Environmental due diligence becomes more complicated when a commercial real estate acquisition involves multiple properties rather than a single asset. Investors still need to understand environmental risk before closing, but the appropriate level of diligence may vary based on property history, current use, financing requirements, and the purpose of the review.
For private equity groups, lenders, and investors acquiring portfolios, the goal should not simply be to order the same report for every property or choose the lowest-cost option. A more effective approach is to establish a consistent environmental due diligence strategy that identifies higher-risk assets early, applies the appropriate level of review, and creates a clear process for escalating concerns when necessary.
Start With Purpose
Before determining whether a property should receive a Desktop Review, Environmental Transaction Screen (ETS), or full Phase I Environmental Site Assessment (Phase I ESA), the transaction team should first determine what the environmental diligence needs to accomplish.
Important questions include:
- Is the property being acquired or refinanced?
- Does the purchaser intend to satisfy All Appropriate Inquiries requirements?
- What environmental scope does the lender or investor require?
- Will the property remain stabilized or undergo redevelopment?
- Are certain assets known to have higher-risk historical uses?
- What level of environmental risk is acceptable to the investment group?
This distinction matters because Desktop Reviews, ETS reports, and Phase I ESAs are not interchangeable.
A Phase I ESA completed under ASTM E1527-21 can be used to satisfy EPA All Appropriate Inquiries requirements when applicable. A limited Environmental Transaction Screen does not satisfy AAI and should not be treated as a substitute when the purchaser intends to pursue certain CERCLA liability protections.
The environmental scope should therefore begin with the transaction requirements, not simply the perceived risk or cost of the report.
A full Phase I ESA is not necessarily required for every property. When the review is being performed for internal risk management, no lender or investor requires a Phase I ESA, AAI compliance is not needed, and the property appears to have a relatively low environmental risk profile, a Desktop Review or ETS may be an appropriate initial level of diligence. The limited review should be paired with clear criteria for escalating the property to a Phase I ESA if potential concerns are identified.
Understand the Different Levels of Environmental Due Diligence
When the transaction requirements allow different levels of review, the scope can be tailored to each property’s risk profile. This can help investors prioritize resources across the portfolio while still applying a consistent decision-making framework.
Desktop Environmental Review
A Desktop Review is generally used as a preliminary environmental screening tool. The scope may include environmental databases, historical information, prior reports, and other readily available property information without completing the full site reconnaissance and research required for a Phase I ESA.
For a large portfolio, the value of a Desktop Review is its ability to screen properties efficiently and direct time and resources toward the assets that warrant closer evaluation. It gives the transaction team an early view of potential environmental risk without automatically applying the cost and timing of a full Phase I ESA to every property. Because the scope is limited, however, the report should not be treated as equivalent to a Phase I ESA.
Environmental Transaction Screen
An Environmental Transaction Screen, or ETS, performed under ASTM E1528 provides a more structured form of limited environmental due diligence. It may be appropriate for certain lower-risk transactions when a full Phase I ESA is not initially considered necessary.
The value of an ETS is the consistent, structured screening process it provides for lower-risk properties. This allows the transaction team to apply a defined review threshold across the portfolio and identify which properties should be escalated. It does not provide the same level of investigation as a Phase I ESA or identify Recognized Environmental Conditions under the Phase I framework.
If the ETS identifies a concern, the environmental professional may recommend escalating the property to a Phase I ESA or another form of additional investigation.
Phase I Environmental Site Assessment
A Phase I ESA provides a more comprehensive environmental review and generally includes historical research, regulatory database review, interviews, site reconnaissance, evaluation of adjoining properties, and conclusions regarding Recognized Environmental Conditions (RECs), Controlled Recognized Environmental Conditions (CRECs), and Historical Recognized Environmental Conditions (HRECs).
For properties where AAI compliance is required, environmental risk is elevated, or the lender requires a full assessment, a Phase I ESA is generally the appropriate scope.
Its value is the more complete basis it provides for underwriting, transaction decisions, and determining whether further investigation or risk management is needed. When properly completed for an acquisition, it may also support the purchaser’s applicable CERCLA liability protections.
Develop a Risk Profile for Each Property
When different levels of review are permitted, the next step is determining which properties warrant the most attention. Current appearance alone is rarely enough to make that determination.
A newly renovated multifamily property, for example, may still occupy land that was historically used for manufacturing. A modern retail center may have housed a dry cleaner years earlier. An apparently low-risk office building may sit beside a property with documented groundwater contamination.
Properties that typically warrant closer environmental review include those with current or historical:
- Dry-cleaning operations
- Gas stations or vehicle fueling
- Automotive repair or maintenance
- Manufacturing or industrial activity
- Chemical storage or processing
- Underground storage tanks
- Waste disposal or landfill operations
- Known spills or environmental cases
- Higher-risk adjoining properties
Planned use should also influence the scope. A property that will remain an existing warehouse may present a different risk profile from the same site being converted to apartments or another sensitive use.
The purpose of portfolio screening is not to classify every historically commercial site as problematic. It is to identify which properties have enough potential exposure to justify more detailed investigation.
Establish Clear Escalation Criteria
One of the most important steps in portfolio environmental due diligence is establishing a consistent process for what happens when a concern is identified.
Rather than making these decisions individually as closing approaches, the investor and environmental consultant can establish escalation criteria before the reviews begin.
For example, a Desktop Review or ETS might trigger a Phase I ESA when the consultant identifies:
- A former dry cleaner or gas station
- A known or suspected environmental release
- An unresolved regulatory listing
- Incomplete underground storage tank documentation
- Significant industrial activity on the property
- Concerning environmental activity on an adjoining property
- A previous environmental report recommending additional investigation
If the subsequent Phase I ESA identifies a REC, the next step might include regulatory file review, a Phase II Environmental Site Assessment, or another targeted investigation.
Having this decision path established early helps the entire portfolio move through diligence more consistently and reduces last-minute disagreements over the appropriate level of review.
Keep Reporting Consistent Across the Portfolio
The value of portfolio environmental due diligence is not limited to understanding each property individually. Investors also need to compare risk across the entire acquisition.
That becomes difficult when reports use inconsistent terminology, different risk thresholds, or entirely different reporting structures. Even when the scope varies between properties, the framework for communicating findings should remain consistent.
A portfolio-level summary can help identify:
- Which level of environmental review was completed for each property
- Properties where no material concerns were identified
- Assets requiring additional investigation
- Outstanding environmental issues
- Findings that could affect closing
- Potential redevelopment constraints
- Environmental costs or contingencies that may need consideration
For private equity groups and institutional investors, this makes it easier to identify outliers. A portfolio of 25 properties may contain 23 relatively straightforward assets and two properties with environmental conditions significant enough to affect pricing or the investment strategy.
Those two properties should receive the appropriate attention without allowing their issues to become lost within dozens of individual reports.
Coordinate Environmental Diligence With the Closing Timeline
Portfolio transactions often operate under compressed diligence periods, making timing especially important. Higher-risk properties should be identified early enough to allow time for regulatory file reviews, site access, sampling, laboratory analysis, and lender discussions if additional investigation is needed.
Waiting until the end of the diligence period to discover that one property requires a Phase II ESA can create pressure on the entire transaction.
This is also why environmental scope should be coordinated with the investment strategy. If several properties are scheduled for redevelopment immediately after acquisition, environmental conditions affecting excavation, groundwater, or vapor may have direct implications for construction budgets and schedules.
A condition that has limited impact on a stabilized property may become much more important once soil disturbance or a change in use is planned.
Use a Risk-Based Approach, Not Simply a Cost-Based Approach
Using different levels of environmental due diligence across a portfolio can create efficiencies, but the decision should be based on environmental risk and transaction requirements rather than report cost alone.
A Desktop Review can be useful for preliminary screening. An ETS can provide structured limited due diligence when its scope is appropriate. A Phase I ESA provides the more comprehensive evaluation required when AAI compliance, lender requirements, or the property’s environmental profile calls for a higher level of review.
The strongest portfolio strategy combines appropriate asset-level diligence with consistent reporting and predefined escalation criteria. This helps investors direct attention toward the properties that present the greatest potential exposure while maintaining visibility across the portfolio as a whole.
Moran Consultants provides environmental due diligence for commercial real estate portfolios and individual assets nationwide. Our environmental team works with private equity groups, lenders, and investors to establish consistent review criteria, identify higher-risk properties, and coordinate Desktop Reviews, Environmental Transaction Screens, Phase I ESAs, and follow-up investigation around transaction timelines.
Frequently Asked Questions
Does every property in a portfolio acquisition need a Phase I ESA?
Not necessarily. The appropriate scope depends on the purpose of the review, lender requirements, property risk, and whether the purchaser needs to satisfy AAI requirements. When AAI compliance is required for an acquisition, limited screenings are not substitutes for an appropriate Phase I ESA.
What is the difference between an ETS and a Phase I ESA?
An ETS is a limited environmental screening designed to identify potential environmental concerns. A Phase I ESA provides a more comprehensive assessment and evaluates Recognized Environmental Conditions under the ASTM Phase I framework.
Can a Desktop Review or ETS lead to a Phase I ESA?
Yes. Portfolio diligence can be structured so that specific findings automatically trigger a higher level of review.
Which properties usually require more environmental scrutiny?
Properties with historical industrial uses, dry cleaners, fueling operations, automotive activities, chemical handling, storage tanks, known releases, or concerning adjoining properties generally warrant closer evaluation. Environmental risk is not limited to activities conducted on the property itself; nearby or adjoining properties may also affect the site through soil, groundwater, or vapor migration.
Why is consistent reporting important in a portfolio acquisition?
Consistent reporting allows investors to compare environmental risk across multiple properties, identify outliers, and determine which findings could materially affect underwriting, pricing, closing, or redevelopment plans.