Logo for DONKEY

Determines the size of a duct network using the static regain, constant pressure gradient, or balanced pressure drop method. Duct sizes can also be fixed and the program handles rectangular, round or oval ducts. DONKEY can calculate duct leakage and heat loss/gain and automatically locate balancing dampers throughout the duct system.

The sound power levels throughout the entire network are calculated at each of the seven octave band frequencies from 63 to 4000 Hz taking into account self generated noise by the fan, ducts, fittings, VAV boxes, registers, grilles and the attenuation of ducts, fittings, plenums and any duct silencers specified. Account is taken of noise transmitted both from the fan down to the terminals and from the terminals back up the network. Quantities for costing purposes are also calculated including erection, fabrication and shop drawing manhours. Screen Shots


duct sizing, equal friction, static regain, balanced pressure drop, duct acoustics, self generated noise, room sound pressure level



Expertise Required

Knowledge of ductwork systems and acoustics is of advantage. A one day training course is recommended.


18 companies in Australia and New Zealand. Originally developed in the 1970s and has since been continually and progressively expanded and enhanced. An AutoCAD interface was added in the 1990s and it is now gaining increased recognition.


HVAC design engineers, local government and university teaching departments.


DONKEY operates via a set of add on menus in AutoCAD. The user enters the supply and return duct layout as a centre line diagram including all the Fittings (Bends, Divided Flow, Combined Flow, Dampers, etc.) which are selected from Slide Boxes. The program calculates the pressure loss, self generated noise level, and attenuation of all of these fittings from data stored in the program.

Terminals, fittings, the fan, plenums, VAV boxes, coils, dampers, etc can all be entered. All the parameters relating to these components including air quantities, duct insulation, sizing method, fan type, etc; are entered in dialogue boxes that are called up on screen.

A �standard� typical 3 metre by 3 metre room is assumed under each air terminal to determine the room NR level. The acoustical properties of this standard room can be modified or alternatively a �special room� with user defined materials and a number of supply and return terminals can also be entered for a more detailed noise calculation.

Comprehensive range and data checking is provided on all input items in the various dialogue boxes. A comprehensive check on the entered duct layout can be carried out prior to the calculations, to ensure ducts are connected, correct fittings have been used, fittings have not been omitted, etc. Comprehensive help is provided in all dialogue boxes and on each drop down menu describing the various commands and input items.


The text file results can be selectively or collectively viewed with a viewing and printing program or the results can be selectively displayed on the drawing.

Computer Platform


Programming Language

AutoLisp, Visual Basic and Fortran


The program has many features that make the inputting of data quite simple including automatic connection of run out ducts to terminals, automatic insertion of fittings and many other features. These enable the powerful and very comprehensive calculations of the program DONKEY to be utilised. Various alternative designs can be quickly and thoroughly investigated and a cost effective design achieved that satisfies the design objective for noise with minimal damper balancing pressure and cost. One of its greatest strengths is that it accounts for self generated noise.


Only works on AutoCAD (2000 or later not LT).





18 High Street
Glen Iris, Victoria 3146


+61 (3) 9885 6586


+61 (3) 9885 5974




Contact ACADS-BSG or visit web site for more information. Price: AU$2244 for single machine copy and significant discounts for multi-machine copies. Demonstration copy available for $50.