California Green Building Code (CALGreen) – Indoor Water Use

These actions are intended to cut back on indoor potable water consumption beyond the required flow rates and compliance. The state’s unstable water supply and the likelihood of future population increase and droughts, California may soon run out of water. The provisions take into account how much energy is needed to purify drinking water.

CALGreen Code Section A5.303.2.3.1: Tier 1 – 12-percent savings.

A schedule of plumbing fixtures and fixture fittings that will reduce the overall use of potable water within the building by 12-percent shall be provided. The reduction shall be based on the maximum allowable water use per plumbing fixture and fitting as permitted by the California Building Standards Code. The 12 percent reduction in potable water use shall be demonstrated by one of the following methods:

1. Prescriptive method. Every plumbing fixture and fitting shall not exceed the maximum flow rate at greater than or equal to 12-percent reduction, as specified in Table A5.303.2.3.1; or

2. Performance method. A calculation demonstrating a 12-percent reduction in the building “water use baseline” as established in Table A5.303.2.2 shall be provided.

CALGreen Code Section A5.303.2.3.2: Tier 2 – 20-percent savings.

A schedule of plumbing fixtures and fixture fittings that will reduce the overall use of potable water within the building by 20-percent shall be provided. A calculation demonstrating a 20-percent reduction in the building “water use baseline” as established in Table A5.303.2.2 shall be provided.

CALGreen Code Section A5.303.2.3.3: – 25-percent savings.

A schedule of plumbing fixtures and fixture fittings that will reduce the overall use of potable water within the building by 25-percent shall be provided. A calculation demonstrating a 25-percent reduction in the building “water use baseline” as established in Table A5.303.2.2 shall be provided. [Tables A5.303.2.2 and A5.303.2.3.1 are not shown for clarity. See the CALGreen Code.]

Intent:

The intent of these measures is to reduce indoor potable water use beyond the mandatory flow rates and compliance with the exception for 12-percent water use reduction found in Section 5.303.2. California’s water supply is unpredictable and likely to be stretched by future population growth and drought periods. The provisions also address the energy demands of treating potable water. A 20-percent reduction is required for the achievement of Tier 2 compliance, and a 25-percent reduction for Enhanced Tier 2.

Note: See Chapter 8 of this guide for forms and templates.

Compliance Method:

1. Specify each fixture or fitting to meet the 12-percent reduction shown on Table A5.303.2.3.1. OR

2. Performance method: A calculation is performed to demonstrate overall 12-, 20- or 25-percent savings using Table A5.303.2.2.

Note: It may prove difficult to locate fixtures needed in a project that have reduced flows beyond the 12-percent level; for example, commercial lavatory faucets, widely available at 0.5 gpm, are not widely available in an 0.4 gpm flow rate (20-percent savings), though aerators are available that can reduce flows to .35 gpm. The performance method may be a preferable path of compliance, where, for example, waterless urinals or recycled water are available.

Enforcement:

Plan intake: The plan reviewer should confirm that the construction documents indicate either the prescriptive or performance method has been submitted for the 12-percent water reduction compliance. If the performance method is used, review the water calculations showing the 12-, 20- or 25-percent reduction.

On-site enforcement: The inspector should verify that the specified 12-percent efficient plumbing fixtures and fixture fittings are installed. If the performance method was used, the inspector will verify that fixtures or systems used to reduce overall water use by 12-, 20- or 25-percent have been installed. The inspector may review the fixture specifications to verify compliance or accept a self-certification form.

(Excerpted from ‘Guide to the 2022 California Green Building Standards Code Nonresidential’ – Appendix A5)

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