We are looking to certify a garment factory in Dhaka which will not have any conventional HVAC systems. We would like to know if the following approach can be used for attempting LEED Optimize Energy Performance Credits.
Our approach is to first calculate the number of hours of thermal comfort as per ASHRAE- 55 . Then calculate energy costs for Baseline case as air conditioned for all hours and compare it with the proposed case as naturally ventilated for number of hours comfortable plus the cost for air conditioning as per ASHARAE 90.1 (baseline case for HVAC).
For Eg – Building Runs for 8760 hrs a year and thermal comfort is met by approx 1000hrs. (This will be derived using simulation software).
Baseline Case – Run simulation for 8760 hrs for ASHRAE 90.1 with Base case HVAC system
Proposed Case – Run Simulation for 7760 hrs for ASHRAE 90.1with Base Case HVAC System PLUS Run simulation for 1000 hrs with passive strategies.
So , basically the savings we will achieve will be mostly because of the 1000hrs of non use of air conditioning.
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 9, 2012 - 9:04 am
I have not looked for it lately but there was an interpretation dealing with this issue. I would check your methodology against the approved methodology for natural ventilation.
Kevin Sullivan
DirectorLeap Sustainability Design Consulting
9 thumbs up
May 9, 2012 - 11:24 am
Thanks for your reply , can you please elaborate on the approved methodology as well . ( specifc to this case scenario )
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 9, 2012 - 12:21 pm
As I recall it was similar to your approach relative to a requirement for thermal comfort evaluation. The modeling was not based on a reduction of simulation hours. This violates a specific modeling protocol (must be a full year simulation all together). The other provision of the ruling as I recall was that the software must be able to directly model natural ventilation without a work around as you propose. Energy Plus models it and probably IES-VE. I do not think that eQUEST or any DOE2 software, Trace or HAP can do it.
If you feel strongly that you can justify your approach I would suggest that you submit an interpretation. On the face of it I do not think it would be an acceptable approach.
Kevin Sullivan
DirectorLeap Sustainability Design Consulting
9 thumbs up
May 9, 2012 - 1:03 pm
thanks for the reply , but this approach nowhere looks to run a simulation for less than a year , it is an yearly simulation for the proposed case which is broken up into two parts , for the times when it meets thermal comfort it will be passive strategies and when it does not it will use ASHRAE basecase HVAC system. Also can you please elaborate on the reply you had given in one of the previous strings for a similar question of modelling natural ventilation buildings where you had told a methodology saying that take ASHRAE basecase HVAC system in both cases and keep temperature setpoints high so that they dont get cooling on .. how do we justify it as an approach ,has any such project been awarded with energy points ,, thanks
Kevin Sullivan
DirectorLeap Sustainability Design Consulting
9 thumbs up
May 9, 2012 - 1:15 pm
Add to that this approach mentioned above has been taken from a technical paper on Advanced Energy Modelling for LEED by USGBC.
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 9, 2012 - 2:03 pm
My confusion on the hours, it obviously did not appear that way to me from your post. The "PLUS" sounded like an additional run.
Regarding the cooling set points - this is a way to include cooling systems where they have not been designed in a way that does not impact energy use. It is a work around regarding where Appendix G requires you to include cooling even if it is not in the proposed design. Many projects have used this methodology and it is common practice. 90.1 requires identical temperature set points but does not dictate what they are. This is independent of natural ventilation but can be related.
I helped write the Advanced Energy Modeling Guide for LEED and that methodology is based on the interpretation I referenced. Again the software must be able to model natural ventilation directly. You cannot use that methodology if the software can't model natural ventilation.
Is the building designed to be naturally ventilated (i.e. no fans/mechanical ventilation)?
Kevin Sullivan
DirectorLeap Sustainability Design Consulting
9 thumbs up
May 13, 2012 - 3:39 am
Thanks for the reply , the building will be designed with extractor fans and shall also have evaporative cooling ( as the sensible loads will be high ) , similar strategies have been used in a few srilankan garment factory buildings , with regards to this can you please tell on an approach that will be acceptable by LEED for energy credits. Thanks
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5909 thumbs up
May 14, 2012 - 11:03 am
So this sounds like a cooled and mechanically ventilated building and not natural ventilation. Hard to tell you the exact approach with only very limited knowledge of the project. Since the project has cooling and mechanical ventilation it seems like it should be pretty straight forward, model the proposed as designed and the baseline according to appendix g. 90.1-2010 added systems # 9 and 10 which can be used in appropriate circumstances.
Kevin Sullivan
DirectorLeap Sustainability Design Consulting
9 thumbs up
May 14, 2012 - 1:42 pm
thanks