site context
External pollution, noise and excessive noise may prevent occupants from opening their windows. Surrounding hard surfaces will absorb heat and release this during the night.
External temperature
On a warm, still day when external temperatures are high, fresh air may not provide enough of a cooling effect to address overheating.
Solar gains
Double-glazed windows with a low-e coating prevent heat from escaping. Houses with unshaded west-facing glass will suffer from higher levels of solar gain in the warmer part of the day. see solar gain through windows
Internal gains
Electrical appliances, occupant activities such as cooking, and building services, e.g. boiler and hot water storage, all have the potential to radiate heat that may contribute significantly to the increasing internal temperatures.
Building design
Modern homes have increased levels of insulation and airtightness, resulting in more heat being retained within the homes. This means any built-up heat in the homes will have to be actively removed.