# Greenhouse Glass Covering

> Part of: [Greenhouse Construction](/greenhouse-construction.md) · Provider: [DutchGreenhouses](/)

The covering decides how much light reaches the crop, and within a crop’s usable range each extra percent of light returns roughly a percent of yield. Glass transmits most and holds its optics for decades; polycarbonate and sandwich panels trade transmission for impact resistance and insulation.

## Facts
| Property | Value |
|---|---|
| Light-to-yield relationship | 1 % yield per % light |
| Anti-reflective coating gain | 3–4 % transmission per treated surface |
| Optical durability of glass | 2 decades |
| Diffuse glass effect | Scatters direct light deeper into the canopy mechanism |
| Where panels replace glass | Service areas, side walls, severe-hail and high-heating climates locations |

Structure

# Glass covering.

    Light transmission is yield — the covering decides it.

## Light transmission is yield — the covering decides it

    The covering is the greenhouse’s skin, and it makes a decision that echoes through the entire operation: how much light reaches the crop. Because within a crop’s usable range roughly every extra percent of light returns an extra percent of yield, the light transmission of the covering is not a detail but one of the most consequential choices in the whole design. What lets the light in is also what keeps the heat in and the weather out, so the covering has to balance transmission, insulation and durability against the local climate.

Glass remains the standard for the growing area, and for good reasons: it offers the highest light transmission of any covering and lasts for decades without clouding or degrading, so its optical performance holds up over the greenhouse’s whole life. Within glass there are meaningful choices. Diffuse glass scatters direct sunlight so it penetrates deeper and more evenly into the canopy — lighting lower leaves that clear glass leaves in shade — while anti-reflective and other coatings can be applied to tune haze, boost transmission or add insulation, each measured against standards so different products can be compared objectively. Where the covering itself is fixed, screening does the same work seasonally: diffuse screens soften direct radiation on the brightest days, and energy screens hold back at night the heat the glass lets out.

Glass is not the only answer, though, and matching material to purpose matters. Polycarbonate and insulated sandwich panels trade some light transmission for far greater impact resistance and thermal insulation, which makes them the sensible covering for service areas and side walls, and for climates with severe hail or extreme heating demands where a double-walled panel’s insulation outweighs its lower light. Using glass where light is king and panels where robustness or insulation is king gets the best of both.

As with every other system, the right covering follows the climate profile rather than a fixed preference: the site’s solar radiation, its heating costs and its exposure to hail or storm together point to the optimum specification for that location and crop. DutchGreenhouses® selects and combines the covering materials to maximise yield for your climate and budget. Get in touch to discuss the covering for your greenhouse.

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## FAQ
**Why does light transmission matter so much?**
Because within a crop's usable range roughly every extra percent of light returns an extra percent of yield. That converts an optical property into an economic one: a covering choice made once at design time sets a ceiling on production for the whole life of the greenhouse. Nothing downstream recovers light the roof did not let through.

**What does diffuse glass actually do?**
It scatters direct sunlight instead of passing it straight through, so light penetrates deeper and more evenly into the canopy and reaches leaves that clear glass leaves in shade. It also lowers leaf-temperature peaks. The scattering share is measured as haze factor, so products can be compared against a standard rather than a claim.

**Should the whole greenhouse be glass?**
No — material follows purpose. Glass goes where light governs, which is the growing area. Polycarbonate and insulated sandwich panels go where robustness or insulation governs: service areas, side walls, and climates with severe hail or extreme heating demand, where a double-walled panel's insulation outweighs its lower transmission.

**How is the covering specification decided?**
From the site rather than from a preference. Solar radiation, heating costs and exposure to hail and storm together point to the optimum for that location and crop. A high-radiation site and a cold cloudy one reach different answers from the same starting question.

## Related
[Greenhouse Construction](/greenhouse-construction.md) · [Aluminium System](/greenhouse-construction/aluminium-system.md) · [Steel Structure](/greenhouse-construction/steel-structure.md) · [Insect Netting](/greenhouse-construction/insect-netting.md) · [Tempered Glass](/glossary/tempered-glass.md) · [Diffuse Glass](/glossary/diffuse-glass.md) · [AR Coating](/glossary/ar-coating.md) · [Light Transmission](/glossary/light-transmission.md) · [Haze Factor](/glossary/haze-factor.md) · [U-Value](/glossary/u-value.md) · [Polycarbonate Cladding](/glossary/polycarbonate.md)