

# Energy screens.

    The fastest payback in greenhouse technology.

## The fastest payback in greenhouse technology

    Of all the systems in a greenhouse, energy screens are often the one that pays for itself fastest. The principle is simple: a screen cloth drawn horizontally beneath the roof at night traps a layer of still air between the crop and the cold glass, sharply reducing the heat that escapes upward. Because heat loss through the roof is the dominant energy drain in a heated greenhouse, cutting it delivers immediate, substantial savings on the largest line of the operating budget — which is why energy screens are standard in every climate that needs heating.

The savings are considerable. A modern energy screen can reduce heat loss by up to around 47%, and it does more than trap warmth: the cloth also modulates infrared radiation, daylight and air movement, giving the grower a lever over the greenhouse's whole night-time energy balance. The best screens combine high thermal insulation with high light transmission — historically a trade-off, since denser, warmer cloths blocked more light — so they can stay closed longer, saving more energy, without starving the crop of the light it needs at the margins of the day.

Because a single cloth cannot do everything, cold and temperate climates increasingly use double screening: two independent screens, each with its own job and its own strategy. One might be a highly transparent energy screen for maximum insulation with minimal light loss, the other a blackout or shade cloth for photoperiod or radiation control, and the two are deployed in combination — both closed on the coldest nights, staged through dawn and dusk — to squeeze out savings a single screen cannot reach.

All of this is orchestrated by the climate computer hour by hour, opening and closing each screen against temperature, light, humidity and the risk of condensation, so insulation never comes at the cost of a damp, disease-prone canopy. Deployed well, screens cut energy bills, stabilise the climate and improve crop quality at the same time. DutchGreenhouses® specifies the screen package and control strategy around your climate and crop. Get in touch to discuss screening for your greenhouse.

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## FAQ
**How much energy do greenhouse energy screens save?**
A modern energy screen cuts heat loss through the roof by up to about 47 percent while it is closed. The annual saving is smaller than that figure, because the screen is not closed all year, and it depends on the cloth, the climate and how the climate computer is programmed to use it.

**Do two screens save twice as much as one?**
No, and this is the most common mistake made when comparing quotes. Screen savings cannot be added together. The first screen works on the greenhouse's full heat loss; the second works only on what is left after the first has done its job, so a reduction factor applies to it. Two cloths rated at 47 percent do not produce 94 percent — the second contributes a fraction of its headline number.

**So is a second screen worth installing?**
In a cold climate or a long heating season, yes — but it should be judged on its marginal saving, not on its rated one. That also explains why trials sometimes report little additional saving from a second cloth: a genuinely small increment is easily lost among the other variables being changed at the same time. The case for the second screen is strongest where the heating season is long enough for a small percentage to compound over many hours.

**What is a screen actually protecting the crop from at night?**
Radiation to the sky, as much as cold air. On a clear night the crop emits heat upward to a sky that is far colder than the outside air, which can pull leaf temperature below air temperature and cause condensation on the crop. A closed screen puts a warmer surface above the plants and stops that exchange.

**Why does a closed screen make humidity harder to manage?**
Because it also holds moisture in. A single closed screen passes roughly 35 grams of water per square metre per hour. An unlit crop producing 10 to 30 grams fits comfortably under it; a lit crop producing 70 to 100 does not, so the screen has to be gapped or the moisture removed another way. Screening and dehumidification are one decision, not two.

**Do energy screens reduce light for the crop?**
Transparent energy cloths transmit most incoming light and are usually only closed at night or during extreme cold, so the effect on the crop's daily light sum is small compared with the energy saved. Cloths with higher insulation values trade some transmission for more saving.

**Can energy screens be retrofitted in an existing greenhouse?**
Yes. Retrofitting is common, provided the greenhouse structure has enough clearance for the screen installation and its wire bed; the climate computer is then extended to automate the new screen alongside the existing systems.

**Does more aluminium in the cloth mean a better energy screen?**
No. Fabric structure decides the energy saving, while aluminium content decides the shade. A closed transparent cloth carrying no aluminium insulates further than a heavily aluminised open shade cloth, and it transmits enough light to stay closed through daylight.

## Related
[Screening](/screening.md) · [Blackout Screens](/screening/blackout-screens.md) · [Diffuse Screens](/screening/diffuse-screens.md) · [Heating](/climate/heating.md) · [Humidity Control](/climate/humidity-control.md) · [Energy Use](/performance/energy-use.md) · [Cold Extreme & Polar](/climate-zones/cold-extreme.md) · [Screen Installation](/glossary/screen-installation.md) · [Light Transmission](/glossary/light-transmission.md) · [Het Nieuwe Telen (HNT)](/glossary/het-nieuwe-telen.md) · [Plant Empowerment (GPE)](/glossary/plant-empowerment.md) · [Tomatoes](/vegetables/tomatoes.md)