Dear all,
I was checking Table 9.5.1 of ASHRAE 90.1-2007 (Lighting Power Densities Using the Building Area Method), and there is a footnote saying "In cases where both a general building area type and a specific building area type are listed, the specific building area type shall apply."
I am modeling an elementary school. This school includes a gymnasium, library, offices, workshops, garage, and a performing arts theater. All these 6 zones are listed in Table 9.5.1.
When modeling the baseline case, shall I assume a lighting power density (LPD) of 13W/m2 (the value for schools/university), or shall I use the values listed in this table for each category of zones? If I use the second option, then I will ONLY be using the "schools/university" entry of table 9.5.1 for the classrooms, since the offices, gym, libraries,...etc have their own LPD.
This will imply that the Building Area Method is very close to the Space-by-space method!
Many thanks!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5899 thumbs up
November 1, 2010 - 8:43 am
The note refers only to the Building Area Method (BAM). Basically it says that if you have a specific building type use that instead of the more general type. For example, if I am building a sports arena on a university campus then I use the sports arena Building Area Type, not the schools/university Type.
You could select individual zones in your building and apply the BAM values to those zones. Often this will not be to your advantage however. Typically the Space-by-Space (S-by-S) method will provide for a higher baseline, so more savings. For example, the gym is 1.1 W/sf in BAM and 1.4W/sf in S-by-S. The classrooms would be 1.2 W/sf in BAM and 1.4 W/sf in S-by-S.
In our expereince the S-by-S method always yields more savings but it certainly does require more effort.
Maya Karkour
EcoConsulting871 thumbs up
November 2, 2010 - 9:31 am
Thanks Marcus,
So do you think that I should use the value for schools/university ONLY for classes, and use different values for the gym, library, offices, theater? This sound to me much like the S-by-S method!
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5899 thumbs up
November 2, 2010 - 9:49 am
I think you should use the S-by-S method to maximize accuracy and savings. We almost never use the BAM in our modeling.
The difference is that the S-by-S method will be far more detailed since you will be entering different values for corridors, stairs, restrooms, storage rooms, mechanical rooms, lobbies, cafeteria, etc.
Maya Karkour
EcoConsulting871 thumbs up
August 5, 2011 - 7:35 am
Hi guys,
FYI, I got a feedback from the USGBC saying that when using the BAM, I should use the LPD of Schools (1.2W/ft2) in all spaces typically included in schools, such as offices, gymnasium, library, auditorium. However, the Parking is not generally found in a typical school, and as such I have to use the LPD of Parking Garages there...
Best regards,