The intent of this credit is to reduce the amount of potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. used for flush fixtures and to minimize the amount of wastewater conveyed to the municipal system. For credit compliance, you have two options:
Option 1: Reduce the quantity of potable water used for flush fixtures (water closet and urinals only) by 50%. You have two ways to make this reduction:
Option 2: Treat 50% of wastewater onsite to tertiary standards and infiltrate it, or reuse the treated wastewater onsite.
To determine your percentage reduction, compare a baseline case with the design case. Note that the baseline for WEc2 is not the same as the baseline for WEp1 and WEc3: Water Use Reduction. Whereas WEp1 and WEc3 count flow (shower, lavatory and kitchen sink) and flush fixtures (toilets and urinals), WEc2 only counts toilets and urinals. The data that you enter on flush fixtures in the LEED Online credit form in WEp1 will automatically populate the credit form for WEc2.
The calculations for wastewater use are based on the number of full-time equivalentFull-time equivalent (FTE) represents a regular building occupant who spends 40 hours per week in the project building. Part-time or overtime occupants have FTE values based on their hours per week divided by 40. Multiple shifts are included or excluded depending on the intent and requirements of the credit. (FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories.) occupants. FTE calculations can sometimes be confusing in certain building types or occupancy types—see WEp1 for more information.
Generally, the easiest and cheapest way to achieve this credit is to install low-flow and waterless fixtures. Using waterless urinals or pint-per-flush urinals in combination with ultra-low-flow toilets (1.0 gpf) or aggressive, dual-flushA type of water-saving toilet that gives a choice of flushes depending on the type of waste solid or liquid. toilets (1.28/0.8 gpf) can work, although it depends on your project occupancy and will need to be verified for each project.
If your project comes up just a little short, consider supplementing some of your potable water use with graywater or rainwater, or installing composting toiletsComposting (or Nonwater) toilet systems are dry plumbing fixtures and fittings that contain and treat human waste via microbiological processes..
Onsite wastewater treatment has a number of environmental and educational benefits, but treating to tertiary standards can be challenging for some projects, especially if they have limited space. The Solaire, a LEED Gold market-rate apartment building in Battery Park City in Manhattan, located wastewater treatment facilities in the basement because above-grade space was at a premium.
Treating to tertiary standards involves extra filtration or biological activity to remove nutrient pollutants such as nitrogen and phosphorus, and it may also involve disinfection. Treating wastewater to this level goes beyond code in most places. Consider technologies that are passive or low-tech in order to minimize operation and maintenance costs.
Once the wastewater has been treated to tertiary standards, you’ll need to determine the best reuse method. Many projects prefer to use it landscape irrigation. This will generally be your cheapest and easiest reuse method. If your project doesn’t have landscaping, consider reusing the treated wastewater for toilet flushing.
Office—In order for office spaces or other buildings to meet the credit through fixtures alone, they will most likely need to include waterless urinals. (Depending on your project, one-pint-flush urinals may work.)
Multifamily and Hotel—Residential and hotel projects, which don’t have urinals in private bathrooms, cannot meet this credit with low-flush fixtures alone, so they have to provide nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. or treat wastewater on site to earn the credit.
The WEc2 calculations are based on the annual generation of blackwaterBlackwater is wastewater containing urine or fecal matter that should be discharged to the sanitary drainage system of the building or premises in accordance with the International Plumbing Code, or sewage, from flush fixtures as documented in WEp1. Note that the scope is not the same as WEp1, which includes both flush and flow fixtures.
Yes, per LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. #10012 made on 05/09/2011, "projects may only count future infrastructure such as reclaimed water systems so long as they will be completed and functional within 1 year." Anything further out than one year may not be counted, however.
Check for local or state incentives for water conservation, which can make this credit more feasible. Rebates are common. Also, some municipalities offer treated wastewater to buildings, which may be used for toilet flushing (although in most places it is restricted to landscape use).
Perform a water-balance study for the entire project in order to make an informed decision about where to focus your water-saving efforts. Survey your project and site for all water sources—stormwater, graywater, and onsite wastewater.
Calculating irrigation water use is not required for this credit; however, understanding how indoor water use compares to outdoor water use can help you gauge where to focus your reduction efforts for the greatest benefit. Some water-saving strategies address both indoor and outdoor water needs holistically. For example, if you treat your wastewater onsite, you can use the treated water to irrigate your landscape as well as to flush toilets. Doing so can contribute to either WEc1: Water Efficient Landscaping or WEp1 and WEc3: Water Use Reduction.
Establish goals for indoor and outdoor water and wastewater reduction. You may want to include those goals in the Owner’s Project Requirements for EAp1: Fundamental Commissioning and EAc3: Enhanced Commissioning.
Consider reducing potable wastewater use by 100%, or treating 100% of your wastewater onsite to tertiary standards, for an Exemplary Performance point.
Determine which option is best for your project:
Some municipalities requiring rainwater capture to reduce stormwater runoff; if this is the case in your area, consider reusing the rainwater for toilet flushing.
Reusing graywater or rainwater incurs additional costs and requires dual plumbing. If you use an under-sink graywater system that shunts the water directly from the sink to the toilet, this also involves additional cost but may be less expensive than a centralized, dual-plumbed system.
Onsite wastewater treatment costs vary widely. Treating to tertiary standards, as required by this credit, can cost significantly more than treating to secondary standards.
Determine if composting toilets or waterless urinals are appropriate for your project. While not common, waterless fixtures can go a long way toward achieving this credit. Composting toilets do affect programming and layout, however, so be sure to consider them early in the planning stages. However, projects often find that installing only a few composting toilets can help them to achieve this credit while offering a great educational asset.
Check with the local municipal wastewater department to see if reclaimed water is available as a source of non-potable water for toilet flushing. If it is available, this will contribute to compliance with Option 1.
Check for codes that may limit your options or force you to obtain a variance. Plumbing codes often restrict or regulate the following water-saving technologies:
Determine your project’s baseline case wastewater generation. This will help you develop your strategy for reduction.
When using the LEED Online credit forms, you need to complete the WEp1: Water Use Reduction—20% Reduction credit form first. Doing so automatically generates your baseline-case usage in WEc2. (See WEp1 for details on determining occupancy, usage, and FTE.)
Reducing your shower or sink flow rate will not help with credit compliance for WEc2 but, will help with WEp1 and WEc3. However, if your project is earning this credit through treating wastewater onsite, it is best to reduce the total quantity of water being treated. Therefore, a reduction in flow fixtures will minimize the total water needing treatment.
Begin developing your strategy for wastewater use reduction based on the option you’ve selected. Research low-flush fixtures, water reuse, and onsite treatment.
Well and pond water are not considered non-potable water for the purposes of this credit and must count as potable water—so you won’t get credit for substituting them for conventional water sources. Water types that do count as non-potable are: graywater (lavatory, sink, and shower water), rainwater, treated wastewater, air-conditioner condensate, reverse-osmosis reject, and sump-pump water.
Consider monitoring wastewater reduction in conjunction with EAc5: Measurement and Verification.
Consider installing permanent water metering for ongoing monitoring of the project’s water use. A submetering system can help operations staff detect problems early and facilitate future LEED-EBOM certification.
Select water-efficient flush fixtures and determine the percentage of reduction from fixtures alone.
Consider the different maintenance requirements for waterless fixtures. Waterless urinals and composting toilets require a different maintenance program from conventional fixtures.
Remember that this credit is based on EPAct 1992 and subsequent rulings of EPAct 2005, the 2006 Uniform Plumbing Code, and the International Plumbing Code. The baseline case for this credit includes these standards:
Track and record information on applicable fixtures, including the manufacturer, model number, and flush or flow rate. This will help you when filling out the LEED Online credit forms. Fill out the LEED Online form early in design simply as a draft to determine if you are meeting the requirement.
Typically, a dual-flush toilet—with the heavy-flow at 1.6 GPF and low-flow at 0.8 GPF—does not meet the credit requirements. However, a 1.0 GPF ultra-low-flow toilet or a 1.28/0.8 GPF dual-flush toilet—in conjunction with waterless or pint urinals—will meet the credit requirements, and you can avoid using non-potable water. For occupancies that do not use urinals, such as residences or hotels, you will not be able to meet this credit through the use of fixtures alone and you’ll find that you have to include non-potable water reuse in your water reduction strategy.
If you cannot meet the credit through the use of fixtures alone, determine how much non-potable water you need to use in order to comply.
Review your water balance study and determine what water reuse would be most appropriate for your project. If the building is residential or a hotel, it might be best to treat and reuse graywater from laundry or shower facilities. If the building is located in a rainy climate, you can capture and reuse rainwater.
If needed, size graywater and rainwater systems to satisfy the credit requirements. Sizing these systems can be more complicated than you might initially think. It’s best to involve a civil engineer or someone familiar with these systems.
Untreated rainwater and graywater may corrode plumbing systems or lead to biological growth. You should plan for water treatment and filtration, or use corrosion-resistant materials. All graywater plumbing and storage must be separate from regular sewage plumbing.
If you will be using graywater, rainwater, or treated wastewater, you’ll need dual plumbing for interior water fixtures. Communicate this need to your civil and plumbing engineers. You should also discuss any location and structural issues if your project is going to have a rainwater cistern—sometimes they take up more space than anticipated.
A dual plumbing system and rainwater or graywater reuse are likely to add upfront costs but the owner may recoup some of that cost in reduced water and sewer charges. However, most current utility rates for water and sewer are too low to justify these systems on a cost basis alone.
Typically, dual-flush and composting toilets have a higher cost over conventional fixtures but reduce water charges. Some ultra-low-flow toilets have a cost premium as well, but it is typically not as significant as a dual-flush or composting toilet.
Compare the baseline and design case water budgets to determine the water reduction percentage for your project. The LEED Online credit form has a built-in calculator to facilitate this calculation. Repeat this process until selection of water fixtures and strategies is finalized and your project’s water reduction goals have been met.
Even if you are attempting Option 2, you will want to select water-efficient fixtures, which minimize the quantity of wastewater treated onsite. To accomplish this, target the most consumptive fixtures to achieve the greatest water reduction, but keep in mind the very different maintenance requirements for waterless fixtures. See WEp1 and WEc3: Water Use Reduction for more information. Also, review the Option 1 steps of this credit.
Determine what type of onsite wastewater treatment is most appropriate for your project. Typical septic-tank-and-leachfield systems used in many rural areas where there are no sewer systems do not treat water to tertiary standards so they can’t be used to earn this credit.
Verify that your onsite wastewater treatment system is capable of treating the wastewater to tertiary standards. State governments determine exactly what constitutes “tertiary treatment” based on allowable remaining levels of certain nutrients and organisms. Your civil engineer will need to be in charge of this determination.
Determine how treated wastewater will be used onsite. It must either be reused, such as for toilet flushing or irrigation, or must be infiltrated onsite.
Treating wastewater simply for sewage conveyance can be expensive, so make the most of tertiary-treated wastewater by using it for as many non-potable water applications as possible—irrigation, toilet flushing, and cooling tower makeup water.
While the capital cost of wastewater treatment is a significant deciding factor, seek technologies or strategies that have low maintenance requirements to keep operations and maintenance costs low. Alarm systems for malfunctioning wastewater treatment systems can be expensive, be sure to research this.
Depending on the technology used and state or local regulations, tertiary wastewater treatment may require contracting with an outside company for operations and maintenance. When researching treatment technologies, inquire about maintenance procedures and requirements.
Include any low-flow or waterless fixtures, water reuse systems, or onsite wastewater treatment systems in your construction and design development documentation.
Be certain that the contractors reviewing construction documents understand the purpose of any dual-plumbing system in the plans. Misunderstandings about plumbing can lead to costly and unsanitary mistakes—like cross-connection with potable water lines.
Consider including signage for water reduction strategies that may require special instructions for use. These may include: occupant signage for operating dual-flush toilets, waterless urinals and composting toilets, and for indicating non-potable water—and operational signage for distinguishing the pipes that carry reused water. Purple piping is commonly used for reclaimed water and, more recently, for recycled graywater.
If reusing graywater or rainwater, or treating wastewater onsite, ensure that the key system components, such as treatment and collection facilities, are not eliminated during value engineering.
Fill out the LEED Online credit form. The total calculated flush-fixture water-use for the baseline and design cases will be automatically generated once the WEp1 credit form is filled out. You will need to provide information on annual reused water amount and, and if necessary, plumbing drawings or calculations illustrating that your non-potable water systems are capable of supporting the quantities determined.
Fill out the LEED Online credit form. The total calculated flush-fixture water-use for the baseline and design cases will be automatically generated once the WEp1 credit form is filled out. You will need to provide information on the blackwater source (toilet or urinal), annual quantity treated, annual quantity infiltrated onsite, annual quantity reused onsite, and plumbing drawings or other documents that detail information about the onsite treatment, infiltration, and reuse capabilities of your project.
Be sure you’ve included startup of a wastewater treatment system in contract documents and scope of services. You may want the commissioning agent to look at the wastewater treatment system too.
The contractor needs to verify that the correct fixtures have been purchased and that applicable water reuse or treatment systems have been installed properly.
Be sure to use purple pipes or otherwise clearly label supply pipes carrying non-potable water. This practice avoids inadvertent cross-connection with potable water lines and provides educational value.
When using an innovative wastewater treatment system unfamiliar to local regulatory officials, include them in regular construction inspections. This often helps to ease acceptance, and avoid unexpected objections or problems.
Apply for water-reduction incentives and rebates through your municipal water authorities.
Provide building managers with manuals for all water fixtures, water reuse technologies, onsite water treatment systems, and unconventional products used.
If a submetering or ongoing monitoring system is in place, be sure to track and record monthly use. This can help detect problems, contribute to a comprehensive M&V plan, and help with LEED-EBOM certification.
Train cleaning and operations staff to maintain atypical fixtures such as waterless urinals, composting toilets, and graywater collection and rainwater catchment systems.
Some wastewater treatment systems require trained personnel to operate them.
Excerpted from LEED 2009 for New Construction and Major Renovations
To reduce wastewater generation and potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. demand while increasing the local aquifer recharge.
Reduce potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. use for building sewage conveyance by 50% through the use of water-conserving fixtures (e.g., water closets, urinals) or nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. (e.g., captured rainwater, recycled graywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area., on-site or municipally treated wastewater).
Treat 50% of wastewater on-site to tertiary standards. Treated water must be infiltrated or used on-site.
Specify high-efficiency fixtures and dry fixtures (e.g., composting toilet systems, nonwater-using urinals) to reduce wastewater volumes. Consider reusing stormwater or graywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area. for sewage conveyance or on-site mechanical and/or natural wastewater treatment systems. Options for on-site wastewater treatment include packaged biological nutrient removal systems, constructed wetlands and high-efficiency filtration systems.
This website offers a plumber’s perspective on many of the major toilets used in commercial and residential applications.
This site provides two reports on independent test results for a variety of toilets’ flush performance and reliability.
ARCSA was founded to promote rainwater catchment systems in the United States. The ARCSA website provides regional resources, suppliers, and membership information, and publications such as the Texas Guide to Rainwater Harvesting.
This manual provides a focused and performance-based approach to on-site wastewater treatment and system management. It also includes information on a variety of on-site sewage treatment options.
WaterSense is a U.S. Environmental Protection Agency program designed to encourage water efficiency in the United States through the use of a special label on consumer products. It was launched in 2006. The WaterSense website offers information on certified products, and other water conservation information from its partners.
The LEED Online credit form offers a useful calculator for this credit that we recommend. The scenarios shown in these sample calculations show how this credit can play out with percentage savings based on fixture selection alone.
The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 WE credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.
Version 4 forms (newest):
Version 3 forms:
These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictions on these forms; for more information, visit LEED Online and click "Sample Forms Download."
Documentation for this credit can be part of a Design Phase submittal.
The Mechanical and Plumbing engineers working on our project have provided us with the capacity of the rainwater tank as well as the volume of captured runoff in a 2 year 24 hour design storm (cf/storm) (needed for SS credit 6.1)
My question is, which methodology should be used in order to compute the annual captured rainwater and deduct it from the calculated flush fixture water use annual volume ?
The engineer should be able to provide an expected amount of annually captured rainwater based on rainwater data and the rainwater management plan.
Has LEED set in precedent for rainwater harvesting efficency rates? My research has shown to assume you will actually capture 60%-90% of your potential rainwater harvest. But 60-90% is quite a range. Any thoughts on the norm or what GBCI would consider acceptable?
Thanks in advance!
I think the range is so wide because it depends a lot on your system—what kind of roofing or collection surface, how it's collected, etc. Is there someone designing your system who can provide input?
Does anyone know if it is possible to pursue both option 1 & 2? I am working on a project that is treating 100% of it's waste water on site via a spetic tank and leech field AND is also using low-flow fixtures and flushing with only captured rainwater and cooling condensate water. So can we purse both options? And exemplary preformance? Any thoughts on the best approach to this to get the max points?
Perhaps purse option 1 under the credit and take exemplary preformance for it. Then apply for an ID credit for our waster water system?
You're going to be able to earn three points here—or four if this is an RPc1 credit in your zipcode.
You can use one or both options to earn two points through credit compliance, and then one Exemplary PerformanceIn LEED, certain credits have established thresholds beyond basic credit achievement. Meeting these thresholds can earn additional points through Innovation in Design (ID) or Innovation in Operations (IO) points. As a general rule of thumb, ID credits for exemplary performance are awarded for doubling the credit requirements and/or achieving the next incremental percentage threshold. However, this rule varies on a case by case basis, so check the credit requirements. point via IDc1.
Does this answer your question?
No RP credits because this an international project. Yes I think I will just use option 1 for 2 pts plus 1 EP point. I was just asking about gettin more points because we are also doing option 2 (treating 100% of wasterwater and infiltrating on site). Perhaps I can take the 3 pts and apply for and ID for pt. for option 2? But I'm pretty sure you can only get 1 ID point per credit. I just feel like we should get more points since we are meet both options 1 & 2 100%. And really both have very measurable positive environmental effects.
Nelina, I think you'll be happy to read this news that RPc1 is available for international projects. There's your fourth point for WEc2!
We are flushing with captured rainwater AND on site septic, attempting to go for two points and an EP. However I am unable to select both option 1 and option 2 simultaneously. Is there any trick to overriding the template?
I have a Project where the land field has very little infiltration and naturally rainwater runs off to the sea. There is no municipal sewer, but water will be treated. Is it possible to obtain this credit by treating the water and not infiltrating it? Instead treated water goes to the sea.
Interesting situation. This seems to be not possible according to the credit language, but I could imagine it being possible, in theory, if you're able to make a case that it's not environmentally damaging in any way, and meets the same credit intent. Do you think you have a shot at doing that?
Yes, I think it might be possible. The only downside that I see is mixing potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. with sea water. Even though it is the natural hydrology of the location, theoretically by doing that I would be reducing the potable water source, (though I´ll try anyway).
The intent of the credit is to “reduce generation of wastewater and potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. demand, while increasing the local aquifer recharge.” I think that what you are doing with wastewater is interesting and does have environmental benefit, but it may not meet the credit intent because your are not reducing potable water demand. If you are, make sure to explain this in your narrative very well and back it up with solid calculations. You may be indirectly recharging the local aquifer by discharging to the sea and could potential make this reasoning if you were able to back it up with some hydrologic cycle information specific to the site. Seems like a long shot....maybe consider an Innovation credit for which you'd need to demonstrate environmental benefits convincingly. Regardless, it's a beneficial strategy as long as quantities of treated water released to salt water is not excessive--as you point out it occurs naturally.
If we use non-potable recycled water supplied by local government, can it be eligible for the point?
The recycled water is still not available for the whole country (Singapore) now, but in next few years, it may be available for all areas.
Thanks and regards,
Yes, municipal treated wastewater is one of the options for this credit.
total daily uses # of FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories. is 3. residential is 5.
3 = (1 full + 2 low)
within 5 uses for residential, how many is full, how many is low?
Direction on this is not included in the reference guide, so I would use a reasonable estimate and explain it. With 5 total uses, I would estimate 2 full, 3 low. You might try 4/1 but that could be viewed as gaming the credit; 3/2 is a little more cautious and reasonable.
My question is in regards to calculating the cistern capacity to reduce sewage conveyance. When completing the LEED letter template, is it based on the capacity of the cistern or the collection of rainwater over a year?
I'm looking at the LEED-2009 WEc2 LEED Online form, and it asks for "annual quantities" of captured rainwater, recycled graywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area., etc. So it seems to be looking for a quantity of water, not a cistern size. Which makes sense, because LEED wants to know how much potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. you're replacing—the system capacity you use to do it is of less interest.
Tristan, you are correct on that, but in regards to this question, If the cistern does not have the capacity to capture all this rainwater, the rest of the water is going to be lost and not able to replace some of the potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. for the flush systems. In our case we have an annual rainwater of 869kGal, but the cistern capacity is around 17kGal. Therefore tecnically the annual "captured" rainwater should be calculated in some type of spreadsheet based on the capacity, is that correct? If that's the case, does anybody know of a spreadsheet where we can calculate this?
Victor, it sounds like what you need is the help of an engineer who has developed an appropriate calculation method. I'm not aware of a spreadsheet out there that can do this for you—or if there is one, I would imagine that it requires some expertise to use.
regarding this credit it is required to (Option 2) to treat 50% of wastewater on-site to tertiary standard. In Vietnam we have different standard for wastewater treatment for different purpose. One of these is treat the sewage treatment water from effluent for irrigation (tertiary). However the limit of the parameter such BOD5 and TSSTotal suspended solids (TSS) are particles that are too small or light to be removed from stormwater via gravity settling. Suspended solid concentrations are typically removed via filtration. are higher than the ones indicated in the "Definitions" paragraph for tertiary standard treatment since we are in Vietnam. Do you think we can still apply for this credit?
Given that this is an international project, I strongly suggest that you submit an inquiry to your LEED reviewer. Theoretically, the LEED standards are to be applied consistently throughout the world as it's adopted in other countries. However, this may be infeasible in certain cases but only GBCI can make that determination. My bias would be to agree with you because the water is treated to tertiary standards of the local governing agencies for the intended use (landscaping) and as long as you meet the overall goal of treating 50% of wastewater on site and reuse it or let it infiltrate you meet the intent of the credit, and this reuse would also contribute to WEc1.1 and 1.2, if you use no potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. for irrigation.
Do septic systems count as on-site wastewater treatment? Our automotive dealership project will treat 100% of their wastewater via a septic system. Floor drains in shop areas will go through an oil/water separator and then into an underground collection tank for later removal by a tanker truck.
Septic systems do count as on-site wastewater treatment, however, for WEc2 purposes you still need to reduce potable waste water quantities for flushing by 50% through standard methods like waterless and ultra-low flow fixtures, or by using recycled grey water, captured rainwater or municipal reclaimed water. Typically, septic systems do not provide a source of tertiary treated grey water for reuse, though you may be able to incorporate this feature in your septic system.
Where is this requirement that in addition to a septic system (leech field) you have to reduce waste water for flushing by 50%? The ref guide gives you two options, and doesn't require that you do both (as far as I can tell).
You are correct, you do not have to do both if you are using option 2, however, you do have to demonstrate that at least 50% of your total wastewater is diverted to the on-site system. This is probably self-evident in most cases, but just to be clear for the reviewers make sure to clearly state the facts. I would also add that even though it's not required to reduce flushing by 50% it's still a good idea.
This question is about calculating FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories. for WEc2 & WEc3 under NC2.2.
In the design review of our project, GBCI has told us we should be using "typical/average daily occupancy" to calculate the FTE/
Transient occupancy for these 2 credits. We thought we were. We have
36 full time employees (50/50 male/female) plus 142 employees that
are in the office for an hour in the morning and an hour at the end
of the day (100 male plus 42 female). These employees consist of
delivery drivers and the outside sales force. We entered these 142
employees in the table under "Student/Visitor" in lieu of equating
them to FTE's so they will not be included in a group that calculates
shower and kitchen sink usage since they do not use these. Are we
calculating this correctly (as "typical/average daily occupancy")?
If not, how should we be calculating it? Thank you!
In my humble opinion you are calculating transient occupancy correctly and classifying them logically as visitors for the reasons you state. However, since they are technically employees, not visitors, this may be the cause for the comment. Often providing a detailed narrative explaining your logic, calculations and approach are helpful to clarify situations that don't follow state requirements exactly. You might also try the calculation converting them to FTEs to determine impact. I suggest a conversation with your review team through the portal prior to re-submitting.
My understanding of this is that RO reject water that is not considered potable by EPA standards could work. For example many lab projects require RO water for their work. This RO reject water can be treated on-site and get used for flush fixtures. This would also satisfy the credit correct?
Yes, this would satisfy the credit since it is replacing use of potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems.. More importantly, you will also want to check your local plumbing code which can be more problematic.
Since RO (reverse osmosis) reject water is higher up “water quality chain” because it is considered at least as clean as potable water you might consider additional reclaimed water uses that need higher quality water.
I have a related question-- we are pursuing an innovation in design credit for process waterProcess water is used for industrial processes and building systems such as cooling towers, boilers, and chillers. It can also refer to water used in operational processes, such as dishwashing, clothes washing, and ice making. savings by collecting 8gpm of RO reject water and using 6gpm of it for cooling tower makeup. Assuming plumbing code allows, we would like to store some of the additional 2gpm into a tank to be reused to flush toilets and urinals and apply to WEcr2. We are obviously not double dipping on any of the reclaimed water (6+2=8...) but have some concern that someone might have a problem with us using the same reclaim equipment to gather water used in two different credits (ID credit, WEcr2). Does anyone have any experience with submitting something like this?
Tips and screenshots on LEED Online documentation.
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