Design Guidance for Education Facilities: Prioritization for Advanced Indoor Air Quality

Atlanta

Peachtree Corners

Developed by

ASHRAE Technical Committee 9.7, Educational Facilities

Design Guidance for

Education Facilities:

Prioritization for 

Advanced Indoor Air Quality

This document was developed by

ASHRAE Technical Committee (TC) 9.7, Educational Facilities.

ASHRAE TC 9.7 is concerned with the application of heating, ventilating,

air-conditioning, refrigeration, life safety, and energy conservation systems to

educational facilities.

Primary Contributing Authors

Raj Setty, PE, CxA, LEED AP Kyle Hasenkox

Christopher Ruch Keith Hammelman, PE

Corey Metzger, PE Itzhak Maor, PE, PhD

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Contents

Intent and Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Prioritization for Advanced IAQ: Checklists . . . . . . . . . . . . . . . 5

Prioritization for Advanced IAQ: Budgetary Guidelines . . . . . . 6

Prerequisites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Ventilation Verification and Testing and Balancing of HVAC

Airside Components (Existing Facilities Only). . . . . . . 8

Risk Tolerance Assessment–Wells-Riley or Equivalent . . 11

Very High Priority Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

HVAC Equipment Filtration Upgrades . . . . . . . . . . . . . . . . 14

HVAC for Wellness/Nurse Suites for Pre-K–12 . . . . . . . . . 16

Classroom and Assembly Space Air Distribution and 

Dilution Effectiveness . . . . . . . . . . . . . . . . . . . . . . . . 19

High Priority Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

IAQ Sensors with Data Aggregation Platform . . . . . . . . . . 21

New HVAC Equipment to Achieve ASHRAE-Recommended

Air Change Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Classroom-Level Air Cleaning . . . . . . . . . . . . . . . . . . . . . . 24

Restroom Exhaust and Air Filtration Upgrades . . . . . . . . . 27

Staff Training and Documentation Organizational 

Platform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

UV-C/UVGI in Air Handling Equipment . . . . . . . . . . . . . . . 29

Medium Priority Tasks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Humidification and Dehumidification Systems. . . . . . . . . . 32

Energy Efficiency Offset Control Schemes for 

Advanced IAQ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Operable Windows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

© 2023 ASHRAE (www.ashrae.org). For personal use only. Additional reproduction, distribution, or transmission in either print or digital form is not permitted without ASHRAE's prior written permission.

4 Design Guidance for Education Facilities

Intent and Scope

The intent and scope of this document is to provide guidance to owners, oper-

ators, designers, and professional service providers on how to best implement

indoor air quality (IAQ) improvements, including risk mitigation strategies, in

educational facilities. It will also help facilitate discussion between designers and

stakeholders, identify minimum recommendations, and discuss further consider-

ations to improve IAQ and reduce the transmission risk of infectious pathogens

and other contaminants of concern.

Purpose

This document should be used to prioritize decisions related to heating, venti-

lating, and air-conditioning (HVAC) system design and operation for existing

facilities (commissioning, maintenance, improvement, and retrofit projects) and

new facilities to improve indoor air quality while limiting energy consumption.

IAQ upgrades can improve learning outcomes and mitigate the risk of trans-

mission of airborne pathogens within the educational environment.

This guide is intended to help qualified professionals, including HVAC engi-

neers; commissioning agents; testing, adjusting, and balancing (TAB) providers;

and facility managers assess existing facilities and identify appropriate design

decisions for new facilities. Every school, and its HVAC systems, is unique and

requires its own distinct solutions. This document provides prioritization themes

but does not replace the efforts of a qualified professional in assessing each facil-

ity’s unique characteristics.

This document is broken into several sections including Prerequisite Tasks,

Very High Priority Tasks, High Priority Tasks, and Medium Priority Tasks. Within

each of these sections are steps or HVAC system strategies for consideration, typ-

ically with base minimum and advanced IAQ strategies, targets, or requirements.

The “base minimum” recommendations, beyond code requirements, should be

implemented to meet a minimum level of air quality and risk mitigation. These

strategies were developed through collaboration and review by members of

ASHRAE Technical Committee 9.7, Educational Facilities, and members of the

Epidemic Task Force (ETF) Schools Team. The recommended strategies have

been implemented across many educational facility systems worldwide.

The “advanced IAQ” recommendations are generally believed to represent

best practices that may not be appropriate for all applications but are worth con-

sideration for adoption to improve beyond the base minimum recommendations.

Various combinations of these strategies have been implemented in facilities to

address concerns related to airborne pathogens and indoor air quality in general.

Design Guidance for Education Facilities 5

Prioritization for Advanced IAQ:

Checklists

Complete Prerequisite Tasks

Ventilation verification and testing, adjusting, and balancing (TAB) of HVAC

airside components

Risk tolerance assessment—Wells-Riley or equivalent

Base Improved Advanced Very High Priority Tasks

HVAC equipment filtration upgrade

HVAC for wellness/nurse suites for pre-K–12

Classroom and assembly space air distribution

effectiveness

Base Advanced High Priority Tasks

IAQ sensors with data aggregation platform

New HVAC equipment to achieve ASHRAE-recommended air

change rates (ACH)

Classroom-level air cleaning

Restroom exhaust and air filtration upgrades

Staff training and documentation organizational platform

UV-C/UVGI for air handlers

Base Advanced Medium Priority Tasks

Humidification and dehumidification systems

Energy efficiency offset control schemes for advanced IAQ

Operable windows

6 Design Guidance for Education Facilities

Prioritization for Advanced IAQ: 

Budgetary Guidelines

Note: The budgetary numbers are to be used for capital planning and does not

substitute for an actual design and construction bid process. The general ranges

can be adjusted based on local and climatic conditions. Users should budget 5%

yearly escalation in the cost ranges after 2023. Budgets will vary based on the age

and condition of the school and HVAC systems. Budget costs assume minimal

architectural work. Structural, phasing, temporary equipment, electrical or plumb-

ing upgrades, extensive demolition of existing system, and replacement of spe-

cialty finishes are not included in the ranges.

Low High Units Prerequisite Tasks

$0.35 $0.60 ft

Ventilation verification assessment

$5000 $15,000 Building Risk tolerance assessment—Wells-Riley or equivalent

Low High Units Very High Priority Tasks

$0.30 $1.50 cfm HVAC equipment filtration upgrade

$350 $500 ft

HVAC for wellness/nurse suites for pre-K–12

$0.20 $0.35 ft

Classroom and assembly space air distribution effectiveness

Low High Units High Priority Tasks

$0.50 $1.00 ft

IAQ sensors with data aggregation platform

$5.00 $10.00 ft

New HVAC equipment to achieve ASHRAE-recommended

ACH

$1000 $2000 Classroom Classroom-level air cleaning

$1500 $3000 Restroom Restroom exhaust and air filtration upgrades

$1500 $2000 Cost/person/

week

Staff training and documentation organizational platform

$0.35 $0.70 cfm UV-C/UVGI for air handlers

Low High Units Medium Priority Tasks

$1.50 $4.00 cfm Humidification and dehumidification systems

$15,000 $35,000 Site Energy efficiency offset control schemes for advanced IAQ

$1500 $3,500 Window Operable windows

Design Guidance for Education Facilities 7

Prerequisites

Establishing an IAQ building-level improvement plan is a process that

involves several components. These prerequisites are about establishing objectives

and existing conditions (where applicable). Without these initial steps, it is not

possible to develop a comprehensive strategy to mitigate risk and maintain a high

level of IAQ. It is important to understand that these strategies reduce, but do not

eliminate, the potential for airborne transmission and must be used as part of a

comprehensive layered risk management approach. It should also be noted that

while the current focus may be on SARS-CoV-2/COVID-19, improving indoor air

quality in education facilities will have similar benefits for other airborne patho-

gens, and studies have shown reduced absenteeism and better performance from

students in facilities with better indoor environments.

The first step is to determine the appropriate level of risk tolerance/mitigation

and associated general system operating characteristics. Once this step has been

completed, the required scope of work for existing facilities or new facilities

should be developed. Factors include, but are not limited to, identifying and prior-

itizing buildings needing improvements, which systems are currently in place, and

whether those systems function as intended. Much of the initial data collection

can be completed by reviewing existing records and documentation where avail-

able. The data may come from record drawings, manuals, control systems, per-

sonnel interviews, or maintenance records. The initial data collection process may

be shared between facility stakeholders including administrative, maintenance and

operations, and HVAC professionals as needed to collect the summary of the sys-

tems to be analyzed.

From this initial facility and equipment list, a scope of work can be generated

to verify the system performance. An HVAC professional should be engaged to

help develop the plan for assessment of the existing equipment and establish a

ventilation verification and testing and balancing of HVAC airside components

plan. A combination of the records and verification reports will create an accurate

picture of the existing systems and their condition.

Next, an initial assessment of HVAC risk can be determined using site-specific

risk analysis tools such as the Wells-Riley Equations, Equivalent Outdoor Air

Rate Calculator, and/or other assessment tools. The resulting analysis should give

an estimate of the risk in specific spaces and may help develop an equitable strat-

egy between facilities and spaces with varying configurations. There are several

mitigation strategies that effect other components of risk, such as common areas,

but the establishment of a summary of the existing conditions and discussion of

risk acceptance are critical in the development of a comprehensive plan, which is

why they are considered prerequisites to the process. While variations of these

prerequisites will exist in different facilities and areas, the inclusion of this pro-

cess and the discussion of it between stakeholders and HVAC professionals is

foundational in the process.

8 Design Guidance for Education Facilities

Ventilation Verification and Testing and Balancing of 

HVAC Airside Components (Existing Facilities Only)

Overview

Perform a physical assessment of existing HVAC infrastructure and provide a

written condition assessment. Verify operation and conditions of existing systems.

This baseline assessment must be performed by a skilled, trained, and certified

technician. Upon completion, the assessment should be submitted to an HVAC

design professional for determination of adjustments, replacements, repairs, and

upgrades. Where possible, this can be compared to record drawings, manuals, and

noted deficiencies in performance.

Involved Parties

A skilled, trained, and certified technician performs the physical assessment in

coordination with facilities personnel and a qualified design professional, as

defined by state or provincial guidelines.

Procedure

Refer to Additional Guidance for sample ventilation verification assessment

test sheets and method of procedures (MOP). Sample procedures should be

altered to meet local requirements, updated recommendations, and site-specific

equipment.

Base Minimum

For All Airside Systems

• Document filter Minimum Efficiency Reporting Value (MERV) values

and ensure proper installation with minimum bypass air.

• Physically verify and document ventilation rates. Adjust the ventilation

rates to accommodate the building elevation and corresponding air den-

sity per ASHRAE Standard 62.1, Ventilation and Acceptable Indoor Air

Quality (6.2.1.1.3).

• Physically verify demand control ventilation (DCV) operates as intended.

A minimum of 10% sampling is acceptable for verification. If carbon

dioxide is used as a surrogate for occupancy, confirm sensors are installed

at space level (not in common return) and confirm calibration of sensors

(minimum of five per facility or 10%).

• Document initial and periodic calibration procedure and implement with

calibration period not to exceed five years.

• Air distribution: Measure a minimum of 10% of all zones/inlets/outlets

for a cfm sampling. These should be representative of the overall HVAC

system. Zones measured should be representative of zones in system

(closest and furthest from equipment, interior and exterior spaces, etc.).

• Document building differential pressures of rooms temporarily occupied

by sick students and staff (i.e., nurses’ isolation rooms). Pressure should

be read between space of concern and adjacent occupied area(s).

Design Guidance for Education Facilities 9

• Document existing sequence of operations (SOP/SOO) and operational

controls.

• Document ambient outdoor CO

conditions and differential to indoor

spaces. Trend the CO

levels over the duration of peak occupancy. If CO

levels exceed recommended limits (typically outside air level +750 ppm

set point or 1100–2000 ppm) for 90 minutes, further recording should be

implemented. Recommended limits are based on ASHRAE TC 9.7 mem-

ber author’s design experience.

• Perform testing of PM

2.5

, PM

, and VOC levels in a minimum of 10%

of the spaces hourly during occupied times over a minimum period of one

week.

• Verify that equipment is operating as outlined in the SOP/SOO.

• Report and remediate any issues and coordinate with the qualified design

professional.

Exhaust

• Air distribution: Survey a minimum of 10% of all exhaust inlets, with

measurements taken in areas that will represent operation throughout the

system. Ensure that systems are all operating in occupied mode.

Figure 1 Testing and balancing of HVAC airside components.

Source: www.nemionline.org/testing-adjusting-and-balancing-hvac-

systems-an-overview-of-certification-agencies/

10 Design Guidance for Education Facilities

Limited or No Existing Mechanical Ventilation

In cases where there is limited or no existing mechanical ventilation, the

assessment should focus on available strategies to provide ventilation including,

but not limited to, operable windows and building chases. Provide the qualified

design professional with documentation for future ventilation improvements for

concurrence.

Advanced IAQ

For All Airside Systems

• Determine air handler capability to accommodate MERV 13 filter.

• Verify physical ability to increase ventilation above scheduled value.

• Verify physical ability to override and/or disable the DCV.

• Measure 100% of all air distribution inlets/outlets.

• Document building pressure relationships of all rooms as recommended

by your HVAC professional.

• Test a minimum of 10% of sensors for accuracy and document the drift of

the sensors in comparison to handheld sensor readings. Calibrate sensors.

• Verify operational controls respond correctly.

• Schedule a periodic physical ventilation verification assessment of pri-

mary HVAC systems every five years.

• Establish a verification and calibration program to confirm operation of

sensors.

Exhaust

• Survey 100% of all air distribution exhaust inlets for a sampling.

Additional Guidance

ASHRAE TC 7.7, Testing and Balancing.

Meyers, F., and T. Pistochini. 2020. Testing, adjusting and balancing HVAC sys-

tems: An overview of TAB certification agencies. WCEC technical report.

Davis, CA: University of California Davis Western Cooling Efficiency Center.

https://wcec.ucdavis.edu/wp-content/uploads/TAB-Technical-Report-

051220.pdf.

• Associated Air Balance Council (AABC).

• National Environmental Balancing Bureau (NEBB).

• Testing, Adjusting and Balancing Bureau (TABB).

IEQ Guidelines. 2022. Copy of all IAQ guidelines reports. https://ieqguide-

lines.org/table.html.

NEMI. 2022. Sample ventilation verification assessment test sheets. https://

www.nemionline.org/vvr-for-contractors/.

NEMI. 2022. Ventilation verification specification. https://www.nemionline.org/

ventilation-verification-specification/.

Ruch, C., and T. Pistochini. 2021. White paper: Proposed ventilation and energy

efficiency verification/repair program for school reopening. NEMI/University

Design Guidance for Education Facilities 11

of California Davis Energy and Efficiency Institute. https://ucda-

vis.app.box.com/v/ProposedVentilationProgram.

UC Davis Energy. 2020. Importance of ventilation in schools. YouTube video,

produced by University of California Davis Western Cooling Efficiency Cen-

ter. https://www.youtube.com/watch?v=F9hB9BgonHs.

Risk Tolerance Assessment–

Wells-Riley or Equivalent

Overview

When prioritizing IAQ projects and budgeting, start with a baseline of the cur-

rent probability of infection. Establish a target goal for the probability of transmis-

sion of infectious airborne assessments, based on HVAC and operational changes.

A risk assessment should be performed as part of the basis of design for any IAQ

upgrade project.

Designers and engineers need to evaluate their design approaches for effec-

tiveness in reducing the risk of transmission. The calculation tool may be used to

compare HVAC options against each other to balance effectiveness and budgetary

constraints.

It is recommended that the stakeholders determine the acceptable level of risk

as defined by their governing bodies.

Involved Parties

Design engineers, facility managers, architects, building operations staff, and

local health officials.

Base Minimum

While there are no 100% solutions to ensure no one will be infected by a virus

in a common space like a classroom, there are operational and HVAC system

changes that reduce the airborne concentration of viruses. The underlying direc-

tive for HVAC engineers is “do no harm.” The application of better filtration,

reduction in exposure time, reduction in occupancy, more fresh air to the building

spaces, and disinfection of the airstream via UV-C all have positive impacts to the

indoor air quality. While there are cost implications to the various applications,

the risk of negatively impacting the IAQ is almost negligible.

Below are some examples of available risk analysis tools. The site-specific

strategy employed should be developed in collaboration with stakeholders and

your HVAC professional. Note that inclusion of these calculators is to provide

examples of risk assessment tools and is not an endorsement of the tool itself.

• 2020 COVID-19 Aerosol Transmission Estimator

• Harvard-CU Boulder Portable Air Cleaner Calculator for Schools, v1.3

• SETTY-5.2, Small Space Airborne Transmission Infection Rate Estimator

12 Design Guidance for Education Facilities

Wells-Riley Equation

where

Advanced IAQ

Advanced IAQ risk assessments should address both the probability of infec-

tion as well as air cleaning strategies. Advanced IAQ assessments should also

address specific airborne contaminants beyond the base IAQ risk assessments.

The site-specific strategy employed should be developed in collaboration with

stakeholders and your HVAC design professional. Advanced IAQ risk assess-

ments should employ a layered mitigation strategy to reduce the probability of

contaminant transmission.

The Wells-Riley model (Fisk et al. 2005; Nazaroff et al. 1998) is used for par-

ticle removal and air disinfection (UV-C, UVGI).

Add to the equation:

Additional Guidance

Bahnfleth, W.P. 2020. Reducing infectious disease transmission with UVGI.

Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/file%20library/

professional%20development/learning%20portal/instructor-led%20training/

online%20instructor-led/final-4-21-2020-ashrae-one-hour-uvgi-course_se-

cured.pdf.

EPA. 2022. Simulation tool kit for indoor air quality and inhalation exposure

(IAQX). https://www.epa.gov/air-research/simulation-tool-kit-indoor-air-

quality-and-inhalation-exposure-iaqx.

infection

= probability of infection

C = number of infection cases

S = number of susceptible

I = number of infectors

p = pulmonary ventilation rate of a person

q = quanta generation rate (based on the estimated epidemi-

ological outbreak use case)

t = exposure time interval

V = volume of the room

Q = room ventilation rate with clean air



infection

1 





--------

–

 

–

1–+



------------------------------



–=



UV = rate coefficient of inactivation by ultraviolet irradiation

Qr = flow rate to the filter



r = filtration efficiency

Design Guidance for Education Facilities 13

Fisk, W.J., O. Seppänen, D. Faulkner, and J. Huang. 2005. Economic benefits of

an economizer system: Energy savings and reduced sick leave. ASHRAE

Transactions 111(2): 673–79.

Nazaroff, W.W., M. Nicas, and S.L. Miller 1998. Framework for evaluating mea-

sures to control nosocomial tuberculosis transmission. Indoor Air 8: 205–18.

NIST. 2022. ViPER—Virus particle exposure in residences tool. https://

pages.nist.gov/CONTAM-apps/webapps/ViPER/.

Sze To, G.N., and C.Y.H. Chao. 2010. Review and comparison between the Wells-

Riley and dose-response approaches to risk assessment of infectious respira-

tory diseases. Indoor Air 20(1): 2–16. https://www.ncbi.nlm.nih.gov/pmc/arti-

cles/PMC7202094/.

14 Design Guidance for Education Facilities

Very High Priority Tasks

HVAC Equipment Filtration Upgrades

Overview

By improving the filtration in the air handlers, it is possible to decrease the

chance of aerosolized viral particles being spread through the air distribution system.

While higher filtration is more effective, it may not be practical, because there

are diminishing returns in improvement of particulate removal and increases in

static pressure and cost. Additionally, existing equipment may have several limita-

tions such as fan static capacity. Higher levels of filtration are better; however,

research has determined that diminishing returns in the effectiveness of particle

removal begin at MERV 13 to MERV 14 filter ratings.

An increase from MERV 8 or MERV 11 represents a substantial increase in

the efficacy of filtration of small infectious particles. Filter frame size should be

evaluated by your HVAC professional to handle the filter upgrade. If the filter

frame cannot be increased, proceed with the highest level MERV filter that will

not require the equipment or ductwork to be changed. The introduction of new fil-

Figure 2 MERV filter models.

Source: Kowalski, W.J., and W.P. Bahnfleth. 2002. MERV filter models for

aerobiological applications. Air Media, Summer.

Design Guidance for Education Facilities 15

ters may create higher O&M and energy costs plus a higher pressure drop, the

impacts of which should be reviewed by your HVAC professional.

Involved Parties

Design engineers, facility managers, architects, TAB contractor/technician,

and building operations staff.

Base Minimum

• Assess existing filtration levels and create an inventory of existing filtra-

tion efficiency (per ASHRAE Standard 52.2) and ventilation volumes.

• Assess ventilation system capacity for higher levels of filtration, includ-

ing motor and physical dimensions of air handlers.

• Apply the highest MERV filter for the HVAC units (local, central, and

DOAS) given limitations with increased pressure drop. MERV 13 is the

recommended minimum.

• Create and follow safe procedures for filter maintenance and operations

per the Occupational Safety and Health Administration (OSHA) and

ASHRAE Standard 180.

• Verify airflows after filtration level changes.

• Monitor loading pattern on filters after changes and adjust filter change

schedules to meet new loading patterns.

• Label all filters with the manufacturer’s name showing the MERV rating

and date of filter change.

Advanced IAQ

• Make duct modifications where required to ensure that a minimum level

of MERV 13 is reached in all areas and MERV 14 where possible.

• Consider adding differential pressure sensors to monitor the status of filters.

• Consider alternate filter locations in return duct or grille, but consider static

pressure drop implications and relationship with outside air dampers.

• Consider the addition of a prefilter to extend primary filter life.

• Consider UL-listed electrostatic devices.

• Consider adding HEPA filters in critical/ higher density areas with lower

outside air volumes.

• Consider additional treatment technology to inactivate airborne infectious

aerosols (refer to the ASHRAE Epidemic Task Force’s document for

reopening schools and universities for additional guidance).

• Consider having facility staff who perform filter change-out procedures

to be trained for proper installation and maintenance of new filters and air

cleaning systems.

Additional Guidance

ASHRAE. 2017. ASHRAE Standard 52.2-2017, Method of testing general venti-

lation air-cleaning devices for removal of efficiency by particle size. Peachtree

Corners, GA: ASHRAE. https://www.techstreet.com/ashrae/standards/ashrae-

52-2-2017?product_id=1942059.

16 Design Guidance for Education Facilities

ASHRAE. 2021. ASHRAE position document on filtration and air cleaning.

Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/file%20library/

about/position%20documents/filtration-and-air-cleaning-pd-feb.2.2021.pdf.

EPA. 2022. What is a MERV rating? https://www.epa.gov/indoor-air-quality-iaq/

what-merv-rating.

UC Davis Energy. 2021. The importance of filtration in schools. YouTube video,

produced by University of California Davis Western Cooling Efficiency Cen-

ter. https://www.youtube.com/watch?v=ycgLBUfIM_c.

HVAC for Wellness/Nurse Suites for Pre-K–12

Overview

This section focuses on the educational facility’s wellness/nurse suite where

students with medical issues are placed during the period prior to them being

transferred out of the facility. It is intended to be a transitory space to temporarily

hold potentially infectious persons. Due to the operation of many facilities, this

space is often located at or near the central office, which also acts in a security

role by controlling access to the facility. The combination of keeping a potentially

infectious person near a specifically designed point where all traffic is being

routed presents an increased level of risk, and additional consideration of strate-

gies to mitigate this risk may be warranted.

The facility size should be considered along with its location, risk tolerance,

and facility operation. A larger facility may have a medical professional occupy-

ing the suite, while in smaller facilities, this task may be completed by persons

with some first aid training and consist of a less complex approach.

This section refers to pre-K through grade 12 facilities. For post-secondary

facilities, refer to ASHRAE Standard 170 or other standards, as appropriate. Due

to the increased possibility of an infected person entering a nurse’s suite, greater

caution and a higher level of air quality must be designed and installed similar to

an airborne isolation room in a hospital. While there are degrees of protection, air

should not be recirculated from this space to other occupied building areas.

Isolation of a nurse’s suite should consist of architectural barriers and con-

trolled pressure relationships between areas to mitigate the risk of airborne trans-

mission. The pressure of the space should be positive to outside but negative to

adjacent spaces, as this approach should reduce risk to the occupants. It is import-

ant to consider the pressure relationships, air changes, space exhaust, and opera-

tional policies and procedures.

Furthermore, the design approach should accommodate the safety and protec-

tion of the attending nurse or staff. When locating a nurse’s isolation suite, the safe

and efficient movement of a sick person from the nurse’s suite out of the building

needs to be considered to minimize the release of pathogens in the building.

Involved Parties

Design engineers, facility managers, architects, and building operations staff.

Design Guidance for Education Facilities 17

Base Minimum

• Wellness/nurse office or suite (any space intended for occupancy by indi-

viduals who are sick or suspected to be sick) should be maintained at a

negative pressure with respect to corridors and adjacent spaces.

• Air may be recirculated within the space only but may not be returned

and recirculated to other spaces. All air leaving the space should be

exhausted to outdoors. Exhaust air may pass through energy recovery

devices serving other building areas being exhausted, as long as systems

comply with ASHRAE Standard 62.1. Exhaust air intakes should be fully

ducted to intakes in space.

• Air recirculated within the space should be filtered through filter media

with minimum MERV rating of 13.

• Maintain a minimum air change rate to space of six total air changes per

hour (ACH) and minimum of two ACH of outdoor air. All air in the wait-

ing areas and the isolation room should be exhausted when building or

space is occupied.

• Special attention should be given to proper location of supply air diffusers

and return/exhaust air grilles.

Figure 3

Indicative wellness/nurse suite prototype configuration.

Source: Raj Setty/ASHRAE Epidemic Task Force. 2021. Schools and

universities. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/

file%20library/technical%20resources/covid-19/ashrae-reopening-

schools-and-universities-c19-guidance.pdf.

18 Design Guidance for Education Facilities

Improved IAQ

• Create a school/building-specific nurse’s isolation suite. The number of

isolation rooms will depend on the school programming requirements.

• Do not mix supply air and return air from isolation room with any other

spaces when in isolation mode.

• Maintain a minimum clean ACH of 6 in all conditioned spaces in the

nurse’s suite, 10 ACH in the waiting room, and 12 ACH in the isolation

room(s). All air in the waiting areas and the isolation room should be

exhausted when building or space is occupied.

• Exhaust directly to outdoors. Follow ASHRAE Standard 62.1 require-

ments to avoid re-entrainment of contaminated air. If there is a concern of

recirculation, HEPA filtration on exhaust could be added.

• The nurse’s suite should be under negative air pressure in relation to

building corridors and adjacent spaces.

• Follow applicable ASHRAE Standard 170’s most recent tables for gen-

eral outpatient spaces (Table 8-2) and 2019 California Mechanical Code

(Ventilation).

• Supply air should have a minimum of MERV 13 or higher filtration.

• Special attention should be given to proper location of supply air diffusers

and return/exhaust air grilles (low return is recommended). In the isola-

tion room, the exhaust grille should be located close to the patient in the

proper elevation.

• Provisions for biohazard waste and personal sanitation including, but not

limited to, hand wash, showers, water closets, etc.

• Provisions for PPE storage and application to mitigate the risk of PPE

becoming contaminated.

Advanced IAQ

• Create school/building-specific nurse’s isolation suite(s) based on the

unique school population.

• 100% OA dedicated outdoor air unit (DOAU) with air-to-air energy

recovery (no cross contamination/carryover in the energy recovery heat

exchanger). The unit should be capable of switching to recirculation/min-

imum OA when applicable with the ability to provide and control the

desired thermal conditions (space temperature and humidity).

• Treat as Airborne Infectious Isolation (AII) per ASHRAE Standard 170

and ASHRAE Handbook, Chapter 9 (2019).

• ACH = 12 to 20.

• Add UVGI to dedicated HVAC unit or other approved disinfection tech-

nology. Upper air room (with fan as an option) UVGI can be also consid-

ered, specifically in critical areas such as isolation and waiting rooms.

• Dedicated bathrooms that should be kept under negative pressure in rela-

tion to adjacent spaces.

• Nurse’s station infirmary beds should be defined based on the population

of the school (typically 1 bed /200 students).

Design Guidance for Education Facilities 19

• Recommend locations of nurse’s office HVAC on an exterior wall.

• Maintain pressure relationship for room, ante room, and corridor.

• Directional airflow designer to consider the airflow pattern.

• Establish an annual verification program to confirm airflows and pressure

relationships by a certified technician.

• Follow maintenance and operations schedule established in ASHRAE

Standard 62.1.

• Add a separate power supply for all equipment and ventilation to standby

power system.

• Provide permanently mounted sensors for IAQ monitoring and occu-

pancy. At minimum, parameters such as CO

, total volatile organic com-

pounds (TVOCs), PM

2.5

, and PM

should be monitored.

Additional Guidance

ASHRAE. 2017. ASHRAE Standard 170-2017, Ventilation of healthcare facili-

ties. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/technical-

resources/standards-and-guidelines/standards-addenda/ansi-ashrae-ashe-stan-

dard-170-2017-ventilation-of-health-care-facilities.

ASHRAE. 2022. ASHRAE Standard 62.1-2022, Ventilation and acceptable

indoor air quality. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/

technical-resources/bookstore/standards-62-1-62-2.

ASHRAE Epidemic Task Force. 2021. Schools and universities. Peachtree Cor-

ners, GA: ASHRAE. https://www.ashrae.org/file%20library/technical%20re-

sources/covid-19/ashrae-reopening-schools-and-universities-c19-

guidance.pdf.

NIEHS. Handout 1: Infection control checklist for risk assessment and precau-

tions for construction & renovation. https://tools.niehs.nih.gov/wetp/public/

Course_download2.cfm?tranid=9806.

Classroom and Assembly Space 

Air Distribution and Dilution Effectiveness

Overview

While it is possible to identify the location of the potential infector in some

applications, that is not applicable in a classroom. Any occupant may potentially

be an infector. Given that the potential infector could be anywhere in the room, the

best applied strategy should ensure there are no direct drafts that could concen-

trate infectious aerosols. Maintaining good mixing will also reduce thermal stress

and conform to energy standards such as ASHRAE/IES Standard 90.1 for dis-

charge air temperature requirements.

Involved Parties

Design engineers, facility managers, architects, and building operations staff.

20 Design Guidance for Education Facilities

Base Minimum

• Ensure air grilles and diffusers are in good operating condition and are

not configured such that they will create drafts.

• For modifications or new distribution systems, follow ASHRAE/IES Stan-

dard 90.1, which limits discharge temperature to 20°F (11°C) above room

temperature.

• Design intent should minimize cross-flow between occupants but maxi-

mize room volume dilution.

• Minimum outside air should not be substituted with increased ventilation

effectiveness strategies.

• Review temporary dividers impact on air distribution to avoid creation of

drafts and concentrations of flow.

Advanced IAQ

• Follow ASHRAE Standard 55 requirements to maintain a maximum of

5.4°F (3°C) of temperature difference between the head and foot level of

the space and air velocity.

• The ASHRAE Handbook—HVAC Applications recommends mixing;

however, care must be taken to minimize transfer air among occupants.

• Consider vertical separation in flow patterns including, but not limited to,

supply air high and return air low, underfloor air distribution (UFAD),

and displacement ventilation (DV). Different strategies should be ana-

lyzed for different operating conditions in climate zones where both heat-

ing and cooling operation will be required during occupied periods.

• Air cleaners may be considered to improve IAQ, but their impact on

existing distribution effectiveness should be reviewed.

• CFD modeling can be used to consider different approaches and model

various classroom configurations and desk arrangements.

Additional Guidance

ASHRAE. 2019. ASHRAE/IES Standard 90.1-2019, Energy standard for build-

ings except low-rise residential buildings. Peachtree Corners, GA: ASHRAE.

https://www.ashrae.org/technical-resources/bookstore/standard-90-1.

ASHRAE. 2020. ASHRAE Standard 55-2020, Thermal environmental conditions

for human occupancy. Peachtree Corners, GA: ASHRAE. https://

www.ashrae.org/technical-resources/bookstore/standard-55-thermal-environ-

mental-conditions-for-human-occupancy.

Design Guidance for Education Facilities 21

High Priority Tasks

IAQ Sensors with Data Aggregation Platform

Overview

IAQ sensors distributed throughout the building will provide a baseline IAQ

profile of the entire building. The goal of this section is to inform practitioners on

how to prepare sensors and interpret readings for an IAQ-centric HVAC system.

The driving force for our industry is energy efficiency, which has been the pre-

dominant underlying engineering design dogma. This must now be balanced with

a high level of indoor air quality for the health and welfare of the learners. The

best way to balance IAQ and energy efficiency is to deploy a suite of IAQ sensors

to provide a data-driven approach to proper HVAC operations.

The designer must, at a minimum, evaluate PM

2.5

/PM

1.0

/PM

0.5

, CO

, tem-

perature, TVOCs, and humidity, which all paint a picture of the optimal air quality

for the teaching space. Baseline should be created in spaces that reflect a mini-

mum of six months of data collection through both occupied and unoccupied

times. Sensors should be UL 2905 compliant.

Involved Parties

Design engineers, facility managers, architects, and building operations staff.

Base Minimum

• IAQ sensors deployed at all HVAC main central air handling stations

during all periods of occupancy.

• IAQ sensors deployed at 10% of the classrooms to provide an IAQ profile

of the distribution systems.

• Readings should be taken daily, and trending data shared with a BMS or

web/cloud-based data repository and reporting platform. Design team to

set thresholds for CO

, TVOCs, and PM levels. Thresholds should incor-

porate time elements and be established on local outdoor air quality as the

baseline.

• Monitor PM

2.5

, CO

, temperature, TVOCs, and humidity.

• Establish an ongoing testing and verification program as per Table 8.1 in

ASHRAE Standard 62.1:

Inspection/Maintenance Task

ad. Verify the accuracy of permanently mounted sensors whose

primary function is outdoor air delivery monitoring, outdoor air

delivery verification, or dynamic minimum outdoor air control,

such as flow stations at an air handler and those used for demand

control ventilation, including CO

sensors. A sensor failing to

22 Design Guidance for Education Facilities

meet the accuracy specified in the O&M manual shall be recali-

brated or replaced. Performance verification shall include output

comparison to a measurement reference standard consistent with

those specified for similar devices in ASHRAE Standard 41.2 or

ASHRAE Standard 111.

Advanced IAQ

• IAQ sensors deployed throughout the building at no less than one sensor

per 3000 ft

• Readings should be taken every five minutes and trending data shared

with a BMS.

• Data aggregation and analysis software to be provided to create an IAQ

daily profile.

• BMS should calculate the PM

2.5

, CO

, temperature, TVOCs, humidity

levels of degradation from peak occupancy to baseline normal levels.

HVAC should be capable of adjustments to increase CADR levels to

bring the classroom IAQ to baseline levels within 60 minutes of peak.

Baseline algorithms should take IAQ alarms and adjust HVAC sequences

for flushing, higher ventilation, or airflow changes to improve the IAQ in

real time. Possibly incorporate totalizers for number of hours room is out-

side of specified parameters so that either scheduling or equipment can be

modified to improve IAQ.

• Consider monitoring PM

, PM

1.0

, and different types of volatile organic

compounds.

• Physically verify sensor accuracy annually.

• Consider revising control strategy to maximize IAQ. If there is good outside

quality air of a suitable temperature and humidity, maximize outdoor air.

Additional Guidance

AIRNOW. 2022. Air quality index (AQI) basics. https://www.airnow.gov/aqi/aqi-

basics/.

ASHRAE. 2022. ASHRAE Standard 62.1-2022, Ventilation and acceptable

indoor air quality. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/

technical-resources/bookstore/standards-62-1-62-2.

CDC. 2019. NIOSH pocket guide to chemical hazards. https://www.cdc.gov/

niosh/npg/npgd0103.html.

EPA. 2022. Creating healthy indoor air quality in schools. https://www.epa.gov/

iaq-schools.

IEQ Guidelines. 2022. Copy of all IAQ guidelines reports. https://ieqguide-

lines.org/table.html.

UC Davis Energy. 2020. Importance of ventilation in schools. YouTube video,

produced by University of California Davis Western Cooling Efficiency Cen-

ter. https://www.youtube.com/watch?v=F9hB9BgonHs.

Design Guidance for Education Facilities 23

New HVAC Equipment to Achieve 

ASHRAE-Recommended Air Change Rates

Overview

New HVAC systems should be designed to comply with the most current

adopted mechanical and building codes within the jurisdiction where the facility is

located, including the code-required minimum ventilation standard. In the absence

of a code official or authority having jurisdiction over the design and construction

of a new HVAC system, or an adopted code, ASHRAE recommends designing the

systems to provide the minimum ventilation rates in the breathing zone as deter-

mined using Table 6-1 in ASHRAE Standard 62.1, Ventilation and Acceptable

Indoor Air Quality.

Involved Parties

Design engineers, facility managers, and building operations staff.

Base Minimum

As determined in accordance with Table 6-1 in ASHRAE Standard 62.1-2019,

MERV 13 filters for all recirculated air.

Air Distribution

Design systems to provide well-mixed air. Avoid air velocities that create

drafts or create airflow across or from one occupant to another.

Space Total Air Changes Per Hour

• Three to six ACH minimum during occupied periods. The maximum

should be based on design loads.

• Reduced volume during unoccupied periods is acceptable to conform to

energy code requirements.

Air Cleaners

Consider air cleaners with HEPA filtration to supplement ventilation systems

and distribution design to ensure minimum space air change CADR levels are

met. This can include multiple air cleaners positioned to best provide air cleaning.

Noise

Design systems for maximum 40 dB in classrooms.

Equipment Motor Horsepower

Include a safety factor when sizing fan motors so the unit accommodates an

increase of 25% above design external static pressure in the future.

24 Design Guidance for Education Facilities

Advanced IAQ

For Dedicated Outdoor Air Systems

Design the systems (equipment size and air distribution network) so they can

be set to a pandemic mode of operation and deliver 30% more ventilation air than

the code or base minimum. Filter ventilation air with MERV 13 filters.

For Central Station Air Handling Systems

Design the systems (equipment size and air distribution network) so they can be set

to a pandemic mode of operation and deliver 30% more ventilation air than the code or

base minimum. Filter all outdoor air and recirculated air with MERV 13 filters.

Design units with 100% outside air economizers so units can provide 100%

ventilation during times of the year when outside conditions can meet the HVAC

loads in the building and maintain thermal comfort.

Space total air changes per hour: six to eight ACH.

Air Cleaners

Consider air cleaners with HEPA filtration to supplement ventilation systems

and distribution design to ensure the minimum space air change CADR levels are

met. This should include an air cleaner positioned above the teacher’s desk or area

the teacher should occupy the most during a class.

Additional Guidance

ASHRAE. 2022. ASHRAE Standard 62.1-2022, Ventilation and acceptable

indoor air quality. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/

technical-resources/bookstore/standards-62-1-62-2.

Hear-it.org. 2022. School noise detrimental to hearing and learning. https://

www.hear-it.org/school-noise-detrimental-hearing-and-learning.

Classroom-Level Air Cleaning

Overview

Air cleaners are intended to work with building ventilation systems and are

not to be used as a substitute for building ventilation. While they may assist in

removing infectious particles, they can present additional challenges and risks in

the space.

Benefits

The use of in-room air cleaners (either portable or permanently installed) may

help reduce concentrations of airborne particulate, including airborne pathogens,

from occupied spaces. In-room air cleaners utilizing HEPA filtration may effec-

tively remove nearly all airborne pathogens passing through the unit filter

Concerns

While in-room air cleaners are likely to help reduce airborne pathogen concentra-

tions, they also have implications for operations in the spaces served. Sound power

Design Guidance for Education Facilities 25

levels, potential negative impacts to space air distribution effectiveness, maintenance

personnel safety, and maintenance requirements all need to be considered.

Involved Parties

Design engineers, facility managers, architects, and building operations staff.

Base Minimum

Target code-required ventilation (ASHRAE Standard 62.1 requirements or

equivalent), good air distribution, and increased filtration efficiency.

Design Considerations

For buildings achieving the minimum actions above, addition of in-room air

cleaners may be considered on a case-by-case basis to achieve the owner’s defined

level of risk tolerance. Each type of classroom use case should be included in the

design of air cleaners that will accommodate the peak occupancy. For example,

music rooms and conference rooms should be evaluated for higher air cleaner

deployments.

Limited or No Existing Mechanical Ventilation

In cases where there is limited or no existing mechanical ventilation, provide

in-room air cleaners to provide maximum non-infectious air delivery equivalent

(NIADE) rate. Consideration must be given to air distribution in space, sound

power levels, and maintenance procedures.

Advanced IAQ

Introduce terminal or portable all-electric HEPA/UV machines in each class-

room.

Design Considerations

Target highest achievable NIADE rate for units that will not generate exces-

sive noise or negatively impact space air distribution (should not create drafts that

direct air across one occupant and toward others). Ensure flow patterns maximize

mixing of air in classrooms.

Maintenance Considerations

• Relevant additions to maintenance schedule and operations training.

• Develop maintenance policies for new/added equipment such as local air

cleaners, humidifiers, additional filtration in mechanical equipment, etc.

Portable Unit Specifications

• UV-C light, minimum of 1200 microwatts/cm

• HEPA filter

• Cfm adjustable from 200 to 400 cfm

• Noise sound level under NC 35

• Power 110-volt plug in

26 Design Guidance for Education Facilities

Suggested Guidance for Portable Classroom Air Cleaner 

Installation and Operations

• Air cleaner location

• Place the air cleaner in a centralized location and as close to the main

building HVAC return air grilles as possible.

• For rooms with unit ventilators or HVAC units located near the win-

dows, place the air cleaner in the center of the room.

• If there is noise or there are safety concerns with the electrical wires,

place the air cleaner near the teacher. Generally, adults can generate

more infectious particles than children under 14.

• Make sure the airflow pattern is one way, from occupants to return

air. We want to minimize the recirculation of air amount occupants.

• Location should be adjusted as the classroom furniture is reconfig-

ured. Place the air cleaner near the maximum number of students.

• Air cleaner speeds during class

• Make sure the air cleaner meets the classroom acoustics requirement

and does not hamper the students’ ability to hear the teacher.

• Units have adjustable speeds. Utilize the lower speeds if there are

acoustical issues; otherwise, operate at maximum acoustically suit-

able speed.

• Turn on units at maximum speed one hour before any occupied event

or start of class.

• If there are any noticeable smells from cleaning products, run the

units until the smell dissipates. Cleaning products can increase the

level of TVOCs, which can be harmful at high concentrations.

• Ensure unit placement will not cause additional interaction between

occupants and the equipment.

• Air cleaner speeds after class

• Air cleaner should be running at the full speed allowed during class

break and between classes for a minimum of 10 minutes.

• Turn units off one hour after space is cleaned or is unoccupied.

• Operate units at maximum speed after class.

• Air cleaner operations for weekends

• Keep units off during unoccupied times (i.e., weekends) unless

TVOC levels are high.

• Turn air cleaners on one to two hours prior to class occupancy on

Mondays, if possible, at maximum speed.

Additional Guidance

Allen, J., J. Cedeno-Laurent, and S. Miller. 2020. Harvard-CU Boulder portable

air cleaner calculator for schools v1.3. https://docs.google.com/spreadsheets/

d/1NEhk1IEdbEi_b3wa6gI_zNs8uBJjlSS-86d4b7bW098/

edit#gid=1882881703.

Design Guidance for Education Facilities 27

ASHRAE. 2021. ASHRAE position document on filtration and air cleaning.

Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/file%20library/

about/position%20documents/filtration-and-air-cleaning-pd-feb.2.2021.pdf.

ASHRAE. 2021. In-room air cleaner guidance for reducing Covid19 in air in your

space/room. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/

file%20library/technical%20resources/covid-19/in-room-air-cleaner-guid-

ance-for-reducing-covid-19-in-air-in-your-space-or-room.pdf.

Restroom Exhaust and Air Filtration Upgrades

Overview

Restrooms present a challenge and risk in most schools. With the configura-

tion of most restrooms, it is not possible to maintain social distancing require-

ments and the spaces are higher traffic.

When a cohorting strategy is applied, restrooms are often overlooked, though

they are used by all groups, presenting a risk of transmission between otherwise

isolated groups.

Additionally, toilet flushing and other activities may generate aerosols that

may convey infectious particles. Due to the increased risk in these locations, there

may be additional consideration warranted to mitigation.

Involved Parties

Design engineers, facility managers, architects, and building operations staff.

Base Minimum

• Ensure that all washroom fans are operating correctly and confirm that air

volumes are in accordance with ASHRAE Standard 62.1.

• Ensure that washroom exhaust systems are operating continuously during

occupied periods and before and after the primary occupancy period.

• Ensure that doors opening and closing will not negatively impact airflows

in the washroom. This is relevant where the washroom depends on trans-

fer air.

Advanced IAQ

• Consider application of upper UVGI systems such as recirculating troffer

style systems and passive upper air UVGI.

• Consider using air cleaners to achieve two additional air changes in bath-

rooms.

• Consider using particulate sensors.

• Consider expanding exhaust ductwork grilles to be placed above each

water closet. Where possible, installing grilles in the wall closer to the

fixture and breathing zone is preferred but may not be possible in many

locations.

• Consider increasing exhaust rates to 15% above 62.

• Consider lowering water closet partitions to floor.

• Consider touchless plumbing fixtures.

28 Design Guidance for Education Facilities

Additional Guidance

ASHRAE. 2022. ASHRAE Standard 62.1-2022, Ventilation and acceptable

indoor air quality. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/

technical-resources/bookstore/standards-62-1-62-2.

Staff Training and Documentation 

Organizational Platform

Overview

A dedicated school system-level program for IAQ should be established. A

maintenance and operational sequence must be adopted and strictly followed to

ensure pathogen mitigation efforts and general IAQ objectives are maintained.

Safety and health of all staff and students should be the fundamental basis for all

maintenance schedules. All maintenance procedures, schedules, adjustments,

repairs, upgrades, and replacements should be documented to provide transpar-

ency for all stakeholders.

Stakeholders

The maintenance should be assigned to a skilled, trained, and certified work-

force. The building automation system (BAS), if applicable, should include data

logging and summary reports to identify issues and make energy efficiency

improvements that do not degrade performance. However, all staff should be

aware of the agreed upon operational plans of the facility to ensure the designed

benefits are achieved.

Involved Parties

Design engineers, facility managers, architects, and building operations staff.

Base Minimum

Safety and Risk

All maintenance procedures should be evaluated for safety, given site-specific

equipment and associated safety concerns. Added safety procedures should be in

alliance with OSHA.

Develop a Primary Maintenance Schedule

ASHRAE Standard 62.1, Chapter 8, Operations and Maintenance, provides

the minimum maintenance activity and frequency for ventilation system equip-

ment and associated components.

Advanced IAQ

Develop a Comprehensive IAQ and Risk Mitigation Program

Similar to water quality testing, an air quality testing and monitoring system

should be established. Each jurisdiction should base their IAQ and risk mitigation

program on the goals of “good” air quality in their local region. The program pro-

file should account for outdoor contaminants as well as indoor pollutants. The

Design Guidance for Education Facilities 29

program should establish HVAC upgrades as part of the capital planning effort to

build systems to improve the air quality in the classroom environment. These sys-

tems should consider increased ventilation, better air filtration, better distribution

of clean air, air cleaners, and continuous monitoring.

Develop a Comprehensive Maintenance Schedule

ASHRAE Standard 180 establishes minimum HVAC inspection and mainte-

nance requirements that preserve a system’s ability to achieve acceptable thermal

comfort, energy efficiency, and indoor air quality in new and existing commercial

buildings. All maintenance personnel should consult ASHRAE Standard 180 to

develop a detailed site-specific plan.

Acceptable IAQ parameters should be developed in collaboration with your

HVAC professional and relevant authorities having jurisdiction.

Additional Guidance

ASHRAE. 2018. ASHRAE Standard 180-2018, Standard practice for inspection

and maintenance of commercial building HVAC systems. Peachtree Corners,

GA: ASHRAE. https://www.techstreet.com/ashrae/standards/ashrae-180-

2018?product_id=2016639.

ASHRAE. 2022. ASHRAE Standard 62.1-2022, Ventilation and acceptable

indoor air quality. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/

technical-resources/bookstore/standards-62-1-62-2.

ASHRAE Epidemic Task Force. 2021. Schools & universities. Peachtree Corners,

GA: ASHRAE. https://www.ashrae.org/file%20library/technical%20re-

sources/covid-19/ashrae-reopening-schools-and-universities-c19-guid-

ance.pdf.

NEMI. 2022. Ventilation verification specification. https://www.nemionline.org/

ventilation-verification-specification/.

OSHA. 2022. Personal protective equipment. https://www.osha.gov/personal-pro-

tective-equipment.

UV-C/UVGI in Air Handling Equipment

Overview

UVC/UVGI equipment has been shown to be very effective in deactivating

viruses and other infectious agents. These systems produce light that may be

harmful to occupants, so they should be installed such that they will not affect the

occupants whether being installed inside an air handler, in the upper air zone of

the room, or in a recirculating configuration.

Properly sized and installed UVC/UVGI equipment may act as a supplemental

factor in the room’s clean air delivery, but it is important that it not replace proper

outside air ventilation as defined in ASHRAE Standard 62.1.

UVC/UVGI needs to be serviced regularly to ensure that the bulbs stay clean

and have not been affected by changes in temperature. The expected service life of

many of the bulbs will require regular changes, so access and cost should be con-

30 Design Guidance for Education Facilities

sidered along with the additional heat generated by the lamps themselves. As

more LED technology is developed, it is likely that the cost and maintenance costs

of the equipment will be reduced.

Involved Parties

Design engineers, facility managers, and building operations staff.

Base Minimum

• Consider UV-C/UVGI in spaces that have high occupancy/frequent

changeover where it may not be practical to achieve recommended air

volumes.

• UV-C/UVGI should be designed in coordination with a professional to

ensure the proper level of disinfection is occurring based on the airspeed

and UV-C intensity of airside equipment.

• Provide a UVC fan motor interlock to energize UV-C only when the fan

is operational.

• Provide a UV-C and access door safety interlock. UV-C should de-ener-

gize when door is opened for service.

• Create a dedicated UV-C installation schedule with the following mini-

mum specified requirements:

• AHU tag

• Location

• Peak airflow

• Air velocity

• Cross sectional area

• Distance required

• Distance available

• System type

• UV-C dose @ day 365(µW-sec/cm

)

• UV-C intensity @ day 365(µW/cm

)

• Service considerations should be reviewed on each installation to allow

for proper maintenance.

Advanced IAQ

• Install UVC/UVGI in recirculated air systems.

• Install high air UVGI in higher volume spaces.

Additional Guidance

ASHRAE. 2015. ASHRAE position document on filtration and air cleaning.

Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/file%20library/

about/position%20documents/filtration-and-air-cleaning-pd-feb.2.2021.pdf.

For further resources on UVC use, refer to the following:

• International Ultraviolet Association (IUVA)

• U.S. Environmental Protection Agency (EPA)

• Research Triangle Institute (RTI)

Design Guidance for Education Facilities 31

ASHRAE. 2016. Chapter 17, Ultraviolet lamp systems. ASHRAE handbook—

HVAC systems and equipment. Peachtree Corners, GA: ASHRAE. https://

www.ashrae.org/file%20library/technical%20resources/covid-19/i-

p_s16_ch17.pdf.

ASHRAE. 2019. Chapter 62, Ultraviolet air and surface treatment. ASHRAE

handbook—HVAC applications. Peachtree Corners, GA: ASHRAE. https://

www.ashrae.org/file%20library/technical%20resources/covid-19/i-

p_a19_ch62_uvairandsurfacetreatment.pdf.

ASHRAE. 2020. ASHRAE position document on indoor air quality. Peachtree

Corners, GA:ASHRAE. https://www.ashrae.org/file%20library/about/posi-

tion%20documents/pd_indoor-air-quality-2020-07-01.pdf.

ASHRAE. 2022. ASHRAE positions infectious aerosols. Peachtree Corners, GA:

ASHRAE. https://www.ashrae.org/file%20library/about/position%20docu-

ments/pd_-infectious-aerosols-2022.pdf.

ASHRAE. 2020. ASHRAE Standard 185.1-2020, Method of testing UV-C lights

for use in air-handling units or air ducts to inactivate airborne microorgan-

isms. Peachtree Corners, GA: ASHRAE. https://www.techstreet.com/ashrae/

standards/ashrae-185-1-2020?product_id=2185612.

ASHRAE. 2020. ASHRAE Standard 185.2-2020, Method of testing ultraviolet

lamps for use in HVAC&R units or air ducts to inactivate microorganisms on

irradiated surfaces. Peachtree Corners, GA: ASHRAE. https://www.tech-

street.com/ashrae/standards/ashrae-185-2-2020?product_id=2185696.

Bahnfleth, W.P. 2020. Reducing infectious disease transmission with UVGI.

Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/file%20library/

professional%20development/learning%20portal/instructor-led%20training/

online%20instructor-led/final-4-21-2020-ashrae-one-hour-uvgi-course_se-

cured.pdf.

Illuminating Engineering Society. 2020. Guidance on the use of ultraviolet germi-

cidal irradiation (UVGI) in museum applications. IES WP-1-20. New York:

IES. https://store.ies.org/product/wp-1-20-ies-white-paper-guidance-on-the-

use-of-ultraviolet-germicidal-irradiation-uvgi-in-museum-applications/.

32 Design Guidance for Education Facilities

Medium Priority Tasks

Humidification and Dehumidification Systems

Overview

Consider maintaining relative humidity (rh) at 40% to 60%. Optimal relative

humidity continues to be an area of active research. Dry air below 40% rh has

been shown to:

• Reduce healthy immune system function (respiratory epithelium, skin,

etc.).

• Increase transmission of some airborne viruses and droplets (COVID-19

still being studied).

• Increase survival rate of pathogens.

• Decrease effectiveness of hand hygiene and surface cleaning because of

surface recontamination or disinfectants drying too quickly.

Concerns

If restarting older humidifiers, take care to confirm proper moisture absorption

in the airstream.

Visually inspect humidification and dehumidification devices. Clean and

maintain to limit fouling and microbial growth. Measure relative humidity and

adjust system controls as necessary per ASHRAE Standard 62.1 Table 8-1 (g).

Watch interior spaces to confirm no condensation is occurring, which would

permit mold and moisture issues. Reducing economizer operation is not recom-

mended to improve minimum rh if it means losing negative pressure in rooms or

losing once-through airflow if those strategies are part of the surge plan.

Ensure adequate maintenance capacity and water treatment is available to

safely operate humidifying equipment.

Involved Parties

Design engineers, facility managers, and building operations staff.

Base Minimum

Design Considerations

Indoor relative humidity is a function of seasonal climate and building HVAC.

The range of 40% to 60% rh may reduce contagion and help those who are infected.

Summer classroom design guidelines: 75°F (24°C)/40% to 60% rh. Primary guid-

ance is to design to 50% rh in summer, depending on the classroom system.

During periods of time that the building is both occupied and unoccupied, it is

recommended that maximum humidity levels are addressed to not cause damage

to building materials that may be subject to damage at high humidity levels.

Design Guidance for Education Facilities 33

Consider monitoring the humidity levels in a few classrooms within the build-

ing. Ensure that humidification systems do not generate an increase in particulate

matter.

Advanced IAQ

Design Considerations

Winter classroom design guidelines: 72°F (22°C)/40% to 50% rh. Primary

guidance in winter is 40% to 50% rh via humidifiers/active humidification (central

or local, depending on the classroom/space system). The humidity minimum,

humidifier, and sensor location should be made after consideration of envelope

design due to the potential for condensation within the building envelope.

The levels of 40% rh may be difficult to achieve in northern colder climates

without formation of condensate on glazing or within the building envelope.

Review of the building envelope design is crucial to ensure that damage to the

building envelope will not be created.

Summer classroom design guidelines: 75°F (24°C)/40% to 60% rh.

Energy Efficiency Offset Control Schemes for

Advanced IAQ

Overview

Generalizing for most HVAC systems, with the increase of more ventilation

air, except for economizer mode, it is sufficiently likely to expect higher energy

usage. As advanced air quality centers around maximizing the ventilation air and

disabling demand control ventilation systems, the logical result will be increased

energy to condition the increased outside air being brought into the building in

both the heating and cooling season.

With 8760 hours in a year, the best approach for energy efficiency during the

period of increased ventilation rates is to focus efforts on unoccupied times. In

some schools, this will be 6000+ hours per year. The energy efficiency programs

put in place should not diminish the indoor air quality by adverse ventilation

scheme changes.

Involved Parties

Design engineers, facility managers, building operations staff, and building

controls staff.

Base Minimum

Building management system with all HVAC and lighting integrated.

• Focus on unoccupied hours and adjusting sequences to move to minimal

energy usage during unoccupied times.

• Air cleaners for occupied mode operations in lieu of increasing ventila-

tion rates.

34 Design Guidance for Education Facilities

• Wider temperature bandwidth ranges for occupied zones 5% outside of

ASHRAE Standard 62.1.

• Adjust the discharge temperatures from central air handling stations

based on the specific climate zone within 2% of ASHRAE Standard 62.1.

Advanced IAQ

• Building management system with all HVAC, plumbing, equipment, and

lighting integrated.

• Focus on unoccupied hours and adjusting sequences to move to minimal

energy usage during unoccupied times.

• Air cleaners for occupied mode operations in lieu of increasing ventila-

tion rates.

• Wider temperature bandwidth ranges for occupied zones 10% outside of

ASHRAE Standard 62.1.

• Adjust the discharge temperatures from central air handling stations

based on the specific climate zone within 3% of ASHRAE Standard 62.1.

• Enhanced air quality mode can be implemented into control systems.

This mode will revise CO

set points, run times, and system operation in

accordance with enhanced air quality parameters. This mode can be

quickly activated with one button during periods of elevated pathogen

risk. Alarms can be configured to occur on a regular basis to ensure that

the mode is not left on beyond the intended time frame.

• Incorporate exhaust air heat recovery.

Additional Guidance

ASHRAE. ASHRAE advanced energy design guide—Achieving zero energy

series. Peachtree Corners, GA: ASHRAE. https://www.ashrae.org/technical-

resources/aedgs/zero-energy-aedg-free-download.

ASHRAE. 2021. ASHRAE Guideline 36-2021, High performance sequences of

operation for HVAC systems. Peachtree Corners, GA: ASHRAE. https://

www.techstreet.com/ashrae/standards/guideline-36-2021-high-performance-

sequences-of-operation-for-hvac-systems?product_id=2229690.

ASHRAE Epidemic Task Force. 2022. Building readiness. Peachtree Corners,

GA: ASHRAE. https://www.ashrae.org/file%20library/technical%20re-

sources/covid-19/ashrae-building-readiness.pdf.

Operable Windows

Overview

Any operable window usage for natural ventilation needs to be addressed and

agreed upon with your HVAC professional. Operable windows may be used to

supplement mechanical ventilation, or when no mechanical ventilation exists, nat-

ural ventilation should be considered with an understanding of limitations. While

Design Guidance for Education Facilities 35

operable windows by themselves will not provide consistent ventilation rates,

there are steps that may be added to improve the ventilation consistency.

Natural ventilation requires either an automated system that is maintained by

facilities or a highly trained staff to consistently open and close windows during

scheduled times.

Concerns

• Security

•Noise

• Consistency—Natural ventilation rates are dependent on several factors

including pressure and temperature differentials.

• Seasonal Consistency—Occupants will be inclined to close the windows

during seasonal high and low temperature fluctuations.

• Contamination

• Air Distribution

• Humidity

The best operational control of window opening criteria is to use a BMS with

dew point criteria if relevant to local climatic conditions. There should also be

provisions for the individual classrooms to have alarms or alerts to close the win-

dows based on dew point or other local criteria. In the absence of these automated

controls, please follow the instructions below if the school system is allowing the

teachers to open their windows based on their own personal preference.

Involved Parties

Design engineers, facility managers, architects, and building operations staff.

Base Minimum

Natural Ventilation

Natural ventilation should be performed in accordance with the corresponding

section within the adopted mechanical code or regional requirements—UMC Sec-

tion 402.2 or 402 IMC.

Negative Pressure

To provide a more consistent ventilation rate, the classroom can be operated at

a negative pressure, relative to the outside. With common windows open, either

manual or automatic, an outside air rate can be introduced. If the classroom is

independent of other structures, the ventilation rate can be consistent if the same

number of windows are opened during operation. If the classroom is attached to

other buildings, the exhaust will pull air from outside or from adjacent rooms

based on the path of least resistance. A negative pressure can be introduced by

adding exhaust fans or taking advantage of existing exhaust fans depending on

location.

Develop Manual Window Opening Guideline

Based on regional climate and safety considerations, the guide below may be

used as a starting point with school officials.

36 Design Guidance for Education Facilities

Classroom windows may be manually opened during class per the following

general guidelines during reopening operations.

• Outside temperatures between 50ºF (10°C) and 90°F (32°C): Windows

can be opened.

• HVAC units that are controlled by temperature will automatically

adjust. At lower temperatures, there will be excess running of units

during occupied hours.

• Close windows during unoccupied hours and let HVAC systems run

per schedule.

• Outside temperatures between 35°F (1.7°C) and 50°F (10°C): Windows

may be opened for 15 minutes each hour during occupied times.

• Close windows when unoccupied.

• If the classroom starts to feel too cold, adjust to 5–10 minutes open

per hour.

• Outside temperatures below 35°F (1.7°C):

• Windows can be opened at 50% for 15 minutes every 2 hours.

• If classrooms have no fresh air, open windows at 50% every 15 min-

utes every hour. Monitor any water piping and sprinkler piping for

freeze potential.

• If the classroom starts to feel too cold, adjust to 5–10 minutes open

per hour.

• Classroom windows MUST be closed during unoccupied hours and

weekends.

• Close windows if it is raining or is a humid day to prevent any mold

growth.

Advanced IAQ

• Automated natural ventilation systems may be considered to provide con-

sistent open times. Advanced systems may be linked to a variety of

indoor and outdoor climate sensors.

• Occupant indicators may be provided to indicate to occupants that the

windows should be open.

• Security indicators may be useful to ensure that windows are closed. This

may be accomplished with the addition of end switches on the windows

to verify that they are closed.