Exhibit H Bldg_327_PDR_HVAC_EOL_Replacement.pdf

Memorandum Project Definition Report (PDR)

Date: November 5, 2024

To: Al Schmitt

From: Aaron Heider

Re: Project Definition Report (PDR)

Building 327 HVAC EOL Replacement

ISD/Engineering Project

Summary

ISD Engineering has been requested to develop a PDR to provide possible options to replacing the packaged HVAC unit serving Building 327. Included in this PDR are three options for solutions with associated total project cost estimates. Each option is presented with their own unique pros and cons which are described in narrative below.

Requirements

Per FESHM 1071 – Codes and Standards, the following Codes and Acts govern this project:

• ASHRAE Standard 62.1-2022 Ventilation and Acceptable Indoor Air Quality

• ASHRAE Standard 90.1-022 Energy Standard for Buildings Except Low-Rise Residential

Buildings

• ASHRAE Standard 202-2018 Commissioning Process for Buildings and Systems

• International Building Code, 2021

• International Mechanical Code, 2021

• NFPA 70 National Electrical Code, 2020

• NFPA 90A Standard for the Installation of Air-Conditioning & Ventilating Systems, 2021

• NFPA 90B Standard for the Installation of Warm Air Heating & Air-Conditioning, 2021

Existing Conditions:

Building 327 was originally designed as half open office space and half large conference space. The building is served by a one 35 ton single zone, constant volume, gas heat, electric DX cooling package rooftop unit (RTU). Distribution ductwork enters the building in a single location in the rear of the building (along the south wall), crosses to the front, divides to evenly distribute air inside the building, and terminates with round louvered diffusers. The ductwork is primarily exposed spiral round ductwork hung from the building structure.

The existing unit has been labelled as “end of life” by ISD-Facility Management and requires replacing. Due to improper HVAC zoning of the building, the RTU has been operating at partial capacity, reducing efficiency and quality of the interior environment. Because the unit is oversized for most common daily operation of the space, compressors activate and cool the

Aaron Heider Mechanical Engineer

ISD / Engineering P.O. Box 500, MS 214 Kirk Road and Pine Street Batavia, Illinois 60510-5011

USA

Office: 630.840.2175 aheider@fnal.gov mailto:aheider@fnal.gov space quicker than the unit’s capabilities. The compressors quickly overcool the space and turn off, commonly called “short cycling”. This repeated on/off cycle of the unit has degraded the compressors faster than is to be expected. This operation also prevents the unit from properly dehumidifying the space. Space humidity is removed by cooling the air but can only be removed while the cooling is active. When there are long periods where the building is overcooled, the unit stops removing humidity and allows humidity levels to increase to uncomfortable levels.

This operation creates a cold, wet space that occupants find uncomfortable.

Proposed Options

Option 1: Single Zone Variable Air Volume (SZ-VAV) RTU with Hot Gas Reheat

(HGRH)

A single zone variable air volume RTU allows better load matching with a single packaged rooftop unit. In addition to compressors staging to match space load, the fan also stages to match the compressors. This allows the unit to not only match the cooling required, but also allows the unit to supply the ideal temperature air at low loads. Lowering the supplied air volume at partial load allows the unit to continue to supply air at the target 55°F airflow. A

55°F supply air temperature is selected to both provide an ideal occupant temperature level as well as ideal dehumidification. If the space load continues to drop and the unit is operating too slow to properly dehumidify the space, the HGRH system will activate. HGRH allows the unit to overcool the air, removing the moisture from the airstream, but then returns some of the heat taken out of the airstream back to supply the space with a more appropriate temperature airstream, satisfying the building loads.

Redundant components in the RTU will provide additional resilience to the unit. Two plenum style supply fans allow the unit to continue to provide partial air capacity in the event one fan goes down. Two compressors allow partial cooling to be provided in the event of a compressor failure. And two condensing fans allow the unit to continue to reject heat if one fan goes down.

• Advantages o Cost: Compared to Option 2, SZ-VAV is a lower cost solution. Work would be limited to replacing the existing RTU and indoor temperature sensor. Existing interior ductwork distribution would be reused.

o Resilience: Compared to existing RTU, doubled RTU components provide partial backup in the event of failures.

• Disadvantages o Control: Compared to Option 2, SZ-VAV provides less precise control for the conference space. A single temperature sensor would be located in the open office area, controlling to office occupant comfort.

Option 2: Multi-Zone Variable Air Volume (MZ-VAV) RTU with Hot Gas Reheat

(HGRH)

This option replaces the existing RTU with a multi-zone VAV RTU. The multi-zone RTU supplies a constant 55°F airflow to the ductwork, but works in conjunction with VAV terminal boxes to satisfy the space load requirements. Each VAV terminal box has an internal damper controlled by a space temperature sensor to vary the amount of airflow supplied to the space. If the space load is too low and the supply airflow can’t drop any lower, an attached electric reheat coil will reheat the air to provide the ideal air volume and temperature to satisfy the temperature sensor.

MZ-VAV systems provide tighter control of space temperatures. Because each VAV box has an associated temperature sensor, each space/zone will be able to control the airflow supplied to the space, allowing different portions of the building to better control to the current individual space loads.

Similar to the SZ-VAV system, varying the airflow and staging the compressors will provide the first stage of dehumidification to the building and hot gas reheat will provide a second stage of dehumidification. Redundant components will also provide resilience, allowing the system to operate at partial capacity during a component failure.

• Advantages o Control: Compared to Option 1, MZ-VAV provides more precise control for the conference space. Multiple temperature sensors would be located throughout each area, allowing local control for each thermal zone.

o Resilience: Compared to existing RTU, doubled RTU components provide partial backup in the event of failures.

• Disadvantages o Cost: Compared to Option 1, MZ-VAV will require additional funding. Additional work will be required to install the individual VAV terminal boxes in the existing ductwork and run additional temperature sensors to each box. The existing duct layout would require two terminal boxes to be installed.

Option 3: Two Single-Zone Variable Air Volume (SZ-VAV) RTU with Hot Gas

Reheat (HGRH)

An additional option was analyzed to provide better redundancy: splitting the original

RTU into two, totally independent RTU systems. In the event any component of one unit fails, the other system would continue to operate, even while technicians are working to repair the failed unit.

This option would operate exactly the same as the SZ-VAV system, varying the airflow and staging the compressors will provide the first stage of dehumidification to the building and hot gas reheat will provide a second stage of dehumidification.

• Advantages o Control: This option would provide the same level of control as Option 2. The conference and the office areas would each have their own thermostat controlling their own RTU, allowing local control for each thermal zone.

o Resilience: Doubling the RTUs would allow each zone to operate totally independently from the other zone. Even during repairs, the unaffected zone would remain in operation. Each

RTU would also include the double compressor, double supply fan, and double condenser fan redundancy as Option 1.

• Disadvantages o Cost: This solution almost doubles the cost associated with Option 2 while only increasing the resilience of the system during a repair.

Cost Estimate:

See Attachment 1. The first document is the construction cost estimate. The construction cost estimate is broken down into the three options (O1, O2, O3). Each item is marked with an

“X” under which option it applies to. Items are also color coded, matching with the option headers at the top. Items that are common to all three options are not colored.

Following the construction cost estimate is the total project cost estimate. These numbers are estimated based on historical percentages of the construction cost estimate. When budgeting the project as a whole, the bottom right value lists the total project cost.

Conclusion:

Based on the occupancy and usage of the two areas of the building, ISD-Engineering recommends Option 2. The occupancy level and schedule in the conference space justify the additional cost to install a MZ-VAV system. The resiliency requirements for the space do not justify the cost increase of two SZ-VAV units.

Further study and discussion will be required to determine the desired heating source for the RTU. Currently, the RTU is provided with natural gas heating, but due to recent directives provided to the lab by the DoE and the lab’s own internal sustainability policy, electrification of building utilities is desired. Exchanging natural gas heating for electric heat pump heating may require additional electrical upgrades to the building. This research will be performed during the Final Design phase.

Please contact me at x2175 with any questions.

ISD Engineering Risk Assessment: All True, Engineering Risk Assessment Not Required

T=Formal Engineering Risk Assessment NOT REQUIRED

F=Formal Engineering Risk Assessment REQUIRED

Attachments:

1. Cost Estimate

ISD/Engineering This task is not a GPP or part of a larger project.

Technology This task will use off-the-shelf technology.

Environmental Impact This task may have some or no environmental impact, but no EA.

Vendor Issues Vendors can cause little or no manageable complications.

Resource Availability Resources will be readily available.

Quality Requirements The quality requirements can be easily met with existing infrastructure.

Safety This task will require little or no increased diligence.

Manufacturing Complexity The manufacturing/construction technologies will be routine.

Schedule The schedule for this task is not critical to other projects.

Interfaces This task involves groups from within Fermilab and not outside institutions.

Experience/Capability At least one lead engineer will participate in this task.

Regulatory Requirements Regulatory agencies will have minor to no involvement.

Project Funding A single source will fund this task.

Project Reporting Requirements Reports to senior management will not be required.

Public Impact The public will not be affected.

Project Cost This task will not require laboratory or DOE budget reporting.