MPI doors have been tested for performance in accordance with ASTM C1199-09 Standard Test Method for Measuring the Steady-State Thermal Transmittance of Fenestration Systems Using Hot Box Methods
Products are available with U-factors ranging from 0.57 to 0.36 (R= 1.75 to 2.75). Steel stiffened, polystyrene and polyurethane doors were included in the tests. Ratings are significantly better than those obtained from tests performed on wood and aluminum doors.
Thermal performance tests measure a door's thermal conductivity known as "U-Factor" and its inverse which is termed thermal resistance or R-Value. U-factors have units in the Inch-Pound system of BTUs per hour per square foot per degree (Fahrenheit) or Btu/hr-ft2-F. R-values have the rather unintuitive units of hr-ft2-F/Btu. U-factor is based on measured heat flow through a sample at the temperature difference of the air on the indoor and outdoor sides. New test criteria provide realistic values representative of actual room conditions and are based on the full surface of an operable door rather than just the center portion of the door surface as with old test procedures.
Associated Standards:
- ASTM C1363-05 Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus
- ASTM E1423-06 Standard Practice for Determining Steady State Thermal Transmittance of Fenestration Systems.
- SDI 113 Standard Practice for Determining the Steady State Thermal Transmittance of Steel Door and Frame Assemblies.
ASTM C1363 alone is not intended to determine the performance of fenestration systems. ASTM C1199 has been established for this purpose and is used in conjunction with ASTM E1423 and ASTM C1363. (Source reference ASTM C1363, Scope, para 1.8)
|
Door Type |
R-Value | U-Factor |
| 18 ga Poly Iso Flush | 2.75 | 0.36 |
| 18 ga. Polyiso 6 Panel | 2.69 | 0.37 |
| 16 ga Poly Iso Flush | 2.66 | 0.38 |
| 18 ga. Polystyrene Flush | 2.56 | 0.39 |
| 18 ga Polystyrene 6 Panel | 2.45 | 0.41 |
| 16 ga Polystyrene Flush | 2.57 | 0.39 |
| 18 ga Steel Stiffened Flush (250 TR) | 1.75 | 0.57 |
| 16 ga Steel Stiffened Flush (250TR) | 1.71 | 0.58 |
| 14 ga Steel Stiffened Flush (250TR) | 1.78 | 0.56 |
Why Have Thermal Performance Ratings Changed?
MPI published U-values and R-factors have changed as a result of an update to the testing method of SDI 113 Standard Practice for Determining the Steady State Thermal Transmittance of Steel Door and Frame Assemblies. Previously, only the central portion of the door panel was tested. This did not reflect operable conditions as it did not include the entire door, frame or hardware, which affects the transfer of heat. The updated method now tests the entire operable assembly and employs the use of ASTM E1423-06 as the basic test standard.
It may appear that MPI's products have higher thermal conductivity than they did previously, but that is not true- the products perform the same as they did before- the difference is that the U-value now accurately reflects operable conditions. This improved data helps design professionals estimate the energy efficiency of the building. Always verify the doors and frames you specify provide U-values tested with the improved testing method.
