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A lot is at stake here
EAc1: Optimize Energy Performance is, by far, the most important credit in LEED, based on the number of points available. Up to 19 points are at stake here based on how much you’re able to reduce the project’s predicted energy cost. That large amount of points also reflects the great importance LEED places on reducing energy use and forestalling climate change1. Climate change refers to any significant change in measures of climate (such as temperature, precipitation, or wind) lasting for an extended period (decades or longer). (U.S. Environmental Protection Agency, 2008) 2.The increase in global average temperatures being caused by a buildup of CO2 and other...
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322 Comments
ABSL-3 Baseline vs. Proposed Fan Energy for RTU
I've recently come across a deblitating problem as it pertains to the energy modeling of an ABSL-3 space. The sensitive, high-containment nature of these spaces predicates an essentially CAV, 100% OA unit coupled with a dedicated exhaust fan system. The particular building I'm analyzing is small enough square footage wise (7,000 SF) to dictate a Type 3-PSZ arrangement, aka unitary air conditioners.
The problem that I'm encountering by the intepretation of Appendix G is that I'm unable to credit a realistic exhaust air fan energy into the baseline unitary air conditioner. There are credits allowed for various other system components, i.e. sound traps, fully ducted exhaust, filtration, etc., but this amounts to only a fraction of actual exhaust fan operation. In the end, I'm eating up to half of the amount of year round energy for a 22 BHP exhaust fan. Has anyone been involved with efforts by LEED to rectify this?
On a side note, I also noticed that a question was answered regarding lab spaces in reference to "laboratory spaces that exceed 5,000 CFM" are to have "System 5 or 7 centralized units w/ VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas.". I interpretted this portion of Appendix G as a reference to any solitary lab space that exceeds 5,000 CFM as opposed to "lab spaces" meaning "lab building". Has there been any clarification issued for this wording because it seems as though it could be interpretted either way.
Regardless, although it would seem to help me for my case by allowing me to baseline a combo supply/exhaust fan AHU1.Air-handling units (AHUs) are mechanical indirect heating, ventilating, or air-conditioning systems in which the air is treated or handled by equipment located outside the rooms served, usually at a central location, and conveyed to and from the rooms by a fan and a system of distributing ducts. (NEEB, 1997 edition) 2.A type of heating and/or cooling distribution equipment that channels warm or cool air to different parts of a building. This process of channeling the conditioned air often involves drawing air over heating or cooling coils and forcing it from a central location through ducts or air-handling units. Air-handling units are hidden in the walls or ceilings, where they use steam or hot water to heat, or chilled water to cool the air inside the ductwork., it also calls for a 50% turndown, which again, I am unable to do because of the highly sensitive nature of these spaces.
What is the take on approaching this problem? We often times design buildings that are similar to these spaces and I would hope a 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 could aid in a reasonable precedent being set.
Thank you, all.
Base model minimum efficiencies
Hi,
I have a question about baseline building HVAC minimum efficiency. For instance, system -3 PSZAC, according to ASHRAE 90.1 table 6.8.1 there are different minimum efficiencies requirement, depending on the equipment manufactured year (before 2006 or not). Could the efficiency before 2006 be used for a project to be built in 2012? Thanks.
No it can't.
Home Automation in Multifamily High Rise Residential Project
Dear All,
Would it be possible to claim EAc1 credits for local automation in dwelling units to achieve the following:
(1) Automatic shut down of lighting and HVAC units when there is no occupancy.
(2) Taking advantage of lower electricity tariffs due to smart metering to run appliances at night time?
1. Lighting gets a 10% credit on the room lighting power density (see 90.1 Table G3.2). HVAC occupancy controls would probably require a schedule change so you can get credit but have to follow the exceptional calculation method.
2. Taking advantage of off-peak rates gets tricky since the utility rates in both are supposed to be identical. Just applying an off-peak rate to both models will help capture most but not all of the savings. In order to use a different rate again follow the exceptional calculation method.
How to model chiller for only one wing of an existing building
I am currently working on a LEED v3.0 model in trace 700. It is a historic building originally built in the late 1800s. It has a variety of unique situations that I am unsure of how to model. The project is being renovated in multiple phases. We have received permission to model only the wing that is currently being renovated for our LEED application. An earlier phase of the project installed a chiller to serve the entire building. The chiller is not located within the wing we are modeling and the cooling towers are located across the street where the district heating plant is located. I am using Option 1 (building stand-alone scenario) for the district heating. I would like to model the chiller so I can gain some credit on the plant level. Is this allowed given this situation? If so, how should I model the chiller since it serves the whole building and only a quarter of the building is being modeled?
In similar situations we have been allowed to proportion the load on the chiller associated with the new wing and model that. I think that was a v2 project however. There is a 90.1 provision that says you must model the whole building. So check the interpretations to see if the one we wrote for the project I mentioned above is still in place. If not then you should probably submit a new interpretation request.
Energy Simulation Softwares
Hello everyone,
We are looking for an energy simulation software. Please, could anyone give some feedback about 2 softwares (Design Builder and IES VE-Pro)?
Also, if someone knows about any other software. Could you share, please?
Thanks,
Two very different choices both with strengths and weaknesses. DB runs on Energy Plus and IES runs on Apache (for energy). EP is probably the most robust modeling software but has issues with user-friendliness even with the latest version of DB. EP is US based. I don't have direct experience with IES but it comes out of the UK.
We use eQUEST for most projects. It is free but does not have much technical support.
IES is very robust as well, and has a steep learning curve. It's very good if you have complex systems and/or complex geometry. You can have very detailed HVAC controls. I would recommend using it if you can't model your system in other programs or if you need to squeeze out as many EAc1 points as possible.
Baseline system selection for Laboratory
G3.1.1 exception c stating "For Laboratory spaces with a minimum of 5000 cfm of exhaust, use system type 5 or 7 that reduce the exhaust and makeup air volume to 50% of the design values during unoccupied periods.
Could you please clarify whether this 5000 cfm for individual system or sum of all the system exhaust air?
Please send the link which will have more detailed about this.
Thanks & Regards
Ramesh Narayanan
It is based on the total exhaust for lab spaces in the building. So it is the sum.
Thanks Mr.Marcus. Here this project having both Lab as well as office area. Normally System 3 or 4 has to select for this building (1.e less than 75000 sq.ft and less than 3 floors). Due to exception d for Lab we could select System 5 or 7. Could you please inform me whether the office area can be modeled with system 3. With exception c also the system need to be select system 3 for differ in process load. Pls confirm.
Use the system from Table G3.1.1A for the rest of the building. The exception would only apply to the lab spaces. If any other space qualifies for an exception it can be applied.
Variable Speed Fan Coil Unit
There are more and more companies making fan coil units with VFDA variable frequency drive (VFD) is a device for for controlling the speed of a motor by controlling the frequency of the electrical power supplied to it. VFDs may be used to improve the efficiency of mechanical systems as well as comfort, because they use only as much power as needed, and can be adjusted continuously. motors, automatic variable supply air control rather than traditional 3-speed control, which gives them variable air volume capability similar to the typical VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. system (VAV box/terminal unit). So can variable speed FCUs be treated as VAV systems in the energy model?
Under 90.1, our system should be compared with System 8 VAV with PFP box, but I think it would be unfair to us if we just model it as a constant volume system.
Not sure I understand the question. Model the Proposed as designed and the Baseline according to Appendix G. The Appendix G Baseline system does not change based on the details of the Proposed system.
Well, What I meant is can we call these "variable speed FCUs" a VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. system then?
Because normally when you say VAV it means constant SA air temp fitted with "VAV box", not a hydronic system such as FCUs.........
Normally you would treat FCU as a constant speed CAV system, and it would be disadvantageous to us if this is compared to, in the case of our baseline, a VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. system in the energy model.
So I need to know if we can call our proposed system as a VAV system.
You should model what you have designed in the proposed. How you model it depends on the simulation program. They are all different. In general you cannot model a FCU as a VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. as there tend to be significant differences between the two.
Sounds like you are asking if modeling the variable FCU as a VAV would be an acceptable workaround in the software you are using. If that is correct I would suggest you post your question on one of the simulation software discussion groups at onebuilding.org.
Energy Modeling a Concrete Dome
We are completing an energy model for a concrete dome. We chose the dome structure because it is more energy efficient than conventional building types. This was a design decision. However, we have been told that in the process of energy modeling we are supposed to compare a "dome to a dome". If we have to compare a dome to a dome then we will lose energy efficiency "points". In all fairness, we think we should be comparing a dome to a conventional building type. Please advise.
Unfortunately, ASHRAE does not allow you to get extra credits for the shape of your building when going with the Performance/Energy Modeling approach to energy savings. Your concrete dome will be considered a roof and it's thermal characteristics will be compared to the ASHRAE minimum construction for a baseline roof.
ASHRAE does allow you to take credits for shading provided by your building and allows you to not model that shading on the baseline building.
A dome is not necessarily more energy efficient in operations. As I understand it a dome is simply more material efficient (less materials for a given square footage). So the embodied energy1. Embodied energy is the energy used during the entire life cycle of a product, including its manufacture, transportation, and disposal, as well as the inherent energy captured within the product itself. 2. The energy expended in the process of creating a product, often including the fuel value of its constituent parts as well as transportation to its point of use. can be better. The operational energy depends on many other factors beyond the shape.
LEED 2009 Energy Modeling using HAP 4.3
Is it acceptable to conduct the LEED 2009 Energy Modeling using Carrier HAP 4.3 version?
I read that HAP 4.3 is based on ASHRAE 90.1-2004 whereas in LEED 2009 the reference standard is 90.1-2007..so will there be any compliance issues if HAP 4.3 is used?
HAP is OK. The software does not create the baseline for you, so you'll have to create a baseline based on 90.1-2007.
Yep HAP is fine. It is just the "LEED Report" that HAP generates that is based on the LEED v2 (i.e. 90.1-2004) template reporting.
LEED V2 - NC A Building Housing a CHP Plant for a Campus DES
I have a CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. project that I cannot seem to fit in any one clearly defined compliance path. I have not found a previous LEEDUser discussion that seems to answer my questions.
Our project is a new Campus Utility Plant Building. The building shellThe exterior walls, roof, and lowest floor of a building, which serve to separate and protect the interior from the elements (precipitation, sunlight, wind, temperature variations). is seeking LEED - NC Certification. It is not our intent to certify the Process systems—Boiler Plant, CHP and Electrical Distribution. Our general approach to demonstrate compliance with and percentage energy cost improvement for EAc1, Option 1. Whole Building Energy Simulation is based on an eQuest v3-64 model. As this building obtains all of its electric and thermal energy from AND HOUSES a Combined Heat and Power (CHP) plant for the Campus Thermal Energy system our modeling procedure was guided by the USGBC’s “Treatment of District or Campus Thermal Energy in LEED V2 and LEED 2009 – Design & Construction”, August 13, 2010, and follows the “Performance Path 2 (full accounting)” defined in Appendix D.
It seems clear that the EAp2 &EAc1 Base Case model is constructed per Appendix G. The treatment of the proposed building is not clear to me.
Two questions related to my uncertainty on how to draw the “control volume” for energy flow for our building.
1. How do we allocate CHP electricity to our building? Even though the building obtains all electricity from the CHP, according to Appendix D Page 25, it appears we can only apply the portion of the electricity generated by the CHP that coincides with the thermal heat recovery used in the building. (Track Thermal in eQuest) and the cost of the electricity is the fuel cost for CHP generation of those kWhA kilowatt-hour is a unit of work or energy, measured as 1 kilowatt (1,000 watts) of power expended for 1 hour. One kWh is equivalent to 3,412 Btu.. When we calculate the “allocated CHP electricity “it is less than the electricity required by our building therefor “Scenario A” (page 26). Since in our case, all electricity for the building is CHP generated, the remainder of the electric energy not corresponding to thermal load in the building we also use the cost of fuel for CHP generating the rest of the electricity? If this is our path is there a need to make the distinction?
2. Since it is not our intent to certify the plant, do I include equipment located in the building that does not serve the building? There are 3 LPS boilers (1500 BHP total) and 1 HPS boiler (45s BHP ) that are in the new building to provide heating and process steam to the campus distribution system year round. Can we omit this energy since it is not used in the building? If we do include this energy then we get into the plant efficiency, in essence including the DES system in the certification and that is not our intent.
My 3rd question is to clarify contradictions between the LEED 2009 Reference Guide and the “Treatment of District…” since this document at its publishing was not mandatory.
3. Per “LEED Reference Guide 2009” pg. 268, there is a requirement for EAp2 that the proposed building have a 10% energy cost improvement without the CHP, implying the need for a separate model (parametric run). However, per page 9 of “Treatment of District…” “each project team chooses...” an option “...to show compliance for both EAp2 and EAc1 in a single unified step… under this updated (version 2) DES guidance document, no project team is required to assess both options, nor to model separately for EAp2 and EAc1. This is a substantial difference from version 1 of this guidance intended to simplify the guidance and improve its flexibility” Do I need demonstrate EAp2 compliance?
Obviously LEED was never intended to certifiy a project like this.
I don't think you can exclude the energy consuming equipment in the building. All energy within and associated with the LEED project must be included. Think of it like a manufacturing plant. Since the building uses thermal and electric energy generated within the building you can't really treat the equipment like a process load exclusively however. Perhaps you will need to treat it as both as a source and the majority as process.
You will need to comply with EAp2.
The complexities of your issues, as you probably know, require considerable research and thinking - more than a volunteer like me has time for.
Anyone done a project like this?
I'm working on a project EXACTLY like this. Well, pretty similar. A few thoughts:
1) Re your question #3 - use the latest DES guidance, rather than the 2009 reference guide. You can show prerequisite compliance with either Option 1 or Option 2.
2) model your building as though it was supplied by the DES, but the DES was outside the building. This is actually covered in the definition of "downstream equipmentDownstream equipment consists of all heating or cooling systems, equipment, and controls located within the project building and site associated with transporting thermal energy into heated or cooled spaces. This includes the thermal connection or interface with the district energy system, secondary distribution systems in the building, and terminal units." in the DES guidance (p7).
"Exception: When the building housing the thermal energy plant is itself seeking LEED certification, then the project shall treat the DES equipment as “downstream equipment” for the following prerequisites and credits:
• EA prerequisite 1
• EA prerequisite 2
o Mandatory Measures: The district energy equipment shall comply with all mandatory measures from ASHRAE 90.1-2004.
o Prescriptive Method: The district energy equipment shall comply with any applicable prescriptive requirements
o Performance Method: The district energy equipment shall be modeled as upstream equipmentUpstream equipment consists of all heating or cooling systems, equipment, and controls that are associated with a district energy system but are not part of the project building's thermal connection or do not interface with the district energy system. It includes the central energy plant and all transmission and distribution equipment associated with transporting the thermal energy to the project building and site., NOT downstream equipment. USGBC recommends that such projects use modeling Option 2 (described below).
• EA prerequisite 3
• EA credit 3
• EA credit 4
• EA credit 5"
I am also working on exactly this building type: Central Plant with CW, HW, and electric distribution. No CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source.. I know there have been discussions elsewhere on this forum re: process loads, but our problem seems unique to the building type... must we treat secondary plant equipment for heat rejection (ventilation fans, air conditioning for electric rooms) as a downstream building process load, or can those loads somehow be modeled as virtual downstream loads distributed amongst all connected buildings? The heat rejection process loads account for 60% of the total load in the Central Plant, which negates all energy efficiency measures implemented on the remainder of the building. We are struggling to meet EAp2.
Cooling tower's motor
Cooling tower's performance is covered in 90.1 Table 6.8.1G, but does its motor have to comply with Table 10.8 Minimum Efficiency for Motors?
The efficiency requirements in Table 10.8 are law in the US. It is not legal to make motors with lower efficiencies. So if the cooling tower motor is covered by the law it should be in compliance.
If outside the US, if the cooling tower motor is covered by the motor type in the table then yes it would need to comply.
Exceptional calculation - hot water use reduction in hotel
We're working on a hotel that will have a reduction in hot water consumption throughout the hotel (particularly in the guestrooms, where 2.0 GPM showerheads and 1.0 GPM faucet aerators will be installed). We would like to include the predicted energy savings from the reduced hot water use in the energy model through an exceptional calculation, but no one on our team has used this method on a NC project before (we are currently working on a LEED for Homes Midrise project where the low-flow showerheads and faucet aerators are accounted for in the energy model). I found one LEED NC Interpretation which states, "energy savings for reduced hot water consumption can be counted in DHWDomestic hot water (DHW) is water used for food preparation, cleaning and sanitation and personal hygiene, but not heating. energy calculation," but the interpretation does not specifically mention showerheads or faucet aerators. Has anyone successfully used this exceptional calculation for a NC 2009 project before? Also, would the hot water system need to be downsized in order to use the exceptional calculation, or can the system sizing remain as is since the hotel operator has approved the low-flow showerheads and faucet aerators and has no plans to change them in the future?
Yes, we've had several projects use exceptional calculations for energy savings from lower flow fixtures, but not without some back-and-forth between our modelers and the EAc1 reviewers. ASHRAE 90.1-2007 makes this a little easier as the practice is allowed per Appendix G, Table G-1 Modeling Requirements, section 11. Service Hot-Water Systems, item i, Exception 1:
"Service hot-water usage can be demonstrated to be reduced by documented water conservation measures that reduce the physical volume of service water required. Examples include low-flow shower heads. Such reduction shall be demonstrated by calculations."
(Under ASHRAE 90.1-2004 this language was only added in Addendum A, so some projects following 90.1-2004 got questioned by reviewers; USGBC issued a memo on 4/26/2007 permitting the use of addenda.)
In a nutshell, the calculations should estimate the reduction of hot water volume, not just the total water volume reduction, by excluding cold water use from fixtures. If possible, you may want to align any assumptions with historical data on hot water & energy usage from the local utility. The energy savings are thus demonstrated by reducing the total building process flow input (gpm) for service water heating. In that way you wouldn't have to change the system sizing. Hope that helps.
No need to do an exceptional calculation.
Make sure the calculations are consistent with WEc3.
The reviewer will want to at least see the major assumptions which went into your calcuations including estimations of the percentage hot water versus cold water flow, the delta T of the DHWDomestic hot water (DHW) is water used for food preparation, cleaning and sanitation and personal hygiene, but not heating. system, and the anticipated hot water temperatures at the fixtures. ASHRAE HVAC Applications, Chapter 50 is a good source of information.
Most of the time you will be asked to show your calculations for this strategy but it should not be entered in the form as an exceptional calculation.
heating load unmet hours
in the energy modeling result using HAP, the heating load unmet hours turns out to be 2000, however it shouldn't exceed 300 hours, knowing that our system is chilled water not dx units and the Tstat throttling range =1.
The older versions of HAP counted simultaneous hours, so overstating the total. The latest version fixed that issue.
Thanks Marcus, I am using version 4.5 is there a later version?
I think that is the latest. Sorry I don't know HAP well enough to offer further specific suggestion. Often this issue is related to schedules, most commonly during morning warm, and allowing the fans to cycle during unoccupied periods. At least that is our experience but we use eQUEST.
Check out the HAP Users forum at http://onebuilding.org/
EAC1 Credit Information
Under the credit information website with "Credits, Credit Details, Points, Thresholds" listed. The Path is noted as "12% new/8% existing (1 pt) while our template form notes 10 points documented. Why are these not consistent? Does the owner of the credit have to check the "R 30% new/24%26% existing (10 pts) manually?
I am not sure I understand your question. Please explain the inconsistency. The form automatically calculates the points based on the percentage of cost savings.
Is your project a combination of new and existing? If so the form calculates the appropriate, adjusted thresholds and accompanying points.
The issue resolved its self once the thresholds was selected on the website and the credit was filed as complete. Thank you.
Landscape lighting
Appendix G (Table 3.1) states that lighting power for building facades has to be modeled in the energy simulation. However, it is not clear if landscape lighting should also be taken into account.
Do we have to implement the external lighting of the building grounds (walkways, landscape lighting...)?
Thanks
All energy use within the LEED project boundary must be included.
Landscape lighting should be included within the space lit. If none of the tradable surfaces apply then it is an unregulated, process load and must be modeled identically in both models.
Baseline HVAC Equip Vs. Proposed HVAC Equip
Question:
Does the HVAC system for the baseline have to be the same type as the proposed design HVAC equipment?
(ie. could you use a VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. roof top with electric reheat on the base and for the proposed use geothermal system.)
The Baseline Case is determined by Table G3.3.1 in ASHRAE 90.1 Appendix G. It depends on factors like the building use (residential vs commercial), size (area and number of floors) and heating source (fossil fuel vs electric)
The situation you describe is not possible. An all-electric heat pumpA type of heating and/or cooling equipment that draws heat into a building from outside and, during the cooling season, ejects heat from the building to the outside. Heat pumps are vapor-compression refrigeration systems whose indoor/outdoor coils are used reversibly as condensers or evaporators, depending on the need for heating or cooling. In the 2003 CBECS, specific information was collected on whether the heat pump system was a packaged unit, residential-type split system, or individual room heat pump, and whether the heat pump was air source, ground source, or water source. system gets to compare against an all-electric baseline case, but depending on the size of your building, the baseline case system type would be heat pumps, or VAVVariable Air Volume (VAV) is an HVAC conservation feature that supplies varying quantities of conditioned (heated or cooled) air to different parts of a building according to the heating and cooling needs of those specific areas. with fan powered boxes and electric resistance heating.
VOLTAGE DROP - HIGH-RISE BUILDINGS
The ASHRAE requirement (Prerequisite for LEED) limits voltage drop in feeders to 2% based on demand. So while the ampacity of the cables is well below the allowable maximum, voltage drop becomes the limiting factor in high-rise buildings. The NEC limits the feeders to 3% voltage drop (5% overall).
Can anyone comment on the counter-productive nature of this requirement for cities like New York? The larger feeder sizes in high-rise buildings becomes costly for owners and takes up more space. How is this an energy saving measure?
Energy Modeling: Dome (Design) vs. Dome (Baseline)?
I am working on the LEED Certification of a 23,000sq.ft. concrete "business continuity" dome. It is literally a concrete dome. This building type was selected because it is resilient to hurricane weather and it is also typically more efficient than typical construction types.
The engineer for this project says that in terms of energy modeling he think he should compare a "dome to a dome". Doing so, our demonstrated efficiency is a lot less than if we were to compare a dome to a conventional building type. In my opinion, we should be doing the latter because the decision to use a dome over a conventional building was a design decision. But we do not know what to expect from GBCI reviewers.
Can anyone advise?
Nena,
In ASHRAE 90.1 Appendix G, Table G3.1 Section 5 requires you to use equivalent dimensions for the exterior envelope in the baseline & proposed - I read this as comparing "dome to dome".
Thanks Kim, this stinks because our decision to use a dome over a conventional building was an intelligent design decision and if we have to compare a dome to a dome then we will not be rewarded for it. :(
By the same logic, it could be argued that one should get credit for building a smaller building than originally proposed, or smaller than what could have been built. (or a different use, or in a different part of the world, etc.) It's a slippery slope - pretty quickly we lose track of what 90.1 is trying to measure. That's why 90.1 established ground rules - the line has to be drawn somewhere. In your case, you're stuck on the wrong side of that line.
Modeling PCW Heat Rejection for DES vs. System 5 (DX Cooling)
I am working on a building that supplies process cooling water (PCW) to lab spaces. The PCW rejects its heat through a heat exchanger to the chilled water system from a district energy plant. Therefore, my proposed design would allow a 4.4 COP for electric consumption by the district energy plant (CHW system) serving my building's PCW system. Because of the system pressures, a CHW pump is not required for the proposed design.
How should I model the PCW energy in the baseline design? Because I essentially have DX equipment in the baseline design, could I reference a type of equipment under ASHRAE 90.1-2007 Table 6.8.1C efficiency requirements? Say "Air cooled, with condenser, electrically operated; All capacities; 2.80 COP"?
It's not clear to me which parts of this system are within your project.
You should take a close look at the latest District Energy System (DES) guidance from the USGBC.
If the PCW loop is cooled from the DES, it should be treated the same as any other building cooling loads. What you compare to depends on your DES modeling approach.
Comparing Process Pumping between Baseline and Proposed
I am working on a lab building near the coast where seawater is pumped into the building for use by researchers. The system gets complex, but essentially we are controlling these large "raw" seawater pumps with VFDs to maintain a specified seawater tank level. Additional "filtered" seawater supply pumps are specified with VFDs to maintain a system pressure setpoint near the point of use.
The similar size pumping systems of Appendix G (HHW and CHW) call for constant volume pumping riding the pump curve with a peak power in W/gpm. How would I show savings for our proposed system of variable speed pumping vs. constant speed pumping when a load profile is unknown? Has anyone had a similar building model?
Do I generate an assumed operation for the pumps, one as operating continuously (baseline) and one as partial energy consumption during off-hours (proposed)? What peak power should I use for the baseline pumping (same as proposed or a certain W/gpm)? Please advise, this also would apply to process cooling water pumping on variable frequency drives.
This is a building process load. For LEED, you should model that separately as an Exceptional Calculation Measure (ECMEnergy conservation measures are installations or modifications of equipment or systems intended to reduce energy use and costs.). Provide a narrative explaining your justification for the improvement. You'll need to estimate a load profile based on your best understanding of the use.
At first glance, I think probably you can't take credit for schedule differences, but can take credit for things like motor efficiency, and VFDs. You might want to put together a draft and submit to the reviewers as a LEED Interpretation.
The process cooling loop is different, and I think would be modeled as I indicated above.
LEED 2009 for New Construct, Optimize Energy Perform - EA CR 1
I have two buidings on the same site/project boundry.
Do I model the two buildings as one building? If I did two seperate models I am not sure how I would show this on the LEED Credit Template.
They are both considered major renovations so the % inprovement / point scale is the same for both buildings.
Yes, model them as one building. I recently went through the same scenario. Be sure to read the LEED for Multiple Buildings and On-Campus Building Projects to ensure you are follwing the corret procedures in not only this credit but others.
Also check the MPRs regarding multiple buildings within a single submission.
EAC1 - Day Lighting & Other Lighitng controls input
Hi,
We've only done the mechanical portion for this project but the client assigned to us the EAc1 credits. So, we're just coordinating whatever electrical information we need to complete the form. I asked the assigned engr. for their daylighting and other lighting controls (design/baseline) and he said we could declare "NONE" since there is no credits claimed for this project. By the way, i shared email below for his reasons:
" These were not claimed previously on the T24 due to the fact that the project had beaten T24 requirements by 47% even without lighting control credits. Further, as you implied, the purpose of form EAC1 Table 1.4, is to compare between the proposed and baseline models, so "none" will still be the correct response to the baseline portion of both day lighting and other lighting control credits (as our design portion will only list the claimed credits). I do not have all of the information I need to calculate the effective aperture of the exhibit and classroom areas (where the automatic day lighting controls are located), so I am unable to give you the day lighting control credits at this time".
Is this acceptable or i believed we should provide info under this field and if they don't have any lighting controls, how can they passed their T-24? I'm not a technical person, and just want to clarify.. for every design, is daylighting or lighting controls always included?
Appreciate any inputs.
Regards,
Susan
If it's not in the building, it shouldn't be in the model. If it's not in the model, it shouldn't be on the Credit Form. You should only call out lighting controls beyond what is required by ASHRAE 90.1. In most cases you can't claim credit for occupancy sensors.
Daylight responsive lighting certainly does not become part of every design.
CHP modelling Option 1 question
I think I posted this question on the wrong page beforehand, so I'll post it again here.
We are trying to account for a CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. plant near our project in our energy model. The owners of the plant are very secretive and treat efficiency data as a trade secret, so it appears that we would have to go for the Building stand-alone scenario in the USGBC's DES Guidance (i.e. Option 1).
Looking through the methodology, we would have to model the non-DES parts of the system as per ASHRAE App G. However, according to the guidance, the parts of the building supplied by the DES would have to use a "virtual DES rate", which is derived from the virtual energy rate by multiplying the fuel and electric rates by a weighting factor. I assume that the weighting factor reflects some sort of average CHP efficiency, though the guidance does not explain it any further where those weightings numbers come from.
So far I can make sense out of this, but the last sentence of the guidance for Option 1 states that the same virtual DES-rates should be used as inputs for both the Baseline and Proposed buildings, which is where it gets very confusing. If we use the same rates for both Baseline and Proposed cases, aren't we just modelling the same building as if it didn't have any CHP at all? It appears to be that this approach eliminates any efficiency improvements arising from the use of the CHP plant and we would just be modelling as we would have done without any CHP.
Could anyone help me shed some light on this? Thanks for any help in advance.
You say that the owners "treat efficiency data as a trade secret" so there is no way to know if any "efficiency improvements arising from the use of the CHPCombined heat and power (CHP), or cogeneration, generates both electrical power and thermal energy from a single fuel source. plant" actually exist. Thus, you can't take credit for any efficiency improvements in the plant.
That is how Option 1 is intended to work.
Modeling OA for naturally ventilated space
We have a project that is a parking garage structure. All of the enclosed circulation, storage and restroom areas are provided with natural ventilation via operable windows and no air conditioning systems. However, there are four small rooms (about 140sq.ft. each) used as offices and they are provided with ductless split systems and operable windows for natural ventilation as the ductless systems are not really equipped to take and condition outside air. To show compliance with EAp2 and EAc1 we are planing to model only the areas provided with a/c thus the four offices. I was wandering if anybody had a similar situation where the space is provided with a/c and is relaying on operable windows for natural ventilation and how the outside air is modeled. My appriach is to model the same amount of OA (the minimum required by ASHRAE) in the baselinaand proposed wich would be in accordance with Appendic-G 3.1.2.5. I know is hipotetical, but what other approachcould I take? Would we need an interlock to shut down the a/c unit when the window is opened or do something special from energy consumption stand point?
For the energy simulation you have to model with the baseline mechanical systems also inplace for your design case model. Put the fancoils in as additional with priority 1, baseline system priority 2. The baseline will then kick in when your system does not meet the ventilation or heating cooling requirements. The baselines model's windows don't open.
If you have a naturally ventilated occupied space you should seperately proove that natural ventilation is sufficient (i.e. with a simulation or calculation). you can use the results in the energy simulation for ventilation rates through windows, but watch out that you don't let in too much outdoor air through the windows, else the design case will be more energy expensive.
FYI - check the LEED Minimum Program Requirements. Parking structures are not eligible for LEED Certification.
Baseline Virtual Energy Rate
I am in the process of submitting the LEED templates (2009 NC) for EAp2/EAc1.
The building in question has been modeled using Energy Pro and has calculated a baseline virtual energy rate for natural gas at $28.3098/therm. The proposed virtual rate is $9.4581/therm....much lower.
When a difference > 10% occurs, LEED requires a narrative to explain why.
Bottom line, I have no idea why the virtual rate is so high for the baseline. The building is largely powered from electricity with water heater and some kitchen equipment being served by gas.
Any ideas?
Not sure what your doing, but it is wrong. Typically, natural gas prices are in the +/- $1/therm range. You're off by at least a factor of 10.
I'm guessing you've set up some sort of rate structure that includes a connection fee or similar regardless of usage, and your gas consumption is so low that the connection fee dominates. My advice would be to redo the rate structure to get rid of the connection fee, or provide a detailed explanation to LEED.
ASHRAE compliance with naturally ventilated building
As per the guidelines, my baseline mechanical system is incorporated into the naturally ventilated design case model 1 to 1, as a priority 2 kind of system that kicks in when the naturally ventilated facility does not meet the heating cooling or ventilation loads.
However, the autosizing is currently also on in the design case building and system sizing has shown reduced capacities for the mechanical systems, as expected. Is this allowed or should I manually input the sizing results from the baseline model for coils, fans, pumps etc. In end effect this will not change anything, but I'm not sure what the LEED reviewers will think about it.
Any opinions?
I am using e+
Building Envelope Requirements for Continuous Insulation
We have a project that has structural masonry walls, and interior steel studs. Appendix G requires 7.5 c.i. for our walls, so I have two questions:
1. Can the continuous insulation be located on the interior wall and can it be just spray foam and not continuous board insulation?
2. What is the rule for insulating between floors in this case? Do we have to spray foam in between the steel and CMU between floors?
I don't recal Appendix G specificly requiring a c.i. It does indicate that Steel-framed above grade walls from section 5 are to be used for the baseline model, which allows either a maximum assebly U-value or minimum insulation R-value. I wouldn't worry so much about the c.i. as long as the model meets the assembly requirements.
Showing energy savings in drug manufacturing facilities
Has anyone performed an exceptional alculation to demonstrate energy savings in a drug manufacturing facility for EAc1? We are trying to demonstrate an improvement and savings by lowering the required classification of spaces.. I.E. changing from a Grade A space at 90 fpm requirements to Grade B, C, or D. This can reduce the air change rates drastically. This of course reduces building loads and energy consumption drastically, shrinks the HVAC equipment, and may even reduce the overall building footprintBuilding footprint is the area on a project site used by the building structure, defined by the perimeter of the building plan. Parking lots, parking garages, landscapes, and other nonbuilding facilities are not included in the building footprint. that is required.
Has anyone successfully done this for LEED? Maybe this also falls under the Innovative Category, for shrinking the building footprint? If anyone has any advice to offer, that would be great; example project, resource, website, etc.. This may fall under the realm of process load reduction.
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