OpenStudio is getting there and now has Standard 90.1 2004, 2007, and 2010 Components available on the BCL to generate baseline schedules, constructions, and loads relatively quickly. However, BCL Measures to create Appendix G HVAC systems are not available yet, although I'm guessing there are plans for them.

A motivated user could write Measures to automate the entire process of generating a baseline model complying with 90.1 Appendix G from a proposed model - i.e. overwriting the proposed components with the appropriate baseline ones and then changing the HVAC system(s). For example, my company has been developing some of the pieces to do this as time/projects allow - e.g. add Appendix G System # to the model and then set the VAV fan power coefficients.

Update: October 2016

OpenStudio now has a measure called Create Baseline Model available on the BCL.

Trace can do it. They've had all the library components for years, but just introduced automatic creation of the baseline model. I haven't used it, but have seen a model someone else did where they used it. It was a simple building/model, but the baseline looked pretty good.

IES-VE does it very well, and has capability for ASHRAE 90.1-2004, 2007, and 2010. There are a couple things the user has to edit- i.e. number of chillers & boilers- but it's very minimal. The baseline model is fully visible and editable, so it accommodates any required customization (such as with existing buildings). It outputs much of the LEED documentation in reports: i.e. LEED Online form Table EAp2-4 through 7. They have also included an interface to California's new Title 24-2013 API, CBECC-Com. Note that moderate knowledge of the VE is still required to create a baseline model. It is done in a series of steps, with the ability to alter inputs at each step.

If you are in Canada and are doing LEED under the M/NECB code

EE4 does support this kind of work in a similar manner for MNECB 1997.

CAN-Quest (The Canadian version of eQuest) will support this for NECB 2011. The beta is out if you contact NRCan's OEE Janet.Hudy@NRCan-RNCan.gc.ca for this. It is still under development.

As Matt has mentioned above. There is similar work to create the NECB 2011 standards into OpenStudio that is currently in development / proposal stage.

eQUEST can do it also.But eQUEST is not currentlyable to perform a complete conversion of the proposed model input to a 90.1-2007 Appendix G compliant model.Detailed information can be shown in “Building Energy Use and Cost Analysis Program Supplemental Manual: LEED Compliance Analysis December 2009” Detailed information about the conversion as following:

DesignBuilder v4.1 provides the functionality required for LEED and ASHRAE 90.1 modelling but is missing some enhanced features such as automatic baseline building creation, automatic simulation of the 4 rotations and a full set of LEED-specific report outputs.

Generally I use Energyplus, but I know that IDA-ICE and IES-VE developed tools to create the baseline model automatically. A feedback from the users of those tools would be interesting. Regards