This section establishes the minimum design requirements that shall be satisfied by the Plumbing Design Professional. City of Chicago Building Codes and standards may take precedence over these requirements. However, where these requirements exceed those of local code, these standards shall take precedence.
This section contains a description of the major components of the plumbing systems for the proposed building construction or renovation project. This narrative applies to the design process for the proposed building still in the schematic design phase or the renovation project under design development. This narrative is an attempt to only address the major systems and equipment that will have significant cost implications to the overall project budget. The details of the systems and designs are still to be developed as the project progresses, and must be in accordance with CPS Master Specifications and Standard Plumbing Details and Schedules.
Service
Domestic Water Service shall be sized based on the total building fixture code analysis prepared by the EOR at the beginning of the project, and updated as required throughout. Total service shall take all water usage into account, including any irrigation, out-buildings, Fire Protection and irrigation or other exterior usage. If the determined service size of the domestic water is within 10% of a greater size service, the larger service size shall be chosen in case of future increased demand. Incoming water service shall be at a minimum or 30 psi with a maximum of 80 psi. The use of code compliant backflow prevention is required on all incoming water services. CPS prefers to avoid the use of exterior hot-boxes whenever possible. Use of a hot-box requires approval by CPS.
Projects seeking LEED certification will include whole project water service metering (LEED Prerequisite) and may require Submetering of specific systems. Both to be connected to and report to the building information automation system. Design to facilitate submetering where applicable.
Sanitary Service sizing shall be sized based on the total building fixture code analysis prepared by the EOR at the beginning of the project, and updated as required throughout. Total service size shall include the discharge from special waste systems including, but not limited to, grease waste, oil waste, acid waste and sump systems. If the determined size of the Sanitary Service is within 10% of a greater size service, the greater service size shall be chosen in case of future increased need.
Storm Water Service shall be sized based on the overall roof areas and other points of entry to the system. All Storm piping shall be routed to a minimal number of connections to the exterior retainage system or City Storm Sewer. Capture for reuse may be considered on some projects and shall coordinate rain leader location with potential reuse applications.
Building Plumbing Demand
The total building plumbing demand shall be calculated by the EOR using a Fixture Unit Schedule. This form shall include all fixture types used in the building, quantities of each, and the code dictated fixtures units for both Sanitary Waste, Domestic Cold Water and Domestic Hot Water. This form shall show totals for each service in fixture units, and the corresponding flow rate in GPM, for proper verification of the sizes. This document shall be submitted at the 60% design review for verification of all service sizes and for coordination with other trades.
For designs of services for new annexes, which will tap into the plumbing services of existing schools, the plumbing service sizing calculations must include a Fixture Unit Schedule showing all fixtures in both the new annex and the existing school. This is to prove that the existing service is sized sufficiently to serve both the existing building as well as the new annex.
Fire Protection
Part of the overall Domestic Water load is for service to the Fire Protection system. The EOR shall obtain the required water need from the Fire Protection Engineer and add that to the overall building load. If this load is greater than the service load calculated based on the building fixtures, then that will be the demand used for the overall service size. EOR to verify the pressure of the incoming service and communicate this information to the Fire Protection Engineer for determination of the need for a Fire Pump System. The water service for the Fire Protection system shall be taken off the main prior to the meter assembly and backflow prevention device.
Exterior Usage
All water connections for use exterior of the building, and approved, testable, backflow prevention device shall be installed. The preferred design is to branch off a non-potable water line within a Mechanical or other back-of-house space with the required backflow preventer.
Building Water Use Calculations
Use the LEED v4 Indoor Water Use Reduction Calculator spreadsheet as a tool to reduce water usage by a minimum of 20% below the baseline. This calculator requires calculation of full-time equivalent building occupants and visitors. Refer to Appendix "X" for calculation guidance.