There are several options for a simple and economical limitation of the leaf opening in order to reduce heat loss in ventilation mode. Figure 1 shows an example of a GU non-adjustable opening stop. A small (about 10 mm) ventilation gap does not allow an unreasonably fast air exchange to occur and saves heat energy.
Opening limiters (GU): A - for aluminum windows and 2-leaf wooden windows; B-for windows made of wood and plastic.
In the pivoting position, such a limiter allows you to leave about 0.01 m for ventilation with a sash size of 1200x1600 mm. With a driving force of 4 N / m2, an air flow of approximately 35 m3 / h can be predicted through such a gap.
In the tilted position, the opening stop, when positioned near the handle, leaves a gap of about 40 mm. This situation results in a pass area of 0.015 m2 and an air flow of 55 m3 / h with the same driving force.
JET adjustable opening limiter for wooden window ventilation (GU).
There is also a more advanced type of sash opening limiter - with an adjustable gap. In fig. 2 shows a similar device from GU. Its design allows you to change the size of the gap between the sash and the frame from 0 to 10 mm by simply turning the handle on it. Thus, the inflow of cold air from the outside can be easily adjusted to the required level of comfort.
One of the important advantages of such opening limiters is the possibility of constant ventilation through windows with a purely rotating sash. With their help, you can give pivot windows fundamentally new quality features.
It should be emphasized that regardless of the hardware used, the aforementioned opening stops can be installed on new and old windows, both on pivot and tilt-and-turn windows, and on transoms. The material of the window blocks can be anything: wood, metal, PVC. Installation is a simple operation and does not require very high qualifications.