With the nights now becoming much warmer extra ventilation is needed. If your windows are fitted with trickle vents they should be left open and provide a background air flow through the rooms.
If you need more air through the house, but are worried about leaving the windows open, particularly the ground floor ones, you can use the night vent facility that all of our windows are provided with.
This enables you to open the window sash to the second position on the metal keeps and the sash can be safely left locked in this position without fear of anyone forcing the window open.