U 0.60 metric = R-9.1 imperial: the thermal conversion that every professional should master
- cathiest-germain
- il y a 2 jours
- 2 min de lecture
Metric U and imperial R: the thermal conversion that every professional should master
U 0.60 metric = R-9.1 imperial: the thermal conversion that every professional must master, especially in the field of high-performance windows. The first question to ask is simple: in which system is the U value expressed? Metric (W/m²·K) or imperial (Btu/h·ft²·°F), the two systems are not directly comparable, and a misinterpretation can transform an excellent window into a product that seems average… simply because the conversion has not been done.
The essential technical reminder
Low U-value = high thermal performance
High R-value = better thermal resistance
Direct relationship: R (SI) = 1 / U (metric)
Conversion to imperial: R SI × 5.6782
Examples of conversions from the VST chart: U 0.60 metric = R-9.1 imperial: the thermal conversion
According to the technical data in the document:
U 0.60 W/m² K → U 0.11 imperial → R-9.1
U 0.80 W/m² K → U 0.14 imperial → R-7.1
U 1.00 W/m² K → U 0.18 imperial → R-5.6
These figures clearly demonstrate how a U-value expressed in one system or another can completely change the perceived performance of a window. For any project focused on high efficiency, passive house, energy-efficient renovation, or sustainable construction, these conversions are essential.
Crucial point: thermos vs complete assembly
Many distributors only advertise the U-value of the glazing unit , which is always higher than that of the complete product . However, this value does not reveal the true performance of a window. The real measurement, the one that impacts the building's energy efficiency, is the U-value of the complete assembly: frame + glazing + spacers .
Comparing U values without verifying the system used and without distinguishing between glazing and complete windows can lead to a flawed assessment and inadequate product choices.
