As natural lighting indoors changes on time over a wide range, it is not possible to characterize it by absolute value of illumination on a workplace. As the normalized size relative size - the coefficient of natural illumination (CNI) which represents the illumination relation expressed as a percentage in this point indoors Ev to simultaneous external horizontal illumination of Han created by a diffused light of all firmament is taken:
Filtering - primary stage of sewage treatment - is intended for allocation from sewage of large insoluble impurity up to 25 mm in size, and also smaller fibrous pollution which in the course of further processing of drains interfere with normal work of the clearing equipment. Filtering of sewage is carried out by a water transmission through lattices and fiber catchers.
Quantity of the sites of a firmament seen through svetoproy determine by means of two schedules representing projections of a bunch of the beams connecting the centers of a hemisphere of a firmament to sites of equal light activity on n1yo height (the schedule and by n2 width (the schedule of a light aperture. Geometrical value of KEO in this point of the room makes
where S0, SF - the area of windows or lamps; Sp - the area of a floor of the room; - rated value of KEO; - stock coefficient; - the coefficient considering blackout of windows by the resisting buildings; t0 - the general coefficient of a svetopropuskaniye, t0 = t1 t2 t3, t1, t2, t3 - the coefficients considering losses of light respectively in glazing material in covers of a svetoproyem, in a layer of pollution of an ostekleneniye; r1, r2 - the coefficient considering influence of the reflected light at lateral (top) lighting; h0, hf - the light characteristic of a window (lamp); - the coefficient considering lamp type.