Air leakage (infiltration) that finds its way into the room may either be computed automatically in accordance with recognised research on the subject or the user may over-ride and define their own air infiltration rates. Infiltration air conditions are considered by the program as being at Ambient. Caution should be used to avoid risk of over specifying air infiltration where positive pressure air conditioning and/or ventilation systems apply to the room design under consideration. Air infiltration is more likely to become air leakage in such circumstances and any figures entered for air infiltration only likely to adversely affect (increase) the final air conditioning loads.
(Coldwind)
The program automatically enters typical air change/infiltration values based upon studies for rooms of various sizes and with fairly traditional designs and construction materials. These may be over written by clicking in the alternative options label but will suffice to provide reasonable and safe values if more precise figures are not known.
It should be noted that Coldwind's default Infiltration rates make the assumption that the overall room volume is automatically adjusted to take into account displacement by the volume occupied by product in the room. The percentage lost to displacement varies as a function of both room volume and also aspect ratio of internal floor area compared with room height. If a user prefers that this should not be the case then the program provides the facility for these default rules to be over-riden through application of a 'Special Features Code'.
SI operation
Infiltration may be specified using any one of four methods:- Air changes per day (24 hour day); Litres per second; Cubic metres per minute; Cubic metres per second. The program, with the benefit of automatically established room volume, automatically computes the remaining values against any one of the four input methods selected.
Imperial operation
Infiltration may be specified using any one of four methods:- Air changes per day (24 hour day); Cubic feet per second; Cubic feet per minute; Cubic feet per hour. The program, with the benefit of automatically established room volume, automatically computes the remaining values against any one of the four input methods selected.
Recommended number and size of freezer room PRV (Pressure Relief Valves) Room m³ PRV cm² in² 100 1 30 5 200 2 60 9 400 3 90 14 750 4 120 19 1500 5 150 23 3000 6 180 28 6000 7 210 33 12500 8 240 37 25000 10 300 46 50000 15 450 70 100000 20 600 93
See also:
additional ventilation from other loads selected
air changes (per day [24 hours])
ventilation
Special Features Codes