The short answer: if you plan to grow into late fall or through the winter, choose twin-wall polycarbonate, because it holds heat better and spreads light evenly. If you mostly grow from spring to fall and want the most light and a clear view, clear panels do that best. Many of our greenhouses give you both, with a twin-wall roof and clear walls.
What is the difference?
Twin-wall polycarbonate is two layers of polycarbonate joined by thin ribs, with an air space in between. That trapped air is what gives it its insulating value. The structure also diffuses light, so sunlight spreads evenly through the greenhouse instead of landing on your plants as harsh, direct rays.
Clear polycarbonate is a single, glass-like sheet. It lets the most light through and gives you a clear view in and out, but as a single layer it holds less heat than twin-wall.
Both are polycarbonate rather than glass, and Palram-Canopia's specifications list UV protection for both.
How they compare
| Twin-wall | Clear | |
|---|---|---|
| Light transmission | 79% to 82%, depending on thickness | 90% |
| Light quality | Diffused and even | Direct |
| Holding heat | Better, thanks to the air layer | Lower, single layer |
| View | Translucent: light and shapes, not a clear view | Clear and glass-like |
| Thickness on the models below | 4 mm, 6 mm or 10 mm | 0.7 mm |
Light transmission figures are Palram-Canopia's, as listed on each product page.
Which of our greenhouses use which panels
- Twin-wall all round: Mythos and Essence (4 mm, 82% light), Bella (6 mm, 80%) and Glory (10 mm, 79%).
- Clear all round: Harmony (0.7 mm, 90%).
- Twin-wall roof, clear walls: Hybrid, Balance in 8 ft and 10 ft widths, Oasis, Americana, Victory Orangery and Lean-To (4 mm roof at 82%, 0.7 mm walls at 90%).
Other lines, including our Rion resin greenhouses, list their panels on each product page.
What we suggest for a Canadian winter
- Heating through the winter? Go twin-wall. The air layer helps hold the heat you pay for. The Glory pairs its 10 mm panels with a rating of 100 kg/m² (20.5 PSF) of snow and 100 km/h winds.
- Growing from spring to fall? Clear or hybrid panels give seedlings more light and give you a clear view of your plants. Plan on good ventilation and some shade in July and August.
- Want a bit of both? A hybrid puts twin-wall on the roof to soften the overhead sun, and clear panels on the walls for light and a view.
Panels are only part of the winter picture. The snow rating belongs to the whole greenhouse, and the heat comes from your heater, so see our fall greenhouse checklist and our winter heating calculator before the cold sets in.
Still deciding?
Take our greenhouse quiz, compare models side by side on our model comparison page, or call us at 1-877-322-5487. We are a Canadian family business and a certified Palram-Canopia dealer since 2007.