AskCodeMan

I was wondering if anyone knew if there was much of a difference in the 95 vs. 09 editions.

I am not familiar with the different energy forms, I am trying to contact someone who is and who can answer your question.

The following is copied off of the ACCA site for the new version of Manual D:

Design a residential duct system in less time with the streamlined Manual D duct procedure. The newly released Manual D has been significantly revised to include:

Updated and expanded VAV guidance, with detailed examples.
Impacts of excess length, sag and compression in flexible ducts.
New equivalent length values for flex duct junction boxes.
Manual D provides:

A single set of ANSI-recognized duct sizing principles and calculations that apply to all duct materials
System operating point (supply Cfm and external static pressure), and airway sizing for single-speed and multi-speed (ECM) blowers
A method for determining the impact of duct friction and fitting pressure drop on blower performance and air delivery
The most comprehensive equivalent length data ever published.
You can apply the Manual D procedure to constant volume systems and zoned variable air volume systems, over a full range of duct construction materials. Manual D includes a number of informative appendices related to air distribution systems (e.g., equipment and air-side components, controlling excess air when VAV dampers close, duct loads, duct leakage and duct system efficiency, air quality issues, noise control, minimum air velocity for ducts; codes, standards and best practice issues; and commissioning issues). 300 pages

From my reading the main differences seem to be:
- expanded calculations for duct length equivalents
- a better VAV section, the old one was fairly basic
- the addition of duct info related to the new variable speed furnaces
- it also seems like there's a little more emphasize on flex duct issues. The old flex duct info was also kind of basic. I think maybe because flex duct wasn't as prevalent (or acceptable) in the earlier years.
The new book doesn't cost too much so ordering it might not be a bad idea if you deal with duct design regularly
Hope that helps.