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Introducing ctrl-flow, an online tool for Design of High-Performance Control Sequences

Welcome back our past Contributing Editor with an important message for

Paul Ehrlich Consultant focused on energy efficiency and building to-grid integration

 I would like your help in trying to get the word out about a new tool that has just been developed by Lawrence Berkeley Labs.  This tool is an online website that is intended to help building system designers develop control sequences.  The initial release of the tool allows designers to input information about a project, and it will output an edited version of the sequences defined in ASHRAE Guideline 36.  Editing the guideline manually is a challenging task that takes from 2 – 6 hours and is easy to do wrong.  Using this tool only takes a few minutes.  The tool is limited in what it does on the initial release – but it will be expanded over time to add more systems and functions.

See attached for information that can be posted.


Paul Ehrlich, PE

There are many advantages to using high-performance control sequences, but these are often
hard to specify and deploy correctly properly. ASHRAE Guideline 36 provides a great starting
point to develop an accurate sequence, but editing what is in the guideline is also a challenge.
To help with this, Lawrence Berkeley National Laboratory (LBNL) has developed a new software
tool called ctrl-flow with funding from the US Department of Energy. This tool is freely
available for online use at
The initial release of ctrl-flow allows designers to easily input project information, the desired
systems, and their configurations. The tool will then provide an edited sequence based on
ASHRAE Guideline 36-2021 is specific to the selected options. This saves the time and
effort needed to manually edit the guideline and reduces the risks of editing errors.

Currently, the tool supports the following:
 Options for SI or IP units
 Code compliance for ASHRAE 90.1 / 62.1 or California Title 24
 Selection of climate zones
 Airside systems, including Multiple-Zone VAV Air Handlers and Cooling-only and Reheat

VAV Terminals
Future releases of the tool will include:
 Support for a broad range of systems, including all systems in Guideline 36
 The ability to provide additional project information and then download more detailed
Documentation including:
o Points lists
o Systems diagrams
o The control logic for the specified sequence in the Control Description Language
(CDL) as well as in the Control Exchange Format (CXF)
o A Modelica model of the HVAC system selected that can be used with tools such
as the Spawn of Energy Plus.

The tool is designed to help support the needs of HVAC system designers, control contractors,
commissioning agents, and energy modellers in evaluating and deploying advanced control
sequences. More information on the tool is available on the site or by contacting