Potable Water Reduction Clarifications - Living Building Challenge 4.0

Baseline Data

The Institute’s baseline data (see Table 5-1) is averaged from a variety of sources, including the Pittsburgh 2030 District, Seattle 2030 District, the United States Environmental Protection Agency and the Commercial Buildings Energy Consumption Survey. The numbers have been averaged and reduced by the average percentage each building type uses for landscape and irrigation.

Table 5-1 Baseline Potable Water Use by Occupancy Type

Creating the Baseline

To establish the baseline, project teams are encouraged to use the ILFI-provided data in Table 5-1, which can be used without pre-approval when the project includes all end-uses identified for the project type in Table 5-3. Projects intending to use the data from Table 5-1 that do not include all end-uses indicated for the project type in Table 5-3, will need to reference the guidance in Baselines Customized by Standard End Use below to make adjustments. Projects may use the entire baseline allotment for a category if any of the end-uses associated with it, as listed in Table 5-3, are included in the project. Projects may propose a project-specific baseline where established data from their region or site are more reflective of project conditions, and/or the project contains specialty occupancy or end uses essential to the project function that are outside the typical conditions represented in Table 5-1. See Customized Baselines below for requirements.

The baselines provided by ILFI in Table 5-1 are based on actual annual metered water use and therefore reflect “typical” occupancy patterns. For example, the daily baseline for schools accounts for a 3-month summer vacation and 2-week winter break. Similarly, the office data assumes occupancy 5-days a week and typical vacation and holiday patterns. Project teams need only adjust the baseline in table 5-1 if their occupancy schedule deviates from typical use for that project type; for example, a summer home that will only be occupied 3-months a year.

If a project has more than one Typology (for example, a renovation project with an addition), the efficiency target is established by calculating a weighted average based on reductions required per Typology and the percentage of Project Area occupied by each Typology. See example under Calculations.

Mixed-use projects must calculate their baselines in a way that does not mix units of consumption rate (i.e. per square ft/meter or per person). To use data that are in different units, separate baselines must be set for each occupancy type and the actual water use for each occupancy type metered separately. Alternatively, custom data may be used to create a weighted blended average. See guidance under Customized Site-or Region-Specific baseline below.

Customized Baselines
All customized baselines, with the exception of Baselines Customized by Standard End Use, must be submitted for approval in advance through a Request for Ruling.

Customized baselines may be calculated on a per square foot or per capita basis, but not a combination. Project teams are encouraged to use volume per capita per day (gallons or liters) as this rate is typically a more accurate measurement of water used.

The baseline must not include water used for irrigation or landscaping, as that water is required to be non-potable and has already been removed from the baseline data in Table 5-1.

Baselines Customized by Standard End Use
The Institute has provided a breakdown of typical water end uses to aid in establishing an appropriate baseline for all end-uses that are within the tenant’s control (see Tables 5-2 and 5-3). Where the project scope does not include one of the potable water end use categories identified in Table 5-3 for the project’s occupancy type, the corresponding percentage must be subtracted from the baseline target provided in Table 5-1. For example, a residential space that does not include laundry within the building must reduce its baseline by 16 percent. Similarly, if a commercial building has no water-consuming equipment for any of its space conditioning systems, for example a building that relies on an air-cooled variable refrigerant flow system, then the baseline should be reduced by 36%. However, a building that has any instance of water-consuming equipment in its space conditioning system, for example a recirculating cooling tower, does not need to take any reduction for the category.

Note that Interior projects may not exclude water-consuming fixtures that already exist within their tenant space just because they do not plan to upgrade them. If the fixtures are within the project’s control, they must be included in the baseline, final project scope, and calculations. Fixtures within the project space are assumed to be within the project’s control; where this is not the case, the project team will need to include in the Ready Audit submission, a lease agreement or other documentation showing the fixture is not within the occupant’s control.

In the documentation for the Ready Audit submittal, project teams using a Baseline Customized by Standard End Use must identify the end uses within the Project Area and show the adjustments in the baseline calculation. Pre-approval through a Request for Ruling is not required.

Customized Site-or Region-specific Baseline
Projects may propose an alternative baseline when established data from their region or site are more reflective of project conditions. Mixed-use projects wishing to establish a single baseline total (rather than separate baselines for each use type) will not be able to rely solely on the data in Table 5-1 in all cases and will need to develop a customized site baseline. To establish a single baseline, mixed-use projects must identify alternative baseline data as needed so that all data are expressed in the same unit (per person or per unit of area), and calculate a weighted blended average for each occupancy type across the percentage of building area or occupant number the occupancy type represents (see Multiple Typologies example in the Calculations for weighted average methodology). The resulting baseline consumption rate must be in a single consumption unit, either per square feet/meters or per person.

Proposed reference data for customized site-or region-specific baselines must:

Be from within the project region or a region with a comparable climate, and reflect a use mix similar to what will exist when the project is completed;
For site-specific data, reflect or be adjusted for an occupancy intensity as close to design occupancy as possible;
For regional data, have been collected by a governmental agency or research organization with authority or expertise related to water consumption;
Have been collected no earlier than 2012, or demonstrate water systems compliant with EPAct 2005 standards (effective November 2005).

The customized site-or region-specific baseline must be submitted for approval in advance through a Request for Ruling that demonstrates compliance with the guidelines in this section per the following:

An explanation of how the proposed baseline is more appropriate to the project than would be derived from the rates in Table 5-1;
A list and drawings showing all of the end uses within the Project Area;
A clear citation of all reference data used;
A description of the methodology used to develop the baseline;
The resulting calculation.

Customized Specialty End Use or Occupancy Type Baseline
If the project contains a specialty end use essential to its function that is clearly not accommodated in the end uses listed in Table 5-3 or is an occupancy type not listed, the project team may propose an alternative baseline referencing any or a combination of the following:

Metered or capacity-based data from a comparable site;
Calculations based on applicable regulatory requirements or government programs;
Manufacturer specifications for products or systems that meet performance requirements.

Any assumptions on rate or frequency of use must be made explicit and tied to documented owner data, published studies or tools, regulations, or manufacturer specifications. Project teams must document a diligent effort to develop a baseline from data collected no earlier than 2012 or that demonstrates compliance with governmental standards effective no earlier than 2006.

The custom baseline must be submitted for approval in advance through a Request for Ruling that demonstrates compliance with the guidelines in this section per the following:

An explanation of how the proposed baseline is more appropriate to the project than would be derived from the rates in Table 5-1, including how the specialty end use or occupancy is essential to the project and affects water consumption;
A list or drawing showing the end uses within the Project Area;
A clear citation of all reference data used;
A description of the methodology used to develop the baseline, including any use assumptions;
The resulting calculation.

Table 5-2 Water End Uses in Buildings

Table 5-3 Water End Uses Assumed in Baseline

Percentages of total use. See Baselines Customized by Standard End Use for additional guidance on applying the information in the table to establish customized baselines.

Landscape and Infrastructure Typology Baseline
Landscape and Infrastructure projects with water-using facilities that do not fit into any of the occupancy types in Table 5-1 shall establish a baseline using the fixture baselines in table 5-5. However, if the project is replacing an existing facility, historic metered data can be used to set the baseline instead. Examples of water-using Landscape and Infrastructure facilities eligible to use this baseline approach include standalone public restroom facilities, public shower facilities, small maintenance buildings or custodial buildings. For facilities with water-using fixtures or features not included in Table 5-5, project teams will need to propose a project-specific baseline for preapproval through a Request for Ruling per the requirements under Creating the Baseline above.

Project teams will need to establish a baseline for all fixtures per the example below (Table 5-4). Reduction calculations will be based on the aggregate water use. Reduction can be achieved by either reducing flow rates of each fixture to 30% for existing or 50% for new, or by eliminating potable water use for specific fixtures. For example, using rainwater to flush toilets would reduce the potable water usage for toilet fixtures to zero gallons per flush.

Projects using this baseline approach are still required to meter water use during the performance period, though the consumption reflected in the metered data is not part of the compliance evaluation.

Table 5-4 Example baseline and reduction targets for Landscape and Infrastructure

Table 5-5 Baseline Potable Water Use by Fixture Type for Landscape and Infrastructure

Demand Reduction

The project team must reduce the project’s potable water use by the required percentage based on the project Typology. The percent reduction is measured against a baseline.

Potable water reduction can be achieved in multiple ways and through a combination of strategies, such as:

Low-flow and waterless fixtures.
On-site rainwater harvest for potable or non-potable use (e.g., toilet flushing, laundry, or building cooling).
On-site water reuse for potable or non-potable use (e.g., using laundry water for irrigation or toilet flushing).
Connection to a municipal reclaimed water system to offset potable water use for non-potable uses.

Projects that supply 100% of onsite water needs (as required under I06 Net Positive Water) through exclusively onsite resources, are considered to have met the water use reduction requirement of this imperative.

For affordable housing projects, handprinting is also an acceptable strategy either in combination with any of the above strategies or as the sole approach for achieving the potable water reduction goals.

Municipal Reclaimed Water

Project teams may use water from a municipal reclaimed water system as a resource for non-potable water, so long as the water supplied is municipally treated domestic sewage and not non-treated or minimally treated water that is sourced from the municipality’s potable water supply. Similarly, project teams may also contribute their treated greywater or treated domestic sewage water to the system. Any supplied water must be treated to the same or acceptable standards as the water in the reclaimed water system and used beneficially. Even if it is installed off site, any piping used to connect the project to the municipal system must meet the requirements for all other Imperatives being pursued by the project.

Performance Period

See Performance Period clarifications, in Imperative 07, Energy and Carbon Reduction (C4) which provides guidance applicable to both water and energy on baselines and occupancy.

Clarifications

Irrigation Clarifications