Design Implications of Glare: Exploring 5 Factors

What is Glare?

Glare, also known as visual discomfort is defined by the Illuminating Engineering Society (IES) as one of two conditions:

  • Too much light

  • Excessive contrast, meaning the range of luminance in the field of view is too great

One of the commonly used Glare metric is Annual Solar Exposure (ASE). Used by both LEED and the WELL building standard, the ASE measures the percentage of floor area that receives at least 1000 lux for at least 250 occupied hours (occupied hours) per year. It helps determine how much of space receives too much direct sunlight, causing visual discomfort (glare) or increase cooling loads. 

Annual Solar Exposure for good daylight quality within the space. Cove.tool allows both Spatial Daylight Autonomy and Annual Solar Exposure analysis within minutes taking directly from your Revit, Sketchup, Rhino or Grasshopper 3d files.

Here are 5 Ways Glare Impacts your Design

1. Visual Comfort: The goal of a successful facade is many cases is to Create uniform distribution of daylight to reduce uncomfortably high brightness ratios. This refers to having abundant daylight, but not feeling the need to put on a pair of sun glasses inside a building.

2. Cooling Load: Glare represents hot spots that are created on the interior of the building due to a high amount of direct solar exposure. This solar exposure, depending on the performance of the glass being used, can add significantly to the peak cooling loads. This makes the system larger than otherwise necessary adding to the overall project cost.

3. Energy Use: This relates to the point above about “cooling load”. As we increase the cooling load of the space, we are also using more energy for the building. Cutting out glare, would help remove the hot spots, right size the mechanical system and reduce the energy use.

4. Cost: The ability to right size a system also ensures that the project cost is not increasing.

5. Occupant Productivity: Glare not only causes your vision to be distorted, it can also be quite painful. Under glare-filled conditions, your eyes are forced to continually attempt to distinguish the glare from the visual tasks. This leads to headaches, eyestrain, and fatigue. For buildings like Hospitals, Offices, Educations and Research facility, the difference in productivity between Glare Filled and Glare Free spaces can be drastic.


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