Design conditions
Every load calculation starts with outdoor and indoor design conditions. Pick a city preset (typical values) or enter your project's design basis.
Location preset
Presets are typical summer design values for learning. Use the values in your project design basis or the authority's requirements.
Outdoor
Indoor
Room cooling load
Describe the room. The peak-hour load updates as you type, with each component shown. Tap , or for plain explanations.
Room
Facades
Internal gains & ventilation
Load breakdown at peak hour
Working
4D hourly peak and 3D sun
The same room from 06:00 to 20:00. Play the day: the sun moves, the sunlit facades heat up, and the chart shows when the room peaks.
Supply air and psychrometrics
The sensible load sets the supply airflow. The latent load and the outdoor air set how much moisture the coil must remove.
Psychrometric states
Mini psychrometric chart
Working
Duct sizing by equal friction
An AHU serves several rooms like this one through a trunk with three tees and six diffusers. Set the friction rate and velocity limits; each section is sized automatically.
Layout (plan)
Section schedule
Static pressure and fan selection
The fan must overcome the index run on the supply side, the return side and the AHU's own components. Edit the allowances to match the AHU data.
AHU internal and return allowances (Pa)
Result
Index run breakdown
3D ductwork
The sized network in 3D. Colour shows velocity; the index run glows amber. Tap any section.
Engineer's notes
Lessons from real design reviews.