Why Acrylic (Perspex) and Polycarbonate Outperform Glass for Greenhouse Glazing
Published on: 09/12/2024
The choice of glazing material in a greenhouse is critical to its success, directly impacting light transmission, temperature regulation, and plant health. While glass has been a traditional choice, modern materials like acrylic (commonly known as Perspex) and polycarbonate offer numerous advantages that make them superior for greenhouse use. These materials not only enhance greenhouse performance but also play an important role in fostering optimal conditions for plant cultivation, particularly through their exceptional UV properties.
The Role of Glazing in Plant Cultivation
Glazing is a greenhouse's most vital component, serving as the barrier that controls light entry, temperature stability, and weather resistance. The ideal glazing material must:
- Allow Sufficient Light Transmission: Sunlight is essential for photosynthesis, driving plant growth and productivity.
- Regulate Heat: Effective glazing moderates internal temperatures to prevent overheating or excessive cooling.
- Protect Plants from Harmful Radiation: Exposure to harmful UV rays can damage plants and degrade materials within the greenhouse.
Given these demands, acrylic and polycarbonate emerge as superior choices, meeting and exceeding the needs of greenhouse growers.
Superior UV Protection for Healthier Plants
One of the standout features of both acrylic and polycarbonate is their ability to manage ultraviolet (UV) radiation effectively.
- Acrylic: Naturally blocks most UV rays while allowing visible light to pass through. This protects plants from potential UV damage, such as leaf scorching or cellular degradation, while still supporting healthy photosynthesis.
- Polycarbonate: Typically features advanced UV-resistant coatings that not only shield plants from harmful UV rays but also protect the material itself from degradation. Polycarbonate remains clear and functional even after prolonged sun exposure.
Why This Matters for Cultivation:
UV protection is essential in preventing plant stress and damage, particularly for delicate crops that are sensitive to high-intensity sunlight. By filtering out harmful rays while preserving beneficial light, acrylic and polycarbonate create a controlled environment where plants thrive. Additionally, these UV-resistant properties extend the lifespan of the glazing material, maintaining greenhouse performance over time.
Optimal Light Transmission for Plant Growth
Light is the lifeblood of any greenhouse, and acrylic and polycarbonate deliver exceptional light transmission to meet this need:
- Acrylic: Allows up to 92% of sunlight to penetrate, rivaling the clarity of glass while offering better durability. Its smooth surface ensures even light distribution, preventing shadows or dark spots that can hinder growth.
- Polycarbonate: While slightly less transparent than acrylic (around 85% light transmission), it diffuses light more effectively, reducing glare and preventing hotspots that can damage plants.
These materials provide the right balance of light intensity and quality, ensuring consistent exposure for plants throughout the day.
The approximate light transmission percentages for various glazing materials is shown in the table below.
|
Material |
Light Transmission (%) |
|
Clear Glass |
85–90% |
|
Double Glass |
75–85% |
|
85–88% |
|
|
90–92% |
|
|
Clear Styrene * |
80–90% |
* Styrene provides decent light transmission but is less durable and more prone to yellowing over time compared to polycarbonate and acrylic.
Durability Against Environmental Stress
Greenhouses must endure various environmental challenges, including storms, hail, and fluctuating temperatures. Acrylic and polycarbonate excel in durability compared to glass:
- Impact Resistance: Acrylic is about 17 times stronger than glass, while polycarbonate is up to 250 times stronger. This resilience protects the greenhouse from damage caused by hail or debris.
- Weather Resistance: Both materials are designed to withstand prolonged exposure to the elements. Both materials resist yellowing, while polycarbonate’s UV coatings prevent discoloration or brittleness.
Why This Matters for Cultivation:
A durable glazing material ensures uninterrupted plant growth by maintaining greenhouse integrity during adverse weather. This reliability minimizes disruptions and reduces the need for frequent repairs or replacements.
Lightweight and Easy to Handle
Both acrylic and polycarbonate are much lighter than glass, simplifying installation and maintenance.
- Ease of Installation: Their lightweight nature makes them easier to transport and install, especially for larger greenhouses. Panels can be easily cut to size and customized for specific designs.
- Structural Benefits: Lighter materials reduce the load on greenhouse frames, enabling the use of simpler, cost-effective structures without compromising stability.
For gardeners and growers, this versatility provides flexibility in creating functional yet aesthetically pleasing greenhouses.
Thermal Regulation for Consistent Growth
Temperature control is another critical aspect of greenhouse cultivation. Acrylic and polycarbonate offer better thermal insulation than traditional glass, helping to maintain stable internal conditions:
- Acrylic: Offers moderate insulation, balancing heat retention and light transmission to create an optimal growing environment.
- Polycarbonate: Retains heat effectively, reducing energy costs associated with heating the greenhouse during colder months.
Why This Matters for Cultivation:
Stable temperatures promote steady plant growth and reduce the risk of stress caused by extreme temperature fluctuations. This is especially important for crops requiring specific climate conditions.
Safety and Shatter Resistance
Acrylic and polycarbonate are significantly safer than glass, particularly in environments where safety is a concern:
- Acrylic: Breaks into larger, blunt pieces if subjected to extreme force, reducing the risk of injury.
- Polycarbonate: Virtually shatterproof, making it the safest choice for greenhouses in homes, schools, or community gardens.
This added safety is a major advantage, particularly in high-traffic areas or where accidental impacts are likely.
Conclusion
When it comes to greenhouse glazing, acrylic (Perspex) and polycarbonate offer unparalleled benefits over traditional glass. Their superior UV protection not only safeguards plants from harmful radiation but also preserves the materials’ integrity for long-term use. Combined with excellent light transmission, exceptional durability, and ease of handling, these materials create the perfect environment for thriving plant cultivation.
For growers seeking to maximize productivity, reduce maintenance, and ensure a safe, efficient greenhouse setup, acrylic and polycarbonate stand as clear, forward-thinking choices.
Frequently asked questions
Polycarbonate sheet can be cut using a circular saw, a jigsaw or any type of saw with a fine-tooth blade. We recommend laying the polycarbonate sheet flat on a firm surface, such as a workbench, and clamping it down before cutting. If you are using clamps to hold the material down, we suggest placing wood between the clamps and polycarbonate sheet to prevent any damage to the surface of the polycarbonate. Manufacturer safety precautions should always be followed when using any type of saw. See our ultimate guide to polycarbonate for more information on polycarbonate and it's uses.
Clean with a mild solution of water and washing detergent using a soft microfibre cloth.
All of the different types of plastics that are available on our website, whether they be a panel, a disc, tube or rod, show the weight of the piece you require once you have entered your dimensions, shown in grams or kg.
The weight of any plastic can be calculated using the simple formula: Weight = Volume x Density
Read our blog post on how to calculate the weight of a variety of different plastics covering panels, discs, road and tube.
The Perspex brand has become synonymous with the manufacture of the highest grade acrylic available. It's clear Perspex sheet transmits 92% of all visible light (unmatched by any other manufacturer), is internationally recognised as a safety glazing material meeting the requirements of ANSI Z.97 and BS 6262, offers a ten year weathering guarantee and is manufactured right here in the UK. Perspex also boasts market leading environmental credentials having committed to meeting a detailed set of environmental targets by 2020.
Perspex is also very well known for the wide range of materials and colours it offers which is again unmatched by any other acrylic manufacturer. To the best of our knowledge, we stock and supply the widest range of Perspex colours in the UK including clear cut to size acrylic, high gloss coloured acrylic, frosted, fluorescent, matte effect naturals, metallic, tinted and their latest offering - the sweet pastels range. All of these materials are available cut to size and ready for application.
Depending on where you live within the UK, it may be possible to buy acrylic sheets locally, however you should be aware that most of the large DIY retailers will only stock clear acrylic, in a small selection of sizes and thicknesses, which means you'll need the tools to cut it to size at home. The advantage of buying from Simply Plastics is that you can purchase the exact size you require, there will be no wastage and you don't need any tools to cut to size - furthermore, to make it easier we'll deliver it directly to your home or workplace just a few days later. We are based in Colchester, just 30 minutes from London but we deliver right across the UK.
When deciding whether Cast Acrylic or Extruded Acrylic is best for your project it’s worth considering the specific application and desired finish you hope to achieve. The table below provides some examples of the most suitable type of acrylic sheet to use for specific applications.
| Cast Acrylic | Extruded Acrylic | |
| Application |
|
|
In our experience, whilst some projects/applications will require specific characteristics of either Cast or Extruded Acrylic, in most cases the choice can be made based on either colour, thickness or cost, as below:
- Clear or Colour: Extruded acrylic is generally only manufactured in clear, black and white and therefore if there is a requirement for any other colour, Cast Acrylic is the only choice.
- Thickness: Cast acrylic is commonly manufactured in thicknesses up to 100mm whereas extruded is generally available in a maximum thickness of 20mm (Simply Plastics stock up to 50mm in Cast and 10mm in Extruded).
- Cost: Extruded is marginally cheaper and therefore any requirement for a large quantity of sheets/panels, where the benefits of cast acrylic are not important, is likely to be more cost effective produced in Extruded acrylic.
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