Which greenhouse cover provides the best insulation and impact resistance, though at higher cost?

• A. Glass
• B. Plastic films
• C. Polycarbonate panels
• D. Fiberglass

Answer: (C)

Choosing a greenhouse cover involves balancing heat retention and durability against price. Polycarbonate panels excel here because their multiwall construction traps air, which improves insulation by reducing heat loss. At the same time, they are exceptionally tough and resistant to impact, much more so than glass, fiberglass, or thin plastic films, making them a reliable option in environments prone to hail or bumps.

Glass, while very clear and good for light transmission, is brittle and offers limited insulation due to its solid, single-pane nature, and it can crack under impact. Plastic films are inexpensive and light but tend to have poorer insulation and durability, so heat escapes more easily and the cover wears out faster. Fiberglass provides some insulation, but its impact resistance is not as high as polycarbonate and it can degrade or discolor over time, reducing clarity and effectiveness.

So, when you need the best combination of insulation and impact resistance and can accept a higher upfront cost, polycarbonate panels are the strongest choice.