Mercer County Library System - West Windsor Bid Solicitation Report.pdf

50 Millstone Road Building 300 - Suite 110

East Windsor, NJ 08520

(609) 945-8000

(609) 945-8080 (fax)

Penn’s Plaza

2 Penn’s Way - Suite 400 New Castle, DE 19720

(302) 613-5030

(302) 613-5739 (fax)

MERCER COUNTY LIBRARY

SERVICES

WEST WINDSOR LIBRARY

BID SOLICITATION REPORT

BY:

On-Board Engineering February 24, 2025

50 Millstone Road Building 300 - Suite 110

East Windsor, NJ 08520

(609) 945-8000

(609) 945-8080 (fax)

Penn’s Plaza

2 Penn’s Way - Suite 400 New Castle, DE 19720

(302) 613-5030

(302) 613-5739 (fax)

Table of Contents

Section 1 Feasibility Report – Overview

Section 2 Feasibility Report – Roofing

Section 3 Feasibility Report – Mechanical

Section 4 Feasibility Report – Structural

Appendix 1 Existing RTU information & Photos

Appendix 2 ASHRAE Documentation

Appendix 3 ASHRAE HVAC Systems and Equipment

Appendix 4 ISO-Aire Supporting Documentation

Appendix 5 Mech. Equipment Selections

Appendix 6 Drawings - Roof Plans and Details

Appendix 7 Roofing Specifications

Mercer County Library Services

West Windsor Library

Feasibility Study

SECTION 1: Feasibility Summary Overview

Executive Summary:

The existing rooftop material has become porous over years of wear and tear and is leaking in many places. On-Board recommends the option to replace the roof rather than overlay. For the

HVAC and Mechanical costs and scope, replace all of the units in kind and consolidate new rooftop units where possible, if feasible. It is assumed that the Mechanical unit replacement and the roof repair will occur simultaneously. If the rooftop is replaced/repaired without the unit replacement, costs will increase.

Scope Summary:

Mercer County desires to provide HVAC and Roofing repairs and upgrades to a few libraries in the Mercer County Library System. The libraries include Ewing, Lawrence and West Windsor

Library. These libraries serve as centralized information for the County. During the COVID-19 pandemic, the libraries provided information, PPE and other disaster mitigation services. This report will lay out the roof replacement at the West Windsor library.

Roof Option Considerations:

Solution: Complete D&R and New Roof

The existing roof of the West Windsor building has a number of places that are leaking, as shown on the plans in Appendix 6. The first option to consider in roof repair is to dismantle and remove

(D&R) and then replace it with a new roof.

Rooftop Equipment Option Considerations:

Solution: Replace in Kind each recommended rooftop unit

The existing units on the roof will be replaced in kind with similar units of similar tonnage and load. This does not require all mechanical to be updated to current code restrictions

Recommendations:

Given all of the information achieved for roofing, On-Board recommends the solution of removing the existing roof, updating the insulation using a Polyiso rigid board material and replacing the roof with new EPDM roofing material.

For Mechanical, On-Board recommends replacing each unit in kind on the roof and updating the ducting as necessary.

Cost Estimate:

It should be noted that construction staging, inflation, material availability and labor rates can affect the actual cost of the project.

Permitting:

The contractor shall be responsible for obtaining all permits for this project. For Mercer County, the Planning Department shall be contacted to apply for any permits. The following permits should be considered:

- Building Permit

- Construction Permit

- Environmental Permit if certain materials are used or changed and if more than 25% of the commercial roof is being replaced, which applies in this case.

Codes:

The following codes apply to all designers and contractors:

- IBC, chapters 13, 15 and 16

- New Jersey Roofing Codes o Minimum R-value of 30

Preliminary Schedule:

The timeframe for this particular project at West Windsor library hinges on several different options and variables. The following preliminary milestone schedule is subject to change based on these variables

- Mercer County bid for detailed design: 3 weeks

- Detailed Engineering and design: 6 weeks

- Mercer County Bid for Construction 3 weeks

- Bid Award and Kick-off 1 week

- Mercer County to order equipment o Longest RTU lead time: 8-12 weeks

- Contractor to obtain permits as necessary: 4 weeks

- Contractor to complete roof work: 3 weeks o Each large area to be blocked off for 1 week each

- Mechanical Contractor to complete installation: 4 weeks

- Roofing contractor to complete follow-up repairs: 2 weeks

TOTAL: 26 weeks

SECTION 2: Roofing

The existing rooftop material has become porous over years of wear and tear and is leaking in many places. On-Board recommends the option to replace the EPDM roof rather than overlay.

The costs associated with a full roof replacement are higher up front, but will save costly repairs, operating costs and efficiency costs down the road. The cost to replace the roof can be affected by construction staging, inflation, material availability and changes in labor rates. The estimate shall include tear-off, repairing leaking areas, new insulation, new structural supports if necessary, new roofing and labor and materials.

Scope Summary:

Mercer County desires to provide HVAC and Roofing repairs and upgrades to a few libraries in the Mercer County Library System. The libraries include Ewing, Lawrence and West Windsor

Library. These libraries serve as centralized information for the County. During the COVID-19 pandemic, the libraries provided information, PPE and other disaster mitigation services. This report will lay out the roofing replacement.

Current Roofing System:

The information presented in this evaluation is based upon the original construction drawings provided by the client, multiple site visits and public information. West Windsor was designed in

1995, and construction was completed in 1997. The HVAC system for the building includes rooftop air handling units, rooftop exhaust fans, electric duct heaters, and rooftop gravity ventilators.

The Northeast roof over the meeting room areas was replaced recently and will not be modified or replaced during this scope. The metal seam barrel vault roof over the adult reading area will also be outside this scope as there are no immediate issues. The scope will deal with the remaining Ethylene Propylene Diene Monomer (EPDM) roof over the adult stack area, the office area, the work room area, the bathroom area, the children stack area and a small portion near the magazine/new books area. This roof is the original roofing and has been leaking in several areas, requiring patching and repair throughout the years.

Figure 1: Overall main roof

Figure 1 above shows the EPDM roof above the adult reading stacks. It’s evident that wear and tear has affected the roof, and the material is showing its age. Upon close inspection, the EPDM roofing material has developed pockets and areas that are porous and allow water through easily.

The EPDM roofing sits on top of insulation and metal roof decking, which then sits on the main roof steel. There is miscellaneous L4 angle steel under each of the HVAC units for additional support. The thickness of the EPDM room is likely 60 mils, though it is difficult to determine the exact specification thickness without taking a sample.

As mentioned, there are several areas that have visual evidence of leaking that are in need of repair.

Figure 2: EPDM Roof at Masonry wall

Figure 3: Missing flashing

The above images show two (2) such areas as an example. Figure 2 shows the area near the skylight where a portion of the EPDM roofing is porous. Figure 3 shows the intersection of the barrel steel roof and the EPDM roof section. As shown, there is no flashing redirecting the water away from the ductwork of RTU-1. Because of this, the water is able to get under the steel roofing and leak straight into the main reading area inside.

This report will provide options of replacement and of repair through overlay and provide the benefits and detriments of each option. At the conclusion, a recommendation will be provided along with a high-spot cost estimate.

Roof Option Considerations:

Solution: Complete D&R and New Roof

The existing roof on the West Windsor building has a number of places that are leaking, as shown on the plans in Appendix 6. The first option to consider in roof repair is to dismantle and remove (D&R) and then replace it with a new roof. No asbestos discovery or abatement necessary for this building since it was built after 1994.

If the roof is removed, it will be easier for a contractor to perform repairs in the necessary areas to prevent any further leaking. The insulation will be replaced with material that will be more energy efficient and better at keeping the temperature consistent. For an EPDM membrane roof that is situated on a metal deck roofing structure, rigid board insulation is typically the most common type. Rigid board insulation is mechanically attached to the metal decking before the

EPDM material is laid on top to allow for optimal thermal performance. The most popular choice of rigid board insulation is Polyisocyanurate material (Polyiso) due to its high R-value, moisture resistance and ability to withstand compression. R-30 is the most common energy value requirement for new roofs as required by code or government request. The roofing material can be anything from matching the previous EPDM material to PVC to Modified Bitumen.

On-Board recommends keeping a highly accessible material should the roof be replaced. EPDM, TPO and PVC are all accessible and considered single-ply roofing material that can be considered. The thickness of the roof will depend on the cost Mercer County is willing to spend and the R-value that Mercer County wants.

Recommendations:

On-Board has taken the costs, ease of construction, post-installation operating costs and the desires of Mercer Couty through several discussions to arrive at a recommendation that satisfies several aspects for this project.

The given solution (Roof replacement) gives Mercer County the freedom to pursue different roofing materials, different insulation material and consider a vapor barrier if necessary. While removing the roof alone is a high expense, it allows the contractor and engineer to perform a comprehensive integrity assessment on the roof, check for leaks at a higher level and install any additional steel or supports for the new equipment if required. Addressing the leaks while the roof is removed is cheaper for the contract in labor and potentially materials than doing a spot check repair. Additionally, the longevity of a new energy efficient roof is higher than with a roof overlay.

Given all of the information achieved, On-Board recommends this solution of removing the existing roof, updating the insulation using a Polyiso rigid board material and replacing the roof with new EPDM roofing material.

On-Board recommends sticking with the EPDM material at a 45-mils or 60-mils thickness to keep the costs down.

Cost Estimate:

affect the actual cost.

Additional Recommendations:

The following is a list of additional recommendations that should be considered as part of the renovation:

• If the mechanical units and ductwork (and their supports) on the roof are being replaced, it makes sense to remove a majority of the roof around them. The options of how much to remove past the required amount to install the new curbing or curb adapters, the new ductwork openings and supports and the new vents/fans is up to Mercer County. On-

Board’s recommendations fall in line with performing a full roof replacement due to half of the roof already being removed for mechanical installations.

• It is recommended that the roof housing RTU-6, RTU-7, RTU-8, RTU-8A, and RTU-9 not be replaced as it is newer and in good condition given a visual inspection. While some pieces may need to be removed to replace any of the mechanical equipment, the whole roof is in working condition and no leaks were visually found or detected.

Section 3: Mechanical

The majority of the rooftop HVAC equipment has reached or exceeded its useful life and currently utilizes refrigerant R-22 which is difficult and costly to replace. Since all the equipment should be removed from the roof to allow for the roof replacement, it is recommended to replace the rooftop equipment and associated ductwork “in-kind”. Consolidation of some of the HVAC equipment may be practical but would be a costly endeavor due to the required duct and control modifications required. The cost to replace the HVAC equipment can be affected by salvaging newer rooftop equipment, construction staging, inflation, material availability, changes in labor rates, etc.

Scope Summary:

Mercer County desires to provide HVAC and Roofing repairs and upgrades to a few libraries in the Mercer County Library System. The libraries include Ewing, Lawrence and West Windsor

Library. These libraries serve as centralized information and cooling locations for the County.

During the COVID-19 pandemic, the libraries provided information, PPE and other disaster mitigation services.

Current HVAC System:

The information presented in this evaluation is based upon the original construction drawings provided by the client. West Windsor was designed in 1995, and construction was completed in

1997. The HVAC system for the building includes thirteen (13) natural gas fired packaged rooftop air handling units, four (4) rooftop exhaust fans, eighteen (18) zone control dampers

(also known as variable air volume (VAV) boxes), five (5) electric duct heaters, four (4) rooftop gravity ventilators and electric perimeter radiation. The supply and return ductwork serving the library stacks and reading areas are mounted above the roof and include duct silencers to mitigate noise transmission from the rooftop unit into the library.

It appears that the condition of the exposed ductwork may be contributing to the water infiltration and leaking into the building. The photos below are RTU-5 and RTU-4 which is representative of the condition of the older units at the library. For RTU-5, the exposed ductwork and silencer have been covered with a tarp to protect the materials from rain and snow. There is a significant amount of rust at the base of RTU-5 and the duct rolling down into the building which is indictive of prolonged exposure to moisture as compared to the rest of the unit and ductwork.

This can result in unit failure and roof leaks as water infiltrates the unit and ductwork. For RTU-

4, it appears that a tarp was covering the exposed ductwork and that the tarp has been blown off the ductwork. Looking at the exposed ductwork, the corners and edges are frayed exposing the ductwork to the elements. The exposed ductwork shows rust which can allow moisture to penetrate into the ductwork and leak within the space as well.

West Windsor RTU-5

West Windsor RTU-4

The rooftop units serving the administrative areas are ducted directly down through the roof curb into the ceiling space below.

RTU-1 serves the Quiet Study 129, the Lounge 128 and a portion of the southeastern section of

Adult Reading Area-127. The thermostat serving this unit is shown in the Lounge.

RTU-2 serves the southwestern quadrant of the Adult Stacks 130 with the thermostat located on a column within the space.

RTU-3 serves the eastern quadrant of the Display 126, Adult Reading 127 and the

Magazine/New Books 125. The thermostat is shown on the corner of the partition around the

Magazine/Newbooks area.

RTU-4 and RTU-5 serves the eastern side of the Adult Reading Area 127 with the thermostat located on a column within the space.

RTU-6 serves Meeting Room 106 and includes an electric duct heater in the supply duct to this space.

RTU-7 serves Meeting Room 105 and includes an electric duct heater in the supply duct to this space. The unit appears to be controlled by a constant discharge air temperature and allows the reheat coils to maintain the space setpoint. There may be an outside air temperature reset that adjusts the leaving air temperature based upon the season.

RTU-8 serves Storage Rooms 104/104A, Conference Room 103 and the northwestern side of

Vestibule 100. The drawings indicate that the supply duct includes an electric duct heater and include VAV boxes for zone control for the conference room and vestibule. A bypass damper has been provided to maintain system air flow and bypasses air from the supply to the return.

RTU-8A serves Storage Room 107 and Conference Room 108. An electric duct heater is shown in the supply branches serving each of these spaces. The unit appears to be controlled by a constant discharge air temperature and allows the reheat coils to maintain the space setpoint.

There may be an outside air temperature reset that adjusts the leaving air temperature based upon the season.

RTU-9 serves Passage 118, Circulation 131, Gallery 101, the northeastern side of vestibule 100, the Men’s and Women’s Toilet Rooms, Storage Room 112 and Activity Room 109. Zone control dampers are provided for the Circulation, the Activity Room and two (2) zone control dampers for the Gallery Area, one serves the southern side and the other serves the eastern side of the

Gallery. A bypass damper has been provided to maintain system air flow and bypasses air from the supply to the return. The unit appears to be controlled by a constant discharge air temperature and allows the zone damper (VAV box) to maintain the space setpoint. There may be an outside air temperature reset that adjusts the leaving air temperature based upon the season.

RTU-10 serves Work Room 132, Office 136 and Staff 135. Zone control dampers have been provided for each of these spaces. A bypass damper has been provided to maintain system air flow and bypasses air from the supply to the return. The unit appears to be controlled by a constant discharge air temperature and allows the zone damper (VAV box) to maintain the space setpoint. There may be an outside air temperature reset that adjusts the leaving air temperature based upon the season.

RTU-11 serves the north side of the Children Stacks 120.

RTU-12 serves the southern side of the Children Stacks 120 along with Office 124. A zone control damper has been provided for the office.

The performance schedule for these air handling units can be summarized as follows based on the schedule on the drawings:

Mercer County West Windsor Library - Rooftop Air Handling Units (Natural Gas Fired)

Tag Supply Outside

Air

% of

O.A.

Total

Clg

MBH

ESP Gas MBH

IN/OUT

Electric

Volts MCA

Operating

Weight

RTU-1 2800 345 12.3% 76.0 1.00 130.0 104.0 460/3 15.0 960

RTU-2 2000 375 18.8% 71.9 1.00 130.0 104.0 460/3 15.0 930

RTU-3 8500 1055 12.4% 289.3 1.33 470.0 376.0 460/3 ?? 3650

RTU-4 2700 480 17.8% 90.3 1.05 200.0 160.0 460/3 22.0 1500

RTU-5 2000 450 22.5% 73.0 1.00 130.0 104.0 460/3 15.0 960

RTU-6 2000 900 45.0% 74.0 0.70 130.0 104.0 460/3 15.0 960

RTU-7 2000 900 45.0% 74.0 0.70 130.0 104.0 460/3 15.0 960

RTU-8 1100 300 27.3% 28.4 0.80 50.0 38.0 208/3 19.0 560

RTU-8A 800 245 30.6% 28.3 0.90 50.0 38.0 208/3 23.0 560

RTU-9 4460 900 20.2% 143.6 1.10 250.0 216.0 460/3 26.0 1600

RTU-10 1600 320 20.0% 58.2 0.90 125.0 95.0 208/3 31.0 750

RTU-11 3600 450 12.5% 116.3 0.94 170.0 132.5 460/3 29.0 1600

RTU-12 4200 840 20.0% 143.6 0.94 270.0 216.0 460/3 26.0 1600

Please note that typical packaged rooftop air handling equipment is designed to accommodate an outside air rate (ventilation rate) of approximately 20% or less. RTU-6 and 7 serve meeting rooms which require a higher amount of ventilation due to the potential occupancy and specialty equipment capable of providing this ventilation should be provided to ensure proper ventilation and comfort conditions.

The typical life expectancy, useful life, of a rooftop air handling unit is typically 15 to 20 years depending upon maintenance, climate, installation and other factors. Based upon visual inspection of the existing equipment, the following information was gathered (Refer to Appendix

1):

West Windsor Existing HVAC Information

ID No Manufacturer Model Number Serial

Number

Manu

Date Refrig

Working

Condition

RTU-1 York ZE072H12D4A1AAA1A1 N2B1736172 Feb-21 R-410A Yes – New

RTU-2 York ZE072H12D4A1AAA1A1 N2B1704323 Feb-21 R-410A Yes – New

RTU-3 Trane YHH300G4RHA040 154310601D Oct-15 R-410A Yes

RTU-4 Lennox Not Available Not Available Slated for Demo

RTU-5 Lennox GCS24-813-130-1G 5696H01704 Aug-96 R-22 Slated for Demo

RTU-6 Lennox GCS24-813-130-1G 5696H01703 Aug-96 R-22 Slated for Demo

RTU-7 Lennox GCS24-813-130-1G 5696K03065 Sep-96 R-22 Slated for Demo

RTU-8 Lennox Not Available Not Available Unknown

RTU-

8A Trane YHC036E1RH 154310640L Oct-15 R-410A Yes

RTU-9 Trane YHD150G4RHA04H0 154310583D Oct-15 R-410A Yes

RTU-

10 Lennox Not Available Not Available Slated for Demo

RTU-

11 Lennox LGA120HH1G 5696K04108 Sep-96 R-22 Slated for Demo

RTU-

12 Trane YHH150G4RHA040 154310567D Oct-15 R-410A Yes

RTU-1 and RTU-2 are the newest models and are approximately 4 years old. RTU-3, RTU-8A, RTU-9 and RTU-12 are approximately 10 years old or half to two-thirds into their useful life.

Refrigerant Considerations:

Refrigerant R-22: As of January 1,2020, R-22 refrigerant became illegal to import and manufacturer in the United States due to its ozone depletion potential (ODP). Therefore, any R-

22 equipment that has lost its refrigerant charge is difficult and costly to replace the refrigerant.

Refrigerant R-410A: The EPA is phasing out R-410A because of its Global Warming Potential

(GWP). As of January 1, 2025, R-410A will no longer be used. Currently there is one drop-in replacement for R-410A which is R-470A. R-470A is nonflammable with a lower GWP. Other alternative refrigerants maybe emerging as servicing of this HVAC equipment continues.

Refrigerant R-32 and R-454B: As of January 1, 2025, the new environmentally friendly R-32 and

R-454B will be replacing this R-410A in the United States. Countries such as Japan, Korea, India, Russia, Greenland, the Middle East and Australia have been using this refrigerant as an alternative to R-410A for a while.

Equipment Consolidation Considerations:

It appears that the original design considered functionality and exposure along with some design constraints.

• RTU-4 and 5 could be combined since they both serve the same open area. The supply and return ductwork would need to be completely reconfigured to accommodate this consolidation. Both units have their supply and return ducts running above the roof and the majority of the duct reconfiguration could occur above the roof. However, the placement and location of RTU-3 makes this a little challenging since this unit is located between these two (2) units.

• RTU-6 and 7 serve two (2) meeting rooms that can be combined into a single larger room by opening the partition. Potentially these units could be combined into a single unit and large VAV boxes installed to segregate the two (2) spaces to allow them to have independent temperature control.

• RTU-8 and RTU-8A could be combined. The ductwork from these units would need to be completely reconfigured, the reheat coils removed and VAV boxes with reheat coils installed to allow for individualized zone control.

Covid Mitigation Technology:

Filtration & Ventilation:

October 19, 2021, the ASHRAE Epidemic Task Force issued Core Recommendations for

Reducing Airborne Infectious Aerosol Exposure (see appendix 2) which recommended the following:

2. Ventilation, Filtration, Air Cleaning

2.1 Provide and maintain at least required minimum outdoor airflow rates for ventilation as specified by applicable codes and standards.

2.2 Use combinations of filters and air cleaners that achieve MERV 13 or better levels of performance for air recirculated by HVAC systems.

UV Lights:

UV Lights have been a proven technology for disinfection. The 2020 ASHRAE Handbook -

HVAC Systems and Equipment Chapter 17 (see appendix 3) addresses the use of UV-lights in

HVAC applications and some of the critical items have been included here. UV-C energy disrupts the DNA of a wide range of microorganisms which renders them harmless.

Ultraviolet germicidal irradiation (UVGI) in the UV-C band has been used in air ducts and air-handling units for some time, and its use is becoming increasingly frequent as concerns about energy, maintenance, and indoor air quality increases.

Studies have shown that that continuous UVC exposure in occupied areas can result in viral inactivation between 8 to 25 minutes. (see appendix 3)

Important considerations are as follows:

• UV light exposure can degrade and shorten the life of certain filter media, insulation or gasket foams.

• UV exposure can cause eye and skin damage. Safety precautions must be taken.

• UV lamps should be treated the same as other mercury-containing devices and must be treated as hazardous waste.

• The typical useful life of a UV-C lamp is 9,000 hours of continuous use and as a result, these should be replaced annually. Switching lamps on and off will reduce the performance and life expectancy of the lamps.

Bipolar Ionization:

In 2022, ISO-Aire (Appendix 4) described the operation of bipolar ionization and the potential effectiveness of addressing viruses. The information included is summarized here.

Bipolar ionization splits molecules in the air into positively and negatively charged ions.

When bipolar ionization is deployed in the air, the positive and negative ions surround air particles. This added mass helps the air particles to fall to the floor and be captured by the building’s air filter. As the positive and negative ions surround air particles that include pathogens (e.g. viruses, bacteria, mold spores), the ions pull hydrogen away from the pathogen. In the case of a virus, hydrogen is pulled away from its protein coat, or capsid.

Hydrogen is a key component to the structure of the viral protein coat, and without it, the virus is no longer infectious. In June 2020, Global Plasma Solutions issued a release indicating that their product virtually eliminated the SARS-CoV-2 (Appendix 4).

One of the biggest concerns with bi-polar ionization is the creation of Ozone, which is hazardous to breath and can cause serious health issues. Consequently, any bipolar ionization equipment must meet UL 2998 standard certification to validate that no harmful levels of ozone are generated.

Recommendations:

Based upon the information presented, re-using operational equipment may be attractive to reduce costs; However, due to the phase out of R-22, the cost of maintaining and servicing this equipment does not make it practical. Re-using equipment with R-410a is more practical since this refrigerant is currently available and does not have a termination date. Ideally, all the HVAC rooftop Units would be replaced with more modern energy efficient technology. This equipment should be selected to meet the current operations within the library. For estimating purposes, the original design schedule was sent to a local York/Johnson Control Incorporated representative to develop preliminary selections for physical dimensions, weights as well as a budgetary cost for each of the units. These preliminary equipment selections are included in Appendix 5.

As part of the proposed renovation, all the equipment should utilize the latest EPA approved refrigerant and include a minimum MERV-13 filters. All the rooftop ductwork and duct mounted silencers should be removed and replaced. All duct mounted smoke detectors should be replaced as well. The thickness of the insulation on the exterior ductwork should be increased to meet the current energy standards and installed to protect the insulation and ductwork from weather.

At a minimum, new thermostatic controls should be provided with the new air handling units to ensure system compatibility. A centralized control system that integrates and monitors the

HVAC equipment is also recommended for improved performance and trouble shooting.

As part of the replacement, the electrical requirements of the new equipment may be higher than the existing resulting in larger breaker sizes, wire replacement and potentially new electrical distribution equipment. This will need to be addressed during the design for the proposed renovation.

Cost Estimate:

Based upon the equipment selections presented in Appendix 5, the vendor provided a preliminary cost estimate for their equipment. It should be noted that construction staging, inflation, material availability and labor rates can affect the actual cost and that this is a budgetary estimate only.

Per discussion, bipolar ionization is an emerging technology and implementation of this technology into the system may be beneficial and is included in the cost of the new rooftop equipment. Upgrading the building controls to allow for remote monitoring and troubleshooting has also been included.

Additional Recommendations:

The following is a list of additional recommendations that should be considered as part of the renovation and is not included in the cost estimate above but has been added to the cost estimate on the summary section as separate line items:

• With the proposed roof work, the existing rooftop exhaust fans and gravity vents should be replaced.

• The consolidation of HVAC equipment as noted above could potentially reduce annual operating and maintenance costs. It will not alter the construction cost estimate substantially since the cost savings associated with replacing the air handling units will be offset by the increase in duct sizes, the installation of new additional rooftop ductwork, power requirements and structural modifications required to support the consolidated unit and the new ductwork.

• To improve energy performance and operation, the existing electric duct heaters could be replaced with VAV boxes to prevent simultaneous heating and cooling which is prohibited by the Energy Codes. The rooftop air handling units would need to be selected to accommodate a variable flow air handling system, or the ductwork reconfigured to accommodate a bypass damper, which is similar to other systems in the building. This should reduce operating costs.

• Installation of demand control ventilation system to allow the ventilation system to modulate as required to meet the ventilation requirements of the actual occupants. This should reduce operating costs.

• It should be noted that in June 2023, ASHRAE Standard 241 established minimum requirements to reduce the airborne transmission of viruses and these recommendations should be considered during design.

SECTION 4: Structural

The structural aspects of this scope are minimal. If going with On-Board’s recommended solution of replacing the roof and insulation along with the HVAC units, the structural costs will be at a minimum.

Scope Summary:

Mercer County desires to provide HVAC and Roofing repairs and upgrades to a few libraries in the Mercer County Library System. The libraries include Ewing, Lawrence and West Windsor

Library. These libraries serve as centralized information for the County. During the COVID-19 pandemic, the libraries provided information, PPE and other disaster mitigation services. This section will lay out the structural requirements for new roofing and new HVAC equipment for the West Windsor building.

Current Structural Support System:

The information presented in this evaluation is based upon the original construction drawings provided by the client, multiple site visits and public information. West Windsor was designed in

1995, and construction was completed in 1997. The HVAC system for the building includes rooftop air handling units, rooftop exhaust fans, electric duct heaters, and rooftop gravity ventilators. As mentioned in Section 2, it is the recommendation that most, if not all of the units be replaced.

The Northeast roof over the meeting room areas was replaced recently and will not be modified during this scope other than potentially shifting HVAC support members to match the new curbing dimensions. The metal seam barrel vault roof over the adult reading area will also be outside this scope as there are no immediate issues. The scope will deal with the remaining roof structure over the adult stack area, the office area, the work room area, the bathroom area, the children stack area and a small portion near the magazine/new books area.

The roof structure in the adult stack area is a steel superstructure with steel wide-flange columns, W14 or W16 girder beams, 18K7 and 14K1 steel joists and metal stud strapping. Beneath each

HVAC unit and equipment support are supplemental L4 members attached to the steel joists or to the main girders depending on the location. On top of the joists is metal roof decking to which the insulation, wood blocking and roofing material is placed on top.

Figure 1: Adult Stack Interior Steel

The bathroom area and the children’s stack area have similar roofing structures. The main girder beams are W12 members in the children’s area and W16 members in the work room area. The roof joists range from 14K1 joists to 16K2 joists. The supports for the mechanical units and ductwork are similar L4 members that attach to the joists or the main girders. Metal roof decking, insulation, wood blocking and roofing material are similar to other areas.

Figure 2: Children Stack Interior Steel

The work area and the office area consist of mostly W12 or W14 steel beams and metal bracing and strapping for the structure without any joist framing. Metal roof decking, insulation, wood blocking and roofing material are similar to other areas.

Figure 3: HVAC Interior Support

This report will provide options for replacement.

Structural Considerations:

The options for structural roof modifications rely on the recommendations from Section 1 and

Section 2.

Should the recommendation of replacing the roof be accepted moving forward, the roof structure in the areas of replacement will not change as the new insulation and new roofing will have a negligible change to the weight on the roof.

For any of the HVAC equipment being replaced, a design engineer will have to take into consideration the change in dimensions for the length and width. From preliminary engineering and data gathering in section 2 of this report, the weight of the new equipment will be within the accepted tolerance of load so as not to update the steel. However, the dimensions will slightly change on the units, which will require new curbing that may not align with the existing HVAC support steel within the existing roof structure. These L4 members may have to be relocated to line up with the new curbing.

If the dimensions of the new unit are close enough to the existing dimensions, a curb adapter can be utilized to keep the same load points on the roof, therefore eliminating the need to install new support steel in the roof structure.

If the HVAC unit is deemed to stay in place, no modification to the steel is required. Same goes for the duct work on the roof.

Recommendations:

On-Board has taken the costs, ease of construction, post-installation operating costs and the desires of Mercer Couty through several discussions to arrive at a recommendation that satisfies several aspects for this project.

With the replacement option, the contractor can visually assess any of the leaking areas and determine if any structural modifications are required. This will help in any estimate the detail design engineer gives and has the potential of having little to no steel modifications. The roof weight is negligible, and the HVAC unit weights are within an acceptable increase. It is On-

Board’s recommendation to have the roof replaced, assess the steel underneath the leaking areas, and install curb adapters at the HVAC units where possible.

Cost Estimate:

affect the actual cost.

APPENDIX 1: EXISTING RTU

INFORMATION & PHOTOS

APPENDIX 1

RTU-1

RTU-2

RTU-3

RTU-4

RTU-5

RTU-6

RTU-7

RTU-8

RTU-8A

RTU-9

RTU-10

RTU-11

RTU-12

APPENDIX 2: ASHRAE

DOCUMENTATION

October 19, 2021

ASHRAE EPIDEMIC TASK FORCE

Core Recommendations for Reducing Airborne Infectious Aerosol Exposure

The following recommendations are the basis for the detailed guidance issued by ASHRAE Epidemic Task

Force. They are based on the concept that within limits ventilation, filtration, and air cleaners can be deployed flexibly to achieve exposure reduction goals subject to constraints that may include comfort, energy use, and costs. This is done by setting targets for equivalent clean air supply rate and expressing the performance of filters, air cleaners, and other removal mechanisms in these terms.

1. Public Health Guidance – Follow all current regulatory and statutory requirements and recommendations, including vaccination, wearing of masks and other personal protective equipment, social distancing, administrative measures, circulation of occupants, hygiene, and sanitation.

2. Ventilation, Filtration, Air Cleaning

2.1 Provide and maintain at least required minimum outdoor airflow rates for ventilation as specified by applicable codes and standards.

2.2 Use combinations of filters and air cleaners that achieve MERV 13 or better levels of performance for air recirculated by HVAC systems.

2.3 Only use air cleaners for which evidence of effectiveness and safety is clear.

2.4 Select control options, including standalone filters and air cleaners, that provide desired exposure reduction while minimizing associated energy penalties.

3. Air Distribution - Where directional airflow is not specifically required, or not recommended as the result of a risk assessment, promote mixing of space air without causing strong air currents that increase direct transmission from person-to-person.

4. HVAC System Operation

4.1 Maintain temperature and humidity design set points.

4.2 Maintain equivalent clean air supply required for design occupancy whenever anyone is present in the space served by a system.

4.3 When necessary to flush spaces between occupied periods, operate systems for a time required to achieve three air changes of equivalent clean air supply.

4.4 Limit re-entry of contaminated air that may re-enter the building from energy recovery devices, outdoor air, and other sources to acceptable levels.

5. System Commissioning – Verify that HVAC systems are functioning as designed.

APPENDIX 3: ASHRAE HVAC

System and Equipment

CHAPTER 17

ULTRAVIOLET LAMP SYSTEMS

Terminology .................................................................................................................................. 17.1 UVGI Fundamentals ..................................................................................................................... 17.2 Lamps and Power Supplies ........................................................................................................... 17.3 Maintenance .................................................................................................................................. 17.7 Safety ............................................................................................................................................. 17.7 Unit Conversions ........................................................................................................................... 17.9 V energy is electromagnetic radiation with a wavelengthUshorter than that of visible light, but longer than soft x-rays. All UV ranges and bands are invisible to the human eye. The UV spec-trum can be subdivided into following bands:

• UV-A (long-wave; 400 to 315 nm): the most abundant in sunlight, responsible for skin tanning and wrinkles

• UV-B (medium-wave; 315 to 280 nm): primarily responsible for skin reddening and skin cancer

• UV-C (short-wave; 280 to 100 nm): the most effective wave-lengths for germicidal control: radiation below 200 nm is also called vacuum UV and will produce ozone (O3) in air

Use of ultraviolet (UV) lamps and lamp systems to disinfect sur-faces, room air, and airstreams dates to about 1900; see Riley (1988) and Schechmeister (1991) for extensive reviews of UV disinfection.

Early work established that the most effective UV wavelength range for inactivation of microorganisms was between 220 to 300 nm, with peak effectiveness near 265 nm.

UV-C energy disrupts the DNA of a wide range of microorgan-isms, rendering them harmless (Brickner et al. 2003; CIE 2003). Fig-ure 1 shows the relative effectiveness of UV-C energy at various wavelengths to cause DNA damage. Most commercial UV-C lamps are low-pressure mercury lamps that emit UV energy at 253.7 nm, very close to the optimal wavelength.

Ultraviolet germicidal irradiation (UVGI) in the UV-C band has been used in air ducts and air-handling units for some time, and its use is becoming increasingly frequent as concern about energy, mainte-

The preparation of this chapter is assigned to TC 2.9, Ultraviolet Air and Surface Treatment.

Fig. 1 Relative UV-C Germicidal Efficiency 17.

nance, and indoor air quality increases. UV-C energy is used as an engineering control to interrupt the transmission of pathogenic organ-isms, such as Mycobacterium tuberculosis (TB), influenza viruses, mold, and possible bioterrorism agents (Brickner et al. 2003; CDC 2002, 2005; GSA 2003). In addition, it has been used extensively to irradiate air-conditioning cooling coils to maintain cleanliness and provide energy savings.

This chapter includes a review of the fundamentals of UV-C energy’s impact on microorganisms; how UV-C lamps generate ger-micidal radiant energy; various components that comprise UV-C devices and systems; and a review of human safety and maintenance issues.

1. TERMINOLOGY

Burn-in time. Period of time that UV lamps are powered on before being put into service, typically 100 h.

Droplet nuclei. Airborne particles formed from evaporation of fluids emitted from infected hosts when they cough, sneeze, or talk, containing bacteria or viruses able to transmit disease from person to person. Droplet nuclei generally have an aerodynamic diameter less than 5 m, which allows them to remain suspended in air for long periods; thus, they can be carried on normal air currents in a room and beyond to adjacent spaces. When inhaled, droplet nuclei can penetrate into the alveolar region of the lung.

Erythema (actinic). Reddening of the skin, with or without inflammation, caused by the actinic effect of solar radiation or arti-ficial optical radiation. See CIE (1987) for details. (Nonactinic ery-thema can be caused by various chemical or physical agents.)

Exposure. Being subjected to something (e.g., infectious agents, irradiation, particulates, and/or chemicals) that could have harmful effects. For example, a person exposed to M. tuberculosis does not necessarily become infected.

Exposure dose. Radiant exposure (Jm2, unweighted) incident on biologically relevant surface.

Fluence. Radiant flux passing from all directions through a unit area in Jm2 or Jcm2; includes backscatter (reflection).

Germicidal radiation. Optical radiation able to kill pathogenic microorganisms.

Irradiance. Power of electromagnetic radiation incident on a surface per unit surface area, typically reported in microwatts per square centimeter (Wcm2). See CIE (1987) for details.

Mycobacterium tuberculosis. The namesake member of the M.

tuberculosis complex of microorganisms, and the most common cause of tuberculosis (TB) in humans. In some instances, the species name refers to the entire M. tuberculosis complex, which includes M. bovis, M. africanum, M. microti, M. canettii, M. caprae, and M.

pinnipedii.

Optical radiation. Electromagnetic radiation at wavelengths between x-rays ( 1 nm) and radio waves ( 1 mm). See CIE (1987) for details.

gerardp Highlight

17.2 2020 ASHRAE Handbook—HVAC Systems and Equipment Permissible exposure time (PET). Calculated time period that humans, with unprotected eyes and skin, can be exposed to a given level of UV irradiance without exceeding the NIOSH recommended exposure limit (REL) or ACGIH Threshold Limit Value® (TLV®) for UV radiation.

Personal protective equipment (PPE). Protective clothing, hel-mets, goggles, respirators, or other gear designed to protect the wearer from injury from a given hazard, typically used for occupa-tional safety and health purposes.

Photokeratitis. Defined by CIE (1993) as corneal inflammation after overexposure to ultraviolet radiation.

Photoconjunctivitis. Defined by CIE (1993) as a painful con-junctival inflammation that may occur after exposure of the eye to ultraviolet radiation.

Photokeratoconjunctivitis. Inflammation of cornea and con-junctiva after exposure to UV radiation. Wavelengths shorter than 320 nm are most effective in causing this condition. The peak of the action spectrum is approximately at 270 nm. See CIE (1993) for details. Note: Different action spectra have been published for pho-tokeratitis and photoconjuctivitis (CIE 1993); however, the latest studies support the use of a single action spectrum for both ocular effects.

Threshold Limit Value® (TLV®). An exposure level under which most people can work consistently for 8 h a day, day after day, without adverse effects. Used by the ACGIH to designate degree of exposure to contaminants. TLVs are listed either for 8 h as a time-weighted average (TWA) or for 15 min as a short-term exposure limit (STEL).

Ultraviolet radiation. Optical radiation with a wavelength shorter than that of visible radiation. (See CIE [1987] for details.)

The range between 100 and 400 nm is commonly subdivided into

UV-A 315 to 400 nm UV-B 280 to 315 nm UV-C 100 to 280 nm

Ultraviolet germicidal irradiation (UVGI). Use of ultraviolet C-band energy to kill or inactivate microorganisms. UVGI is gen-erated by UV-C lamps that kill or inactivate microorganisms by emitting ultraviolet radiation, predominantly at a wavelength of

253.7 nm.

UV dose. Product of UV irradiance and exposure time on a given microorganism or surface, typically reported in millijoules per square centimetre (mJcm2) or microwatt seconds per square centi-metre (W·s/cm2).

Wavelength. Distance between repeating units of a wave pat-tern, commonly designated by the Greek letter lambda ().

2. UVGI FUNDAMENTALS

Microbial Dose Response Lamp manufacturers have published design guidance documents for in-duct use (Philips Lighting 1992; Sylvania 1982; Westing-house 1982). Bahnfleth and Kowalski (2004) and Scheir and Fencl (1996) summarized the literature and discussed in-duct applica-tions. These and other recent papers were based on case studies and previously published performance data. The Air-Conditioning and Refrigeration Technology Institute (ARTI) funded a research proj-ect to evaluate UV lamps’ capability to inactivate microbial aerosols in ventilation equipment, using established bioaerosol control device performance measures (VanOsdell and Foarde 2002). The data indicate that UV-C systems can be used to inactivate a substan-tial fraction of environmental bioaerosols in a single pass of air through a duct.

For constant and uniform irradiance, the disinfection effect of UV-C energy on a single microorganism population can be ex-pressed as follows (Phillips Lighting 1992):

Nt N0 = exp(–kEeff t) = exp(–kDose) (1) where N0 = initial number of microorganisms Nt = number of microorganisms after any time t

Nt N0 = fraction of microorganisms surviving k = microorganism-dependent rate constant, cm2(W·s)

Eeff = effective (germicidal) irradiance received by microorganism, Wcm2

Dose = Eff t, (W·s)cm2

The units shown are common, but others are used as well, includ-ing irradiance in Wm2 and dose in Jm2 (note: 1 J = 1 W·s).

Equation (1) describes an exponential decay in the number of liv-ing organisms as a constant level of UV-C exposure continues. The same type of equation is used to describe the effect of disinfectants on a population of microorganisms, with the dose in that case being a concentration-time product. The fractional kill after time t is (1 – Nt N0). In an air duct, the use of Equation (1) is complicated by the movement of the target microorganisms in the airstream and the fact that the UV-C irradiance is not of constant intensity within the duct. In addition, the physical parameters of the duct, duct airflow, and UV installation have the potential to affect both the irradiance and the microorganisms’ response to it. As is the case with upper-room UV installation design, the design parameters for UV-C in-duct applications are not simple because of some uncertainty in the data available to analyze them, and because of secondary effects.

A key difference between surface decontamination and airborne inactivation of organisms is exposure time. Residence time for in-duct devices is on the order of seconds or fractions of seconds. In a moving airstream, exposure time is limited by the effective distance in which the average irradiance was calculated; for instance, at 500 fpm, 1 ft of distance takes 0.12 s. Therefore, neutralization methods against an airborne threat must be effective in seconds or fractions of a second, depending on the device’s characteristics, and high UV intensity and/or more in-line depth to extend exposure time of the airstream is generally required. Conversely, when irradiating surfaces in an HVAC system, exposure time is typically continuous, so much lower levels of UV intensity are required.

Susceptibility of Microorganisms to UV Energy

Organisms differ in their susceptibility to UV inactivation; Figure 2 shows the general ranking of susceptibility by organism groups.

Viruses are a separate case and are not included in Figure 2, because, as a group, their susceptibility to inactivation is even broader than

Fig. 2 General Ranking of Susceptibility to UV-C Inactivation of Microorganisms by Group

Ultraviolet Lamp Systems 17.3 bacteria or fungi. A few examples of familiar pathogenic organisms are included in each group for information (see Table 1). Note that it is impossible to list all of the organisms of possible interest in each group. Depending on the application, consult a public health or med-ical professional, microbiologist, or other individual with knowledge of the threat or organism(s) of concern.

As shown in Figure 2, vegetative bacteria are the most suscepti-ble to UV-C, followed by the Mycobacteria, bacterial spores, and, finally, fungal spores, which are the most resistant.