Light Transmission Factor (LTF)

• The amount of daylight that penetrates the glazing as a percentage of total light.
  A low LTF value means less light.

Solar Factor (SF)

• The amount of heat (energy) that penetrates the glazing as a percentage of total energy.
  A low SF value means less heat (energy).

Illuminate using daylight

• Daylight can provide sufficiently for many of our needs for light whether in work or play.
  However, as daylight is variable and of limited availability, design and use of daylight thus required much effort and a higher initial cost.
   

• Usage of natural sunlight reduces energy (heat and light) consumption and thus reduces energy-related costs.
   

• Too much (or too little) heat and light from usage of daylight may not be desired in certain cases,
  indoor climate will need to be designed together with daylight constructions and ventilation to give the desired indoor climate.

Source of daylight

• Sun and sky are two primary sources of daylight for designers, whereas reflected daylight is secondary.

Daylight sources whether primary or secondary can cause the following:

1. Direct Glare
2. Reflected Glare (Veiling Reflection)
3. Discomfort Glare
4. Disability Glare (Veiling Luminance)
5. Blinding Glare