Solar and Visual Reflectance

ladybug-tools
1

Hi dear Community.

Are there any valid references for solar and visual reflectance to assign different materials for shading in energy simulation?
I look up for those values in the Ashrae fundamentals handbook and Energyplus documents but didn’t get anything.

I will be appreciated it if anyone can help me with that.

Best,
Nariman

2

The short answer is “No.” People have different preferences for the colors of their buildings and so there’s no consistent standard that could be used for all buildings.

Maybe the only document that gives some guidance is the European Standard EN 12464, which has recommended the following ranges of reflectance for major interior surfaces (walls, floor and ceiling) in indoor work places:

  • Ceiling: 0.7 to 0.9
  • Walls: 0.5 to 0.8
  • Floor: 0.2 to 0.4

This is where the honeybee “Generic Default” reflectances come from. But I’ll be the first to admit that always using a 0.5 reflectance for walls as we do in honeybee is usually pretty far from reality. Still, I guess it’s the best we can do in early design when we don’t know what color the walls will be.

I’ll also say that exterior reflective roof membranes (aimed at lowering urban heat island) tend to start out with reflectances around 80% when they are installed and then gradually will gather dust to ultimately have relfectances around 50%-60% at the end of their life. For all other building elements, there isn’t really a standard and it’s all down to what colors and material pallets a client prefers.

3

Thanks @chris but my research is on metal properties and their effect as external louvers (aluminum, chrome, brass, and steel are my materials) and I wanted their properties to find whether they have effect on energy consumption or not.
Many thanks for your comprehensive explanation.