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Beyond code compliance, but doable
This prerequisite is a big one, not only because it’s required for all projects, but also because it feeds directly into EAc1: Optimize Energy Performance, where about 15% of the total available points in LEED are at stake. Master the minimum requirements under EAp2, and you will be well on your way to earning points under EAc1. Keep in mind that any LEED-NC v2.2 project registered after June 26, 2007 must achieve at least two energy use reduction points via EAc1 methodology. Plan for this in your approach to EAp2.
You won’t earn the prerequisite by accident, though. Although “energy efficiency” is on everyone’s lips, the mandatory and performance-based requirements for EAp2 go beyond code compliance in most places. That said, there is nothing...
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51 Comments
Outdoor air ventilation rates
ASHRAE Standard 90.1-1999 Section 11.4.3(d) requires that the minimum outdoor air ventilation rates are modeled the same between the Proposed and Baseline models. But in our energy models, these rates do not match. Has anyone run into this issue before or have any suggestions for how to address this?
Probably a better place to post this question would be on the appropriate software discuss group found at onebuilding.org.
Envelope Requirements for Existing Building under LEED NC2.2
If an existing building without any exterior wall modifications is applying for LEED NC2.2, does the assembly U-value of the exterior wall for the proposed building need to comply with table 5.5 in 90.1-2004?
It seems ASHRAE does not require this for modeling per Appendix G, but I heard that a similar project was rejected by LEED because the U-value of unmodified exterior walls was above the maximum allowed by 90.1.
Thank you,
No. See Table G3.1.5 Baseline (f).
It does not seem plausible that a prerequisite would be rejected for non-compliance with a prescriptive (not mandatory) measure. If this did happen the project team should tell GBCI that the reviewer is incorrect.
Energy Model Primary Responsibility
We have had a bit of a challenge with our first attempt at LEED documentation. The Design Development MEP work was done by one engineering firm and the MEP Construction Docs. are being created through the contractor by a subcontractor MEP firm. The energy modeler is a third party consultant which contracted through the MEP design engineer and produced a DD energy model. Now we would like to take the next step to finalize the energy model, but the mechanical subcontractor is resisting taking primary responsibility. Contractual obligations aside, should we be able to reasonably expect the Mechanical subcontractor to step up to a primary role to finish revising the energy model?
Sounds like you have a design engineer and a design model. You then would have an admin MEP preparing the documents and it would make logical sense for them to do the final model since this is just another document. Are they OK with documenting other MEP related LEED credits? If they have taken responsibility for the design implementation I do not understand why they would not take responsibility for the final model (contractual issues aside). LEED does not care who does the final model.
warehouse ventilation
We are in the process of modeling a warehouse for leed 2.2. that is mechanically ventilated in the summer time and heated thru infrared heaters in the winter. The space is considered conditioned according to Ashrae 90.1 therefore we are modeling a cooling system and keeping the cooling temperature set point as high as possible. The question I am facing is how to model the ventilation fans in the base line is it going to be the same as the proposed with the same CFM and considered process or I will have to model only the minimum Ashrae ventilation rates in the base line.
The ventilation rate in the Proposed will likely drive the Baseline supply air flow since the OA rates would need to be the same. It would not be considered process but would likely be identical anyway for the reason above. So do not use the ASHRAE minimum in the Baseline.
Alternative Compliance Approach
Hi all!
We have used a computer simulation model for our office project. Is it possible to submit documents which were exported from the simulation model separated into exact sectioning as the original leedonline pdf document as an alternative compliance approach?
I do not think that this will be possible but I need to be sure in order to provide accurate information to our HVAC engineers.
You will need to fill out the online credit form. If you submit a pdf then the data is not retrivable.
LED Lamps in Incandescent Fixtures
I have a very well-intentioned hotel owner that would like to use LED lamps for energy reduction, but wants to install incandescent fixtures because of their lower costs. Compatibility issues aside, as we model this, we are following ASHRAE 90.1 requirements that we model using the fixture rating and not the lamp wattage. This is of course having a sizable impact on our energy model. Vendors are telling the owner that his LED lamps should apply where LEED is concerned and he keeps asking us to revisit this. Is anyone aware of allowances / exceptions for using the lamp wattage for LEED instead of fixture ratings in ASHRAE energy modeling? Thanks
LEED would defer to the Standard in this case. The Standard has this provision to prevent folks from claiming energy savings and then back-sliding into a less efficient choice. So savings associated with screw-in LEDs do not count under 90.1 and therefore LEED.
Show the owner/vendors Section 9.1.4(a). It is very clear and there is a very good reason for it.
Latest Guideline for modeling labs in LEED v2.2
I've read the CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide's and found ID#'s 5350, 2042, and 1819 as the most relevant. But I am just wondering if there is a simplified direction out there for modeling Labs for LEED v2.2. It is very clear that we may not use Labs21, but the blanket statement of following addenda for ASHRAE 90.1-2004 seems to be a bit too general.
Many of the addendum which were added and now make up Appendix G in 90.1-2007 addressed lab facilities. Since you can use 90.1-2007 appendix G in v2.2 project you might try doing so. Just to be clear you can use 2007 Appendix G methodology but while using the 90.1-2004 values.
Low cost strategies to achieve minimum U values
I have been working on this project where the client does not want to spend too much extra over the conventional methods of construction that are followed here in India. AAC blocks and cavity walls are not an option in this case. We are following the prescriptive method and my target U value for the roof is U-0.50 w/m2K and the target U value for walls is U-1.25 w/m2K. As per the planned methods of construction, we are missing the required U value by quite a margin for the roof and by a little for the walls. I have also included the links to our e-quest calculations made to this effect. I have the following questions:
How can I bridge the gap without using any of the expensive insulation products?
Can we include high SRIThe solar reflectance index (SRI) is a measure of a material's ability to reject solar heat, as shown by a small temperature rise. Standard black (reflectance 0.05, emittance 0.90) is 0 and standard white (reflectance 0.80, emittance 0.90) is 100. For example, a standard black surface has a temperature rise of 90_F (50_C) in full sun, and a standard white surface has a temperature rise of 14.6_F (8.1_C). Once the maximum temperature rise of a given material has been computed, the SRI can be calculated by interpolating between the values for white and black. Materials with the highest SRI values are the coolest choices for paving. Because of the way SRI is defined, particularly hot materials can even take slightly negative values, and particularly cool materials can even exceed 100. paint as one of the layers for making these calculations?
How can I include the white cement putty work that will be done on both sides of the wall?
Is it correct to include the inside air layer in these calculations?
Some low cost material options that can help us achieve the target for the roof and walls?
Any advice would be much appreciated. Thanks
Roof Calculation: http://bit.ly/oMBxOR
Wall Calculation: http://bit.ly/qTUaSI
Hi Yusuf,
Why are you following the prescriptive method? Are you not pursuing any EAc1 points? Was the project registered before the two point minimum (6-26-2007)? Are you following one of the prescriptive guides, like the ASHRAE AEDG?
First your wall and roof calculations must be performed according to Appendix A in 90.1. Simply calculating the layers at a point is usually not an acceptable methodology. You are supposed to determine the overall U-value of the assembly to demonstrate compliance.
Paint does not address resistance, it addresses radiant gains. Not sure about the putty.
Hi Marcus
We are not pursuing LEED certification. We are pursuing IGBC green homes rating and the prescriptive approach was chosen because energy modelling for such a large project is too expensive. To show envelope compliance all we need to do is show that the wall and the roof assemblies meet the criteria mentioned above.
Are you saying creating layers on e-quest and getting the overall R value of the wall/roof is not the right method?
Hi Yusuf,
Since this is a LEED forum I assumed you had a LEED related question.
For ASHRAE 90.1 projects one cannot calculate overall assembly U-values by adding up layers. Regarding eQUEST it depends on how you create the layers. The point is to account for thermal bridging, voids, etc. in the overall calculation. This is why we must use Appendix A. Taking an extreme example like a steel framed wall without any continuous insulation. Even with R19 batts in the cavity the overall U-value of the wall is about R9 as I recall.
Best of luck with improving your U-values to meet the prescriptive criteria, not sure I can help you there.
Glycol Chiller
Would like to know, does Glycol Chiller need to meet AHSRAE 90.1 , COP or IPLV requirement. We only use these glycol chiller to make ice at night time.
thanks
Does the chiller meet the COP and IPLV requirement before adding the glycol? If so you meet the mandatory provision of 90.1 since the ARI testing procedure is conducted with water. Adding the glycol will reduce the efficiency in your actual design and just penalize your overall energy performance.
Hi Marcus,
i shall speak with our supplier later. i'm a bit curious to know more. Though the glycol chiller are meant to operate at night only as to make ice, do the this chillers also require to meet ASHRAE requirement?
As I understand it yes.
Hi I found the following passages in the 90.1-2007 Standard and 90.1-2010 Manual:
1. In the standard page 33, it states: "Chiller designed to operate outside of these ranges or application utilizing fluids or solution with secondary coolants (e.g., glyci solution or brines) with a freezing point of 27 degree F or lower for freezing protection are not convered by this standard."
2. In the 90.1-2010 Manual page 6-11, it states: "For those centrifugal chillers selected for nonstandard conditions, the efficiencies from Table 6.8.1C are adjusted by a factor, Kadj, as..... (adjustment formula on the same page)"
"The efficiency requirements apply only to chillers with full-load design conditions in the following ranges: (design conditions upper and lower limits on page 6-12)"
3. In the 90.1-2010 Manual page 6-15, there is a Q&A section specifically deals with ice storage chillers, and it states: "Chillers that are not specifically designed to operate at conditions outside the ranges listed in Section 6.4.1.2.1 - chilled water supply of below or equal to 36 degree F - are EXEMPT........"
So it seems to me that ice charging chiller can be exempt, no?
Water heating equipment
I have a gas storage water heater, with an input capacity of 84.000 BtuA unit of energy consumed by or delivered to a building. A Btu is an acronym for British thermal unit and is defined as the amount of energy required to increase the temperature of 1 pound of water by 1 degree Fahrenheit, at normal atmospheric pressure. Energy consumption is expressed in Btu to allow for consumption comparisons among fuels that are measured in different units./h and a volume of 14 gallons, I am lost in placing this equipment in the categories and subcategories from Table 7.8
Looks like it should be classified as a gas instantaneous if it has only 14 gallons of storage.
Existing equipment
I have a new construction that will use an existing water heater and hot water systema, reused from from an existing building, of the same Owner. The existing building was modular type, and the hole hot wate system, including the water heater and pipping, will be reused in a new construction.
Would this situation apply for the Exception 7.1.1.2 ?
The exception states "When the service water heating to an ADDITION is provided by existing service...."
Your project is new construction.
The LEED project reviewer probably would not allow you this exception.
25% default process energy cost
If I have a project which will have a process energy cost higher than 25% of the total energy cost of the reference building can I simply assume the 25% default? From what I can tell the guide only asks for the process load to be documented if you are claiming your process load cost is less than 25% of the total energy cost for the reference building.
You must accurately model the expected energy consumption. Energy modelers are not allowed to use the default if the actual process energy is greater than 25%.
Fenestration NFRC testing
I am working on LEED-NC project in a India. India does not use NFRC standards for fenestration rating, and does not use ASHRAE 90.1 as the energy efficiency baseline.
Under the mandatory provisions section in the Building Envelope portion of the ASHRAE 90.1-2004 standard, it requires for Fenestration that, "U-factors are determined in accordance with NFRC 100."
NFRC 100 lists both physical testing and computer simulation as required pathways for getting products certified by NFRC.
We have a situation where we have a unique curtainwall design that will not be replicated on any other projects. We do not wish to get our curtainwall product certified by NFRC, but the ASHRAE 90.1 standard states that we must follow the NFRC 100 protocol for determining the assembly U-value of a curtainwall product.
We have been informed in the past by designers and engineers in the US that the "typical" practice used for unique curtainwall designs is to do ONLY a simulation of the curtainwall assembly in the WINDOW (or equivalent) program to determine a curtainwall assembly U-value, and to leave it to the manufacturer of the curtainwall system as to whether or not they wanted to go the full distance to get their new curtainwall product NFRC certified.
This process of determining a curtainwall's assembly U-value does not seem to specifically require the full NFRC 100 procedure, as inferred by the ASHRAE 90.1-2004 standard. It is our interpretation that the reference to NFRC 100 within the ASHRAE 90.1 standard is referencing the requirements for computer simulation programs and minimum product sizes used for the simulation activities.
Would we be considered in compliance with the NFRC 100 standard if we followed the simulation protocols within the NFRC 100 standard but not the physical testing methodologies of the NFRC 100 standard in order to determine the assembly U-value of a curtainwall system?
You can read the document at - http://www.nfrc.org/documents/1997_NFRC100.pdf
See section 5.1. As I read it you can do simulations only.
EPA Target Finder?
Dear all,
I noticed an input box in the LEED Online submission templates, asking for the Target Finder Score.
The credit language argues that this is not necessary. Can I leave it as blank? Or shall I put any arbitrary value?
Many thanks!
There are a number of instances in which the LEED reference guide outlines the information required to document credit compliance yet the LEED Online template requires additional information. The Target Score is required if the building occupancy can be scored by the Portfolio Manager. The score has not impact on the EA Credit #1 point total.
Energy savings by use of Solar Hot Water system
Hi,
We use Vis. Doe-4.1 as the simulation software for modelling and need a clarification whether USGBC accepts the savings demonstrated by use of Solar Hot water system in the proposed case against the Electric Hot Water System in the baseline case.
Yes it does. The baseline would be electric if your backup water heating system is electric. If it is gas the baseline would be gas.
Standard 90.1 provisions
If Standard 90.1 does not apply to multi-family structures of three stories or fewer above grade, and our project is a three story army barracks how do we prove compliance? Can we still model our building using appendix G for EAcr1?
Sounds like the project is in a grey area. I assume it is not eligible for LEED for Homes since there would likely be no kitchens. In the past I had argued that such projects could apply the provisions of ASHRAE 90.2 but use Appendix G (somewhat loosely) from 90.1. I don't think that is in writing anywhere so you might need to submit your own CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide.
Energy Modeling and Process Energy
We are working on a unique project that has a very large process load that totals 56% of the total energy use for the building. This calculation is based on the process being in full operation during the normal hours of occupancy. The process however is only in operation for 1 hour a day. Is it correct to use the one hour assumption in the energy model? The energy reduction percentages are 20% different depending on which way we treat it.
If the process is only planned to be in operation for one hour for the first couple of years of operation then it would be legitimate to model it that way.
My project is facing the same problem too. It is a airplane manufacturing center in China. The equipment energy consumption will take more than 80% of the overall load. The plant will be operated 8 hours per day. Anyone have idea on this situation? I think this kind of project should be treated specially, can I run the simulation excluding the heavy equipment load? Just think this load is different from the normal process load.
No you cannot exclude the heavy equipment load. In your situation you will need to find energy savings in the manufacturing process. The challenge is establishing an appropriate baseline. See above discussions for more details.
Energy Modeling for a manufacturing facility
We are going forward with the construction of a manufacturing facility. I have a question regarding energy modeling. Is there any standard that can help us understand how the production process is to be incorporated into the modeling? Specially, since every production process is unique and building a baseline becomes a hard task.
Thank you for your support.
You hit the nail on the head. The hard part is determining an appropriate baseline for any claimed process load energy savings. Unfortunately the USGBC has not provided any more definative guidance on this subject beyond what can be found in the CIRs. My firm was able to claim a significant amount of savings for process energy strategies on a manufacuturing facility and the baselines were not questioned. However, it is the individual LEED reviewer who evaluates the appropriateness of the baseline on a case-by-case basis so opinions can vary.
The best advise I can give you is to try to justify/document a basline that reflects current industry standard practice. You then make the case that what you are doing exceeds that standard practice.
HVAC Equipment for the DataCenter
We are doing a major renovation project with an existing datacenter which uses approximately 120 tons (20 tons/unit). We discovered that the units serving the datacenter are using a refrigerant that did not meet EAp3, so we verified with the manufacturer that we can change it one that does comply; however, the efficiency of the unit will likely go down 5-10%. Our calculations reveal that a drop in efficiency above 8% will not meet EAp2, but the manufacturer cannot tell us exactly what the efficiency drop will be. The original scope of the project did not inlcude replacing these HVAC units as they are not due for replacement for a few years, but we're not sure what the best course of action is at this point.
So if your units use CFCsChlorofluorocarbons (CFCs) are hydrocarbons that are used as refrigerants and cause depletion of the stratospheric ozone layer. (R11 and R12) you are correct that they would not meet EAp3. Since those units would have to be at least 15 years old it is difficult to believe that the new ones are less efficient. Double check with the manufacturer.
You do have the option under EAp3 of developing a phase out plan. This may be a way to buy you the few years until the units are scheduled for replacement. I also seem to recall that if a project could demonstrate that the retrofit is not cost effective (payback over 10 years) then it does not have to be retrofitted or replaced. Check the CIRs for any details about that last method.
Well, actually, it's not compliance with EAp3 that concerns me because we can swap out the refrigerant with a non CFC and meet EAp3, but if the efficiency of the unit drops below the ASHRAE/IESNA 90.1-2004 minimum efficiency requirements, then we wouldn't meet EAp2. I'm looking thru the CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide database to see if there's any precedents for phase-out plans to meet EAp2.
G. Mathew, if your design meets EAp2 and for EAp3 today, and you commit to phasing out the refrigerant over say 3-5 years, and since LEED is asking for your design's energy efficiency rate now (and not in three years), it seems that your project could comply with EAp2 and 3 and be certifiable now.
While the impact of EAp3's phase out on EAp2's energy efficiency are noteworthy, it seems that predicting the building's energy efficiency rate in 3-5 years and advising the owner of the possibility of actual savings reported to USGBC being less than the design is beyond your current LEED project requirements which are tough enough to comply with. Please let me know if I have this wrong, but in any case I hope you do certifiy now and then all informed as to how this works out-- and a big thanks for sharing this dissonance bewteen LEED credits, John
Prototype Downsizing
If a retailer downsizes it's prototype store by say 10% for the launch of a new green building prototype, can they take credit for the energy efficiency asociated with the smaller footprint? It seems like ASHRAE is only set up to compare buildings of the same size, but in fairness it also seems that the base building should be modeled for the old larger prototype and the design case should be for the smaller new prototype. Thoughts?
Appendix G requires that the proposed and baseline buildings be identical in number of floors and conditioned floor area (Table G3.1-1). So this measure would not be eligible for savings in LEED. The purpose of Appendix G is to give us a uniform methodology to compare against other projects. Allowing this kind of measure could certainly lead to a slippery slope of unverifiable claims.
Even though you can't claim credit in LEED the baseline you proposed is certainly a valid one for comparison during the design process. Comparing a new prototype to the current one in a model calibrated to actual performance would be very useful for gauging actual savings related to specific design decisions. SInce the more valid baseline during design would likely be a current prototype rather than an Appendix G baseline for calculating actual savings, it would make sense to draw comparisons against the current prototype to determine the cost-effectiveness and interactive effects of various energy saving strategies.
This kind of effort is, after all, the real purpose of energy modeling.
On Site Energy
I'm working on a project where the client actually produces steam on site which provides electrical and HVAC power to the whole facility. It's a petrochemical plant so I'm not sure how to handle this. They use very little grid energy as well. Could this be an Innovation in Design credit? I'm at a loss as to how I can capitalize on this resource.
The environmental advantage to combined heat and power (CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source.) systems is that an on-site facility like this can take advantage fo the waste heat produced in the process of making electricity. Conventional grid power is about 30% to 35% efficient. CHP systems can approach 80% efficiency. So this can be a major energy saver overall.
For LEED projects please refer to the District Energy and CHP guidance documents on the USGBC web site for LEED v2.2 projects - http://www.usgbc.org/DisplayPage.aspx?CMSPageID=2061
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