Arc Re-Entry Guide
Summary
Arc Re-Entry is a set of tools to support a safe, confident return to work, school, and play.
Re-Entry builds on Arc’s long-standing performance categories with new capabilities to assess
facility management, evaluate occupant experience, and measure indoor quality. With Arc
Re-Entry:
1) Any project can collect, manage, and score infectious disease-related information about
facility management, occupant experience, and indoor air quality.
2) Arc Essential subscribers can analyze performance and create customized reports for
projects and portfolios.
Consistent with Arc’s broader mission, these tools can be used to create feedback loops
between management intent and real world outcomes. As always, Arc will use this information
to recognize leadership and celebrate people and organizations delivering superior real world
performance.
Arc Re-Entry:● Supports the iterative assessment of facility management and occupant experience -not the health of individual occupants or infection risk.
● Aggregates and interprets information reported by facility managers and occupants -the information provided is only as useful as the quality of the incoming data and theunderlying scientific literature used to interpret it.
● Data are subject to automated quality tests -- not document review.
Recommended citation: Pyke, C.R. and K. Koh (2022) Guide to Arc Re-Entry (version 1.3). Arc Skoru, Washington, DC,
URL: https://www.arcskoru.com/sites/default/files/Arc%20Guide%20to%20Re-Entry.pdf

2

Contents
Summary

2

Quick Start

4

Introduction

5

From Performance to Re-Entry
Re-Entry Comprehensiveness Score

6
9Facility Management
Referencing LEED, WELL, and RESET
Sample Facility Management Response
Examples of Relevant Public Health Authorities
Facility Management Comprehensiveness Score

10
12
12
13
14

Occupant Observations
Sample Occupant Observation Responses
Occupant Observations Comprehensiveness Score

15
16
18

Indoor Air Quality
Sample IAQ Measurements
IAQ Comprehensiveness Score
Tips for Entering Spatial Data Coverage
Tips for Entering Temporal Data Coverage

19
20
21
22
24

Analysis27

Conclusion

29

Contact

29

About Arc

29

3

Quick Start
Getting started with Arc Re-Entry is easy:
1. Login to Arc, access an existing project or create a new one. Users must have a LEED
Online or USGBC.org site user account. New users can create one for free.
2. After logging in, select a project and find the Leadership tab on the left side. Selectthe Re-Entry category. The tab provides three options:○

Send Facility Manager survey○

Send Occupant Observation survey○

Add IAQ data

3. After sending surveys or adding data, you can review information about eachcategory in the Meters & Survey section. Each component has a Data, Details, andDocumentation tab. The Details tabs provide a summary of responses, and charts toview performance over time.
If you need support, please reach out to the Arc team for help.

4

Introduction
The COVID-19 pandemic has had a sweeping impact on the global property industry. Many
authorities and academic researchers predicted a global pandemic and described its
potential consequences. However, it remains difficult to fully envision the scope of its impact on
our everyday lives with emerging variants of concern. It has changed so many aspects of how
we live, work, and play. After months of lockdowns and quarantine, many communities areseeking to establish a new normal. This means returning to workplaces, schools, and places ofrecreation, public assembly, and worship.
In the last couple years, we have learned a lot about how to keep ourselves safe during thisre-entry, enough to know that it will require a thoughtful, coordinated, and sustained effort.
Along with vaccines and personal protective equipment (PPE), we must create a layered“defense in depth” to break the chain of infection. This means keeping people separated,cleaning and sanitizing surfaces and spaces, circulating and filtering air, and much more.
The good news is that we only need one break in the chain of infection to stop the spread of
disease. The bad news is that we need to create those breaks all the time, everywhere. This is achallenge of professionals who design, build, and operate our built environment. We are very
good at creating exceptional projects that, at times, deliver exceptional performance.
However, we are not so good at delivering consistent performance everywhere, all the time.
This reflects the reality of managing buildings and places. These are complex engineered
systems, often unique in design, and subject to all manner of operating conditions andoccupant behavior.
While we cannot expect to be perfect, we can create systems to provide situationalawareness, offer transparency for stakeholders, and use information to improve performanceover time. This is our aspiration for Arc Re-Entry: a set of tools that help facility and portfolio
managers organize and communicate their infection control plans and learn from occupant
observations and measured indoor air quality. We envision that these tools will be used
repeatedly to improve performance over time as we learn more about what works to control
the spread of infectious disease.
Arc Re-Entry provides tools for a marathon, not a sprint. With the possibility of more variants,
there is no telling how long the pandemic will last or what forms it may take in the future. To that
end, we have worked to get started quickly with simple, practical features that we believe canprovide value over time. We are also committed to improving these tools in the months ahead5to meet this important moment and help us safely and confidently re-enter the places where
we live, work, and play.

From Performance to Re-Entry
Arc measures and scores the operational performance of spaces, buildings and places. Arc
scores distinguish leaders and help make real world performance measurement a ubiquitouspart of green building practice.
The Arc Performance Score provides a weighted combination of information in five categories,
including:
●
●
●
●
●

Energy and Emissions
Water
Waste
Transportation
Human Experience

The Arc Performance Score powers LEED for Operations and Maintenance v4.1 and LEED
Recertification.
The Arc Human Experience category collects and scores information on two equally weighted
sub-categories:●●

Perceived occupantsatisfaction
Measured indoor air
quality, including CO2
and TVOC

Arc Re-Entry expands andadapts tools and metrics in Arc
to support the management of
infectious disease transmission1.
Arc Re-Entry is focused on the management of infectious disease, specifically COVID-19. Management
recommendation would be significantly different for other aspects of health and well-being. Relevant
resources for other issues include the International WELL Building Institute, the Green Health Partnership,
and peer reviewed literature (e.g., Worden et al. 2020).
1

6

Arc Re-Entry can complement existing building rating systems or be used as a stand-alone tool.
Figure 1. Illustration of Arc Re-Entry support components, including data collection for facility
management policies and procedures, occupant observations, and measured indoor air
quality.
.
Figure 2. Arc Re-Entry can provide a starting point for health and green building rating systems,
including the WELL Health-Safety Rating and LEED v4.1 O+M.

Arc
Re-Entry leverages existing capabilities, including Arc’s long-standing occupant satisfaction
survey and requirements for indoor air quality measurement. These are supplemented by two
new surveys and an expanded set of indoor air quality metrics.
Figure 3. Arc Re-Entry data areentered in a new category under
Meters & Surveys tab.

theAdditionally, Arc Re-Entry allows
managers to document and shareconnections with relevant publicauthorities. This makes it easier towhy facility managers haveselected a given set of infection
strategies. In turn, Arc Re-Entry helps
managers evaluate how
occupants experience theirhealthexplaincontrol

7management strategies and how they may be reflected in measured indoor air quality. This
provides the basis for repeatable feedback loops between management intent and measured
outcomes.
New components introduced with Arc Re-Entry include:●

New facility management survey: The new facility manager survey requests information
about infection control policies and procedures and alignment with relevant authorities(e.g., the World Health Organization, etc.).

●

New surveys for occupant observations: The new occupant observation surveys include
long-standing questions about occupant satisfaction, as well as new opportunities toshare experiences with disease control-related features, such as signage or access to
disinfecting products.

●

New indoor air quality metrics: The new indoor air quality metrics expand on Arc’s
existing set of measurements and change interpretations to align with disease control
objectives. This means that CO2 and TVOC are found in both the long-standing Human
Experience category, as well as Re-Entry. However, the metrics have changed fromconcentrations of pollutants to the fraction of time above a threshold. Additionally, the
new section requests information about relative humidity and particulate matter;aspects of air quality linked to disease transmission or susceptibility. All of these IAQ
factors can be measured with either portable instruments or sensor networks (e.g., Arc
partners arbnco and QLEAR).

All together, the new Re-Entry elements include 120 variables, including simple binary
responses, measurements, andsupporting documentation.
Information about each variable isavailable through Arc Re-Entry Meters
spreadsheet.
Figure 4. Arc Re-Entry supports therepeated evaluation of infection
control strategies. The bold elements
explicitly addressed in the tool. The
elements, Implementation andAnalysis, are taken outside of the tool.

are
gray

Iterative Analysis

8Arc Re-Entry is not a “once-and-done” assessment. Arc Re-Entry is designed to be an iterativeevaluation of the comprehensiveness of infection control practices. It is designed to provide
transparency about management intent and support a comparison between intentions andoccupant experiences and measured outcomes. Fundamentally, the power of the tool is in its
repeated use. This means that it does not have a clearly defined stopping or end-point. Rather,it should be used as long as it is needed to improve management and build confidence forre-entry and on-going operations.

Re-Entry Comprehensiveness Score
Arc uses scores to interpret and integrate performance measurements. Arc scores for energy,
water, and waste are benchmarked using a Reference Set. Arc scores for transportation andhuman experience are based on mathematical functions. Neither of these approaches isappropriate to interpret re-entry-related information. Benchmarks do not exist, and research toestablish quantitative guidelines is still preliminary and, in some cases, conflicting. However,there is still a need to aggregate and interpret information for facility managers andstakeholders. Consequently, Arc calculates a Re-Entry Comprehensiveness Score (“CompScore”).
The Comp Score is a 0 to 100% measure of the fraction of positive responses compared to thetotal number of potential positive responses. The Comp Score is average of three components:
facility management, occupant observations, and indoor air quality. The Comp Score should
be interpreted as a simple indicator of the number of self-reported actions implemented by thefacility and scope of occupant or measured indoor quality data describing conditions in a
facility:●Comp Score = 0: The facility reports no disease control practices and procedures,
occupants uniformly observe no disease control features, and no indoor air quality data
are collected.

●

Comp Score = 100: The facility reports on all requested disease control practices andprocedures. The facility managers provide supporting documentation for each element.
Occupants uniformly observe disease control features. Indoor air quality information isconsistently collected throughout the facility.

Comp Scores between 0 and 100 indicate a simple proportion of potential affirmative
responses. There is no weighting beyond the equal proportions assigned to facility
management, occupant observations, and indoor air quality.

9In some cases, a response may not be applicable to a given facility. When a user selects “notapplicable”, the question is removed from both the numerator and the denominator of theComp Score equation. For example, a question about increasing outdoor air supply might be
not applicable for an open air venue. The absence of this response does not “count against”
the Comp Score.
Note: There is no way for Arc to independently verify the applicability of responses at this time,and users should consider this when evaluating Comp Scores. Third-parties, including theInternational WELL Building Institute and RESET may provide third-party verification, such as
on-site or data audits.
It is also important to note that Comp Scores are not a direct indicator of health or the risk of
disease transmission. They are exactly what the name implies, an indicator of the relative
comprehensiveness of management practices, occupant observations, and indoor air quality
measurements.
Over time, it may be possible to use Comp Scores to evaluate the effectiveness of different
combinations of facility management to disease transmission. However, this will necessarily be a
retrospective analysis, possible only after re-entry has taken place (e.g., does a higher Comp
Score result in a lower risk of infection). It is not possible to conduct this type of analysis until
people have returned to different types of spaces, and we have a distribution of responses (i.e.,some have or have not gotten sick). Until then, we can attempt to consistently implement Best
Practices and measure results.

Facility Management
Facility managers cannot stop the spread of infectious disease on their own. They do play animportant role in creating conditions that may reduce the rate or likelihood of diseasetransmission. They can use management interventions to break the chain of infection. Thismeans limiting the introduction of virus-carrying occupants, reducing the likelihood of spreadthrough the air and on surfaces, and facilitating the use of barriers and personal protective
equipment to prevent exposure.
Arc Re-Entry uses a survey to ask facility managers about:
1. Infection control policies and procedures.
2. Authorities used to inform or align the facility’s policies and procedures.
3. Specific elements included in the facility’s policies and procedures.

10Each element includes a yes or no question and the opportunity to provide supporting
information as a hyperlink or file. The facility managers survey asks facility managers to identify
a number of specific strategies recommended by some authorities, including:●

Infection control policy or procedure: This is a written plan applicable to the facility
guiding effort to reduce the spread of infectious disease (e.g., the Hines Return toOccupancy Plan or the BXP Health Security Plan).

●

Alignment with public health authorities: This question documents references oralignment with published guidance from government, academic, or non-profit sources,
such as U.S. Centers for Disease Control Interim Guidance for Businesses and Employers
Responding to Coronavirus Disease 2019, ASHRAE Guidance for Building Operations
during the COVID-19 Pandemic, BOMA Getting Back to Work: Preparing Buildings for
Re-Entry, USGBC LEED Safety First: Re-Enter Your Workspace Pilot Credit, or IWBI’s WELL
Health-Safety Rating. Alignment is interpreted as the intent for building management tosubstantially reflect material aspects of the referenced authority.

●

Communications and signage: This question addresses signage and othercommunications intended to reduce disease transmission, such as advice regarding
hand washing, social distancing, and personal protective equipment wearing.

●

Occupant screening: This question addresses policies, procedures, or practices intended
to prevent disease carrying people from entering the facility. This may take the form ofhealth checks, temperature screening, or other measures, such as recommendations in
the U.S. Centers for Disease Control COVID-19 Employer Information for Office Buildings.

●

Paid sick leave: This question addresses potential incentives or disincentives for facility
management staff and contractors to work while sick. Paid sick leave has been shown
to reduce the likelihood of working while sick and, in turn, spreading disease (see Pitchler
et al. 2020).

●

Social distancing: This question addresses interventions to promote social distancing,including physical barriers, seating, workstation design, and other strategies. Relevant
guidance varies by facility type, such as the United Kingdom Department of Digital,
Culture, Media, and Sport, Guidance for providers of outdoor facilities on the phased
return of sport and recreation in England (December 2021).

●

Ventilation and outdoor air supply: Some authorities have recommended increasing
ventilation rates and the supply of outdoor air. Strategies to increase outdoor air supply

11

vary, and they could be interpreted as increasing daily supply through 24/7 operations
or increasing average air flow.
Some facilities may also increase fresh air supply by encouraging the use of operable
windows. If selected, supporting documentation should explain specific strategies
applied to this facility. Relevant research includes findings such as Li et al. (2020) andguidance such as ASHRAE’s Position Document on Infectious Aerosols and the RESET
standard (e.g., requirements for real time tracking).
●

Air filtration: Some authorities have recommended enhancing HVAC filtration byincorporating HEPA filters or UVGI systems . Under some circumstances, this may reduce
disease transmission. Guidance varies for the type and level of filtration recommended.
If selected, supporting documentation should explain the type of filtration used by thefacility and relative contextual information about HVAC design or operations. Relevant
research includes Bolashikov and Melikov (2009) and guidance includes CIBSE Guidanceon Ventilation during COVID-19 and the National Air Filtration Association. Projects may
consider RESET Core & Shell or Commercial Interior guidance for the measurement andmanagement of indoor and outdoor airborne particulates. More information on HEPA
filters and UVGI can be found here.

●

Elevator operations: Some authorities have identified elevators as a potential high riskarea. Consequently, they have provided guidance for rider density, waiting, andcleaning. Relevant research includes Kandel et al (2014) and COVID-19 Precautions forMulti-unit Residential Buildings (2020) published by the Canadian National Collaborating
Centre for Environmental Health.

Referencing LEED, WELL, and RESET
Facility and venue managers may elect to use elements of the LEED or WELL rating systems to
inform their policies and procedures. They can reference rating systems or individual credits
as authorities. This reflects that these credits are based on a specific interpretation ofunderlying research and guidance. This makes them practical tools to guide facility
management. Examples of relevant authorities include:●

U.S. Green Building Council: LEED credits, including Safety First: Re-Enter Your
Workspace and Safety First: Cleaning and Disinfecting Your Space●International WELL Building Institute: Strategies referenced in the forthcoming WELL

12

Health-Safety Rating●

RESET: Strategies related to indoor and outdoor air quality measurement andmanagement in the RESET Air Standard 2.0.

These and other rating systems are providing timely, best practice-based guidance for facility
managers and occupants.

Sample Facility Management Response
A facility management might respond to the survey with the following:●

Does the facility have an infection control policy or procedure?
○ Yes, file upload: 123_Main_St_Infection_Control_Plan_Section2.pdf●

Is the policy or procedure aligned with one or more authorities?
○ Yes, file uploads: U.S. Centers for Disease Control Guidelines, LEED Safety First:
Re-Enter Your Workspace Pilot Credit●

Does the policy or procedures include specific strategies for:○

Disease control communication and signage■ Yes, file upload: 23_Main_St_signage_photo.jpg○

Clean and disinfection to address disease transmission■ Yes, hyperlink: LEED Safety First: Clean and Disinfect Your Space○

Occupant screening■ Yes, file upload: 123_Main_St_occupant_screening_policy.pdf○

Paid sick leave for staff and contractors■ Yes, file upload: 123_Main_St_employee_policy.pdf○

Social distancing (e.g., floor markers, barriers)?
■ Yes, file upload: 123_Main_St_Infection_Control_Plan_Section1.pdf○

Outdoor air supply■ Yes, file upload: 123_Main_St_Infection_Control_Plan_Section2.pdf

13

○Ventilation rates■ Yes, file upload: 123_Main_St_Infection_Control_Plan_Section3.pdf○

HVAC filtration■ Yes, file upload: 123_Main_St_Infection_Control_Plan_Section4.pdf○

Elevator management (e.g., limiting occupancy, targeted cleaning)■ Yes, file upload: 123_Main_St_Infection_Control_Plan_Section5.pdf

Examples of Relevant Public Health Authorities
Facility managers may be required or elect to align their infection control practices with any
number of authorities. This may include government agencies, academic institutions, or
non-governmental organizations. At this time, the specific combination of applicable
authorities is likely to vary by location, type of facility, and special designations (e.g., essential
vs. non-essential activities). This means that Arc cannot recommend a specific set of
authorities for any given facility. It will maintain examples of authorities, and, when possible, itwill share lists of authorities reported by Re-Entry users.
Examples of authorities that may be referenced by facility managers include:●

Guidance for COVID-19 (U.S. Center for Disease Control) [Link]●

5 Ways to Optimize Buildings for COVID-19 Prevention (Center for Active Design) [Link]●

COVID-19 Disinfectant List (US Environmental Protection Agency) [Link]●

Position Paper on Airborne Infectious Disease (ASHRAE) [Link]●

Getting your workplace ready for COVID-19 (World Health Organization) [Link]●

Coronavirus Resource Center (BOMA International) [Link]●

Coronavirus Resources (BOMA Canada) [Link]●

REHVA COVID-19 guidance document, April 3, 2020 (Federal of European Heating
Ventilation and Air Conditioning Associations) [Link]●

Coronavirus (COVID-19) Advice (CIBSE) [Link]

Arc can deliver these surveys and track responses within a specified time period. Users may
select the interval that surveys are repeated. The default recommendation is monthly or upon asignificant change in operations.
14

These new meters are available as API end-points for Arc partners. Review the Arc Integration
Guide for more information.

Facility Management Comprehensiveness Score
Arc will generate a Facility Management Comprehensiveness Score (“Comp Score”). The
Comp Score will reflect a 0 to 100% measure of the fraction of positive responses compared tothe total number of potential positive responses.
The Facility Management component has 37 data elements, including boolean responses (i.e.,yes, no) and opportunities to provide a supporting link or file.
A Facility Management Comp Score of 100% indicates that a facility manager provided a“yes” answer for each question, along with a supporting link or file. Multiple file uploads areallowed, but they do not increase the Comp Score.
By default, the Facility Management Comp Score is based on the most recent response to the
Facility Management Survey. The most recent response supersedes all previous responses forthe purposes of the Comp Score. Arc maintains a record of previous responses to eachapplicable question.
In contrast to other components, responses to the Facility Management Survey are consideredvalid for an indefinite period of time (i.e., no time limit or moving window is applied to thesedata).
Table 1. Comparison of the existing Arc survey with the Re-Entry Facility Manager Survey.
Existing Arc Facility
Management Survey
None

Re-Entry Facility
Manager Survey
Operating plans, policies, and procedures
Alignment with public health authorities
Plan or policies includes strategies for:● Occupant communication and signage● Cleaning and disinfection● Occupant screening● Social distancing● HVAC management● Elevator management

15

Occupant Observations
Arc has long-standing tools to understand occupant satisfaction. This includes an email-based
survey asking occupants about their experience. The survey dynamically expands to ask formore information about reasons for satisfaction or dissatisfaction. This simple occupantsatisfaction instrument provides the foundation for an expanded set of occupant observations
to support re-entry.
The goal is to support an iterative feedback loop between the intentions of facility
management and the experience of occupants. To this end, occupant observations becomea source of “ground truth” to confirm expectations or identify needs for management action.
New re-entry elements include:●●●●

Observations about the presence of disease control signage
Observations about occupant screening, such as temperature checks
Perception of proper PPE wearing
Perception of social distance

Users are asked to evaluate each on a 5-point Likert scale:

Each element is associated with a free text box which provides opportunities to suggest
opportunities for improvement if the response is less than “always”.
Users can select one of three types of surveys to fit their situation:●●●

Base building only
Tenant space only
Whole building

16This selection changes the introduction to the survey to request observations from the selected
scope. Each option asks the respondent to reflect on a different area, such as only common
areas (base building) or their organization’s workspace (tenant space).
The selected survey can be targeted at specific groups, including:●●●

Facility management team or crew
Tenants or other habitual occupants
Visitors

Information about scope and groups is stored with responses to support follow up analysis.
Individual survey responses are anonymous with no identifiable information (i.e., an Arc user
can see the scope and group, but not the identity of individuals).
Arc will deliver these occupant observation surveys and track responses within a specified time
period. Users may select the interval that surveys are repeated. The default recommendation is
weekly. Arc can also provide project-specific links that can be distributed through other email
or social media platforms.
The occupant survey end-points can also be directly populated by Arc’s integration partners
during the Arc API.

Sample Occupant Observation Responses
The project manager makes two selections to control the framing and distribution of theoccupant survey. First, the manager selects the scope of the response (base building, tenant
space, or whole building). Second, the manager selects the group (facility management
team/crew, tenants/vendors, or visitors).
An occupant might respond to the survey with:
1. Occupant satisfaction17

a. If satisfied, select the options that significantly enhance your satisfaction:
Thermal comfort

Light

Cleanliness

Daylight

Views

Air quality

Sound

Privacyb. If dissatisfied, select the options that significantly reduce your satisfaction:
Dirty

Glare

SmellyPrivacy

StuffyHumid

Acoustics

DraftyHot

Bright

Cold

Views

Dark

Sound

2. Observations about the presence of disease control signagei.

If not always, where is disease control signage missing?
1. 7th floor kitchen
Observations about occupant screening, such as temperature checks18

3. Do you have access to handwashing and disinfection?

4. Does the facility support social distancing?

5. Do people maintain social distance?

a. If not always, where is social distance not maintained?
i.
Elevator lobby

Occupant Observations Comprehensiveness Score
Arc will generate an Occupant Observations Comprehensiveness Score (“Comp Score”). The
Comp Score will reflect a 0 to 100% measure of the fraction of positive responses compared tothe total number of responses.
For Facility Management, this means that there are six scored data elements (questions), eachwith a maximum value of 4 on a 5-point 0-to-4 scale. This means that the most comprehensive
possible is an average of “always” (a value of 4) for all six items -- a total potential value of 24.
As a default, survey responses are aggregated over a rolling 31-day window and compared tothis maximum value on a scale of 0 to 100%.

19

This means that a facility with uniformly positive responses for all six indicators will receive ascore of 100% for a 30 day period. Data older than 30 days do not contribute to the Occupant
Observations Comp Score.
Note: The occupant observation survey also contains a seventh question, “Do you feel
protected from infectious disease in this facility?”. Responses to this high level question can
inform management. However, they are not directly related to comprehensiveness, and they
are not scored.
Table 2. Comparison of the existing Arc occupant survey with the Re-entry occupant
observation survey.
Existing Arc
Occupant Survey
Occupant satisfaction plus:● If satisfied, source of satisfaction● If dissatisfied, source of dissatisfaction

Re-Entry
Occupant Survey
Existing Arc occupant survey plus additional criteria:
Disease control signage● Present in the common areas● Present in my workspace
Presence of occupant screening● Present in the common areas● Present in my workspace
Access to handwashing and disinfection● Access in common areas● Access in my workspace

Indoor Air Quality
Measurements of indoor air quality provide proxy measures for factors believed to be
associated with disease transmission. It is important to note that none of the measurements
identified below provide direct information about infectious agents. Rather, they describe
proxies for conditions identified by scientific literature.
Measurements and interpretations include:●

Relative humidity: Relative humidity between approximately 40 and 60% has beencorrelated with reduced disease transmission. Recent reviews such as Wang et al. (2021)
and Marr et al. (2019) summarize the literature.

20●

CO2 concentration: High indoor CO2 concentrations indicate inadequate ventilation or
crowding. Building standards (e.g., ASHRAE 62, EN 16798-1) have consistently sought toencourage greater ventilation to dilute indoor pollutants and pathogens. High CO2
concentration levels have also been correlated with reduced cognitive performanceand alertness. Recent reviews such as Azuma et al. (2018) summarize the literature.

●

TVOC concentration: TVOC concentrations are not directly related to diseasetransmission. They are included here, because they may provide information about
excessive applications of cleaning products and/or inadequate ventilation. Reviews by
the US Environmental Protection Agency and Lawrence Berkeley National Laboratory
provide more information.

●

Particulate matter concentration: The presence of relatively high concentrations ofparticulates may indicate inadequate ventilation or filtration. There is limited evidence
that particulate matter concentrations may be related to the rate of viral spread under
specific circumstances (e.g., Setti et al. 2020 based on data from Northern Italy). Highambient particulate concentrations have been linked to greater incidence of chronic
respiratory diseases such as COPD and asthma, and a host of other health issues. The
respiratory conditions may in turn exacerbate the susceptibility to, and impact of,
COVID-19 on individuals.

Each metric will be assessed to determine the fraction of occupied space and time coveredby measurements. In turn, these data are interpreted to estimate the fraction of occupied
hours when conditions are in the good, acceptable, or “investigate” range.

IAQ Measurement Strategies
The effective measurement of IAQ is not as easy as walking around with a sensor or sticking amonitor on the wall. Generating relevant, representative data requires a systematic,
hypothesis-driven measurement strategy. There is targeted guidance for the measurement of
CO2 and PM2.5:● Re-Entry: Guide for CO2 Measurement● Re-Entry: Guide for PM2.5 Measurement
More information and training is available for both of these resources, including YouTube videos
and Education @ USGBC courses:● USGBC Course: CO2 and PM2.5 Guides for Schools in Arc Re-Entry● Youtube: Measuring Indoor Air Quality in Schools

21Below is an example of IAQ measurement thresholds for floor area coverage in a school:

IAQ measurement covering<25% of school floor area

IAQ measurement covering
approximately 50% of school
floor area

IAQ measurement covering
approximately >90% ofschool floor area

Sample IAQ Measurements
Projects may have any combination of IAQ measurements. The following example illustrates
information that may be provided for a project with relative humidity (RH) and carbon dioxide.
Relative humidity
Spatial coverage● RH is measured by stationary, in situ sensors for each HVAC zone
● The spatial coverage is estimated at 100% for the period
Temporal coverage● RH is measured by in situ sensors for each HVAC zone at 5 min intervals● The facility HVAC service operates 60 hours.
● There is at least one RH measurement per zone for all 60 hours● The temporal coverage is estimated at 100% for the period
Performance
22

●
●

RH data ranged from 41% to 58% across all zones and all measurements during
operating hours.
The performance value is 100% in “good” status, 0% in “warning”, and 0% in“investigate”.

Carbon dioxide
Spatial coverage● CO2 is measured by hand-held sensors in 10 out of 100 rooms or enclosed spaces.
● The spatial coverage is estimated at 10%.
Temporal coverage● CO2 measurements occurred over 2 hours during the period● The facility operates 60 hours.
● The temporal coverage is estimated at 3% for the period
Performance● CO2 measurements ranged from 500 ppm to 1,300 ppm.
● The performance value is 50% “good” (≲750 ppm), 30% in “warning” (750-1000 ppm),
and 20% in “investigate” (>1,000 ppm).
The other variables follow a similar pattern.

IAQ Comprehensiveness Score
Arc will generate an IAQ Comprehensiveness Score (“Comp Score”). The Comp Score willreflect a 0 to 100% measure based on spatial coverage (floor area, rooms, or HVAC zones),
temporal coverage (operating hours), and performance (time in “good” range). Each of thesefactors has a maximum value of 100, so the maximum value per measurement is 300. This isrepeated across all six measurements (relative humidity, CO2, TVOC, PM1, PM2.5, and PM10).
A few details about how this is computed:
Spatial coverage indicates the fraction of the project covered by each type of sensor. Users
should assume that an individual sensor covers approximately 500 square meters (5,280 squarefeet) (RESET Air Standard for Commercial Interiors) or following guidance from their vendor or
product manufacturer (e.g., arbnco Best Practice Guide). While sensor coverage will differ
based on building layouts and installation practicalities, projects should aim for the smallest
effective coverage area of a sensor, and the coverage area of a single sensor should not23

exceed 500 m2. For example, at least one sensor in each HVAC zone or enclosed room could
suffice for adequate coverage, provided those zones or enclosed rooms are smaller than 500
m2 each. .
As examples:●●●

Measurements from one relative humidity sensor covering 500 m2 in a 5,000 square meter
open space would be presumed and documented to provide a coverage of 10% (500m2 / 5000 m2).
Estimate an effective radius around each sensor and derive the covered area based on
manufacturer or vendor guidance (e.g., arbnco Best Practice Guide).
Follow and reference guidance from a third-party standard, such the RESET Air Standard
2.0 for the design and operation of monitoring networks.

Another strategy would be to use in-duct or air distribution system-based measurements. Thesemay provide an efficient way to cover large fractions of a facility. In this case, coverage isbased on the floor area covered by the air distribution system:●

Air quality can be monitored within the mechanical system. communicating the qualityof the air being delivered by landlords and operators to occupants. An in-duct strategy
should ensure that sensors are installed on supply air ducts and cover a combined floorarea equivalent to no less than 30% of the building area (RESET Air Standard for Core &Shell).

Arc assumes that coverage continues from the last reported value through the present unless
this value is changed due to reorganization of space or sensor layouts. Arc combines values asan average of daily values to provide an estimate for a given time period.

Tips for Entering Spatial Data Coverage
Some users may not be able to provide a quantitative estimate of spatial data coverage.
We know that there are many potentially confounding factors and unknowns (e.g., the area
covered by any given sensor). It is important to remember that the purpose is to provide arough estimate of the fraction occupied space associated with each measurement (i.e., areyou covering a small fraction of the area, most of the space, or all of the space).
If a quantitative estimate is not possible, users may estimate coverage and enter thefollowing values:●

Low Coverage: <25% of occupied space is associated with measurements24○Enter 25% for the applicable date range●

Medium Coverage: 25%-75% of occupied space is associated with measurements○ Enter 50% for the applicable date range●

High Coverage: >75% of occupied space is associated with measurements○ Enter 100% for the applicable date range

Describe your estimate with a piece of document. This can be a simple note explaining yourrationale.
Temporal coverage indicates the fraction of time covered by IAQ measurements during thelast 30 days. For Arc, a time period is “covered” if at least one measurement is taken during theperiod in a project.
For the purpose of infection control, we are assuming 24/7 operations and 1 hour as afundamental unit of temporal coverage (a.k.a., freshness period for measurements).
Consequently, temporal coverage is defined as the percentage of hours within a period thathave one or more readings for a given parameter. Additional measurements during a given
period do not increase coverage (i.e., temporal coverage has a maximum value of 100%
which is satisfied by at least one reading each hour). This means that 1 day has a maximum of
24 readings that will count towards temporal coverage.
As an example, one measurement taken during a 1-year period would provide a coverage of
0.01% (1/8760); presuming 24/7 operations. Considerations for the calculation include
measurement rate (interval between observations) and reporting interval (period over whichmeasurements are aggregated and sent to Arc).
A high measurement rate, e.g., those recommended by standards such as WELL and RESET, arebetter for a richer, more representative characterisation of IEQ. To keep this metric simple, Arcrequires a report only every hour (i.e., the reporting interval).
Arc assumes that coverage continues from the last reported value through the present unless
this value is changed with new value. Arc combines values as an average of daily values toprovide an estimate for a given time period.

Tips for Entering Temporal Data Coverage
Some users may not be able to provide a quantitative estimate of temporal data coverage.

25

We know that there are many potentially confounding factors and unknowns. It is importantto remember that the purpose is to provide a rough estimate of the fraction occupied hours
associated with each measurement (i.e., are you covering a small fraction, most hours, or allof them).
If a quantitative estimate is not possible, users may estimate coverage and enter thefollowing values:●

Low Coverage: <25% of occupied hours are associated with a measurement○ Enter 25% for the applicable date range.

●

Medium Coverage: 25%-75% of occupied hours are associated with a measurement○ Enter 50% for the applicable date range.

●

High Coverage: >75% of occupied hours are associated with a measurement○ Enter 100% for the applicable date range.

Describe your estimate with a piece of document. This can be a simple note explaining yourrationale.
Performance is divided by thresholds into three categories: good, warning, and investigate.
Each period is assigned to one of the three categories.
Performance is typically integrated over some period of time, most often hours or days. These
periods may contain any number of sensor readings. The intent is to communicate thepercentage of time in each category. For example:●●

If hourly (for sub-hourly) data are available, Performance would be calculated as theaverage of hourly values. Missing values would be excluded from Performance,
because they are already accounted for in the preceding metrics.
If daily data are available, Performance would be calculated as the average of daily
values. Again, missing values would be excluded.

The result would be the average fraction of periods in each of the three categories over thelast 30 days. Data older than 30 days do not contribute to the IAQ Comprehensiveness Comp
Score.
The IAQ Comp Score combines the three equal elements:●

Spatial Coverage

26

●
●

Temporal Coverage
Performance (as the fraction of time in the “good” condition)

The result is that a project has a maximum score of 300 reflecting the comprehensiveness ofdata and measured performance. The same structure is used for each of the sub-components(i.e., relative humidity, CO2, TVOC, and PM).
Table 3. Draft thresholds used to assign time in each condition: good, warning, investigate.
These thresholds are subject to further review and adjustment based on sensor uncertainty.
Source: Parag Rastogi, arbnco.
Low
Parameter

Investigate

Warning

High
Good(Accept
able)
CO2

350

n/a

Warning

Investigate

Units

Includedin Comp
Score

>1000

ppm

Yes

(Acceptabl
e)350-750

1,000

SourceCIBSE Guide
A 2018 (Table
4.1, 4.5)
LEED v4.1
O+M Beta
Guide

RH

30

30-40

40-60

60-70

>70

%

Yes

CIBSE Guide
A 2018

TVOC2

0

n/a

0-175

175-200

>200

µg/m3

Yes

RESET v2 2018

PM1

0

n/a

0-12

12-15

>15

µg/m3

No

TBD

PM2.5

0

n/a

0-12

12-15

>15

µg/m3

Yes

RESET v2 2018
WELL v2 2020,
Optimization
1

PM10

2

0

n/a

0-30

30-35

>35

µg/m3

No

WELL v2 2020,
Optimization
1

TVOC measurements in ppb should be converted to µg/m3 using a conversion factor of 3.767.

27

Note on Data Quality
Objective measures of data quality are not currently part of the IAQ Comp Score. However,the quality of IAQ measurements is a significant management issue, and it varies significantly
based on a variety of factors, including sampling design, sensor placement, sensor capabilities,
sensor maintenance, data processing, and more (RESET Standard). An extensive peer-review
literature is emerging in this area with publications such as Sun et al. 2019 and Chojer et al.
2020, and the U.S. Environmental Protection Agency Air Sensor Toolbox. Arc Re-Entry users may
consider the benefits of third-party accredited hardware as one element of a comprehensive
strategy to promote data quality.
Table 4. Comparison of the existing Arc indoor air quality with the new re-entry enhanced
indoor air quality.
Existing Arc
Indoor Air Quality
Annual measurement of:● 95th percentile CO2 concentration● Maximum TVOC concentration

Re-Entry
Enhanced Indoor Air Quality
Existing Arc occupant survey plus additional criteria:
Data coverage● Fraction of occupied space and timecovered by sensing
Relative humidity● Fraction of occupied hours within optimal RH
range
Particulate matter● Fraction of occupied hours below threshold

Analysis
Arc provides all users information through the Re-Entry under the Performance tab. This provides
a summary of the overall Comp Score, along with sub-scores for Facility Management,
Occupant Observations, and Indoor Air Quality. This allows users to track thecomprehensiveness of re-entry efforts day-by-day. Note that this contrasts with other Arc
reporting, which provides month-by-month trends. Users can view occupant experiences for
specific scopes and groups with the selection tool.
Figure 5. The Arc Re-Entry dashboard provides a day-by-day overview of thecomprehensiveness of infection control practices, along with sub-scores for facility
management, occupant observations, and indoor air quality.

28Arc Essential users can also create and customize a Re-Entry Report. This is available throughthe Report tab. Users can select thedefault Arc logo or upload their own
image.
The project Re-Entry Report provides all
the information in the Performancetab, plus a comparison between the
project and all other Re-Entry
participants. Over time, Arc expects toallow users to refine the comparison,such as comparing a project to a
specific portfolio or group. This
capability will be more valuable as
more data becomes available.
Figure 6. The Arc Re-Entry Report(available to Arc Essentials subscribers)
provides a one-page overview ofpolicy elements and the presence ofdata from occupants and IAQ
measurements.
The Re-Entry Report provides a
one-page overview of activities,
described as a “scorecard”. The

29

scorecard can be distributed separately from the report as an “at-a-glance” summary of
infection-control efforts. The check marks indicate a positive response, the presence ofoccupant feedback, and the availability of at least some measured IAQ data in eachcategory. There are no minimums for these elements at this time; the presence of any data issufficient to receive a check mark.
The following sections provide more detailed information about each category, including
details about the relationship between management expectations (plans and policies) andoccupant observations.

Conclusion
The Arc Re-Entry provides practical tools to collect, manage, and interpret information about
facility management, occupant experience, and indoor environmental conditions. These tools
can help inform and improve facility management and support effective communications withoccupants.
Arc Re-Entry does not stand alone. Ideally, it should be deployed as part of a comprehensive
infection control management system which includes input from public health and industrial
hygiene specialists. This type of comprehensive system recognizes that protection comes fromthe consistent, end-to-end operation of the management process, not any single strategy or
technology. Arc can support this process, but it cannot guarantee outcomes.
As part of the right management system, Arc Re-Entry can help build the knowledge andconfidence needed to safely occupy the places where we live, work, and play.

Contact
Contact Chris Pyke (cpyke@arcskoru.com) to provide feedback or get more information.

About Arc
ArcSkoru (Arc) is a wholly-owned subsidiary of the Green Business Certification, Inc. It is based in
Washington, DC dedicated to making real world performance measurement an integral andubiquitous part of green building practice.
Learn more at www.arcskoru.com
30