Water-use reduction is a good opportunity for all projects to earn points. If you’re familiar with this credit from earlier versions of LEED, though, keep in mind that it’s gotten harder. LEED 2009 introduced WEp1: Water Use Reduction as a prerequisite, calling for a 20% reduction for all projects. In contrast with NC-v2.2 WEc3, which used to award one point for a 20% reduction, the points for 2009 now start with a 30% reduction with for two points, and go up to four points for a 40% reduction.
The baseline for measuring water savings has also become more demanding. The LEED 2009 baseline for commercial lavatory faucets is 0.5 gallons per minute (gpm), whereas the previous baseline was 2.5 gpm.
Even with these more stringent requirements, both the credit and the prerequisite should still be fairly easy to achieve with careful fixture selection. You also have the option of replacing 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 non-potable sources—for example using captured rainwater, or reusing lavatory water, to flush toilets.
Since you will already be designing fixtures to meet the 20% prerequisite, it is not much of a stretch to meet the 30% threshold to start earning points under this credit.
If you pay close attention to the flow rates of the water fixtures you select (gallons per minute for flow fixtures and gallons per flush for flush fixtures), you should be able to achieve a 30% reduction in water use by using widely available efficient fixtures—at a minimal cost premium and without compromising comfort.
Dual-flush options like Sloan's Uppercut dual-flush flushometer are a common way to help earn this credit. Image – Sloan Valve Co.Some typical approaches here include low-flow faucets with sensors, low-flush or dual-flush toilets, and low-flush or waterless urinals. Use of 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. and rainwater for toilet flushing is also a fairly common way to contribute to the credit.
Combining several of these strategies can bring your water savings within the 30%–40% range, maxing out your points for this credit. A 45% reduction makes you eligible for an 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 under IDc1.
Take note: both WEp1 and this credit address interior water use only, but certain strategies that apply to this credit—like graywater reuse—can also be applied to outdoor water use reduction. It is also important to understand that the prerequisite and credit only cover water closets, urinal, lavatory faucets, showers, kitchen sink faucets and pre-rinse spray valves. Other water using appliances and irrigation are not included.
When water-efficient fixtures first appeared in the 1990s, they often didn’t perform very well, creating a lot of doubts that still may be harbored by some project team members. Research and development as well as new testing protocols have really changed things since then, so make sure these doubts are put to rest. Providing hands-on experience with efficient fixtures by visiting another LEED building is a good way to do this.
A copy of the plumbing fixture schedule from the project's construction documents, outlining detailed information for each flush and flow fixture specified (including fixture manufacturer, model number and flow rate) helps the review team verify that those fixtures are part of the construction contract. In the absence of such documentation, a copy of project-specific specifications and details or a project-specific contractor’s submittal with manufacturer’s cut sheets highlighting flush and flow rates for each fixture specified can be provided.
USGBC originally created this guidance document to address common questions project teams encountered when documenting WE credits. The calculations in these forms are fairly complex and are generally not addressed in the reference guide. The guidance document is intended to guide the user through the process of filling out the form, but is not intended to create any new requirements.
If the bar sinks installed have a similar usage pattern and are similar fixture type as for those in kitchens then these should be included.
Mop sinks, janitor sinks, swimming pools, bidets, and safety showers are considered 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. and are not included. Consider only the showerhead and not the tub spout.
Additionally, commercial kitchen sinks and bar sinks including pot sinks, prep sinks, wash down, and cleaning sinks are considered process water and are not included.
However, pre-rise spay valves must be considered. If your project is registered after the 11/1/2011 addenda release then the pre-rinse spray valve flow rate must be 1.6 gpm or less in order to comply with the prerequisite. If your project has a pre-rinse spray valve that has a higher flow rate than 1.6 gpm, then the project is not in compliance and the pre-rinse spray valve would need to be revised in order to be eligible for LEED certification.
Yes. Once you enter the project occupancy the WEp1 form calculates the default daily FTE shower uses.
If those fixtures are outside the LEED Project Boundary, they should only be included if your project is LEED-CI, however.
This duration is intended to prevent LEED projects from claiming credit for reducing the duration below 12 seconds; durations less than 12 seconds are not permitted for LEED calculations as shorter intervals are insufficient for typical hand washing
Yes. Although the focus is water efficiency of the installed fixtures, onsite sources of nonpotable water such as captured rainwater, 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., air conditioner condensate, cooling tower bleed off water, etc., can be applied via an alternative compliance path. Refer to the Water Use Reduction Additional Guidance document for further information.
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. #10214: "A project without eligible water fixtures in the LEED-NC project boundary is exempt from WEp1. Should such a project wish to pursue points under WE Credit 3, they may do so by evaluating WEc3 performance based upon all of the fixtures that are necessary to meet the needs of the project occupants, even if they are located outside the project boundary."
Not for individual fixtures. You only have to meet the LEED requirements for your fixtures as a group.
Private usePrivate use applies to plumbing fixtures in residences, apartments, and dormitories, to private (non-public) bathrooms in transient lodging facilities (hotels and motels), and to private bathrooms in hospitals and nursing facilities. applies to plumbing fixtures in residences, apartments, and dormitories, to private (non-public) bathrooms in transient lodgingLodging are facilities that provide overnight accommodations to customers or guests, including hotels, motels, inns and resorts. facilities (hotels and motels), and to private bathrooms in hospitals and nursing facilities. Any fixtures that are not in one of those more residential-focused situations are considered to be public fixtures.
LEEDuser has seen numerous comments on our forums suggesting that reviewers are providing little leeway for situations like this, even in a case just like you describe. Even a 10% bump toward women to account for possible future trends was not deemed sufficient. At this point (February 2013), LEEDuser is not aware of clear guidance on when a nonstandard gender ratio would be accepted, nor are there any applicable LEED Interpretations for LEED 2009 projects. If you have any relevant experience on this, please let us know!
LEED assumes a baseline of 300 seconds for a shower, and LEEDuser has heard of review comments rejecting controls that would shorten this duration for the design case. 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 or LEED Interpretation would likely be needed to make a case.
Yes—refer to LEED Interpretation #5819, issued 8/31/2004 and modified 4/1/13 to apply to NC-v2.2 and NC-v2009 projects. Quoting the relevant text from LI #5819: “A whole building approach to process water must be used (including washing machines, dish washers, drinking fountains, cooling towers, etc.) The project must demonstrate a process water savings that is equal to or greater than 10% of the regulated water usage as calculated in WEc3. The project should obtain information on the average amount of water use for each type of equipment to determine an appropriate baseline and demonstrate that the increased efficiency compared to the baseline exceeds the 10% WEc3 threshold. Required submittals for this innovation would include: 1) A narrative explaining what strategies were used and how the baseline was developed. 2) Calculations demonstrating performance compared to the baseline. 3) Cut sheets showing water usage of equipment used.”
NC projects have also had success using Schools WEc4 as an ID credit. Also see LEED Interpretations #808 (issued 7/8/2004) and #5752 (issued 5/13/2005) for some history on this issue. You can also earn an EP point for 45% savings under the Water Use Reduction credit, but it appears, based on the most recent ruling, that the 45% savings should be based on regulated (non-process) fixtures alone.
Include goals for water-use reduction in the Owner’s Project Requirements (OPR) for EAp1: Fundamental Commissioning. Reduced use of hot water with efficient fixtures can save a lot of energy.
Perform a water-balance study for the entire project to inform decisions about where to focus water-saving efforts. Understand which end uses require the most water, identify all alternative water sources available onsite—such as rainwater and graywater—and note opportunities for using that water for interior water use and/or irrigation.
Outdoor water use is not part of this credit. But looking at the whole system to understand how indoor water use compares to outdoor use can help you gauge where to focus reduction efforts for the greatest benefit. Some water-saving strategies can address both indoor and outdoor water needs holistically. For example, graywater collected from interior sink fixtures can be used for landscape irrigation, benefiting WEc1: Water Efficient Landscaping. However, this strategy will not contribute to a water reduction for this credit.
Appliance and process water uses such as clothes washers, dishwashers, cooling tower makeup, and others, need not be included in the LEED water use reduction calculations for this prerequisite and credit.
You can earn an Exemplary Performance point through IDc1 for a 45% reduction. To help you meet this threshold, you can include appliance and process water in the calculations, even though that’s not allowed for the standard credit calculations.
Establish preliminary goals for water-use reduction. Consider setting water-reduction goals higher than the 40% reduction required by this credit, and aim for a reduction greater than 45% or higher for exemplary performance under IDc1. You are likely to need rainwater or graywater reuse to reach this threshold.
Up-front costs for a 30% reduction may be minimal, since project teams will already be integrating water-saving techniques for the 20% reduction prerequisite.
Target your efficiency efforts at fixtures that use the most water.
For residential projects, showers typically use more water than other fixtures due to the duration of use.
For commercial projects, toilets and urinals typically use more water than other fixture types.
When water-efficient fixtures first appeared in the 1990s, they often didn’t perform very well, creating a lot of doubts that still may be harbored by some project team members. Research and development as well as new testing protocols have really changed things since then, so make sure these doubts are put to rest. Providing hands-on experience with efficient fixtures by visiting another LEED building is a good way to do this. Providing information on testing results of products is another good way to sway hesitations (see GreenSpec’s related products in the right-hand column for more information).
Are composting toilets an option? While not common, composting toilets are waterless fixtures that go a long way toward achieving this credit. However, they do affect programming and layout, so consider them early in the planning stage.
Consider replacing potable water use with alternative sources such as collected graywater, rainwater, municipally supplied treated wastewater, or wastewater treated onsite for reuse.
Well and pond water are not considered “reused” for the purposes of this credit and must count as potable water—so you don’t get credit for substituting them for conventional water sources. Water types that do count as reused are:
Graywater and rainwater collection systems can offer a potential non-potable water source for interior applications. However, you may find that it is easier—based on code issues and simplicity of system design—to direct reused water to an irrigation system or cooling tower. All solutions should be viewed in the context of finding the best whole-system approach for building and site water use.
Consider occupants when debating whether to use graywater or waterless and/or dual-flush fixtures. Cultural perceptions of these types of applications may need to be evaluated to gauge whether they will be successful in your building. It is also a good idea to have education outreach in order for building occupants to know how to use the new fixtures and to understand the importance of water reduction strategies.
Check local codes and restrictions. Throughout the U.S. there are widely varying laws addressing water use, and many states have very different approaches to rainwater collection and greywater/blackwater reuse.
Check for local incentives through municipalities and utilities that reward or encourage water-saving strategies—as well as restrictions that may apply. Rebates are common, as are plumbing codes restricting certain water-savings technologies such as waterless urinals, graywater reuse, onsite wastewater treatment and reuse, rainwater harvesting, composting toilets, and other strategies. See Resources for more.
Determine the number and types of occupants in the building. The water-use calculations are based on occupant use and the number of full-time equivalent (FTE) occupants, including employees and visitors—not the number of water fixtures.
The FTE occupancy number you use must be consistent with the FTE occupancy numbers used in all your other LEED credit submittals, including:
Determine user groups for the various water fixtures, as not all occupants may be using all fixtures. For example, employee restrooms and customer toilets in a retail store have different usage patterns that would affect the water use calculations if the fixtures were different. For example:
Run preliminary water use calculations to establish the baseline water use and confirm goals for water-use reduction. This should include clearly identifying target flow and flush rates for fixtures.
Like the prerequisite, this credit only includes core water uses—bathroom sinks, toilets, urinals, showers, kitchen faucets and prerinse sprays.
Janitors’ sinks, pot-fillers, and tub faucets can be left out, as they are used to fill containers with a fixed water volume regardless of the flow rate.
The baseline for commercial lavatory faucets has been changed in LEED 2009 to 0.5 gpm, from 2.5 gpm in previous LEED rating systems. There are a handful of aerators and commercial faucets that perform better than 0.5 gpm, but the use of this low baseline means that you will probably need to focus on getting water reductions elsewhere.
Reductions in potable water used in flush fixtures can also contribute to the achievement of WEc2: Innovative Wastewater Technologies.
Healthcare projects are not permitted to include exam room sinks within their WEp1 and WEc3 calculations. These sinks would be considered "process water" and thus should not be included; in addition they are commonly regulated by different standards, and three uses per day would not capture their water use levels.
Select water-efficient fixtures and strategies. Gather information on applicable fixtures, including manufacturer, model number, and flush or flow rates.
Use the calculator built into the LEED Online credit form to help facilitate decision-making. Re-run comparisons between the baseline and design-case water budgets until the final selections of water fixtures and strategies have been made and the project’s water reduction goals are satisfied.
Design and size graywater and rainwater systems to match non-potable water demand for needs such as toilet flushing, cooling tower makeup, and irrigation.
Untreated rainwater, graywater, and blackwater can corrode plumbing systems, or lead to biological growth. Teams should plan for water treatment, filtration, or using corrosion-resistant materials. The use of seawater for toilet flushing, which is less common, can cause similar problems.
Piping to interior water fixtures is doubled when graywater or rainwater is reused in addition to potable water. This is likely to add upfront costs, but can potentially reduce water and sewer charges.
Sensors on toilets and faucets are sometimes perceived as saving water. However, several studies have shown that while they may offer some hygiene or other operational benefits, they increase water use substantially, due to “phantom flushes” and faucets running longer than needed as they may interpret the flow of water as a solid object. If you do choose lavatory sensors, look for models with adjustable flow durations, and test the sensitivity of the sensor.
The LEED calculation estimates a standard 15-second use for faucets, so setting the flow duration to a shorter time of 10 seconds interval can help save water and contribute to earning the credit.
Flow restrictors and aerators can cost only a few dollars per fixture and can help add efficiency to more conventional sink fixtures. This can also be an easy inexpensive way to retrofit existing faucets; however, make sure restrictors or aerators are compatible with faucet fixtures.
Many commercial toilets can be retrofitted with dual-flush flushometers, which can cost less than installing new dual-flush toilets. Check with manufacturers for retrofit compatibility.
Toilet-lid-sink retrofits for standard toilets are one of the most basic and easy graywater reuse tools available, costing around $100. When toilets are flushed, potable water first flows though the sink for handwashing before filing up the toilet tank for flushing.
Specify efficient water fixtures in construction documents. Be sure to include specific flow and flush rates (gpm or gpf) for each type of fixture.
Specify signage for water fixtures or strategies that may require special instructions for use, or educate users on water savings. This may include signage for explaining proper operation of dual-flush toilets, waterless urinals, indicating non-potable water if supplied at faucets, and distinguishing pipes carrying reused water for operations and maintenance personnel.
If collecting rainwater or reusing graywater, ensure that the key system components, such as water treatment and cisterns, are not removed during value engineering.
Apply for any water-reduction incentives and rebates available through local municipal water authorities or utilities.
Fill out the LEED Online credit form and upload water fixture cut sheets to LEED Online.
The contractor should ensure that the correct fixtures have been purchased and that applicable water reuse systems or specified metering systems have been installed.
Make sure supply pipes carrying non-potable water are clearly color-coded and labeled to avoid inadvertent connection with potable water lines.
Provide building managers with manuals and guidance for all fixtures and fittings, water-reuse technologies, onsite water treatment systems and unconventional products.
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.
Train cleaning and operations staff to maintain atypical fixtures such as waterless urinals, faucet sensors and other unconventional fixtures.
Excerpted from LEED 2009 for New Construction and Major Renovations
To further increase water efficiency within buildings to reduce the burden on municipal water supply and wastewater systems.
Employ strategies that in aggregate use less water than the water use baseline calculated for the building (not including irrigation). The minimum water savings percentage for each point threshold is as follows:
Calculate the baseline according to the commercial and/or residential baselines outlined below1. Calculations are based on estimated occupant usage and must include only the following fixtures and fixture fittings (as applicable to the project scope): water closets, urinals, lavatory faucets, showers, kitchen sink faucets and pre-rinse spray valves.
The following fixtures, fittings and appliances are outside the scope of the water use reduction calculation:
Use WaterSense-certified fixtures and fixture fittings where available. Use high-efficiency fixtures (e.g., water closets and urinals) and dry fixtures, such as toilets attached to composting systems, to reduce 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. demand. Consider using alternative on-site sources of water (e.g., rainwater, stormwater, and air conditioner condensate, 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 nonpotable applications (e.g., toilet and urinal flushing, custodial uses). The quality of any alternative source of water being used must be taken into consideration based on its application or use.
This is a referenced standard for this credit.
WaterSense label helps US consumers choose high-quality, water-efficient products.
This document from USGBC offers guidelines to help you properly set up fixture usage groups in the LEED Online credit form, avoiding common mistakes associated with the water-efficiency prerequisite and credit.
A spreadsheet model that uses water/energy relationship assumptions to analyze the potential of water savings and associated energy savings.
A map with regional water information.
Search for local rebates for water efficiency products.
Searchable national database of toilet rebates.
This chapter addresses the following questions: What's the problem? What practices might be used to solve it? How effective are they? What do they cost? Where have they been used successfully? Practices for system users residential, industrial/commercial, and agricultural are presented first, followed by practices for system operators.
An advocate for water-efficient products and programs. Provides information and assistance on water conservation efforts.
Information and links to a range of water-related issues.
Offers web-based information exchange, workshops, and other educational opportunities.
Compilation of 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. laws.
Carefully research products and examine cut sheets to find fixtures and fittings meeting the credit requirements, as shown in these examples.
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."
This sample form for WEp1 is from a real project whose name was changed on the form. (Note that WEp1 was achieved for this project even though this sample displays that the form was not completed.)
Documentation for this credit can be part of a Design Phase submittal.
do these count in our standard water calculations? if not, can we include them as 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. to earn exemplary? in the FAQ section above it states that water fountains and other fixtures that are considered process water can be included to earn an exemplary point.
No, they don't count as regulated fixtures under WEp1/c3.
You could probably include them as 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., but how would you demonstrate savings? I see filling stations as saving packaging, not water, and I'm not aware of appreciable water savings from one filling station to another. I would probably not choose to include them.
thanks Tristan, that was my thinking too. As i talked through it with a colleague, it began to take shape as an innovation credit though. I can see some savings in water if using a standard drinking fountain as the baseline, since people stand there and let the water run while they are drinking...a lot, if not most of it goes downt he drain as they are drinking. If you compared that to filling a water bottle, there is very little waste, tyically you drink ALL the water that goes into a water bottle. also, by eliminating plastic water bottles in a building, you would eliminate a lot of waste to be hauled off-site. Even if the plastic water bottles get recycled, it still is cost to haul it off, and there is a cost to recycling them too. just a thought. anyone tried this?? i know in the high education world, a lot of Universities are going to these bottle fillers for environmental reasons.
I think they're great solutions. However, I am not fully convinced that you can claim savings for a filling station over a water fountain. I think they are different fixture types. And refilling a bottle saves packaging compared to getting a new bottle, and saves water compared to slurping from a fountain, but you had to have that bottle to begin with, and that took energy and resources.
It could contribute to an innovation credit, but keep in mind the rule of thumb that a single technology generally cannot earn an innovation point. I would look at it in the context of comprehensive waste reduction.
I have completed the form for WEp1 & WEc2. When I go to finish WEc3 it doesn't show the savings from the rainwater harvesting with the flush fixtures. Is there a differnet place I need to supply the additional savings information?
Unfortunately, the savings from WEc2 are not linked to WEc3. You will have to check the special circumstances box in WEc3 and write in your actual water savings there. I have done this before, and it was accepted by the reviewer.
For some background on our project:
- we have on-site rainwater capture as well as connection to a municipal non-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. supply
- the municipal water is used to top up the rainwater storage tank in times of low rainfall (i.e. rainwater + municipal water are combined in the same tank)
- water from the tank is used to satisfy 100% of the building's flushing and irrigation demand (i.e. 100% from non-potable sources)
Our problem is:
- municipal non-potable water cannot contribute to WEp1 or WEc3 whereas it can count towards WEc1 and WEc2 (as per the USGBC water use additional guidance document)
- While we can estimate the proportion of rainwater that ends up as irrigation water or flushing water, the project does not receive any recognition of the rainwater used for irrigation as the municipal supply can satisfy the 100% non-potable irrigation requirement without rainwater.
My question is:
- As there is no net environmental difference, can the project elect to apportion captured rainwater to suit the project (i.e. 100% for flushing and 0% for irrigation)? This would ensure that the project gets full recognition for the rainwater facilities installed onsite, drastically simplify assumptions and arbitrary calculations and prevent the need to install two separate rainwater and municipal non-potable water tanks (pipes and fittings) just to achieve full points.
Any input from project with similar experiences would be most helpful.
If possible I would like to avoid having to submit 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!
The water use of dual flow faucets that has two positions, would be a weighted average of both?
1º: 1,58 gpm
2º: 2,37 gpm
As a dual flush toilet water use is calculated with 2 low+1full..
If the fixture family is "private lavatory" would the fixture type be "other"?
Is there a calculator tool or methodology that we should use when submitting our annual rainwater collection (kGal) calculations for LEED?
Our calculations are currently based on BS 8525 Rainwater Harvesting as the project is located in UK.Will this be acceptable?
Ameet, there is no specific methodology that is requred for rainwater calcs, as long as your numbers, assumptions, and methods make sense.
Evidently, installing automatic shut-off controls for showers is deemed as not water saving strategy by the USGBC's LEED Department. It is not clear what "problem" the USGBC is trying to solve in this case.
A recent project review comment stated that duration controls for showers is a not "published exception" in the LEED documentation. Of course, the review found no problems with forcing the reduced duration time being used for the both the baseline and design cases as if the duration was a schedule. Using the same reduced duration time is not a "published requirement" in the LEED documentation.
The USGBC's LEED department fails to see the link between claiming something is nor published, therefore not allowed, and simultaneously enforcing something that is not published.
The review comment received is copied below. The project was not a prison, gym, or school, project types which might use automatic shower controls as standard practice. These are the only cases I can think of where it would be inappropriate to claim a duration reduction.
"The calculations indicate that water savings are claimed via a non standard design case duration for the showers of 45 seconds due to an automatic shut off feature. Please note that the flow duration for showers should be the same in the baseline and design cases as there are currently no published exceptions allowing design case savings for showers with an automatic shut off from the default baseline duration of 300 seconds."
Our project is a 50% office- 50% lab building. Are laboratory sinks to be accounted for in this credit calculation?
Project teams are permitted to include classroom sinks provided the flow fixtures installed have a similar usage pattern and are similar fixture type as for those in bathrooms. However, project teams are not permitted to include exam room sinks as these are considered 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.; additionally, exam room sinks are commonly regulated by different standards and 3 uses per day would not capture the water use associated with these fixtures.
Not sure if your laboratory sinks are a similar fit to one of the above described situations. In any case I would suggest including a narrative describing the typical use pattern for the laboratory sinks and why you have either included or excluded from the calculations.
Read through the LEED Interpretations. There are a few that describe a sink being used for more than one purpose (handwashing) allowed to not be included in WEp1/c3 calculations.
To obtain -40%, we'd like to use (in France) Water Closet dual flush fixtures 2-4 liters. We commonly use 3-6 liters, apparently, the 2-4 l flow presents difficulties from the health point of view. Have you ever had the case?
Nicolas, I am not sure of your question? Are you asking if there are health issues with 2-4 l fixtures? Do you mean health code issues, or actual practical problems? If the former, I don't know—if the latter, I haven't heard of issues.
I have never quite understood what happens when a building uses many different types of fixtures. We are working on a gated community where all the villas use same type of fixtures but the common facilities like the club house and the spa use different type of fixtures. If there are 1200 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. then how is one supposed to know how many times the fixtures in the common facilities will be used and how many times the fixtures in the villas will be used?
If the fixtures in the common facilities are more efficient, the project team would automatically be tempted guesstimate a higher number of uses in the common areas, hence getting a higher net saving. What protocol should one follow in such a case?
The standard way to approach this issue is by using appropriate usage groups. You will have to estimate the 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 the common facilities. Yes, it may tempt the team to estimate a higher number. If the villas are residential units there is greater potential for water savings than the common fixtures, which use the stricter UPCUniform Plumbing Code/IPCInternational Plumbing Code standards.. For example baseline lavatory faucet in commercial is 0.5 gpm and in residential is 2.2 gpm.
Thanks Crissy... The development is in Hyderabad, India. So we do not have any UPCUniform Plumbing Code/IPCInternational Plumbing Code standards. The buyers of the villas are allowed to choose the fixtures they want in their home with some restriction from our side but we have a free hand as far as the common facilities go. So we can get very efficient in the common facilities but we may have to settle for lesser savings in the villas. We have no clue how we can guess the user groups right and how do we justify this to the rating agency?
Yusuf, one suggestion I make to people is to look for a similar facility in the area or under the same ownership or development group and conduct some research into usage patterns there.
Mr. Yusuf, the best way to define user groups and identifying FTEs for each usage group, you can define less efficient fixtures in villas in comparison to more efficient fixtures in common areas. Common areas will be accessible to all users or visitors but residential areas will be accessible to only specific occupants.
We are working on a college dormitory and trying to calculate the daily uses for kitchen sinks. The only kitchen is on the first floor of the dorm and not in each dorm room. Since this is a residential building, we technically should have 5 kitchen uses per person per day, but this is also a college dorm and occupants will not be using the kitchen too often (at least from my experience). Has anyone submitted a similar project and altered the daily kitchen sink uses? Perhaps if we submit a thorough narrative they will accept our calculations. I was thinking 1 use/day/person. Thank you!
In your submittal include a narrative explaining the project-specific conditions that justify using a lower daily kitchen sink use value for the residents.
Does anyone have experience with using a 1 gpm aerator in a residential setting? We typically use 0.5 gpm aerators in commercial settings which has worked fine. However, I'm concerned that a 1 gpm aerator will not have sufficient pressure to clean toothbrushes, razors, etc.
The pressure should be the same with less water. I don't think there should be any issues with using 1 gpm aerators.
Jeremy, You might want to check out the WaterSense guidelines and tested fixtures they approve for use in private bathroom. They suggest between 0.8 and 1.5 gpm for private lavatories where tooth brushing and other gunky business takes place: http://www.epa.gov/watersense/docs/faucet_spec508.pdf
Due to "Water use reduction Additional Guidance" from July 14,2011 Nonresidential Default Lvatory Faucet duration has changed from 15 to 30 sec.
Because of that from our previous calculations water use reduction above 40% we have 39.75%.
Do you think that If we have started our certification on December 2010 we can use special circumstances to achieve additional point which we had before july new rules for calculations? We have done quite big invests on fixtures so maybe you can give us a hint how to defend it.
Thanks in advance for any comments.
I was just filling out the form too and noticed the same change. Although it now defaults at 30 seconds, the form does allow you to change the number of seconds back to 15 if that helps. I wouldn't consider this alternative compliance and just submit normally.
OK, but the case is that, except metering faucet where we can take data from cutsheet, we have to put default value which "might be modifed for special circumstances".
Do you think that requirements change during construction process might be considered as special circumstances?
I have some slight doubts about the way commercial prerinse spray valve should be integrated in the calculation. Those are quoted in the credit language, but then, there is no information anymore: no calculation example, no quotation in the Reference guide, and no reference in the template. Does it mean that as long as the prerinse valve flow is under 1,6gpm, it's ok, and that the actual consumption is not taken into account in the calculation?
This is a new edition to the WEp1 v4 of the credit. I believe your assumption is correct. As long as the pre-rinse spray value is 1.6 gpm or below it complies with the requirement. The actual consumption does not appear to be taken in to account in the calculation.
That is correct. Prerinse spray valves must in all cases be 1.6 gpm or less. And for projects using the v04 WEp1Prerequisite Form, savings cannot be claimed for prerinse spray valves.
I was wondering if anyone could provide guidance for calculating the transients for the residential component of a mixed use facility? We are working on a multi-story mixed-use development that includes office, retail, and multi-family residential.
The 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. and transient calculations for the office and retail components are pretty straight forward, but I have been unsuccessful in finding any references to calculating transients for residential occupancy. Table 1 in Appendix 1 of the Reference Guide provides default occupant per square foot numbers for multiple occupancy types, but nothing for multi-family residential. I may have missed it, but I could find no such reference in LEED Homes either.
I would think that we would need to account for some degree of transients/visitors for the residential component as the apartment tenants would likely have visitors who would possibly use their restrooms; and there would be prospective tenants meeting with leasing staff, who might utilize the public restrooms.
Certainly this isn't the first mixed-use and/or multi-family project to pursue LEED certification. What have others done for this occupancy type? Is there any guidance or rule of thumb published anywhere that I may refer to? Thanks in advance for any help!
There currently is no explicit guidance on how to calculate visitors for residential components of a project, and from past experience, this has not been included in the water use calculations. If you did want to include visitors as part of the residential component, I assume you could estimate the number of transients / visitors and propose an estimated usage but it seems like this can be excluded altogether. Have you checked with GBCI?
We are planning to run some onsite tests to determine how water efficient are our showerheads. Since the 80 psi water pressure referenced within the EPA 1992 is not relevant for our project, we are about to get inspiration from the 8/27/2004 - 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 ruling (revised on 9/1/04) and test both baseline and design fixtures and use an alternative path.
Can any showerhead, having a 2.5 GPM water flow at 80 psi (manufacturer data), be use for the test or shall it be LEED accredited?
Does anyone know such a showerhead model or any supplier?
Does anyone have experience with such onsite tests? Is there any EPA testing program or guidelines?
Thank you in advance for your help!
Nicolas, it seems you an use any 2.5GPM showerhead at 80psi for your testing. There aren't any LEED accredited showerheads, so you don't have to worry about that.
If all the plumbing fixtures are to be installed in future by tenant, and if I check Tenant Neutral for WE p1; I will not be able to achieve the prereq. 20%. Is this typical?
Yes. That's correct. Because it's assumed that the tenant than just meets Epact 1992 not improves it by 20%. You will have to have some improvement with fixtures installed in the building. Keep in mind just because the tenant installs them all, doesn't mean you would not consider them in the calculation.
I'm debating how to set up my fixture groups for a large healthcare project. Initially, it makes sense to split into two groups: inpatient and outpatient/other. But 2/3 of the patient tower is devoted to Women. We have a floor of NICU and another floor of LDR/CSection on top of that. Would it make more sense to split up the inpatient into similar departments? The issue is accurately accounting for male patients. If I go with inpatients than the m/f ratio is a blended number and I would upload a pdf showing the calculation. If I break out the inpatients more, I won't have to do that and it would be clearer to a reviewer. But more time consuming for me. Initially, I was going to group the outpatient/other functions by similar hours/days of operation but the toilets are common to both groups. Now we'll use 24/7/365.
Susan, sorry that you didn't get a reply on this question. Did you make a decision on what to do here?
I realized that the gender of the patient is irrelevent because the patient bathroom does not have a urinal in it. Then I developed a spreadsheet that bases staffing off bed count which was the key to engaging the hospital staff as they think that way. We went with a 24 hour calculations for everyone one which further simplified who is in what category. We will upload the back up spreadsheet when we submit next month. It took some time but eventually we were able to streamline this process.
The LEED NC for Retail rating system indicates a baseline performance of 1.6 gallons per flush (gpf) for all water closets except blow out fixtures, which are assigned a baseline performance of 3.5 gpf. As I understand it, blow out fixtures differ from tank-type water closets in that they are wall mounted and rely on water pressure rather than gravity for flushing. They are typically installed in public places at least partly because tampering with them is more difficult.
I am unclear whether "siphon-jet" water closets such as the model described below would be considered a blow out fixture or not for the purposes of this credit.
The Sloan WETS 2050.1201-1.28 SOLIS is sensor-activated flushometerA device that utilizes pressure from the water supply system, rather than the force of gravity, to discharge water into the bowl of a toilet or urinal. It is designed to use less water than conventional flush toilets. and wall-hung fixture with siphon-jet flushing action and 1.28 gpf. Specs are available at the following URL:
According to Kohler, a blow-out water closet is one that has a non-siphonic trapway at the rear of the bowl, and integral flushing rim and jet. Since the water closet you referenced has “siphon-jet flush action” I would assume that it is not considered a blow-out water closet and would use 1.6 gpf as its baseline flush rate.
I work with a lot of industrial facilities which are designed for ratios that vary from the 50/50 M/F standard. Typically, these facilities are designed with toilet facilities to accommodate 70/30 or 80/20 M/F ratios. This is a result of historical trending and other data provided by the clients (not to mention common sense). We have submitted projects using these ratios and have "earned" the points. More recently, when submitting the same documentation for similar facilities, we are seeing the following comments from the GBCI reviewers: "The calculations require a balanced, one-to-one sex ratio unless project conditions exist (such as a male dormitory) which would affect the gender ratio for the life span of the building and warrant an alternative ratio." And, "...current staffing level is not an acceptable rationale for deviating from the standard usage ratio of 50/50 M/F."
Can someone please offer an explanation for why the change? I have reviewed both the v2.2 and v3.0 (2009) reference guides as well as the Templates in LEED online and I can find nothing in any of these documents that substantiates the reviewer's comments in the above paragraph that "...current staffing level is not an acceptable rationale for deviating from the standard usage ratio of 50/50 M/F."
My guess is someone wrote a manual for the reviewers to follow and they're following the wording of this manual that we don't have access to.
I'm figuring as much, but it doesn't seem right that they can change the rules mid-stream. Plus, it's not even accounted for in LEED 2009. Very frustrating. Each time I think I have the credits figured out and "this time we will get it through on the first try", they seem to change the rules.
I've suggested to USGBC that they look at this issue and consider putting out an addenda so that everyone is on the same page.
The gender ratio being defensible for the life of the building is actually from 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 Ruling dated 9/14/2006, "Also, you should be sure to use a 50/50 male/female ratio unless there is strong evidence of an alternate ratio for the projected life of the building."
The "strong evidence" aspect is apparently at the reviewer's discretion, and I have seen them rule both ways. To futher complicate things there are quite a few new reviewers undergoing training right now, so more fluctations between past and more recent reviews should be expected for awhile.
Tristan - I have two questions:
1) If our building is designed TO CODE with an 80/20 ratio, it would not seem to make sense to use a 50/50 ratio. The evidence for the particular facility I am trying to get certified right now is in the fixtures themselves: 2 women's toilet total, 4 men's toilets plus 4 men's urinals - for a total of 8 fixtures. These facilities have long histories (30 years plus) of operating at these ratios. Should we simply explain this in better detail to the reviewers? Again, it doesn't seem to make sense for the calculations to use a 50/50 ratio when that is not what the building is designed for or how it will be used "for the life of the building".
2) I can understand, perhaps, changing the rules with an Addenda for v3.0 (2009), but should not all v2.2 projects be held to the same standards? We have three projects that have used ratios other than 50/50 and these earned the points with no problem - exact same type of facilities. I plan to cite those certified projects in my reply to the reviewers. This has worked for other clarifications.
How well did you explain the permanance of the fixtures in the given ratio in your submittal? If it were up to me I'd say you have enough evidence, provided it's properly explained. I'm not GBCI, though, so I can't speak for how they see it.
I am currently working on a project where we are returning an historic building to original use (hotel). It was built in 1926 and had been used as a retirement home for the past 45+ years. The plumbing fixtures in place are original and utilize considerable amounts of water (3 GPF) for toilets, etc. In calculating the improvement efficiency, do I have a case to argue that Title 24 - 2005 (California) is an unreasonable 'baseline case'? We show significant improvement from that standard, but the reality is that we are dramatically improving water consumption over the existing conditions.
I'm curious what kinds of obstacles you're facing in getting water use below the baseline. Theoretically you can replace all the fixtures and fittings necessary to get you there. What's the case you'd make for a looser requirement here?
Also, maybe I'm forgetting something obvious, but does LEED require a different baseline for projects subject to CA Title 24?
My intent may not have been clear. We are not facing obstacles getting water use reduction below baseline. My hope, however, was to show 'real world' savings. Where the reference guide baseline assumes reduction from 1.6 gpf to 1.28, we will be reducing from 3.0 to 1.28. Significantly lower draw on municipal resources.
We have a number of complications which make some other credits very hard to achieve ( historically significant building with large single pane operable windows which must remain), any assist here would increase our desired compliance.
LEED does not require a different baseline for CA Title 24 projects.
My gut reaction is that you won't be able to successfully argue this. ItsSeems to fall in the category of doing a great job making a big reduction, but it's not something that LEED gives extra credit for.
Think about it from a LEED policy perspective, and how difficult it would be to draw a clear line between projects deserving of extra credit for this kind of situation, and projects not deserving. LEED solves this by creating a single benchmark for what it considers a reasonable conventional baseline.
You may be able to get extra credit through RPc1, if this is an applicable credit, and through synergies with WEc2.
Fair enough. I do understand it must be difficult to try to find an acceptable template for all project types. In a project where we are being both innovative and historically reverential, situations arise where doing the right thing is sometimes rewarded big, other times not so much.
Thanks for your time reviewing this.
Rick, seems this is one of the obstacles of LEED (real world vs. base case). Unfortunately there's no way to "prove" that you have 3gpf fixtures, and they are not going to send someone to check every renovation project out there. Thus the reliance on a standard as Tristan mentions above.
Hi, i'm working on a residential building where we are installing a permanent water metering system to monitore each residents water use. The residents have access to a website where they can easily follow their usage and related it to a cost. Research show that residents reduces their water usage with 20% if they get feedback on their usage.
Is it possible to include this 20 % reduction to meet the requirements for this credit? I'm thinking of writing a narrative and describing how the intent of the credit is met, although using an alternative compliance path.
Nobody seems to be replying to these threads which is disapointing.
Your question seems similar to mine below in that it is not covered under any descriptions on how to achieve the credits in any of the LEED literature.
I agree with what you are proposing but the only means to verify if it will be acceptable is probably to post 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. Of course I would anticipate that you will get an ambiguous answer and that final approval or rejection would be based on the acutal audit.
I would be surprised if this credit was awarded based only on the water metering system you describe. While research may show a 20% reduction from this kind of system it still relies on behavior rather than the efficiency of the installed fixtures.
The metering system is still a great idea, I just don't think it will be sufficient to prove compliance with this prerequisite, especially since you'd be hard pressed to prove actual savings in a new building.
I took over Deborah's project above. We did not recieve additional credit for water savings thorugh the monitoring system. This means we just barely made it over the 20 % threshold with our fixtúres and fittings, but got no points under WEp1. Unfortunately.
How do you calculate the water use reduction for a mixed use building which contains 7 floors of commercial space and 34 floors of residential space? How do you account for the different usages for each floor type?
The documentation for this credit is mostly populated from the LEED Online form for WEp1. When you're documenting WEp1 in the LEED Online form, you have he opportunity at the beginning to define "Fixture Groups," which could correspond to different usage types like those in your project.
I have a similar project type with split occupancies of office/retail on one floor and residential multi-family on three floors. My question is relative to calculating transients for the residential component. Appendix A in the LEED reference manual provides guidance for 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. and transients for various occupancy types, but nothing for residential/multi-family. Because we couldn't find any guidance initially on the residential floors, we assumed one visitor per residential unit. Is there any rule of thumb for calculating transients for multi-family projects?
Additionally, in the preliminary review comments, the reviewer suggested that "transients of the building should be removed from the calculations associated with these fixtures [residential] since they do not have access to these fixtures." This does not seem right as a visitor to a residential tenant would likely use the tenant's restroom, and not go down to the first floor to use the public restrooms. Thoughts?
William, I agree with your logic and I don't know of any other resources for residential transients.
Have you learned more since you posted this?
Many CIRs address the issue 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. to an extent, but it seems there might be multiple strategies for accounting for various occupancies. (Hotels near transit can exclude guest occupants- v2.2 SSc4.2 1/23/09, modifying the FTE to place guests in the transients category - v2.1 SSc4.2 6/20/2008, etc). And many of the referenced CIRs are built up from College Campuses, then Airports, but Hotels still seem a little mysterious.
For FTE it is clear: CIR v2.1 SSc4.2 6/20/2008 and the guest belong in transient calculations.
But would guests count toward a Residential occupancy (same usage rate essentially as a home, i.g. there at morning and night)?
Based on this CIR, guest would only be transient in the correct FTE, right? Whereby certain transient populations can be excluded from the calculations in determining the number of required bike storage spaces and showers.
Ssc4.2 is really about making biking more convenient for full time users, however, in this credit, FTE numbers have an impact on usage and occupancy numbers effect overall end water use (and water reduction).
It seems awkward then to place hotel guests in transient for WEc3.1 as guests are more likely to shower and use water fixtures.
I'm posting this same inquiry in SSc4.2 in regards to FTE numbers for hotel guests.
This should have a preview option. I forget some things.
I'd like to add the question about usage rates as well to this.
The LRG has water use calculations which indicate fixture usage rates based on residential standard calculation methodology presented in the LEED-NC v2.2 Reference Guide, Third Edition on page 142.
So, would guests count toward a Residential occupancy (same usage rate essentially as a home, i.g. there at morning and night)? Unless special conditions exist, projects should assume a 50/50 male/female ratio and an average of 5 fixture uses per day for residential usage.
Any thoughts are appreciated.
I would calculate hotel guests as residents, and yes, they should definitely have an assumed 50/50 male/female usage. This is always true unless there is a very specific and provable reason otherwise, which I can't really foresee for a hotel. You would also have FTEs (hotel employees) and transients (visitors + those who come for events, conferences, etc.) These would all be calculated separately in the WEc3 template. You will have to work with your client and design team to determine how many transients are appropriate based on event spaces and other hotel practices.
Thanks Mara, that's what we suspected after looking thru LRG BD+C (we are analyzing this for NCv2.2). But, still, for SS4.2 should different FTE be applied vs WEc3? As 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 v2.1 SSc4.2 6/20/2008 where the guests belong in transient calculations.
I was wondering if the USGBC has provided any guidance regarding calculating the 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./Transients/Visitors, etc for a hospital. Should patients be partial FTEs or visitors? Does it depend on the kind of patient that they are (outpatient vs inpatient)? Do any of the hospital FTE, such as inpatients have to be residential FTE? Is there guidance in LEED for Healthcare? Our project is registered under LEEDv2.2.
Mara: perhaps you have a good idea from your hospital experience?
There is limited guidance from the USGBC on this matter. Inpatients are considered to be residents; outpatients are transients.
Calculating transients is often an exercise in estimation, and this is especially true for healthcare, because so many of the staff are mobile -- e.g. doctors on rounds who may pop into a building for just a few minutes or maintenance personnel who work in one building periodically but may have a permanent home in a different building. This type of occupant is usually a transient, although you should use common sense to determine your approach. You should work with your client to estimate these numbers, as well as outpatients and typical visitors per inpatient. They will probably hate this! Start with everything you know about the building, then and ask questions as specific as possible. For example, a desk in an office building often represents 1 FTE... but it could represent 3 in a hospital nurse station... even if the desk is used only two individuals, because shifts are often 12 hours.
I have not found the LEED for Healthcare draft (now quite old) to be useful on this topic, as it's something that is more likely to be addressed in a reference guide.
Capturing rainwater for interior water use can reduce stormwater runoff quantity.
This prerequisite is the starting point for the credit. The same water-saving strategies apply to both places.
Water use reductions for toilets and urinals are calculated both in WEc3 and in WEc2, helping earn points in both places.
Water use reduction, particularly reduction in hot water use from showers and sinks, directly translates into energy savings.
Water-use metering and hot water metering are worth including in a measurement and verification plan.
Do you know which LEED credits have the most LEED Interpretations and addenda, and which have none? The Missing Manual does. Check here first to see where you need to update yourself, and share the link with your team.
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