patrick henry high school analysis of building ventilation
TRANSCRIPT
Patrick Henry High School
Analysis of Building Ventilation Systems
Minneapolis Public Schools
COVID 19 Analysis of Building Ventilation Systems Project Number: 20-472.00 October 1, 2020
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 2
Title Page
Building Information Building Owner: Minneapolis Public Schools Building Name: Patrick Henry High School Square Footage: 208,856 sf 4320 North Newton Avenue Minneapolis, MN 55412
KFI Project Manager Information
Larry Justin, P.E. Senior Project Manager KFI Engineers 670 County Road B West St. Paul, MN 55113-4527 [email protected] 651-771-0880 - Office 651-771-0878 – Fax
Site Contacts
Curtis Hartog, P.E. Executive Director Capital Planning, Construction & Maintenance Minneapolis Public Schools 1250 West Broadway Avenue Minneapolis, MN 55411 [email protected] 612-668-0284 - Office 612-806-1274 – Fax
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 3
Table of Contents
Title Page ...........................................................................................................................................2
Table of Contents ...............................................................................................................................3
Glossary of Terms and Abbreviations ..................................................................................................4
Executive Summary ............................................................................................................................6
Disclaimer ........................................................................................................................................ 16
Introduction .................................................................................................................................... 17
ASHRAE Guidance ............................................................................................................................ 18
Building Assessment/Recommendations .......................................................................................... 19
HVAC System Filtration and Ventilation .................................................................................................. 19
Intake and Exhaust Separation ................................................................................................................ 46
Building Automation System ................................................................................................................... 46
Health Office and Classroom Area Air Flow ............................................................................................ 47
Potential Isolation Areas ......................................................................................................................... 48
Appendices ...................................................................................................................................... 49
Appendix A – Matrix of Existing HVAC Systems ...................................................................................... 50
Appendix B – Building System Maps (KFI overlay) and MPS Equipment Maps ...................................... 60
Appendix C – MERV Filter Ratings ........................................................................................................... 65
Appendix D – Portable HEPA Filtration Units .......................................................................................... 66
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 4
Glossary of Terms and Abbreviations
ACH Air Change per Hour
• A measure of air flow in a specified volume of space
AHU Air Handling Unit
• HVAC equipment, typically contains fans, filters, and heating and/or cooling coils
AII room Airborne Infection Isolation room
• Room with mechanical systems designed to reduce the spread of airborne
infection disease to other areas
ASHRAE American Society of Heating, Refrigerating, and Air-conditioning Engineers
• Professional organization that supports industry research and publishes design
best practice guidelines and standards
BAS Building Automation System
• Control system for building HVAC and lighting systems
CAV Constant Air Volume
• Describes the type of control of an AHU- this type of unit varies the supply air
temperature but not the volume of air flow
CFM Cubic Feet per Minute
• Measure of volumetric flow, typically used for air flow
DOAS Dedicated Outdoor Air System
• AHU that supplies 100% conditioned outdoor air (does not mix ventilation air
with recirculated room air)
ERU / HRU
Energy Recovery Unit / Heat Recovery Unit
• AHU with a heat exchanger to transfer heat between exhaust air and incoming
outdoor air
HEPA High Efficiency Particulate Air (filter)
• A type of filter that can remove at least 99.97% of particles with a size of 0.3
microns.
HVAC Heating, Ventilation, and Air-conditioning
• Term used to describe building systems and technical expertise of professionals
MERV Minimum Efficiency Reporting Value
• A filter’s ability to capture particles between 0.3 and 10 microns in size
• A higher MERV rating captures a larger percentage of small particles
• See Appendix D for MERV ratings and ratings by particle size
OA Outdoor Airflow
• Ventilation air flow
RTU Roof Top Unit
• An HVAC system located on the roof that contains all heating and cooling
equipment in one packaged unit
SF Square Feet
• Measure of area
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 5
TAB Test and Balance
• Measurement and adjustment of building HVAC equipment.
VAV Variable Air Volume
• Describes the type of control of an AHU- this type of unit varies both the supply
air temperature and the volume of air flow to a zone
• Also used to describe the piece of equipment in a zone that includes a damper to
reduce airflow (VAV box)
VRF Variable Refrigerant Flow
• A type of refrigeration system that includes an outdoor condensing unit and
indoor fan units with a cooling coil. Sometimes the indoor unit also includes a
heating coil.
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 6
Executive Summary
Minneapolis Public Schools (MPS) requested individual facility ventilation studies for all occupied elementary, middle school, and high school buildings. These studies identified improvements to the air-handling units (AHUs) and ventilation in the buildings that will allow the building to meet current ASHRAE guidance to limit virus transmission in the ventilation system in the building. Adequate outdoor airflow, or ventilation, can dilute the number of viral particles in the breathing zone of a space. Effective filtration can remove particles from the air. However, viral particles are extremely small. Most filters are not rated to capture particles as small as the virus that causes COVID-19, but some can capture a large fraction of viral-sized particles. While it will not be practical to rely only on filtration, increasing filtration levels will reduce the number of viral particles in the air. This report provides the results for Patrick Henry High School. KFI has reviewed existing HVAC plans, Test-and-Balance (TAB) reports, and the building automation system (BAS). KFI has also performed an onsite evaluation for the facility. Patrick Henry High School has multiple air-handling units and packaged rooftop units that supply conditioned air to the building occupied spaces including classrooms, lunch room, kitchen, several gymnasiums, and the auditorium. The filtration levels of each HVAC system are detailed in the Building Assessment section, and the final filter MERV levels are provided in Table 1, Table 2, and Table 3. A staff office adjacent to the nurse’s area could potentially be converted to an isolation room. The conversion would require installation of a dedicated exhaust in the room, and rebalancing of RTU-28. A new exhaust fan and room pressure controller will need to be added to maintain the required pressure relationship.
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 7
Through this project, a number of conditions were identified that could be corrected immediately. Table 1 summarizes these immediate corrections. Table 2 summarizes recommendations for future system updates that do not require significant capital improvements. Table 3 identifies recommended improvements that will require a capital program expenditure to complete. These improvements should be part of a larger capital effort for improvement to ventilation systems Districtwide. Table 1: Summary of Immediate Corrections
System Tag Existing
Filtration Level*
Serves Work in Progress
AHU-1 MERV11 Band
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-2 MERV11 Classrooms
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-3 MERV11 Choir
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 8
System Tag Existing
Filtration Level*
Serves Work in Progress
AHU-4 MERV11 Lunch Room
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-5 MERV11 Gymnasium
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-6 MERV11 Exercise
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-7 MERV11 Art/Computer Room
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 9
System Tag Existing
Filtration Level*
Serves Work in Progress
AHU-8 MERV11 Classrooms
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-9 MERV11 Community
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-10 MERV11 Gymnasium Aux.
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-11 MERV11 Auditorium
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 10
System Tag Existing
Filtration Level*
Serves Work in Progress
AHU-12 MERV8 Girl’s Locker Room
• Replace filters with like-for-like MERV8
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Increase economizer lockout to 71°F
from 55°F
AHU-13 MERV8 Boy’s Locker Room
• Replace filters with like-for-like MERV8
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Increase economizer lockout to 71°F
from 55°F
AHU-14 MERV8 Gymnasium
• Replace filters with like-for-like MERV8
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
AHU-15 MERV8 Gymnasium
• Replace filters with like-for-like MERV8
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
RTU-20 MERV11 Classrooms
• Replace pre-filters with like-for-like
MERV8
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 11
System Tag Existing
Filtration Level*
Serves Work in Progress
RTU-21 MERV11 Classrooms
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
RTU-22 MERV11 Classrooms
• Replace pre-filters with like-for-like
MERV8
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
RTU-23 MERV11 Classrooms
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
RTU-24 MERV11 Offices
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 12
System Tag Existing
Filtration Level*
Serves Work in Progress
RTU-25 MERV11 Classrooms
• Replace pre-filters with like-for-like
MERV8
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
RTU-26 MERV11 Classrooms
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
RTU-27 MERV11 Offices
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
RTU-28 MERV11 Classrooms
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 13
System Tag Existing
Filtration Level*
Serves Work in Progress
RTU-29 MERV11 Classrooms
• Replace pre-filters with like-for-like
• Replace final filters with MERV14
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
RTU-30 MERV11 Classrooms
• Replace pre-filters with like-for-like
MERV8
• Change schedules to start at 3:30 AM
• Change exhaust fan to a 24-hour
schedule
• Disable demand control ventilation in
BAS
• Increase economizer lockout to 71°F
from 55°F
Table 2: Summary of Recommendations without Significant Capital Expenditures
System Tag Existing
Filtration Level*
Serves Recommendations
AHU-1 MERV11 Band • Rebalance unit to increase outdoor air
to 1,840 cfm
AHU-2 MERV11 Classrooms • Rebalance unit to increase outdoor air
to 1,370 cfm
AHU-3 MERV11 Choir • Rebalance unit to increase outdoor air
to 1,080 cfm
AHU-5 MERV11 Gymnasium • Rebalance unit to increase outdoor air
to 1,260 cfm
AHU-6 MERV11 Exercise • Rebalance unit to increase outdoor air
to 1,030 cfm
AHU-7 MERV11 Art/Classrooms • Rebalance unit to increase outdoor air
to 2,850 cfm
AHU-8 MERV11 Classrooms • Rebalance unit to increase outdoor air
to 4,450 cfm
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 14
System Tag Existing
Filtration Level*
Serves Recommendations
AHU-9 MERV11 Community • Rebalance unit to increase outdoor air
to 610 cfm
AHU-10 MERV11 Gymnasium Aux. • Rebalance unit to increase outdoor air
to 520 cfm
AHU-11 MERV11 Auditorium • Rebalance unit to increase outdoor air
to 6,280 cfm
AHU-14 MERV8 Gymnasium • Rebalance unit to increase outdoor air
to 2,680 cfm
AHU-15 MERV8 Gymnasium • Rebalance unit to increase outdoor air
to 2,680 cfm
RTU-20 MERV11 Classrooms
• Rebalance unit to increase outdoor air
to 7,850 cfm
• Confirm design static pressure, if static
pressure is available replace final
filters with MERV14 or measure the
actual brake horsepower (BHP) of fan
before filter replacement to determine
if it needs to be replaced
RTU-21 MERV8 Classrooms • Rebalance unit to increase outdoor air
to 4,440 cfm
RTU-22 MERV11 Classrooms
• Rebalance unit to increase outdoor air
to 4,710 cfm
• Confirm design static pressure, if static
pressure is available replace final
filters with MERV14 or measure the
actual brake horsepower (BHP) of fan
before filter replacement to determine
if it needs to be replaced
RTU-25 MERV11 Classrooms
• Confirm design static pressure, if static
pressure is available replace final
filters with MERV14 or measure the
actual brake horsepower (BHP) of fan
before filter replacement to determine
if it needs to be replaced
RTU-27 MERV11 Offices • Rebalance unit to increase outdoor air
to 3,490 cfm
RTU-28 MERV11 Classrooms/Nurse’s Area • Add standalone HEPA filtration in the
Nurses Area
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 15
System Tag Existing
Filtration Level*
Serves Recommendations
RTU-30 MERV11 Lobby
• Confirm design static pressure, if static
pressure is available replace final
filters with MERV14 or measure the
actual brake horsepower (BHP) of fan
before filter replacement to determine
if it needs to be replaced
Table 3: Summary of Recommendations Requiring Capital Expenditures
System Tag Existing
Filtration Level*
Serves Recommendations
RTU-28 MERV11 Nurses Area • Convert Staff Office into potential
Isolation Room
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 16
Disclaimer
Performance guidelines provided in the report are for informational purposes only and are not to be construed as a design document. Recommendations implemented should be installed in conformance to all local code requirements. Ventilation and filtration recommendations are provided based on ventilation requirements in the Minnesota 2020 Mechanical Code and guidance from ASHRAE on limiting viral transfer. If equipment was installed under an earlier code that equipment is not required to comply with the 2020 code.
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 17
Introduction
Patrick Henry High School is a four-story facility educating high school students. The building was originally constructed in 1926, with multiple renovations and additions, the building is currently 208,856 SF. Variable-air-volume (VAV) systems provide heating, cooling, and ventilation to all areas in the building except the gyms and locker rooms. The gym and locker room air handlers are constant volume. Condensing units with D/X coils provide cooling. All air handling equipment was either upgraded or replaced in a 2016 remodeling project. Students have not occupied the school building since March of 2020 due to the COVID-19 pandemic. The SARS-CoV-2 virus causes coronavirus disease, or COVID-19. The SARS-CoV-2 virus is new and research into the virus and disease spread is still evolving. So far, we have learned that primary transmission route of the virus is via the air in droplets and aerosols. Recommendations for reducing the spread of COVID-19 focus broadly on: 1) maintaining social distance between people, 2) sanitizing and cleaning surfaces, and 3) reducing the number and circulation of viral particles in the air. HVAC systems can influence this last item. Adequate outdoor airflow, or ventilation, can dilute the number of viral particles in the breathing zone of a space. Effective filtration can remove particles from the air. However, viral particles are extremely small, on the order of 0.12 microns. Filters are typically rated by the size of particles that will be removed, for example, MERV 14 filters are rated to remove 95% or greater of particles down to 3 microns. While it will not be practical to rely only on filtration, increasing filtration levels will reduce the number of viral particles in the air. ASHRAE guidance is available online at: https://www.ashrae.org/technical-resources/reopening-of-schools-and-universities. This report provides the results for Patrick Henry High School. KFI has performed the following scope of work:
• Reviewed the existing HVAC building plans and test and balance reports (TAB) to identify
recommended improvements to the systems to meet current ASHRAE guidance for COVID19.
• An on-site assessment of the facility was restricted due to current building occupancy.
• KFI interviewed current building engineers for information on existing conditions.
• Reviewed the building automation system (BAS) to determine potential control changes to
improve indoor air quality.
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 18
ASHRAE Guidance
The American Society of Heating Refrigerating and Air-Conditioning Engineers (ASHRAE) provides research, standards, and continuing education that typically define best practice in the HVAC industry. ASHRAE has been developing industry standards for best practice in reducing HVAC spread of airborne illnesses for years. ASHRAE has released guidance for schools and universities to prepare for the reopening of school buildings. This advice focuses on three core principles aimed at reducing the spread of COVID19:
1. Increase outdoor air where possible
a. Follow current ventilation standards at a minimum
b. Ventilate at least 2 hours prior to occupancy
c. Disable demand-controlled ventilation during the pandemic
2. Increase filtration levels where possible
a. MERV15 filtration provides similar filtration levels as an N95 mask (95% of particles
entrapped to 3 microns in size)
b. MERV14 filtration is recommended where possible
3. Maintain indoor environments between 40% and 60% relative humidity and temperatures
between 68°F and 78°F where possible
This project focuses on the first two principles above. It seeks to evaluate the ventilation and filtration levels in the existing systems, to evaluate system capacity to increase outdoor air and filtration levels, and to evaluate building control systems to recommend changes. Temperature maintenance for buildings is provided in Board Regulation 3520A. Due to the complexity of establishing and maintaining relative humidity in a space, MPS is not evaluating the relative humidity as part of this study.
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 19
Building Assessment/Recommendations
HVAC System Filtration and Ventilation Variable-air-volume (VAV) systems provide heating, cooling, and ventilation to the building. A summary of the systems in the building is provided in Table 4. A matrix was developed for the school systems with airflows, static pressures, filtration, and control details. This matrix is provided in Appendix A. Table 4: System Overview
System Age Serves System Type
AHU-01 2017 Band Rooms VAV
AHU-02 2017 Classrooms VAV
AHU-03 2017 Choir Rooms VAV
AHU-04 2017 Lunch Room VAV
AHU-05 2017 Gymnasium CAV
AHU-06 2017 Exercise Room CAV
AHU-07 2017 Art and Classrooms VAV
AHU-08 2017 Classrooms VAV
AHU-09 2017 Community Room CAV
AHU-10 2017 Gymnasium Aux CAV
AHU-11 2017 Auditorium CAV
AHU-12 1977 Girl’s Locker Room CAV
AHU-13 1977 Boy’s Locker Room CAV
AHU-14 1977 Gymnasium CAV
AHU-15 1977 Gymnasium CAV
RTU-20 2013 Classrooms VAV
RTU-21 2017 Classrooms VAV
RTU-22 1996 Classrooms VAV
RTU-23 2017 Classrooms VAV
RTU-24 2017 Offices VAV
RTU-25 2017 Classrooms VAV
RTU-26 2017 Classrooms VAV
RTU-27 2017 Offices VAV
RTU-28 2017 Classrooms and Nurse’s Office VAV
RTU-29 2017 Classrooms VAV
RTU-30 2017 Lobby CAV
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 20
AHU-01 AHU-01 serves the lower level band and office spaces. This unit operates with a supply fan located in the lower level, and distributes variable volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 5. Table 5: System Ventilation and Static Pressure AHU-01
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-01 3986 1711 1720 1834 4.05 1.67
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the design code airflow of 1,840 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 1.
Figure 1: Filter Bank – AHU-01
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 21
AHU-02 AHU-02 serves the lower level choir room. This unit operates with a supply fan located in the lower level, and distributes variable volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 6. Table 6: System Ventilation and Static Pressure AHU-02
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-02 4730 1189 1180 1368 3.8 1.55
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 1,370 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 2.
Figure 2: Filter Bank – AHU-02
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 22
AHU-03 AHU-03 serves the lower level classrooms, storage rooms and offices. This unit operates with a supply fan located in the lower level, and distributes variable volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 7. Table 7: System Ventilation and Static Pressure AHU-03
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-03 2094 1015 1011 1073 3.2 1.32
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 1,080 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 3.
Figure 3: Filter Bank – AHU-03
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 23
AHU-04 AHU-04 serves the lower level lunch room and kitchen. This unit operates with a supply fan located in the lower level, and distributes variable volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 8. Table 8: System Ventilation and Static Pressure AHU-04
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-04 12072 4670 4657 11025 3.8 3.25
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 4.
Figure 4: Filter Bank – AHU-04
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 24
AHU-05 AHU-05 serves the lower level gymnasium. This unit operates with a supply fan located in the penthouse over the auditorium stage, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 9. Table 9: System Ventilation and Static Pressure AHU-05
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-05 3141 945 957 1256 3.95 1.94
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 1,260 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 5.
Figure 5: Filter Bank – AHU-05
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 25
AHU-06 AHU-06 serves the exercise room on the second floor. This unit operates with a supply fan located in the penthouse over the auditorium stage, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 10. Table 10: System Ventilation and Static Pressure AHU-06
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-06 3141 959 957 1021 3.95 1.9
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 1,030 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 6.
Figure 6: Filter Bank – AHU-06
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 26
AHU-07 AHU-07 serves the lower level art and computer classrooms. This unit operates with a supply fan located in the lower level, and distributes variable volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 11. Table 11: System Ventilation and Static Pressure AHU-07
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-07 8381 2558 2545 2846 4.65 3.32
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 2,850 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 7.
Figure 7: Filter Bank – AHU-07
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 27
AHU-08 AHU-08 serves the first-floor science classrooms. This unit operates with a supply fan located in the lower level, and distributes variable volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 12. Table 12: System Ventilation and Static Pressure AHU-08
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-08 7563 3328 3309 4443 4.65 2.81
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 4,450 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 8.
Figure 8: Filter Bank – AHU-08
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 28
AHU-09 AHU-09 serves the lower level community room. This unit operates with a supply fan located in the lower level, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 13. Table 13: System Ventilation and Static Pressure AHU-09
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-09 1567 386 363 607 3.3 0.95
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 610 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 9.
Figure 9: Filter Bank – AHU-09
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 29
AHU-10 AHU-10 serves the lower level auxiliary gymnasium. This unit operates with a supply fan located in the lower level, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 14. Table 14: System Ventilation and Static Pressure AHU-10
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-10 1283 420 416 513 3.9 1.22
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 520 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 10.
Figure 10: Filter Bank – AHU-10
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 30
AHU-11 AHU-11 serves the auditorium on the first floor. This unit operates with a supply fan located in the penthouse over the auditorium stage, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 15. Table 15: System Ventilation and Static Pressure AHU-11
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-11 6280 4955 4900 6277 3.3 2.54
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 6,280 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 11.
Figure 11: Filter Bank – AHU-11
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 31
AHU-12 AHU-12 serves the girl’s locker room on the lower level. This unit operates with a supply fan located in a mechanical penthouse over the gymnasium, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 16. Table 16: System Ventilation and Static Pressure AHU-12
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-12 7209 7897 8000 NA 3.3 2.54
The design outdoor airflow is not applicable because outside air supplied to the space is used to make up the exhaust fan air flow from the space. This unit has MERV 8 pleated filters. The high percentage of outside air to make up exhaust keeps contaminants at a low concentration. We do not recommend increasing filtration for this unit. The filter bank for this unit is shown in Figure 12.
Figure 12: Filter Bank – AHU-12
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 32
AHU-13 AHU-13 serves the boy’s locker room on the lower level. This unit operates with a supply fan located in a mechanical penthouse over the gymnasium, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 17. Table 17: System Ventilation and Static Pressure AHU-13
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-13 7209 7897 8000 NA 3.3 2.54
The design outdoor airflow is not applicable because outside air supplied to the space is used to make up the exhaust fan air flow from the space. This unit has MERV 8 pleated filters. The high percentage of outside air to make up exhaust keeps contaminants at a low concentration. We do not recommend increasing filtration for this unit. The filter bank for this unit is shown in Figure 13.
Figure 13: Filter Bank – AHU-13
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 33
AHU-14 AHU-14 serves the varsity gymnasium on the first level. This unit operates with a supply fan located in a mechanical penthouse over the gymnasium, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 18. Table 18: System Ventilation and Static Pressure AHU-14
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-14 6682 2451 2500 2673 NR* 1.76
*NR = Not Reported in TAB report The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 2,680 cfm. This unit has MERV 8 pleated filters. There is no room in the filter section of the air handler to add final filters. We do not recommend increasing filtration for this unit. The filter bank for this unit is shown in Figure 14.
Figure 14: Filter Bank – AHU-14
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 34
AHU-15 AHU-15 serves the varsity gymnasium on the first level. This unit operates with a supply fan located in a mechanical penthouse over the gymnasium, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 19. Table 19: System Ventilation and Static Pressure AHU-15
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
AHU-15 6682 2530 2500 2673 NR* NR*
*NR = Not Reported in TAB report The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 2,680 cfm. This unit has MERV 8 pleated filters. There is no room in the filter section of the air handler to add final filters. We do not recommend increasing filtration for this unit. The filter bank for this unit is shown in Figure 15.
Figure 15: Filter Bank – AHU-15
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 35
RTU-20 RTU-20 serves second-floor media center. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 20. Table 20: System Ventilation and Static Pressure RTU-20
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-20 15049 5860 5850 7837 NR 1.3
*NR = Not Reported in TAB report The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 7,840 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Appendix A summarizes filter sizes. Design total static was not listed in TAB report. We recommend measuring the actual brake horsepower to determine if the fan can maintain the same flow rate with a higher filtration level before the filters are replaced with MERV14. The filter bank for this unit is shown in Figure 16.
Figure 16: Filter Bank – RTU-20
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 36
RTU-21 RTU-21 serves first-floor classrooms. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 21. Table 21: System Ventilation and Static Pressure RTU-21
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-21 7558 3870 3461 4440 4.6 3.11
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 4,440 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 17.
Figure 17: Filter Bank – RTU-21
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 37
RTU-22 RTU-22 serves third-floor science classrooms. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 22. Table 22: System Ventilation and Static Pressure RTU-22
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-22 8006 4155 4150 4704 NR 1.4
*NR = Not Reported in TAB report The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 4,710 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Appendix A summarizes filter sizes. Design total static was not listed in TAB report. We recommend measuring the actual brake horsepower to determine if the fan can maintain the same flow rate with a higher filtration level before the filters are replaced with MERV14. The filter bank for this unit is shown in Figure 18.
Figure 18: Filter Bank – RTU-22
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 38
RTU-23 RTU-23 serves first-floor classrooms. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 23. Table 23: System Ventilation and Static Pressure RTU-23
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-23 15604 5920 5900 9167 4.6 3.11
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend maintaining the actual outside airflow. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 19.
Figure 19: Filter Bank – RTU-23
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 39
RTU-24 RTU-24 serves first-floor administration offices. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 24. Table 24: System Ventilation and Static Pressure RTU-24
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-24 5720 1087 1055 608 4.0 2.58
The actual outdoor airflow is greater than both the design and code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. We recommend maintaining the actual outside airflow. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 20.
Figure 20: Filter Bank – RTU-24
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 40
RTU-25 RTU-25 serves third-floor classrooms. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 25. Table 25: System Ventilation and Static Pressure RTU-25
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-25 13805 5644 5609 8110 4.75 4.67
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend maintaining the actual outside airflow. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure listed above, this unit will not support an increase in filtration without replacement of the fan motor. Before replacing the MERV 11 final filter with a MERV 14 final filter, we recommend measuring the actual brake horsepower to determine if the fan can maintain the same flow rate with a higher filtration level. The filter bank for this unit is shown in Figure 21.
Figure 21: Filter Bank – RTU-25
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 41
RTU-26 RTU-26 serves third-floor classrooms. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 26. Table 26: System Ventilation and Static Pressure RTU-26
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-26 10148 3660 3650 5962 4.7 2.73
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend maintaining the actual outside airflow. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 22.
Figure 22: Filter Bank – RTU-26
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 42
RTU-27 RTU-27 serves rooms on all four levels. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 27. Table 27: System Ventilation and Static Pressure RTU-27
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-27 11813 2478 2465 3490 3.55 2.46
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend increasing the outdoor airflow to the code outside airflow of 3490 cfm. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 23.
Figure 23: Filter Bank – RTU-27
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 43
RTU-28 RTU-28 serves first-floor classrooms and the nurse’s office. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 28. Table 28: System Ventilation and Static Pressure RTU-28
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-28 7903 3205 3200 2498 4.35 2.69
The design outdoor airflow is lower than the actual level of outdoor air as measured and recorded in the Building Start TAB report. We recommend maintaining the actual outside air volume shown. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 24.
Figure 24: Filter Bank – RTU-28
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 44
RTU-29 RTU-29 serves first-floor classrooms. This unit operates with a supply fan located on the roof, and distributes variable volume mixed air to the spaces below. Airflows and static pressures for this unit is summarized in Table 29. Table 29: System Ventilation and Static Pressure RTU-29
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-29 9385 3030 3024 5157 4.6 2.6
The design outdoor airflow is lower than the code level of outdoor air as calculated with ASHRAE’s default occupancy for each space. The outdoor air level was likely designed for the predicted actual occupancy in each space rather than the default occupancy levels – a method that is code compliant. The outdoor air level was designed in accordance with the 2012 code in which requirements differ from the current code. We recommend maintaining the actual outside airflow. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filter with a MERV 14 final filter. The filter bank for this unit is shown in Figure 25.
Figure 25: Filter Bank – RTU-29
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 45
RTU-30 RTU-30 serves first-floor gymnasium lobby. This unit operates with a supply fan located on the roof, and distributes constant volume mixed air to the spaces. Airflows and static pressures for this unit is summarized in Table 30. Table 30: System Ventilation and Static Pressure RTU-30
System Area Served
[sf] Actual OA
[cfm] Design OA
[cfm] Code OA
[cfm] Design Total
SP [in wc] Actual Total
SP [in wc]
RTU-30 4125 1088 1082 1083 3.15 4.33
The design outdoor airflow is lower than the actual level of outdoor air as measured and recorded in the Building Start TAB report. We recommend maintaining the actual outside air volume shown. This unit has MERV 8 pleated pre-filters and MERV 11 pleated final filters. MERV 14 filtration is recommended where possible per ASHRAE. Based on the available static pressure, this unit will not support an increase in filtration without replacement of the fan. We recommend replacing the MERV 11 final filters with MERV 11 final filters. The filter bank for this unit is shown in Figure 26.
Figure 26: Filter Bank – RTU-30
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 46
Intake and Exhaust Separation All intakes and exhaust vents are separated by more than the recommended 10 feet of distance. There are no concerns about recirculating exhausted air.
Building Automation System Detail of the BAS review are included in Appendix A. Before the building is occupied we recommend changing the system operation schedules to have the AHU fan start 2 hours before occupancy. We recommend disabling demand control ventilation and introduce max OA. Although demand control ventilation was not identified on some of the graphics, the District standard has been to include this for large volume occupied zones such as gyms, lobbies and cafeterias. If demand control ventilation exists, we recommend disabling. Maximizing the economizer mode would help with ventilation when outside temperatures are 71°F or below. We recommend disabling the economizer sequence once outside air temperatures reach 71°F. In addition to increasing the enable temperature for economizer modes, we recommend implementing max VAV box damper positions for all VAV boxes during economizer mode to maximize the ventilation airflow through the VAV boxes.
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 47
Health Office and Classroom Area Air Flow The outdoor air flow for RTU-28 that serves this area is 40.7% of the maximum supply flow. Air from the health office is mixed with the general RTU-28 return air from classrooms so it would need a separate system to serve as an isolation area. A stand-alone HEPA filtration unit located in the health office would limit the viral particles that are returned to the unit. The nurse’s area (green) and classrooms (red outline) is located on the first floor as seen in Figure 27.
Figure 27: First Floor - Main Office Area (Red), Nurse’s Area (Green), and Potential Isolation Room (Blue)
Below is a summary of the Nurses Area air flow in Table 31. Table 31: Nurses Office Air Flow
Health area HVAC System
Supply Air Flow to
Health Room (cfm)
Area of Health Room (sf)
Ceiling Height of Health Room (ft)
Current ACH Percent OA
RTU-28 500 475 9 7.0 40.7%
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 48
Potential Isolation Areas An area has been identified that could be renovated to serve as an isolation room (blue) for students who fall ill during the day. This area would need to be designed around ASHRAE Standard 170-2017 Ventilation of Health Care Facilities for Airborne Infection Isolation (AII) Rooms. The airborne infection isolation room would need to be maintained with a negative pressure relationship to adjoining rooms with a minimum of 2 ACH of outdoor air and a minimum 12 ACH of total supply air. All room air will need to be exhausted. If the 12 ACH of supply air is not possible, a HEPA filtered recirculating unit could be provided to increase equivalent ACH requirements. When the room is not used for airborne infection isolation conditions, the room would need to remain with a negative pressure relationship and the minimum supply air rate could be reduced to 6 ACH. MPS directed us to review areas near the nurse’s office to identify areas that could serve as airborne infection isolation room. At this facility, the staff office (blue) next door to the nurse’s area could potentially be converted to an isolation room. Airflow for this space is shown in Table 32. Table 32: Airflow of Potential Isolation Areas
Room or Area
HVAC System
Supply Air Flow
(cfm)
Floor Area (sf)
Ceiling Height
(ft)
Current Total ACH
Current ACH of
OA
Required ACH
Required ACH of
OA
Staff Office RTU-28 510 493 9 6.9 2.8 12 2
The potential isolation room (blue in the figure above) is served by RTU-28 along with the nurse’s area. If this area were to be converted to an airborne infection isolation room it would need to have the room walls sealed, a new exhaust fan for the dedicated exhaust system sized at approximately 15 ACH (1070 CFM) and rebalance supply air from the VAV box to 855 CFM. A new exhaust fan and room pressure controller will need to be added to maintain the required pressure relationship. The anticipated capital construction costs would be between $20,000 to $40,000. Access to the isolation room and nurse’s office is highlighted above.
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 49
Appendices
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 50
Appendix A – Matrix of Existing HVAC Systems
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 51
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 52
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 53
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 54
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 55
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 56
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 57
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 58
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 59
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 60
Appendix B – Building System Maps (KFI overlay) and MPS Equipment Maps
COVID 19 Analysis of Building Ventilation Systems KFI Engineers • KFI – 20-472.00 Patrick Henry High School Copyright 2020 KFI Engineers
Minneapolis Public Schools 65
Appendix C – MERV Filter Ratings
https://www.nafahq.org/understanding-merv-nafa-users-guide-to-ansi-ashrae-52-2/