The Sun's Radiation
Solar Gain is also sometimes referred to as solar heat gain or passive solar gain. The terms refer to the increase in temperature in a space or building as a result of solar radiation.
The sun's radiation travels in short wavelengths through the glazing of a room, the objects inside the space absorb these short wavelengths of radiation and emit heat at longer infrared wavelengths. These waves cannot travel through glazing and will be contained in your space increasing the internal temperature. This is Solar Gain.
The amount of solar gain will increase with the strength of sunlight coming into a space generally through the glazing.
Controlling Solar Gain
Controlling solar gain in a highly glazed environment is possible with the use of Solar Control coatings. These coatings reduce the amount of solar radiation that can enter a space through the glazing and thus reduce the amount of solar gain.
A more high tech solution would be to use controllable Electro-Chromic Glass that shifts from clear to dark automatically depending on ambient sunshine, season or atmosphere, to provide actively regulated comfort automatically, responding the external and internal temperatures to manage your internal climate.
Managed Solar Gain can actually be used to help supplement your heating system and save money on heating bills by raising temperatures in a room during colder periods. For example keeping curtains and blinds open on a sunny winter's day will keep a space warm using the Solar Gain from the sun's radiation, reducing the amount of domestic heating required.