[Bldg-sim] Hotel Renovation and ASHRAE 90.1

Christian Stalberg cstalberg at naturalintelligence.us
Tue Jul 26 02:48:07 PDT 2011


   When modeling an existing building as the baseline building under
   ASHRAE 90.1 Appendix G you place the fenestration as found (area) and
   original u-values for the envelope including fenestration.

   On 07/25/2011 17:13 Jim Dirkes <jim at buildingperformanceteam.com> wrote
   ..

   Dear Forum,

   (Excuse cross-posting!)

   I'm now modeling a hotel which is seeking LEED certification.  The
   "Executive summary" goes like this:

   * Lower Level and 1st floor are ~25,000 square feet and contain meeting
   rooms, offices, and Lobby.

   * Floors 2-12 are guest rooms.

   * The building is all-electric, so I'll use Baseline System #2 for
   guest rooms and #4 for the remainder.

   * The pre-renovation structure was ~80% windows in Climate Zone 2A.

   * Post-renovation, the guest rooms floors will be ~45% glass and the
   remainder will be ~50% windows.

   The part I'm uncertain about is how to model the walls and windows.
   ASHRAE 90.1 Table G3.1, item 5f says

   "f. Existing Buildings. For existing building envelopes, the baseline
   building design shall reflect existing conditions prior to any
   revisions that are part of the scope of work being evaluated."

   That seems to say that the 80% windows becomes the baseline envelope
   definition....

   On the other hand, the new design will certainly save a LOT of energy!

   Please let me know your thoughts about:

   a) whether the Baseline walls and windows should be modeled "as
   original" for their "U" value, SHGF and ....

   b) whether the normal 40% maximum glazing applies to an existing
   building renovation for either the Baseline or Proposed design.

   Thanks in advance!

   I know I'm not the first one to walk this path, but it's the first time
   I have walked it!

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