The
Air Cavity Calculator is used as a tool for rapid calculation of
equivalent heat conductivity of small air cavities and air gaps based on the
input of their dimensions and heat stream direction.
To calculate equivalent heat conductivity (lambda) the application uses formulas
defining calculation of heat transfer resistance of air spaces described in EN ISO
6946:2005 Appendix B  please be aware of limitations related to its application (e.g.
small, closed air cavities).
Calculation regulation are geared to European norms
EN ISO 6946 and EN ISO 100772 and cover two dimensional calculations.
Heat Stream direction 
Definition of heat stream direction:
 Horizontal (default)
 Upwards
 Downwards

Thickness (stream dir.) 
The thickness of the cavity measured in the heat stream
direction.
Remark: Thickness and width can be swapped via a context menu. 
Width 
The width of the cavity (perpendicular to the thickness)
Remark: Thickness and width can be swapped via a context menu. 
Temperature difference dT 
The difference of temperature between cavity boundaries in
the heat stream direction. 
Equiv. Resistance 
Equivalent heat transfer resistance of particular air
cavity 
Equiv. Lambda 
Equivalent heat conductivity of particular air cavity 
Result 
Calculation result is replaced by the actual value. 
Remark: According to normative regulations one shall set the
temperature difference, if exact value is not known, accordingly. Buttons "5K (EN 6946)"
and "10K (EN 10077) set this value to one of magnitudes required in these
respective regulations.
For the very usual case of non rectangular air cavities normative regulations
define following procedure to account for:
An equivalent conductivity is to be calculated for a fictive rectangular
cavity. Such fictive cavity shall be constructed as follows:
 create a rectangle surrounding the cavity of interest.
 the area of a fictive cavity rectangle shall be equal to the area original
(non rectangular) cavity.
 the ratio of width to the height of the fictive rectangle cavity shall be
the same as of the rectangle surrounding the original.
The conductivity calculated for such fictive rectangular cavity
is the used instead for the (non rectangular) original air cavity.
Heat Stream direction 
Definition of heat stream direction:
 Horizontal (default)
 Upwards
 Downwards

Thickness (stream dir.) 
The thickness of the rectangle surrounding the cavity measured in the heat stream
direction.
Remark: Thickness and width can be swapped via a context menu. 
Width 
The width of the rectangle surrounding the cavity (perpendicular to the thickness)
Remark: Thickness and width can be swapped via a context menu. 
Area 
The actual are of the real (non rectangular) air cavity 
Temperature difference dT 
The difference of temperature between cavity boundaries in
the heat stream direction. 
Equiv. Lambda 
Equivalent heat conductivity of particular air cavity 
Result 
Calculation result is replaced by the actual value. 
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