Kohler Ronan Consulting Engineers - KR Vision Newsletter - Issue 7, Winter 2018

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Key Considerations of Stair Pressurization Design Life safety systems in high-rise buildings are extremely critical not only for building occupants, but also for the firemen and women using these systems to save lives. There are many different kinds of life safety mechanical systems that can be designed such as smoke control, post-fire smoke purge, and pressurization. Each system serves its own purpose and each is required for different scenarios in the International Building Code. This article will discuss relevant considerations when designing a stair pressurization system. Keeping It Simple The key to designing a successful stair pressurization system is to keep the design simple across all disciplines. Simple design approaches that have been proven successful are the following: (1) the provision of the required two-hour rated wall assembly around the stairwell and mechanical stair pressurization system, which eliminates the need for fire smoke dampers (FSD) for each mechanical penetration, and (2) the provision of an additional two-hour rated assembly around the mechanical shaft. This second provision

State Official measuring the amount of force required to open the door and to activate the push bar

allows for easier construction when the contractors seal the stairwell. Simplicity can also work for controlling the pressurization system and reducing the square footage of the stairwell. Having less FSDs to control, as well as a straight forward programming logic to ramp up the fan to maintain the static pressure set point, will reduce the potential for error and component failure. Additionally, by maintaining a pressurized stairwell to a minimum of .10 inches of water and a maximum of .35 inches of water, and by providing an automatic sprinkler system, we eliminate the need for a stairwell vestibule. Power The introduction of a stair pressurization system can affect several electrical systems which in turn affect architectural space programming. A stair pressurization system requires power from a standby generator through a continuous raceway. The standby equipment (switchboards, transformers, panelboards, automatic transfer switch, etc.) must be located in a dedicated onehour rated room, separate from a normal power room, and ventilated directly to and from the exterior. The exit stairwell doors must be equipped with magnetic hold opens as well as smoke detectors to initiate the fire alarm system thereby initiating the stair pressurization system. The quantity of smoke detectors can be reduced if elevator lobbies and exit stairwell doors share a common space, allowing the smoke detector to serve a dual purpose of initiating both stair pressurization and elevator recall. Through extensive coordination between the architect and engineer, the added cost of providing a stair pressurization system may be controlled and prove to be cost effective. Air Pattern The purpose of the stair pressurization ALL TEXT Š2018 KOHLER RONAN, LLC

Pressure manometer used to measure the difference in pressure inside and outside the stairwell

system is to prevent smoke from the building from infiltrating the emergency egress for the general public and life safety personnel. That being said, when the system is operational, the air throw and pressure will definitely be felt. Further, this pressure can hamper the functioning of self-close doors, require greater force to open, and cause the system to fail upon testing and inspection. Engineers and architects should ensure that the air outlet is not directly facing stairwell doors. This is especially important for the exit door at the discharge level as this door swings outward, making it more difficult to close if an air outlet is directly blowing on it. Air outlets should be spaced at every other floor for even pressure distribution, and the architect and engineer should make full use of intermediate landings for equal continued on page 4

IN THIS ISSUE Early Observations


RevitÂŽ Corner 3 On the Boards


Early Observations & Assessments in Existing Buildings Know Before You Go Architectural and engineering design of new buildings is very different than that of renovation projects. Too often architects and engineers approach the design of existing buildings head-on, without any preliminary analysis of the building’s existing systems. This can lead to an unearthing of items that were not previously considered at the project’s genesis or during budget review. Will the client’s scope involve improving the existing building’s systems due to code issues? Are the existing systems sized to accommodate the proposed scope? Are there outstanding filing issues that will affect project closeout? Obtaining the answers to the above and other questions at the onset of the conceptual phase of a job can significantly reduce redesign, scope creep, schedule impacts, and unforeseen costs during a later phase of the project. So, how do we avoid these things from happening on our job? Performing a Due Diligence Assessment (DDA) can help mitigate these issues. Unlike a traditional survey of the systems at the start of the design phase, a DDA occurs at the early conceptual phase. By implementing this task prior to the design phase, it can help clarify project intent, clearly delineate scope, and aid in understanding overall MEP project impact and costs. The DDA analysis typically involves: Highlighting Code Deficiencies in Existing Systems Verifying Capacity, Condition, and Life Expectancy of Existing Equipment Review of MEP Systems Connectivity and Effect on Architectural Programming Highlighting Code Deficiencies in Existing Systems Though systems may be operational, that does not necessarily mean that they have been designed or installed per the

applicable code. Although the intended scope of work might be minimal, tying into a noncompliant code system could necessitate significant system upgrades in order to satisfy codes. Case Study 1 A client planned to renovate two classrooms and all the corridors of a 7-story building. The renovation was limited to new receptacles for equipment/ devices, power for mechanical equipment, and new lighting. The building was equipped with an emergency generator. The design intent was to have the new lighting connect to the existing emergency panel. At the MEP DDA walkthrough, the engineer observed that the emergency generator system had not been installed to code. Additional scope was then required to reconfigure the existing emergency distribution, yielding both unanticipated scope and subsequent cost change. Verifying Capacity, Condition, and Life Expectancy of Existing Equipment Understanding the available capacity, condition, and life expectancy of existing equipment can have significant impact on a project. Without knowledge of available capacity of power, airflow, water, and requirements for replacement, it is impossible to understand if a new space can be supported both physically and financially by using the existing MEP/FP systems. What is the age of the equipment? Has it recently been refurbished? Is pre-construction testing/recalibration needed to verify equipment integrity and capacity? Understanding the answers to these

Figure 1: Sample Pre-construction Air

questions is necessary to determine the resiliency of the equipment that will be supporting the new space/programming. Refer to Figure 1. Case Study 2 An office renovation job called for reusing the existing air handling unit to serve the new programming. Existing drawings indicating airflows were made available to the design team and the values indicated on the plans appeared to be in line with what the design intent would require. At the DDA walkthrough, it was noted that the equipment was original and at the end of its useful life. Furthermore, the base building engineer noted that the system was only operating at a percentage of its original capacity. The design engineer requested that a pre-construction air reading be provided prior to performing any design scope. It was discovered that the airflows were 63-75% of the original values indicated; adequate airflow was not being provided. The analysis of the age, condition, and capacity of the unit early on in the process allowed the building staff adequate time to make provisions for the replacement of the unit with no additional impact to the project.

Professional Development Kohler Ronan, LLC is a registered provider of AIA Continuing Education Credits. Our professionals have prepared several presentations on relevant and timely industry topics. In the coming months, we will be available to visit your offices and share these presentations. To learn more, or to schedule a visit, please contact Joe Lembo at (203) 778-1017 or via email at krce@kohlerronan.com.




Figure 2: Documentation of Existing MEP Infrastructure

MEP Systems Connectivity and Effect on Architectural Programming Understanding the placement of major MEP equipment and its associated “arteries” can be critical in aiding the architectural programming for a given project. Having this knowledge early on can influence the placement of spaces which shape the architectural plans. Examples include locating kitchens and toilet rooms adjacent to existing risers, keeping sound sensitive areas away from Mechanical Equipment Rooms (MERs), understanding major conduit and piping distribution for the installation of a new elevator shaft, and considering stair and ceiling limitations due to existing building transfers on the floor. Refer to Figures 2 & 3. Case Study 3 A new retail tenant specified that a kitchen would occupy a small portion of the store layout. At the DDA walkthrough, it was noted that the plumbing stacks were located on the opposite side of the proposed location of the kitchen. An additional 450 feet of drain pipe would be required, and the tenants below would need to be notified so that the work could be coordinated through their space. As a result of these findings, the kitchen location was shifted within the architectural programming to avoid the excess runs of piping and running over the tenant space below. Given this discovery within the conceptual design phase, redesign by the architect, kitchen consultant, and MEP consultants was successfully avoided.

Involving an experienced MEP/FP consultant at the earliest conceptual phases of a project will serve to minimize unwanted costs and scheduling delays later. If provided at the onset of a project, simple diagrams and narratives of the existing systems, highlighting utility Points of Entry (POE) and major equipment and pathways, can assist the architect and the entire design team when programming spaces. Evaluating the condition and capacity of equipment is a proven way to avoid additional scope creep during the project’s design phase when both schedule and costs are critical.


Clicking a Revit grid will present you with the following: (1) the 2D or 3D symbol, (2) a break line, (3) a check box, and (4) a lock. The 2D and 3D symbols work in different ways. Grids placed on a “shared levels and grids” workset will be turned on in every floor plan view throughout the project. A 2D grid moves or modifies only in that specific view. A 3D grid moves in all views. We recommend utilizing 2D for ease of organization. Be careful when working within the grid so as not to inadvertently select 3D as this will change that grid in every view across the entire project. The break line gives you the option to move the grid head alone, up or down, in order to avoid multiple grids smashing into each other. The check box turns the grid head on or off for the grid you have selected. You can do this on either end of the grid. If we are setting up all the north/south grids to show up on the top, you can turn the bottom off. Likewise, if you are interested in east/west grids, you can turn off the right side.

Figure 3: Existing Equipment Tables


Lastly, the grid can be either locked or unlocked. Locked indicates that the grid is locked with all the other grids in that area; when you select one grid in order to adjust it, all other grids that are locked will move with it. To move one grid individually, unlock it and it will separate itself from the group.

On the Boards Renderings Courtesy of Mecanoo with Beyer Blinder Belle

New York Public Library, Mid-Manhattan Library | New York, NY

Kohler Ronan is excited to announce that the New York Public Library’s Mid-Manhattan Library Construction Phase has begun. The Mid-Manhattan Library, one of New York City’s most heavily-used circulating branches, will undergo a complete upgrade of MEP/FP systems. With a goal of achieving a minimum of LEED Silver Certification, special emphasis is being placed on sustainable design solutions. High-efficiency equipment, including magnetic bearing chillers, air handlers with energy recovery wheels, and demand control ventilation will reduce the energy load of the overall building. The renovations are anticipated to reduce the building’s carbon footprint by approximately 75%. The library is expected to be completed in 2019. Stair Pressurization...continued from page 1

spacing. A variable frequency drive (VFD) should be utilized to control the fan in order to provide optimal air balancing and to fine tune the differential pressure required for effective stairwell pressurization. Construction Standards The most important aspect of a successful stair pressurization system is the quality of construction provided by the contractor. Since the pressurization system is designed based on infiltration

of the stairwell versus the infiltration of the building during different seasons, it is crucial that the stairwell and building are built to the specifications assigned by the engineer. The stairwell should be tight and sealed correctly for its rating; the doors should be plum and tight. The magnetic hold opens and smoke detectors for each floor landing should be programmed to respond within 10 seconds and activate uniformly if one device is initiated. Scheduling the stair pressurization test

with state inspectors prior to receiving a Certificate of Occupancy should only be done when the building is completely balanced and the engineer is presented with an acceptable Air Balancing Report. If the conditions in the building are not as designed, the system may fail. The failure can then be falsely diagnosed since it is unclear if the issue is building balancing or system design.

About the Firm Kohler Ronan is a multi-disciplined engineering consultancy dedicated to providing exceptional mechanical, electrical, plumbing, fire protection, and technology design, as well as comprehensive energy analysis, sustainable design, and commissioning services. From our offices in Danbury, Connecticut and New York, New York, our team of over 60 professionals collaborate with prominent architectural firms on a wide array of regional and nationally recognized project assignments. Commissions include those for world renowned museums, fine and performing arts centers, prestigious universities, state-of-the-art educational facilities, luxury residences, and premier recreation establishments. Additionally, we have the privilege of designing specialty systems for landmark sites and historically significant buildings across the country. For more information, please visit our website at kohlerronan.com or connect with us on social media. 4

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