Results 1 to 2 of 2

Thread: variation in summer dbt & wbt values for with & without outdoor air information

  1. #1
    Member
    Join Date
    2013-02
    Posts
    4
    Login to Give a bone
    0

    Default variation in summer dbt & wbt values for with & without outdoor air information

    we are designing HVAC system for our project. but while doing load analysis in Revit mep 2013 , we stuck to few problems which produces error in our final cooling load calculations.


    as we enter or select project location (in our project it is Pune,Maharashtra,India), & calculate load analysis for room with interior wall type having area of 100 sq.ft. with occupancy of 10 people and 100 watt light & 10 KW power load without giving outdoor air information , then it produce report for SUMMER DRY BULB & WET BULB TEMP. for month of MAY (which is peak temp. of the year).


    but as in second case if we gives value for outdoor air per area say 0.68 per sq.ft. as a ventilation air then it shows report for SUMMER DRY BULB & WET BULB TEMP. for a month of JUNE (which is not peak temp. of the year).
    and in both the cases cooling load values are different
    what is the reason for this? why should it takes different summer DBT & WBT temp. values for calculations?

  2. #2
    I could stop if I wanted to
    Join Date
    2007-06
    Location
    Des Moines, IA
    Posts
    224
    Login to Give a bone
    0

    Default Re: variation in summer dbt & wbt values for with & without outdoor air information

    There's a few things going on here. First, I think what Revit is showing you is what I would call the peak COIL load, not the peak SPACE load. My guess is that it's more humid in June than May but roughly the same dry bulb temperature. Conditioning the outdoor air at that higher WBT takes more energy, thus the change in peaks (coil peaks, not space peak) when you add outdoor air.

    Another way to look at it might be that the peak sensible load (highest outdoor DBT) differs from the peak overall load when you add outdoor air in.

    Notice that the airflow is the same in both cases. I'm not familiar enough with Revit load outputs - can you view a zone or space summary instead of a building summary? That may show a more consistent peak time.

Similar Threads

  1. 2013: variation in summer dbt & wbt values for with & without outdoor air information
    By digambar.h357109 in forum Revit - Conceptual Design Tools
    Replies: 0
    Last Post: 2013-03-12, 05:07 AM
  2. Replies: 0
    Last Post: 2012-04-27, 03:20 AM
  3. Outdoor furniture anyone?
    By r.grandmaison in forum Revit Architecture - Families
    Replies: 1
    Last Post: 2011-02-19, 07:05 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •