# Assigning Detailed HVAC Systems

A walkthrough of how to assign various types of detailed HVAC systems to Dragonfly models in order to obtain the electricity and fuel use of the system.

All detailed HVAC templates in Ladybug have default equipment efficiencies that come from the ASHRAE 90.1 standard. The HVAC systems are assigned using the openstudio-standards gem here: <https://github.com/NREL/openstudio-standards>.

Check out the [Introduction](/ladybug-tools-academy/urban-energy-with-dragonfly/introduction.md) page to find sample files used in this video.

{% embed url="<https://youtu.be/_LV6kJ_xouU>" %}


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