The default R-values for wall (assembly) are referred from:
- ASHRAE table 5.5 when respective ASHRAE code version (2007, 2010, 2013, 2016) is selected.
- Table 140.3-B when respective California Title 24 code version (2016, 2019) is selected.
- Division B-Part 3 when respective NECB cove version (2011, 2015) is selected.
Since there are different types of material assemblies for wall which would affect what value would be used to determine the automated value, cove.tool makes that assumption for the users based on Pacific Northwest National Laboratory (PNNL) building prototypes. Cove.tool will automatically populate the R-values based on location of the project assuming the steel framed walls for all commercial building types except small office (wood framed walls).
For example, if your project (Hospital) is in Atlanta, GA (ASHRAE Climate Zone 3A) and the energy code selected is ASHRAE 90.1 2013, the automated wall R-value (steel-framed) can be seen highlighted in the image attached below:
- Wall R-Value: This measures how effective the wall assembly is as an insulator. The higher the R-value, the greater the insulation performance.
The range for Typical R-values is Low-Performance Insulation (R-5 through R-13), Average-Performance (R-14 through R-25), High-Performance (R-26 through R-50). This may differ based on your project size and use-type, and cove.tool can help better determine which is best for your project overall performance. Wall R-values will be applied to the entire project, if you have more than one type using an area-weighted average method to calculate a single value. If you need assistance calculating the effective r-value for your unique assembly, try out this open-source online tool.
- Wall Emissivity: The emissivity is defined as the fraction of energy being emitted relative to that emitted by a thermally black surface (a black body). Most objects have an emissivity between 0 and 1. The surface of a perfect black body has an emissivity of 1, objects with lower emissivities emit radiation at correspondingly lower rates. Cove.tool is referring ASHRAE Handbook – Fundamentals version 2009 for wall emissivity value. A list of sample wall emissivity values can be found here.
- Wall Area - N: Total wall area for the North side of the building.
- Wall Area - NE: Total wall area for the North-East side of the building.
- Wall Area - E: Total wall area for the East side of the building.
- Wall Area - SE: Total wall area for the South-East side of the building.
- Wall Area - S: Total wall area for the South side of the building.
- Wall Area - SW: Total wall area for the South-West side of the building.
- Wall Area - W: Total wall area for the West side of the building.
- Wall Area - NW: Total wall area for the North-West side of the building.