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Solar gain through windows

When the sun shines (UV light) through the windows, it is either reflected back, or absorbed inside and converted to heat.

The most solar gain is on the west side of a house.
The second most is on south side, but this is easier to prevent with external shades because of the high angle of the sun.

Benefit

Solar gain is great in the winter, heating up your house for free.

Prevention

Once the heat is in, it won’t easily leave the house. So the best prevention is to stop it outside with external shades. Or with the shade of a tree.

Research on London flats by the BBSA: (BIASED)

  • Rooms with internal blinds reduced operative temperatures by 8-13ºC
  • Rooms with external blinds reduced operative temperatures by 12-18ºC

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