@Air 4.0

@Air is a member of Techware’s family of software packages bringing accurate thermodynamic properties of fluids to many popular Windows programs.  @Air provides thermodynamic properties (sometimes called psychrometric properties) and transport properties of moist air. 

The air property functions can be used directly from within applications including Microsoft Excel, 1-2-3 and MathCad.  Add-ins attach the functions so that you can use them as if they were built in to the applications. 

This version supports 32-bit and 64-bit applications.  New 64-bit components include the air function library (DLL), the Excel Add-in and DeskTop Air.  The package also includes 32-bit versions of these components plus the add-ins for 1-2-3 and MathCad.

Programmers can call the functions in the dynamic link library directly from many Windows programming languages such as Microsoft Visual BASIC, Microsoft Visual C++ for Windows and Microsoft Access.

@Air is going to change the way you solve many problems involving moist air!  Your calculations will be greatly simplified and their accuracy will be improved by using the @Air functions.  The functions in @Air will help you calculate the performance of HVAC equipment, evaporative coolers, air compressors and air turbines.  You can conveniently design equipment right on your favorite spreadsheet and your results will be more accurate because you won’t have to interpolate data from tables, read from psychrometric charts or construct graphical solutions.  You won’t have to make perfect gas assumptions either.

What's New in Version 4.0

  • Added 64-bit version of Air property DLL.
  • Added 64-bit version of DeskTop Air.
  • Converted all help files to compiled HTML format.
  • Removed @Air Help link from all versions of Excel and 1-2-3 menus.

What's New in Version 3.2

  • Removed Help file link from Help Menu for Excel 2007 and later.
  • Corrected a bug in the Expansion Tool on DeskTop Air

@Air 3.2 is available as a free upgrade to licensed users of @Air 3.0 or @Air 3.1.

What's New in Version 3.1

@Air 3.1 is a minor upgrade for @Air 3.0.  It includes a new unit set, METF similar to MET but using kg/cm2 for pressure instead of bar.  In addition, it includes some minor bug fixes and improvements to the accuracy of the transport property functions for viscosity and thermal conductivity.

@Air 3.1 is available as a free upgrade to licensed users of @Air 3.0.

What's New in Version 3.0

  • Extends the temperature range upwards from 200 °C, (392 °F) to 2000 °K, (3140 °F).
  • Adds transport property functions:
    • AirPTWC, which calculates specific heat given pressure, temperature and humidity ratio.
    • AirPTWM, which calculates dynamic viscosity given pressure, temperature and humidity ratio.
    • AirPTWK, which calculates thermal conductivity given pressure, temperature and humidity ratio.
  • Includes DeskTop Air, an advanced air property calculator with many improved features over the previous air property calculator.
  • Adds four new unit sets, EngG using psig for pressure instead of psia, SIF, which uses the formal SI units, MPa for pressure instead of bar and °K for temperature, instead of °C, SIK using kPa instead of bar for pressure and MET using the calorie instead of the joule for energy.
  • Allows specific properties to be expressed on either a dry or wet basis.
  • Allows the humidity ratio parameter to be input alternately, as mole fraction or mass fraction.
  • Added new thermodynamic functions:
    • AirPTHs, which calculates saturated enthalpy given pressure and temperature.
    • AirPHTs, which calculates saturation temperature for a given pressure and enthalpy.
    • AirWX, which calculates either the mole or mass fraction given the humidity ratio.
    • AirXW, which calculates the humidity ratio given either the mole or mass fraction.
  • Improved installation program that allows distribution over the web.
  • Includes new thermodynamic functions
    • AirPTHs, which calculates saturated enthalpy given pressure and temperature.
    • AirPHTs, which calculates saturation temperature for a given pressure and enthalpy.
    • AirWX, which calculates either the mole or mass fraction given the humidity ratio.
    • AirXW, which calculates the humidity ratio given either the mole or mass fraction.

Key Features

  • Functions can be used as if they were built in to most popular spreadsheet programs.
  • Accurate properties consistent with ASHRAE tables.
  • Equations based on virial equation of state using second and third order mixing coefficients.  No perfect gas assumptions.
  • Accuracy fully documented.
  • Supports many combinations of input data.
  • Calculates specific volume, enthalpy, entropy, specific heat, viscosity or thermal conductivity.
  • Use English, English Gage, SI Common, SI Formal, SI kPa and Metric unit sets.
  • Functions can be called from many Windows programming languages.
  • Allows pressures up to 50 bar  (725 psia) and temperatures from 180 °K (-135.7 °F) to 2000 °K (3140.3 °F).
  • Uses or calculates humidity ratio, relative humidity, degree of saturation, wet bulb or dew point temperatures.
  • Express moisture as humidity ratio, mole fraction or mass fraction.
  • Express results on wet or dry basis.
  • Check pricing for attractive quantity discounts.

Applications Supported

The @Air package includes various add-ins which link the functions to many popular 32-bit and 64-bit Windows applications.  32-bit add-ins are included for Microsoft Excel Versions for Office 95, Office 97, Office 2000, Office XP, Office 2003, Office 2007 and Office 2010 (32-bit version); Lotus 1-2-3 97 and 1-2-3 Millennium and MathSoft Mathcad Plus Versions 6, 7 and 8.  A 64-bit add-in is included for Office 2010, 2013, 2016 and 365 (64-bit version.)

No programming is required to use the @Air functions with any of these applications. Just follow a few simple steps to load the add-in, and from then on, the functions will be available every time you start the application. You use the functions just like any of the built-in functions. The functions can be used in any spreadsheet formula and any argument to the functions can be a number, a formula or a cell reference.

Programming Languages Supported

All of the steam property functions are contained in a Windows Dynamic Link Library (DLL). The @Air package includes 32-bit and 64-bit versions of the DLL, which supports applications designed for Windows 95, 98, NT, 2000, XP, Vista and Windows 7, 8 and 10.  Function prototypes and LIB files are included in the package to support Microsoft C/C++ compilers. Declaration files are included to facilitate programming with Microsoft Visual Basic or Microsoft Access.

Go Back to Key Features


The following table lists all of the @Air functions currently available.

Function(Input Arguments) Output Value
AirPTWV(P,T,W,unit) Specific Volume
AirPVWT(P,V,W,unit) Dry Bulb Temperature
AirTVWP(T,V,W,unit) Pressure
AirPTW(P,T,unit) Saturated Humidity Ratio
AirPWD(P,W,unit) Dew Point Temperature
AirPTRW(P,T,RH,unit) Moisture
AirPTWR(P,T,W,unit) Relative Humidity
AirPTWB(P,T,W,unit) Wet Bulb Temperature
AirPTBW(P,T,B,unit) Moisture
AirPBWT(P,B,W,unit) Dry Bulb Temperature
AirPBRT(P,B,R,unit) Dry Bulb Temperature
AirPTWU(P,T,W,unit) Degree of Saturation
AirPTUW(P,T,U,unit) Moisture
AirPTWH(P,T,W,unit) Specific Enthalpy
AirPTHs(P,T,unit) Saturated Enthalpy
AirPWHT(P,W,H,unit) Dry Bulb Temperature
AirPHWT(P,H,W,unit) Dry Bulb Temperature
AirPHTs(P,H,unit) Saturated Dry Bulb Temperature
AirPTWS(P,T,W,unit) Specific Entropy
AirPWST(P,W,S,unit) Dry Bulb Temperature
AirPSWT(P,S,W,units) Dry Bulb Temperature
AirPTWC(P,T,W,units) Specific Heat
AirPTWM(P,T,W,units) Dynamic Viscosity
AirPTWK(P,T,W,units) Thermal Conductivity
AirVapPT(Pvap,unit) Saturation Temperature of Water
AirVapTP(T,unit) Saturation Pressure of Water
AirCondPTH(P,T,unit) Enthalpy of Compressed Liquid Water
AirCondPTS(P,T,unit) Entropy of Compressed Liquid Water
AirWX(W) Mole or mass fraction
AirXW(X) Humidity Ratio
AirVer() Version and serial number
P = Pressure
Pvap = water vapor pressure
T = Dry Bulb Temperature
V = Specific Volume
W = Moisture defaults to humidity ratio but can be mole or mass fraction by adding C or M to unit set.
RH = Relative Humidity
B = Wet Bulb Temperature
H = Enthalpy
S = Entropy
C = Specific Heat
M = Dynamic Viscosity
K = Thermal Conductivity
U = Degree of Saturation
X = Mole or mass fraction
unit = Unit Set

The UnitSet argument is used to select the unit set, formulations and other calculation options.

When calling the functions from 1-2-3, the function name is preceded by the "@" character, eg. @AirPTWH(P,T,W,unit) for 1-2-3

Try It

If you wish to try @Air, you may download a fully functioning copy for a 30 day evaluation period.  You may also use this download as a replacement for a lost or damaged copy of @Air 4.0.  If you decide to purchase @Air you may use the download and we will provide you with a serial number for permanent use. Go to our Order page when you are ready to purchase @Air