Polar Shield™ - Thermally Insulated Iron Doors

With Full Thermal Break and High Efficiency Seals - Because America is Colder than you Think!

Thermal Break Insulated Door Polar Shield Door Energy Efficiency Comparison
Polar Shield™ doors have a full Thermal Break in all parts of the door, plus dual seals in window and threshold.
A. 10mm Thermal Break in Jamb
B. 4mm Thermal Break in Stiles and Rails
C. 4mm Thermal Break in Window
D. 4mm Thermal Break in Kick Panel
E. 10mm Thermal Break in Threshold
F. High Efficiency Kerf Seal in Door Stop
G. Dual Seals in Opening Window
H. Dual, Three Bladed, Bottom Sweeps
J. High Density Polyurethane Foam in all cavities.
K. Dual Pane Window with 9mm Argon Gap

Heat Flow in Iron Doors
Conduction Causes 90% of Heat Loss Through an Iron Door
Frost on Inside of Iron Doors
Regular Iron Doors have a U Factor of about 4.0
All iron doors have a closed cell polyurethane foam core. This helps to stop convection and radiation within the structure but it does NOT stop conduction - which accounts for 90% of heat transfer.

Conduction is the movement of heat through the steel structure itself. Since steel is an excellent heat conductor, over 40 times more conductive than glass, conduction is the most important factor to control. If conduction is not controlled by a thermal break, heat will travel from one side of the door to the other quickly. This is extremely inefficient - regular iron doors have a U Factor of over 4.3!.

Regular iron doors conduct heat so that the inside surface of the door stays about the same temperature as it is outside. In winter these kind of doors can become wet with condensation which will drip onto the floor. This can cause damage to flooring and encourage rot or mold. When it gets colder, these doors can even form frost on the inside!

With a U Factor as low as 0.41, Polar Shield™ doors are the only wrought iron doors suitable for all parts of the USA & Canada.

R Values, U Factors and Lambda Values explained

R Values and U Factors are both ways of evaluating energy efficiency.
The difference is that R Value is a measurement of heat loss through a single material, like a sheet of glass, wood or fiber insulation. U Factor is the measurement of heat loss through a complex assembly, like a door or window unit.

Λ (The Greek letter "Lambda") Values are dimensionless factors of insulating capacity, determined through testing. Each material used in building has been tested and given a Λ value.

To get the R Value, the Λ Value is multiplied by the thickness of the material. International R-values are given in SI units (abbreviated from the French: Le système international d'unités). SI R Values are square meter kelvin per watt or m2·K/W.

Confusingly, in the United States, R-values are SAE units of square foot degrees Fahrenheit per British thermal unit or ft2·°F·hr/Btu (aaagh!).

SAE R Values are about 5.68 larger numbers than SI R Values. In both cases, the higher the R Value, the better it is at insulating your home.

U Factor is calculated using the R Values of all the insulating layers of the various regions of a complex structure - it is the reciprocal of the average R Value for the whole unit. The lower the U Factor, the lower the heat loss through the unit.

The U Factor of Polar Shield™ thermally insulated doors is 0.41 compared 4.0 for a regular door. Polar Shield™ has 10 x more insulation than a regular iron door.

About half of the US, and all of Canada can have severe cold in the winter months. In many of these areas, the temperature difference between inside and outside can reach 100º F (38º C), making a thermally insulated door essential.
Cold Climate Areas USA