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High-rise buildings represent a significant investment, and it could be argued that they should be designed to last 100 years. But, what about the systems that comprise the building?
Cast iron waste and vent piping can last up to 100 years when properly installed and utilized. The life expectancy of domestic water piping is not nearly as high. Several manufacturers of copper piping offer a 50 year warranty on the piping – granted this warranty is only for residential installations.
Galvanized steel piping can last over 30 years assuming the water quality is ideal.
Many high-rise buildings are reaching the age where their piping systems must be replaced. Replacement of this piping can be extremely invasive. A renovation project of this sort provides a unique opportunity to review other potential changes.
Does it make sense to redesign the base building toilet rooms? Would revisions to the public corridors provide more flexibility with the toilet room redesigns? Should low flow plumbing fixtures be used? Do the toilet rooms meet ADA compliance?
The big picture must be looked at to ensure a successful end product.
Project case study
The John C. Kluczynski Federal, (JCK), Building is a 45-story federal office building located in the “loop” area of downtown Chicago. This building is among several buildings and structures that comprise the Chicago Federal Center, designed by Mies van der Rohe. JCK was completed in 1975.
Similar to most other high-rise buildings, the JCK building has an internal building core area that is surrounded by tenant occupied areas. This core area contains three sets of public elevator banks; a low-rise, mid-rise, and high-rise bank serving respective portions of the building. Like most high-rise buildings, mechanical floors are utilized for general and horizontal pipe distribution, with risers extending vertically throughout the tenant floors. The restrooms for each floor are located within, or adjacent to, the core area and typically are located between elevator shafts.
The focus of this article is on the recently completed upgrades of the existing domestic water piping system at JCK, which in turn led to the modernization of the restrooms, (henceforth called the ‘Core Renovation’ project).
Driving factors behind the project
A feasibility study was performed on the JCK mechanical piping systems in spring 2008, after a mechanical heating and cooling pipe burst on the 14th floor causing significant flooding on the tenant floor. During this study, samples of existing domestic water piping were sent out for third party analysis. The pipe types consisted of type L copper and schedule 40 galvanized steel. The existing piping was evaluated to determine the amount of corrosive deposits that had built up on the interior of the pipe.
When the interior deposits were removed, the remaining wall thickness was measured and compared to the original wall thickness. One sample of existing domestic hot water piping had corroded so much that a pinhole leak was identified under the external gasket groove, (this was galvanized steel piping utilizing mechanical couplings).
The results of the pipe sampling analysis indicated a critical need for replacement of all domestic water piping 3 inches and smaller to avoid the risk of flooding due to pipe failure. Piping of this size had an overall pipe wall reduction of up to 60 percent. The pipe sampling analysis was also used to assist in the selection of what pipe type to install as part of the new Core Renovation work. The selection was based on the amount of deterioration seen between the copper and galvanized steel pipe samples.
As previously mentioned, many of the core restrooms were located between elevator shafts, making the domestic water piping accessible only from the restrooms themselves. While doing the invasive work to replace the domestic water piping, it only made sense to rework the waste and vent branch piping within the same plumbing chase. The existing waste piping was cast iron hub and spigot, with lead and oakum joints, and the vent piping was galvanized steel piping. All waste and vent piping was replaced with the exception of the risers themselves, which were typically 6 inches or larger. Any leaking or damaged sections of the waste and vent riser piping were of course attended to, such as a broken hub, bad joint, or missing clean out cover.
Given the extent of the rework required to access the domestic piping within the toilet rooms, it also made sense to investigate modifications to the existing toilet room layout in addition to improving the overall appearance and performance. The restrooms were completely redesigned to allow for ADA upgrades, removal of floor mounted toilets, and the inclusion of floor drains, which were not previously installed.
The Core Renovation project was funded by the American Recovery and Reinvestment Act of 2009 (ARRA) for “Energy and High Performance Green Building” building upgrades. The goals of the project included a desire to reduce water consumption, so we decided to incorporate low flow plumbing fixtures. This also helped with the additional goal of achieving LEED Silver Certification.
Existing fixtures within the building included two types of toilets – some 3.5 gallons per flush, (GPF), original to the building, and some more recently updated to 1.6 GPF. The Core Renovation project selected high efficiency fixtures, with toilets utilizing 1.28 GPF, 0.125 GPF at the urinals, and 0.5 GPM faucets on the lavatories. Swapping out the plumbing fixtures accounted for a 37 percent water use reduction against baseline case found in the 2009 LEED Core and Shell Development. According to the LEED calculations, this water reduction accounts for an annual savings of 2.5 million gallons per year, (or possibly more since the baseline case does not factor in any of the remaining original 3.5 GPF toilets).
The new high efficiency toilets required a higher water pressure supply than the previously installed models. According to the flush valve manufacturer, the new water closet flush valves require a minimum of 35 pounds per square inch, (PSI), of residual water pressure. This is a 20 PSI increase compared to the previously installed flush valves in the building.
When designing around these new high efficiency toilets, we had to be extremely careful to ensure the proper water pressure was available at the flush valve, or the toilet would not flush properly.
Due to the height of the building, the original building design incorporated a total of four pressure zones. Each zone had its own dedicated simplex domestic booster pump. Each of the three lower zones utilized a pressure reducing valve, (PRV), downstream of their respective pump.
A prior project involved the installation of four new domestic booster pumps with variable frequency drives. These pumps were piped in parallel to serve all four zones of the building, providing redundancy in case of pump failure. The pump discharge header piping was connected such that it utilized the original PRVs for each of the three lower zones.
As part of the Core Renovation project, the original PRVs were demolished. New pump discharge piping was installed, along with new pressure reducing valve stations, where required. The building’s cold water distribution was broken up into a total of 6 pressure zones. PRV set points and the overall domestic water zones had to be thoroughly analyzed to ensure adequate pressure would be available at the upper levels, without over pressurizing the lower floors of each zone.
The JCK building management system, (BMS), was being upgraded in a separately funded project that ran concurrently with the Core Renovation project. We utilized that project to integrate the domestic booster pump controls into the new BMS. This gave the building maintenance staff the ability to record and track pump usage, pressure fluctuations, and make adjustments to the way the pumps were utilized.
Hot water temperature maintenance
The JCK building, unlike many high-rise office facilities, utilizes centralized domestic hot water heating. Consequently, the hot water is recirculated to maintain temperature. Depending on the length of the unrecirculated run, low flow faucets can take an excessive amount of time to get hot water.
In the case of JCK, the lavatory flow rate was 0.5 GPM, with an electronic sensor run time of 10 seconds, equating to 0.17 gallons per cycle. The new JCK toilet room layout placed a bank of lavatories at each end of toilet room, but to avoid long user wait times for hot water, we had to limit the lengths of uncirculated hot water piping. Rather than running a hot water supply and return riser at each end of the toilet room, we utilized the hot water supply piping to serve one bank of lavatories, and the hot water “return” piping to serve the other bank of lavatories.
The hot water supply piping essentially looped within each pressure zone (See right side of figure 1). =Hot water supply valves were located directly under the lavatories behind an access panel, keeping the length of piping to an absolute minimum.
• The project identified, and removed, five of seven mechanical cooling units off of single pass domestic cooling. These units are now supplied with recirculated water from the existing condenser water system.
• The Core Renovation project involved reworking and updating the public corridors. This provided the opportunity to route new condenser water piping with minimal impact to the overall project budget. Even with the corridor ceilings open, the routing of this piping was challenging at times due to limited open ceiling space, a common issue for many buildings designed by Mies.
• The domestic water make up supply to the cooling tower had a water meter installed to document and analyze water usage.
• From a recycling perspective, an estimated 102,000 pounds of porcelain material was diverted from the landfill and reused on the project. This porcelain was recycled to make more than 57,000 square feet of recycled tile that was installed in all the toilet room floors, and along the rooms’ wet walls (See figure 4). These additional items helped the project obtain LEED Gold Certification on January 10, (under 2009 LEED Core and Shell Development).
With many of the high-rise buildings out there starting to approach the end of their piping’s life expectancy, core renovation projects like this will start to become more commonplace, if not already. One should be sure to provide a holistic approach when undertaking such a project, in order to facilitate pipe access, maximize the ability to implement meaningful changes in performance, and to provide the best overall solution to modernizing the building systems and spaces.