Draught around window
In our experience draughts around a window are caused by 4 main issues, air movement caused by natural air movement (convection), damage to seals, items caught in the seals and trickle vents. It is also important to mention that air movement in a property should be promoted to avoid issues with damp and mould whilst creating a comfortable space.
Convection is the normal movement of air around a window and is caused when cold or warm air moves through a property. Windows can cause this especially if they have a radiator underneath as the warm air rises and sucks in colder air to fill the space. This can be most pronounced on windows on stairwells for example where there is large amount of air movement between upstairs and downstairs.
The seals which go round the windows and keep a weather tight seal can perish and degrade. All Everest windows are made from Qlon which is a memory foam that offers unrivalled performance and keeps its shape and does not degrade. We would advise you check the seal remains in place and if not simply push the seal back into its housing.
Items can also be caught in the window seal or have damaged the seal. Qlon seals can be replaced by a specialist glazier or the householder fairly simply.
Finally you may have a trickle vent installed in the window. These are designed to promote air circulation and do not provide an air tight seal. They are recommended as part of building regulations to promote good ventilation in a building as they enable small amounts of air circulation. This helps with issues such as damp but as explained above convection will increase the speed of air circulation in extreme hot or cold periods.