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Lower cost strategies come first
Capturing useful energy from natural energy flows like sunshine, wind, moving water is a great concept. The technologies to capture this energy aren’t cheap, however, nor do they work equally well in all locations. Typically, it’s hard to generate a significant fraction of total electricity we use onsite.
Before investing a lot of time and energy into this credit, focus on energy efficiency and passive energy collection such as daylighting, natural ventilation, passive solar heating before investing in renewable energy systems. This work will probably pay off faster than renewable energy, and if you do invest in renewable energy, you’ll have a lighter load for it to carry.
What types of systems count
All electricity generated and used on site is counted towards...
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23 Comments
EAp2 - Table L-1 Rated Capacity for Solar Hot Water
Can someone help me understand what to put for "rated capacity" for a solar hot water system? I have the report from the modeling of the system (from Polysun), and I have the SRCC rating for the collectors. Neither of these reports gives me any sort of "rating" as a single value to put into Table L-1 for EAp2. Suggestions?
Rated capacity for PV is kW at rated conditions.
For solar hot water this should likely be the total kBTU of the system at rated conditions.
Off site renewable energy??
Hi, I have the following question: a company that is pursuing LEED certification. Owns a low impact renewable energy plant, but this plan, that is a pass hidraulic plant on a river, is off-site. This cannot be declared as Green Energy since there is not necessary to have a contract with a third party to use the energy, but it is not on-site energy either. Could we account for this energy on this credit? it meets the intencion but is not part of the project even though it will provide all its energy to the LEED building making the proyect offset its energy costs.
Is there a direct line from the plant to the building or does the power go through the grid? If there is a direct line you may be able to make a case.
EA c2 Onsite Renewable output better than projected
ANyone have a precedent that allows the use of the increased real output to close a gap for a second point? We are 0.15% shy of the 7.5% mark after completing the end of project final energy model. Credit EA 6 allows the use of actual electricity used to extrapolate for the total Green Power to be purchased, we want to do the same for the On-Site renewables...
Only projects who do not do an energy model for EAc1 can use the CBECSThe Commercial Buildings Energy Consumption Survey (CBECS) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures. Commercial buildings include all buildings in which at least half of the floorspace is used for a purpose that is not residential, industrial, or agricultural, so they include building types that might not traditionally be considered "commercial," such as schools, correctional institutions, and buildings used for religious worship. CBECS data is used in LEED energy credits. method. Logic would indicate that if you did not do an energy model for EAc1 you could use the actual data. But since you did do one I think you have to use it for EAc2.
Thank you - that is my interpretation also, just hoping for a Hail Mary...
Calculating Percent Relative to Energy Cost versus Consumption
The reference guide indicates that the LEED points are awarded based on providing renewable energy for 2.5% or 7.5% or 12.5% of the annual energy cost, not consumption.
Since the cost rates for various energy sources (including renewables) that comprise a project's total portfolio of energy are likely different, what is the methodology for determining the percentage contributed from renewables?
For example,
IF in the baseline case without any energy from renewables, the annual energy cost for 1,000,000 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. at $0.06/kWh is $60,000
THEN if the rate for renewables were $0.08/kWh, the cost for providing 2.5% of the quantity of energy from renewables would be $2,000 or 3.3% of the overall baseline cost. The cost for 7.5% from renewables would be $6,000 or 10% of the baseline. The cost for 12.5% from renewables would be $10,000 or 16.7% of the baseline.
If this method is correct, wouldn't it favor situations where the rate for renewables is higher than that for energy from non-renewable sources that have a lower rate per unit of energy?
In the examples I've seen before, it appears the calcuations have been done based on energy consumption, or else calculated on cost assuming the unit rates were equal for energy from renewable and non-renewable sources.
Clarification or confirmation would be appreciated.
Thank you!
The LEED v2.2 Reference Guide tells you what rate to use on page 207. Basically you use the virtual rate from the energy modeling results. So the rates are essentially the same for renewable energy since the "savings" are often simply the avoided energy cost.
Synergy with EAcr6: Green Power and EAcr1: Optimize Energy
In conducting a cost-benefit analysis for a client considering a 20KW PV array, I was reading the small print in EAcr1 Exceptional Calculation Method, and it seemed that onsite renewable energy is factored into the proposed energy performance calculation reducing the annual energy costs of the project. In turn, this means that the client would need to purchase less Green Power to earn EAcredit 6. Does a PV system have this synergy with both of these credits. There are an exorbitant amount of credit between these three credits, and it seems like triple dipping, although the language seems to back up potentially gaining points in all of these credits from installing a PV array. If so, can I calculate the energy savings in EAcr1 using the exceptional calculation method even if there is an Energy Model? It seems to good to be true, I appreciate any insight, and I am curious if this exception is new to 2009. Thanks!
No need to use the exceptional calculation method for renewables. Fill in section 1.6 in the template for EAc1.
A PV system counts in EAc1, obviously contributes toward EAc2 and reduces the amount of green power purchase necessary for EAc6.
This synergy has been available in LEED prior to the release of LEED 2009. LEED is purposly structure to give the maximum credit for rnewable energy systems to encourage projects to install them.
Using the DOE CBECS Table
Under Option 2 for On-site Renewable Energy, what is the best method to determine the average electrical energy costs using the CBECSThe Commercial Buildings Energy Consumption Survey (CBECS) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures. Commercial buildings include all buildings in which at least half of the floorspace is used for a purpose that is not residential, industrial, or agricultural, so they include building types that might not traditionally be considered "commercial," such as schools, correctional institutions, and buildings used for religious worship. CBECS data is used in LEED energy credits. tables if there is no histrocial data. The project is a historical renovation and addition on a building that was constructed in 1935, has seen several owners, numerous tenants, and has been essentially vacant for the past three years. Obtaining the past annual energy bills has been unsuccessful and I am unclear as to what numbers I should be using to determine the average electrical energy costs under CBECS.
For example, if I choose to use the Bulding Floorspace Category, at 7,875 sf, the electricity expenditure would be estimated at $8,700 annually. If I where to base it off of the year constructed, 1935, the electricity expenditure would be estimated at $10,300 annually. Is it a combination of all categories, or is there more clarification within LEED regarding the CBECS table that I am unaware of?
I have attched the CBECS link that I am using below
http://www.eia.doe.gov/emeu/cbecs/cbecs2003/detailed_tables_2003/2003set...
Great question... I have been wondering the same thing. I'll let ya know if I find the answer. I don't think too many people use the CBECSThe Commercial Buildings Energy Consumption Survey (CBECS) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures. Commercial buildings include all buildings in which at least half of the floorspace is used for a purpose that is not residential, industrial, or agricultural, so they include building types that might not traditionally be considered "commercial," such as schools, correctional institutions, and buildings used for religious worship. CBECS data is used in LEED energy credits. because I am pretty sure that you will wind up with a lesser % than if you use an energy model. Out here in California, "T24" has been requiring an energy model for years, so everybody has to do one regardless of LEED.
The CBECSThe Commercial Buildings Energy Consumption Survey (CBECS) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures. Commercial buildings include all buildings in which at least half of the floorspace is used for a purpose that is not residential, industrial, or agricultural, so they include building types that might not traditionally be considered "commercial," such as schools, correctional institutions, and buildings used for religious worship. CBECS data is used in LEED energy credits. data to use is contained in the LEED Reference Guide. Refer to the tables on page 206.
Also the use of the CBECSThe Commercial Buildings Energy Consumption Survey (CBECS) is a national sample survey that collects information on the stock of U.S. commercial buildings, their energy-related building characteristics, and their energy consumption and expenditures. Commercial buildings include all buildings in which at least half of the floorspace is used for a purpose that is not residential, industrial, or agricultural, so they include building types that might not traditionally be considered "commercial," such as schools, correctional institutions, and buildings used for religious worship. CBECS data is used in LEED energy credits. data is really intended for projects that do not perform energy modeling. If the energy modeling is performed accurately and the building is designed to be energy efficient, the predicted performance should be better than the CBECS data. The CBECS data is the average consumption of existing building stock. Hopefully if you are building a green, LEED building your performance should be significantly better than that average. So this credit is typically easier to achieve using the modeled data than it is using the CBECS data (as Andrew points out).
SRECs
If a PV system is to be hosted by a 3rd party, and taking the info from CIRs dated 8/21/2009 and 5/16/2006, this would indicate the Building Owner would just need to purchase 100% of SRECs equivalent to the system’s annual rated energy output and there needs to be a 10 year contract in place for this purchase? Can the SRECs be purchased from out of state?
Second scenario - what if the developer installed their own PV system and sold the power to the only tenant in the building. Can they still sell the SRECs in state? Would they have to purchase 100% to offset the sale in order to comply (purchase from from an out-of-state source, which would be Green-eGreen-e is a program established by the Center for Resource Solutions to both promote green electricity products and provide consumers with a rigorous and nationally recognized method to identify those products. eligible)?
Any clarification would be greatly appreciated! :)
If system is hosted by 3rd party, GBCI says: "It has been determined that the project can achieve EAc2 by purchasing a total amount of RECs equal to 100% of the system’s annual rated energy output. There must be at least a 10-year contract for the purchase of the energy output. This 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 supersedes the 200% requirement set by the CIR Ruling dated 5/16/2006."
As per LEED 2009, out of state RECs have to be 200% of the energy output.
For the second scenario, is this a LEED Core and Shell project? The tenant can claim the credit.
Could anyone clarify the following statement:
"It has been determined that the project can achieve EAc2 by purchasing a total amount of RECs equal to 100% of the system’s annual rated energy output. There must be at least a 10-year contract for the purchase of the energy output. "
1)Does the 10-year contract apply to both the REC and energy output purchases?
2)If a system is larger than needed for the project requirements for LEED credit, is it okay to only purchase the RECs for the amount needed for the credit? Or does the purchase of the RECs and the purchase of the enegy output both have to be for 100% of the system output?
Thanks!
Hi Michelle
1) The 10-year contract is for RECA Renewable Energy Certificate (REC) is a certificate representing proof that a given unit of electricity was generated from a renewable energy source such as solar or wind. These certificates are able to be sold, traded, or bartered as environmental commodities, where an electricity consumer can buy the renewable energy attributes of electricty to support renewable energy, even if they are consuming generic grid-supplied electricity that may be supplied by nonrenewable sources. purchase by the project.
2) It is OK to purchase REC amount for partial system output to get LEED credit. However, we would recommend you purchase for all of the output because the credit is not very clear about it. The review may go either ways if you purchase limited amount.
I am working on a 60-unit
I am working on a 60-unit multi-family project under LEED NC v2.2 in which we utilized solar thermal/domestic hot water systems. The project involves the installation of 60 4x8 AET flat plate solar collectors. The system includes 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. meters to verify the level of energy generation over the course of the year. Each solar collector is connected to the electric hot water heater in each of the individual residential units. The solar thermal system pre-feeds the system with hot water. The solar panels will provide approximately 80% of the year-round energy required to supply domestic hot water for the tenants. The electric hot water heater will provide the remaining 20%. The AET collectors used generate an average of 700 BTUs per square foot of panel space per day. On days with favorable weather, each panel will generate approximately 32,000 BTUs. The panels are mounted south facing at a 35 degree angle.
Variables:
Renewable Source: solar thermal/domestic hot water
Backup Energy Type: electricity
Annual Energy Generated: 144,888 kWhr/yr
Rated Capacity: 32,000 BTUs per day per panel
Renewable Energy Cost: $19.50 per million BTUs
Totals: 494,357 kBTUs/y
That's probably a lot more information than I needed to elaborate on for my question, but I figured I'd give as much detailed information as possible to get the right help. My question is relative to the template itself: what specific values need to be input into the boxes for 'Rated Capacity' and 'Renewable Energy Cost'? And, how do I calculate those values given the variables I currently have at hand.
William, maybe I'm not thinking this through enough, but it seems like you've answered your own question—you have the rated capacity and RE cost variables, no?
Yes and no. I have all the variables I need to make the necessary calculations to answer the question. What I'm uncertain on is the specific units of measure for each. The template is looking for a single numeric value - for rated capacity, is this in BTUs, KBTUs, MBTUs or do I need to convert over to kWhr? I'm assuming also that they are looking for annual rated capacity and cost, but the template does not specify this either. It's a simple clarification that I need, but it obviously has an enormous impact on the final percentage that the template generates from your inputs.
William
you are right, all units have to be consistent across these items. You can select the units in 'annual energy generated' drop down menu.
If you decide to input the energy generated in 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., then convert the rated capacity to kWh, using conversion factor of 1 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. = 0.000 293 071 083 33 kilowatt hour.
The energy cost is 'Annual energy generated' x 'energy cost in Kwh/kWh'. Your $19.5/million BTU cost is approx $0.0057/kWh.
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