We are doing a ID+C in a existing building, where the lighting and the envelope are the original ones. We doesn't modified this items.
The original lighting (W/ft2) is better than the ASHRAE table 9.5.1, then we have savings in lighting consumption although no modify the system. The question is we can achieve lighting savings and not apply the requeriments of chapter 9 of 90.1, because the lighting is existing. It's correct, input the real values in the proposed model or we need to introduce the table 9.5.1 values in the proposed and baseline model?
In the envelope, we have the same question, the value of the existing walls, floor and roof are better than the tables of Apendix A of 90.1. Then we have demand energy reduction without any modifications. It's correct, input the real values in the proposed model or we need to introduce de apendix A values in the proposed and baseline model?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
April 12, 2017 - 10:57 am
I think you could meet the prerequisite because your envelope and lighting are better than 90.1 (assuming your lighting is 10% or more better).
Regarding the savings in the model, in general the modeling protocol requires that you model the envelop and lighting identical in the baseline. The models would both include the existing values, so you cannot claim energy savings relative to the existing conditions.
CI projects often do not require a model (although that is an option) as many of the credits are prescriptive. If the prescriptive baseline is 90.1 then you would probably be able to earn points that way.
Marc Maso
1 thumbs up
April 25, 2017 - 9:52 am
Thank you Marcus, I don't understand why the lighting power values in the Baseline must be the existing ones.
As the Ashrae 90.1 Table G3.1.6 marks:,
for the proposed: Where a complete lighting system exists, the actual lighting power for each thermal block shall be used in the model. Ok, the proposed model have the real existing values.
and for the Baseline: Lighting power in the baseline building design shall be determined using the same categorization procedure (Building Area Method or Space-by-Space Method) and categories as the proposed design with lighting power set equal to the maximum allowed for the corresponding method and category in Section 9.2.
Then the baseline model as modeled with the same categories of the proposed design with lighting power of the section 9.2.
Then, if the existing lighting is better than the Table 9.2 Values, why we can't earn savings? Our Savings are about 6% of lighting consumption.
Another question for the same model. The ventilation rates used in the design is the Spanish autorithy, that are bigger than Ashrae 62.1 and the CEN STANDARD 15251-2007. We have used the Spanish value in the Proposed model.
Which one we need to use in the Baseline, the sames values (Spanish) or the lower Ashrae 62.1 values?
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5867 thumbs up
May 1, 2017 - 10:04 am
The 90.1 User's Manual provides more clarity on the existing system issue. By your logic if the existing lighting was worse you would pay a penalty. Essentially you don't get penalized or rewarded for something you have not done. The system was existing so for lighting and HVAC that gets modeled identically. The only exception to that is envelop as that is clearly stated in Table G3.1-5 Baseline (f).
The outside air quantity must be identical in both models. The rate does not matter since you can use the same rate and come up with different quantities of OA in both models. There is an total OA in the proposed model based on the design. That quantity must be modeled in the baseline as well.