Forum discussion
NC-2009 EAp2: Minimum Energy Performance
Actually I'am not able to correlate section 14 required inputs under pressure drop column "CFMd", and the requirements of ASHRAE TABLE 6.5.3.1.1 B in (pascals/ in.w). In other words; how can I know the allowable increase in cfm to compensate for using one MERV 13 filter, or for using fully ducted system for example?
LEEDuser is supported by our premium members, not by advertisers.
Go premium forTo post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.
A portion of our building envelope is historic. Can we exclude it from our model?
For an existing building, do I need to rotate the model?
Our process load is higher than 25%. Do we have to justify that?
Our local code references ASHRAE 90.1-2010. Should I use that for my documentation, or 90.1-2007?
Can mezzanines open to floors below be excluded from the energy model?
How do I provide a zip code for an international location?
For a project outside the U.S., how do I determine the climate zone?
For a project outside the U.S., how do I determine the Target Finder score?
Do hotel rooms need automatic light shut-off control?
How commonly are the 90.1 mandatory compliance forms submitted as part of EAp2/EAc1?
The Section 9 space-by-space method does not include residential space types. What should I use?
Can the Passive House Planning Package (PHPP) be used to energy model for LEED?
Which baseline HVAC system do I use if my building has no heating or air conditioning?
Our project has a diesel backup generator. Should we include it in our energy model?
Can SHGC be higher in the proposed than in the baseline model?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5924 thumbs up
April 2, 2014 - 12:03 pm
The software should be auto-sizing the baseline system airflow so no need to try and "design" it by increasing the cfm. You can double check your baseline fan power calculations using the spreadsheet found in the Documentation Toolkit tab above.
The baseline pressure drop adjustments are intended to compensate for the effect on the baseline fan power related to issues like MERV 13 filter and ducted returns. So you don't do any further adjustments.
Omar Elrawy
Green Building Consultant | ResearcherGreenA Consultants
56 thumbs up
April 2, 2014 - 4:03 pm
then I understand that I can leave this part blank on the Section 14 table, is that correct? and in this case allowable fan power won't be increased
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5924 thumbs up
April 2, 2014 - 4:45 pm
Probably not. In general you need to completely fill in the Section 1.4 tables. I am not sure which version of the Section 1.4 tables you are using or even specifically what you are suggesting that you could leave blank.
The allowable fan power is automatically adjusted by the pressure drop adjustments.
Omar Elrawy
Green Building Consultant | ResearcherGreenA Consultants
56 thumbs up
April 2, 2014 - 5:07 pm
Iam using the "Revised Section 1 4 Tables (Dec 2012)", in the Air-Side HVAC details; whenever I increase the CFMd, the allowable fan power (cell D-30) increase, giving me more allowable fan power, so I need to get use of this allowance, in the same time I don't know the appropriate cfm drop to enter
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5924 thumbs up
April 2, 2014 - 5:40 pm
OK. In Table 1.4.7A it is important to know that you should enter each separate system in its own column or the fan power calculations will not be 100% accurate. You would enter the cfm of supply air from the energy model. You then enter the cfm associated with any of the applicable pressure drop adjustments in the bottom of the form. For example, do not enter the supply cfm for ducted returns unless 100% of the supply air is returned. Use the same proportions as the corresponding proposed system (if the return is 90% of the supply in the proposed apply this proportion to the Baseline). The spreadsheet will then accurately calculate the allowable baseline fan power for each system. Make sure to read the instructions and notes at the top of the page to make sure it is working right.
Omar Elrawy
Green Building Consultant | ResearcherGreenA Consultants
56 thumbs up
April 7, 2014 - 10:28 am
Thank you Marcus. I have another question; now my proposed fans' power are exceeding the Baseline fan power, should I model it the same as basecase fan power, or as found in the design drawings?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5924 thumbs up
April 7, 2014 - 10:31 am
Model the proposed as designed. It is certainly possible that the proposed fans could use more energy than the baseline fans.