Windows allow for light to enter, and sometimes for ventilation.
They sometimes are fitted with a screen - important in mosquito control, to stop the spread of mosquito-borne illnesses as well as for comfort in protection from various small animals..
They affect heating, cooling, the need for lighting, the sense of spaciousness (especially important in small houses), noise penetration from outside, as well as the cost of the building.
Their effect on heating and cooling depends on:
- Placement, orientation to the sun. This cannot be changed without major remodeling of the house.
- Shade, e.g. from eaves, awnings, trees other buildings. Some of these can be changed with effort and (in the case of trees) patience.
- Use of insulated glazing - reflective films or multiple glazing.
- Curtains, especially thermal curtains.
- Thermal mass in the building.