There are almost 80% greenhouses in the market are built by polycarbonate sheet because it deliver number of benefits including high light transmission, thermal insulation and good resistance. As the conditions of greenhouses are different like USDA zone and plants requirement, here are some basic concepts to help you to choose right polycarbonate greenhouse by structure, color and thickness and their effect.
Solid vs. Multi-Wall
Polycarbonate sheet usually come in two types, Solid ( clear wall) and multi-wall (twin-wall mostly, will explain later). Both have same pros including highly impact resistant, UV protection, lightweight, energy efficient and easy to install. Compared with Multi-Wall, solid sheet come with glass like transmission with 90% - 92% and better looks. If you like traditional glass greenhouse and also need long lasting, low cost to replace panels, less maintenance and heat protection features, the solid sheet (clear wall) polycarbonate is right for you.
Shop Clear Wall Greenhouse (Solid Polycarbonate Greenhouse Kit)
In order to provide greater thermal insulation, most of manufactures choose multi-Wall sheet as materials. Many beginner get confused by choosing multi-wall greenhouse because they don't know how will internal structure and thickness of materials impact light transmission and heat insulation.
Multi-Wall sheet is available in twin-wall (2-wall), 3-wall, 4-wall, X and honeycomb internal structures that come with different rating of insulation and light transmission.
Normally, the greenhouse should at least 80% light transmission to keep plants growing, some specific crops may require different. In order to make the best growing environment for most plants, greenhouses are typically constructed of twin-wall polycarbonate sheet because it can deliver 80%to 90% light transmission and balance of thermal insulation. The sheet made by 3-wall and above structures fall in 75% of light transmission range which maybe good for certain plant types or area where the growing season is longer. In general, the golden rule is that thicker polycarbonate sheet provides greater thermal insulation but less transmission, and the thinner one offers more light transmission and less insulation.
R-Value & U-Value
The R-Value is used to measure how efficiency of the insulation. Higher number means higher degree of insulation. For example, Solexx™5mm edition greenhouses can deliver 2.13 R-Value which can make the temperatures not going too high in summer, or drop too much in winter.
The formula for computing R-Value is R=1/U.
The U-Value indicates the amount of heat loss. Lower value means better.
The formula of computing the U-Value is U=1/R.
Structure and thickness affect U-Value, light transmission and R-Value.
| Structure & Thickness | R-Value | U-Value | Light Transmission. |
| 4mm Twin-Wall | 1.43 | 0.68 | 82% |
| 6mm Twin-Wall | 1.54 | 0.65 | 80% |
| 8mm Twin-Wall | 1.60 | 0.58 | 80% |
| 10mm Twin-Wall | 1.89 | 0.52 | 76% |
| 3.5 mm Solexx™ Panels | 2.10 | 0.48 | 75% |
| 5 mm Solexx™ Panels | 2.30 | 0.43 | 75% |
Apply this rule to our brand:
In summary, if you locate in the cold zone #5 to #7 or looking for more heat efficient greenhouse, pay more attention on higher R-Value and lower U-Value. Therefore, twin-Wall 8mm and Solexx™ greenhouse are best chose. Instead, you can choose Twin-Wall 4mm or 6mm. The panel is the key but not only factor to pick the greenhouse. Check our other tips for reference.
Reach us if you have more questions.
