Keder Cladding

This plastic air bubble sandwich material has been specifically developed to combine light transparency with good heat insulation, and is available in 2 metre widths, with a welded seal.

How do we apply the Cladding to our structures?

The Keder Greenhouse system has been specifically designed to be installed with ease and speed, not only in the original installation process but at a later date should any alterations be required.

The structures are designed on a 2 metre increment spacing for the steel frame. Our profile (which the Keder Cladding fits into) is then secured in place. Once the frame has been assembled and the profile is secured in position, the Keder Cladding is fed through the profile, tensioned and secured in place.

Snow Load Test

Keder Cladding is versatile and strong. It withstands high winds and heavy snow fall.
The Product was tested for snow load under real conditions in Amherst, NH in February 2012. The following conditions were applied:

  • Sheet of LP-Keder tested 2m x 2m
  • LP-Keder-Lock-Profile (PVC) used on two sides of the trial stand
  • Tongue and groove system with Cambia battens on the other two sides of the stand
  • Snow weight was determined (5 US liquid gallons = 20.5 lbs.)
  • Geometric shape applied for estimation of snow load: pyramid

(Calculation of weight of snow on Keder - as produced by CE, USA)
Calculation m²=p.v Si-System =m²=492kg/m³.4.47m³=2199.24kg = 4848.50lbs = 2.199 Tonne

Keder cladding reduces summer daytime temperatures as well as retaining heat overnight, whilst insulating properties assist with reducing condensation. The unique bubble design causes a considerable scattering of light up to 83%, 30% of which is healthy infrared light, diffusing through more than 100 air burls (bubbles) per square foot. The diffused light scatters evenly so as to avoid and eliminate the common difficulties of both shading and burning areas within the greenhouse, which ensures the promotion of healthy plant growth.

The layer of sealed air in the Keder sheeting provides a high level of insulation and heat retention. Cladding in Keder has been proven to give up to 50% reduction in heating costs when compared with traditional glasshouses.

Thermal measurements

To provide some technical data on Keder’s energy saving properties, in comparison with other materials on the market, we have set out below relevant information on the heat saving properties. If you need more information please contact us on:
01386 49094 or email sales@kedergreenhouse.co.uk

R Value:

The R Value is the resistance to the flow of heat, therefore the higher the R Value number the better it is.

R-value – Thermal Resistance

Thermal resistance is the temperature difference, at steady state, between two defined surfaces of a material or construction that induces a unit heat flow rate through a unit area, (K.m2)/W: Resistance, thermal, n: the quantity determined by the temperature difference, at steady state, between two defined surfaces of a material or construction that induces a unit heat flow through a unit area.

Energy Savings Table
Product
R Value {(ft2.°F.h)/BTU}ß
Keder Cladding
Polydress LP-Keder Air Bubble Film
1.7

 

Glass covered greenhouse (0.12’’)
0.7

Single glazing and sheeting

PE- Film (5.9 mil)
0.7
 
Polycarbonate covered greenhouse (0.2’’)
1.1
Double glazing combinations
Polyethylene Double Layer inflated (w2’’ air gap)
1.5

Data as produced by RKW SE Polydress LP-Keder Germany

U Value:

The U Value is the measure of the rate of heat loss or gain through a material, and the greater the products resistance to the heat flow the better its insulating value.Therefore the lower the U Value number the better it is.

U-value – Thermal Conductance

Thermal conductance is the time rate of steady state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces, in W/(m2.K). U-value, hence, is the reciprocal of the R-value: Conductance, thermal, n: the time rate of steady state heat flow through a unit area of a material or construction induced by a unit temperature difference between the body surfaces.

Energy Savings Table
Product
R Value {(ft2.°F.h)/BTU}ß
Keder Cladding
Polydress LP-Keder Air Bubble Film
0.5

 

Glass covered greenhouse (0.12’’)
1.4

Single glazing and sheeting

PE- Film (5.9 mil)
1.4
 
Polycarbonate covered greenhouse (0.2’’)
0.9
Double glazing combinations
Polyethylene Double Layer inflated (w2’’ air gap)
0.7

Data as produced by RKW SE Polydress LP-Keder Germany

Thermal:

Thermal resistance (R) and thermal conductance (U) of the materials are reciprocals of one another and can be derived from thermal conductivity (k) and the thickness of the materials.

But one must remember that the given U and R values in the brochure are based on not only the measurement of heat conductivity of the material itself, but on the fact that the material is applied on the greenhouse. The dif- ference is the situation that additional R(se) and R(si) are added to the total R value which will then give a lower U value in return. That why the given k-value cannot directly be translated into U value by doing the calculation U=k/L

K-value – Thermal Conductivity

Thermal conductivity is the time rate of steady state heat flow through a unit area of a homogeneous material induced by a unit temperature gradient in a direction perpendicular to that unit area, W/(m.k): Thermal con- ductivity, n: the time rate of steady state heat flow through a unit area of a homogeneous material induced by a unit temperature gradient in a direction perpendicular to that unit area.

Energy Savings Table
Product
R Value {(ft2.°F.h)/BTU}ß
Keder Cladding
Polydress LP-Keder Air Bubble Film
27.0

 

Glass covered greenhouse (0.12’’)
2.3

Single glazing and sheeting

PE- Film (5.9 mil)
3.1
 
Polycarbonate covered greenhouse (0.2’’)
8.7
Double glazing combinations
Polyethylene Double Layer inflated (w2’’ air gap)
4.9

Data as produced by RKW SE Polydress LP-Keder Germany