Engineering Inputs, Building Envelope

Patrick Chopson avatar
Written by Patrick Chopson
Updated over a week ago

What is a Spandrel?

Spandrels are commonly used architectural elements seen in modern high and mid-rise glass buildings. They commonly consist of opaque glazing materials with minimal insulation used to conceal building elements such floors, columns, HVAC systems, etc. They are exterior elements and typically present between vision glass of each floor. They are also known as "opaque in-fill systems".

Although there are different types of material assemblies for spandrel which would affect what value would be used to determine the automated value, cove.tool makes the assumption for the users based on California Title 24 which says that Spandrel Panels should have a minimum of R-4 or that the weighted average U-factor of the spandrel panels and curtain wall assembly shall not exceed 0.280. For the USA this is a typical value that is achievable in most cases. Higher performing spandrel is possible (and encouraged!) however requires careful design and coordination between architects, suppliers, and contractors to achieve.

  1. Spandrel Area: This area can be imported using the cove.tool plug-in for Revit(v2.4.0) and ArchiCAD(v.1.1.3). Visually inspect the 'cove.tool spandrels' view on Revit to ensure that the spandrels are in the right view. Move the spandrels from exterior walls or windows view by using the visibility settings and visibility tools, to make the geometry appear in the correct 3D view category. Ensure that surfaces only appear in a single view to avoid double counting in the energy model. Once this step is complete, begin your geometry export as usual.

  2. Spandrel R-value: This measures how effective the spandrel assembly is as an insulator. The higher the R-value, the greater the insulation performance. cove.tool is referring California Title 24 (Section 120.7) for the baseline R-value of spandrels for all locations. According to ASHRAE 90.1 (2016, 2019), the glass in the spandrel assembly should have a solar reflectance of 29% and according to ASHRAE 90.1 (2007, 2010, 2013, 2016, 2019), the opaque walls in the spandrel assembly must comply with the steel framed wall requirements. In order to comply with ASHRAE 90.1, the spandrel must reach a U-value of 0.064 Btu/h*sf*F in Climate Zone 4 and 0.037 Btu/h*sf*F in Climate Zone 8. Meeting these values is extremely challenging and hence California Title 24 is referred to as the baseline with a U-value of 0.25 Btu/h*sf*F.

Find the Spandrel R-value input in the baseline page, envelope tab. You can manually change the value based on your project requirements and click on recalculate to update the whole building EUI.

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