NRE Health & Wellbeing Matrix™ Guide

A practical guide to understanding, comparing and using the NRE Health & Wellbeing Matrix™ Library.

What is the NRE Health & Wellbeing Matrix™?

The NRE Health & Wellbeing Matrix™ is a structured decision-support framework designed to compare opportunities for meaningful environmental interaction across different settings, populations and everyday situations. It separates the quality of an environment from other factors such as access, weather, physical demand, recovery opportunity, supervision or adaptability.

Why was the Matrix Library created?

Health and wellbeing discussions often treat “being outdoors” or “being in nature” as if all environments provide the same experience. The Matrix Library was created to examine those differences more carefully and to help people identify realistic ways to increase environmental interaction according to their circumstances.

What does the library compare?

Depending on the matrix, the framework may compare homes, parks, forests, beaches, workplaces, recovery settings, weather conditions, seasonal conditions, accessibility needs or other practical situations. Each matrix is designed around the question it is intended to answer.

What the Matrix is not

The Matrix is not a medical diagnostic tool, treatment plan, clinical score or guarantee of health outcomes. It does not rank people, lifestyles, occupations, income, prestige or social status. It is an educational and decision-support framework for understanding environmental interaction.

One framework, different decision tools

The Matrix Library uses a common environmental classification while allowing the comparison variables to change where necessary. A Beach Matrix may compare different forms of environmental exposure, while the Night Shift Matrix compares environmental quality, recovery opportunity and practical accessibility. The Weather Matrix compares how current weather changes the practical opportunity to use different environments.

This variation is intentional. The comparison axis is selected according to the purpose of each matrix rather than forcing every subject into one identical table.

Environmental quality stays separate The underlying environmental class is not increased by danger, difficulty, distance, prestige, expense or discomfort.

Practical variables are assessed separately Accessibility, weather, recovery opportunity, supervision, adaptability and physical demand may affect practical use without changing environmental value.

Each matrix must answer a distinct question Matrices are retained only where they provide a meaningful decision-support function that is not already answered elsewhere in the library.

The A–E Environmental Classification

The A–E classification describes the relative richness and continuity of environmental interaction available within a setting. It is the common reference system connecting the NRE Health & Wellbeing Matrix™ Library.

What is being classified?

The classification assesses the environmental setting, not the person using it. Grades reflect the combined opportunity for interaction with factors such as daylight, fresh air, vegetation, water, natural surfaces, natural sound, biodiversity, landscape openness and continuity of natural systems. No single feature determines a grade by itself.

Very limited interaction

Predominantly enclosed or artificial environments providing little or no direct interaction with daylight, fresh air, vegetation, natural surfaces, water or changing outdoor conditions.

Limited interaction

Some environmental contact is present through daylight, exterior views, limited vegetation or brief outdoor connection, but the setting remains substantially built, enclosed or environmentally restricted.

Moderate interaction

Meaningful environmental interaction is available through outdoor access, vegetation, gardens, natural light, open air or managed green spaces, although the setting remains comparatively limited, fragmented or strongly managed.

High interaction

Substantial environmental interaction is available through mature vegetation, water, natural surfaces, sustained outdoor routes, habitat diversity or meaningful separation from predominantly built surroundings.

Exceptional interaction

An unusually rich, continuous and diverse environmental setting combining multiple substantial natural systems in a way that clearly exceeds an ordinary Class D environment.

Factors considered when assigning a class

Classification is based on the combined environmental characteristics of the setting. Relevant factors may include:

Natural daylight
Fresh-air exposure
Vegetation quantity and maturity
Tree canopy
Water environments
Natural surfaces
Natural sound
Habitat diversity
Biodiversity opportunity
Landscape openness
Environmental continuity
Length and quality of outdoor routes
Separation from traffic and intensive built disturbance
Opportunities for direct interaction with living systems
Continuity between different natural features
Degree to which the environment remains predominantly natural or built

What does not increase an environmental class

The following characteristics are deliberately excluded as grading bonuses. They may affect safety, accessibility, experience or practicality, but they do not make an environment environmentally richer.

Danger

Remoteness

Physical difficulty

Prestige

Expense

Popularity

Technical challenge

Distance travelled

Longer duration alone

Reduced clothing alone

Barefoot use alone

No clothing alone

Why Class D is deliberately demanding

Class D represents genuinely strong environmental interaction. A setting should not receive Class D merely because it is outdoors, attractive, large or green. Mature natural features, meaningful continuity or substantial environmental interaction must be present.

Why Class E is rare

Class E is not simply a better-looking Class D. It is reserved for exceptionally rich environments where multiple substantial natural systems, habitats or forms of environmental interaction combine with a degree of continuity that clearly exceeds the Class D threshold.

The Class E rule

Before any Class E classification is accepted, it must be challenged against Class D.

If the setting can reasonably be described as a strong example of Class D, it remains Class D. Class E is used only when there is a clear and defensible reason why the environmental interaction opportunity materially exceeds the Class D range.

Environmental value is separate from safety, legality and accessibility

An environment may have a high environmental class while being unsuitable for a particular person, activity, weather condition or time. Conversely, a highly accessible and safe environment may have a lower environmental class. Accordingly, safety, legality, accessibility, adaptability, supervision, physical demand and other practical considerations are assessed separately where relevant. They do not alter the underlying environmental classification.

How Application Matrices Work

Not every Health & Wellbeing Matrix™ asks the same question. Application matrices retain the common environmental classification while introducing additional variables relevant to a particular population, circumstance or decision.

The comparison axis follows the question

The A–E environmental classification provides a common reference across the library, but forcing every matrix to use identical comparison columns would sometimes produce misleading or irrelevant results.

The comparison axis is therefore selected according to the purpose of the matrix. This allows each matrix to remain consistent with the wider framework while functioning as a specialised decision-support tool.

Environmental matrices

These primarily compare environmental settings and the degree of direct environmental interaction available within them. Where relevant, exposure conditions may form part of the comparison.

Population matrices

These examine how environmental opportunities can be used by particular populations while keeping age, disability, supervision, assistance and individual capacity separate from environmental quality.

Situation matrices

These apply the framework to circumstances such as workplace routines or night shift recovery. Practical access, recovery opportunity or other relevant variables may therefore become part of the comparison.

Decision-support matrices

These help users choose between environments under changing circumstances. Seasonal and Weather matrices, for example, retain environmental class while examining how conditions alter practical opportunity.

Examples of purpose-specific comparison variables

Additional variables are used only where they help answer the specific question addressed by the matrix.

Night Shift Environmental class, recovery opportunity and practical accessibility are separated because a rich environment may not be practical immediately around a night-shift schedule.

Children Environmental class, interaction opportunity and typical adult support are separated because supervision requirements do not determine environmental quality.

Seniors Environmental class, interaction opportunity and typical physical demand are separated because effort and mobility requirements are individual factors.

Disability Environmental class, interaction opportunity and adaptability are separated because assistive technology or support can improve access without changing the environment itself.

Seasonal The environmental class remains fixed while seasonal opportunity reflects how local conditions may change practical interaction throughout the year.

Weather The environmental class remains fixed while calm, wind, rain, heat and cold are used to compare practical environmental opportunity under current conditions.

Measure	What it describes	Does it change the A–E environmental class?
Environmental class	The underlying richness, diversity and continuity of environmental interaction.	This is the A–E classification itself.
Interaction opportunity	How much meaningful interaction a particular setting or situation may practically provide.	No.
Accessibility	How realistically an environment can be reached and used by a particular person or population.	No.
Adaptability	The potential to modify routes, equipment, activities or support to improve participation.	No.
Physical demand	The general effort, distance, terrain or movement requirements associated with using the setting.	No.
Recovery opportunity	The relative opportunity for restorative environmental contact within a specific recovery context.	No.
Weather or seasonal opportunity	How current or seasonal conditions influence practical use of an otherwise unchanged environment.	No.

Why separating these measures matters

A nearby backyard may have a lower environmental class than a large nature reserve while being considerably easier to use every day. A mature forest may retain a high environmental class during rain while becoming less practical for a particular activity. An accessible route may allow a person to interact meaningfully with a rich environment without changing that environment's classification.

None of these situations is contradictory. They demonstrate why environmental quality and practical opportunity must be considered separately.

Matrix design rule

The comparison variable must be relevant to the purpose of the matrix. A variable is not included merely because it appeared in another matrix.

Every new matrix should answer a distinct question, use variables capable of answering that question, and preserve the separation between environmental classification and practical considerations. If another existing matrix already answers the same question adequately, a new matrix should not be created solely to expand the size of the library.

Using Multiple Matrices Together

The NRE Health & Wellbeing Matrix™ Library is designed to be used as a connected framework. One matrix may identify the quality of an environment, while another helps determine how practical that environment is for a specific person, situation or set of conditions.

One decision may involve several matrices

A useful environmental decision is rarely based on environmental class alone. The strongest approach is to combine the relevant environmental matrix with any population, situational or decision-support matrix that applies to the circumstances.

Environment + Weather

A Forest Matrix may establish the environmental richness of woodland, while the Weather Matrix helps determine whether current wind, rain, heat or cold makes that environment practical today.

Environment + Population

A Beach or National Park Matrix may describe environmental quality, while the Children's, Seniors or Disability Matrix helps assess practical participation, support, adaptability or physical demand.

Environment + Recovery

A high-class natural environment may offer strong environmental interaction, while the Night Shift Matrix may show that a nearer Class C setting is more realistic during a work cycle.

Environment + Season

The environmental class may remain unchanged throughout the year while the Seasonal Matrix helps identify when access, temperature, vegetation, daylight or surface conditions make interaction more or less practical.

A simple way to use the library

Identify your objective

Decide what you are trying to improve or understand, such as everyday outdoor access, recovery, family participation, weather adaptation or accessibility.

Select the relevant environmental matrix

Use the matrix that best describes the setting being considered, such as home, urban park, forest, beach, mountain or national park.

Check the environmental class

Identify the underlying A–E environmental classification before considering other practical variables.

Add the relevant application matrix

Use Weather, Seasonal, Night Shift, Children's, Seniors, Disability or another relevant matrix where the circumstances require a second layer of analysis.

Compare practical opportunity

Consider access, time, weather, support, physical demand, adaptability and other variables separately from environmental quality.

Choose the strongest realistic option

The best choice is not always the highest environmental class. It is the option that combines meaningful environmental interaction with realistic, suitable and repeatable access.

Example: choosing an environment after a night shift

A worker may have access to a Class E nature reserve, a Class D forest and a Class C backyard.

The environmental classification alone would identify the nature reserve as the richest setting. The Night Shift Matrix, however, may show that travel, fatigue and available time make the backyard the more practical option after waking, while the forest or nature reserve may be better suited to a day off.

The framework therefore does not ask only, “Which environment is best?” It asks, “Which environment offers the strongest realistic opportunity under these circumstances?”

Connection with the 11 Levels of Health Restoration™

The Matrix Library and the 11 Levels of Health Restoration™ address different parts of the same broader framework. The Matrix helps compare the quality and practical accessibility of environments. The 11 Levels describe increasing degrees of environmental interaction and health-restoration opportunity.

Used together, they can help a person identify both where environmental interaction may occur and how that interaction may progressively deepen over time.

Methodology, Quality Assurance & Limitations

The NRE Health & Wellbeing Matrix™ is designed as a transparent, evidence-informed framework. Its classifications are intended to support comparison and decision making while keeping environmental quality separate from individual circumstances and health outcomes.

Evidence-informed, not a clinical scale

The framework draws on established areas of research concerning environmental exposure, daylight, green and blue spaces, physical activity, environmental comfort, access and wellbeing. The A–E classification itself is an NRE framework and should not be represented as a validated clinical measurement scale unless and until independent validation supports such a claim.

Relative classification

A–E classes provide structured relative comparisons between environmental settings. They do not represent a precise dose of nature, a medical treatment threshold or a guaranteed difference in health outcomes between two people or two environments.

Context remains important

Real environments vary substantially. Two parks, beaches, forests or workplaces carrying the same general description may differ in vegetation, noise, accessibility, water, shade, air quality, maintenance, surrounding development and other characteristics.

Individual response varies

People may experience the same environment differently according to their preferences, circumstances, mobility, sensory needs, experience, available time and other individual factors. The Matrix therefore describes opportunity, not a guaranteed personal response.

Quality-assurance principles

Each matrix should be reviewed against the same core methodological controls before publication or substantial revision.

Purpose: The matrix must answer a clearly identifiable question.

Distinct value: It should not merely reproduce another matrix with different wording.

Relevant variables: Comparison variables must match the purpose of the matrix.

Environmental separation: Practical factors must not be confused with environmental class.

No prestige bonus: Expense, reputation, popularity or institutional status do not increase classification.

No difficulty bonus: Remoteness, physical effort, technical challenge and danger do not increase classification.

No clothing bonus: Reduced clothing or no clothing does not independently increase environmental class.

Accessibility separated: Accessibility may affect practical use but does not redefine environmental richness.

Safety separated: Hazards and protective requirements are considered independently from environmental value.

D and E challenge: Every high or exceptional classification should receive additional scrutiny.

Additional review of Class D and Class E

Class D and E classifications require particular restraint because over-classification would reduce the usefulness of the entire system.

A setting should remain Class C unless substantial environmental interaction supports Class D. A setting should remain Class D unless its environmental richness, diversity and continuity provide a clear reason for exceptional classification.

Class E is therefore intentionally uncommon. It is not a reward for dramatic scenery, wilderness, remoteness or difficulty.

Important limitations

The NRE Health & Wellbeing Matrix™ is provided for educational, informational and decision-support purposes. It is not medical advice, diagnosis, treatment, rehabilitation prescription, occupational health clearance or an individual risk assessment.

The framework does not guarantee that a particular environment, duration, activity or level of environmental interaction will produce a specific health or wellbeing outcome.

Local laws, access restrictions, weather warnings, emergency directions, workplace requirements and applicable safety measures remain relevant regardless of a setting's environmental classification.

Where individual health, disability, medication, pregnancy, rehabilitation or other personal circumstances may materially affect participation, appropriate professional advice should be obtained where necessary.

Version control and continuing development

The Matrix Library is intended to remain capable of refinement as research, practical experience and the wider NRE framework develop. Changes should be documented rather than silently altering the meaning of established classifications.

Methodology revisions Material changes to classification principles should be identified through a new methodology version.

Matrix revisions Substantial changes to an individual matrix should be recorded through its revision or version history.

New matrices New matrices should be added only where they provide a distinct and useful decision-support function.

A framework for better environmental decisions

The NRE Health & Wellbeing Matrix™ does not attempt to prescribe one ideal environment or lifestyle. Its purpose is to make environmental differences easier to understand, help people compare realistic options and support more informed decisions about how environmental interaction can form part of everyday health and wellbeing.

NRE Health & Wellbeing Matrix™ Library

The library brings together environmental, population, situational and decision-support matrices within one common framework.

The library is developed according to usefulness rather than a predetermined number of matrices. A new matrix should be published only where it provides a distinct analytical or decision-support function that is not already adequately addressed elsewhere in the framework.

Environmental foundation matrices

These matrices establish the environmental foundation of the library by examining different living and natural settings.

01 Home Health & Wellbeing Matrix™ Environmental interaction within the home environment.

02 Apartment Health & Wellbeing Matrix™ Environmental opportunities associated with apartment living.

03 High-rise Health & Wellbeing Matrix™ Environmental interaction within high-rise living environments.

04 Balcony Health & Wellbeing Matrix™ Using limited private outdoor space for environmental interaction.

05 Backyard Health & Wellbeing Matrix™ Environmental interaction within private outdoor residential space.

06 Urban Park Health & Wellbeing Matrix™ Environmental interaction within managed urban green spaces.

07 Forest Health & Wellbeing Matrix™ Environmental interaction within forest and woodland settings.

08 Beach Health & Wellbeing Matrix™ Environmental interaction within coastal beach environments.

09 River and Lakeside Health & Wellbeing Matrix™ Environmental interaction around freshwater environments.

10 Mountain and Hillside Health & Wellbeing Matrix™ Environmental interaction within elevated natural landscapes.

11 Rural and Countryside Health & Wellbeing Matrix™ Environmental interaction within rural and countryside settings.

12 Rainforest Health & Wellbeing Matrix™ Environmental interaction within dense rainforest environments.

13 Desert Health & Wellbeing Matrix™ Environmental interaction within arid landscapes.

14 Wetlands & Marsh Health & Wellbeing Matrix™ Environmental interaction within wetland and marsh ecosystems.

15 Snow & Alpine Health & Wellbeing Matrix™ Environmental interaction within snow and alpine environments.

16 Coastal Cliff & Headland Health & Wellbeing Matrix™ Environmental interaction within elevated coastal landscapes.

17 Island Health & Wellbeing Matrix™ Environmental interaction within island environments.

18 Cave & Underground Health & Wellbeing Matrix™ Environmental interaction within underground environments.

19 Waterfall & Gorge Health & Wellbeing Matrix™ Environmental interaction within waterfall and gorge environments.

20 Nature Reserve & National Park Health & Wellbeing Matrix™ Environmental interaction within protected natural environments.

Application and population matrices

These matrices apply the environmental framework to particular populations, work patterns and practical circumstances.

21 Workplace Health & Wellbeing Matrix™ Environmental interaction opportunities associated with working environments.

22 Night Shift Health & Wellbeing Matrix™ Environmental opportunities for recovery around night-shift work.

23 Children's Health & Wellbeing Matrix™ Age-appropriate environmental interaction for children.

24 Seniors Health & Wellbeing Matrix™ Environmental interaction considered alongside practical demands in later life.

25 Disability Health & Wellbeing Matrix™ Environmental interaction considered alongside accessibility and adaptability.

Decision-support matrices

These matrices help interpret how changing external conditions affect the practical opportunity to use otherwise unchanged environments.

26 Seasonal Health & Wellbeing Matrix™ How seasonal conditions influence practical environmental interaction throughout the year.

27 Weather Health & Wellbeing Matrix™ How calm, wind, rain, heat and cold influence today's environmental choices.

Why the library has no artificial finishing number

The purpose of the NRE Health & Wellbeing Matrix™ Library is not to reach a particular number of publications. Its purpose is to provide useful, non-duplicative tools.

Additional matrices may be developed where they answer a genuinely different question, introduce a useful comparison variable or materially strengthen the framework. Proposed matrices that substantially duplicate existing tools may be revised, combined or not published.

Choosing which matrix to use

Start with the environmental setting you want to understand.
Use the corresponding environmental foundation matrix to establish the underlying environmental context.
If a population-specific consideration applies, add the relevant application matrix.
If weather or seasonal conditions affect the decision, add the relevant decision-support matrix.
Compare environmental quality with practical opportunity rather than assuming the highest environmental class is automatically the best choice in every circumstance.

Relationship with the 11 Levels of Health Restoration™

The NRE Health & Wellbeing Matrix™ and the 11 Levels of Health Restoration™ are complementary frameworks. They examine different dimensions of environmental interaction and should not be treated as interchangeable grading systems.

Environment and interaction are different questions

The Matrix primarily helps identify and compare the environmental opportunity available within a setting or situation.

The 11 Levels of Health Restoration™ provide a progression framework for considering how environmental interaction may deepen or broaden. Together, they allow the setting and the form of interaction to be considered separately.

The Matrix asks: Where?

The Matrix helps identify the environmental characteristics of homes, backyards, parks, forests, beaches, rivers, national parks and other settings. Application matrices add relevant circumstances such as weather, accessibility, age or work patterns.

The 11 Levels ask: How?

The 11 Levels provide a progression for considering the degree and character of interaction with the surrounding environment rather than simply identifying where that interaction occurs.

A high-class environment is not automatically a high level

A person may visit a rich natural environment while having relatively limited direct interaction with it. Environmental richness and degree of interaction are therefore assessed separately.

A lower-class setting can still be useful

A balcony, backyard or local park may provide less environmental richness than a forest or national park while still offering practical opportunities for regular environmental interaction and progression.

How the frameworks work together

1. Select the environment Use the relevant Health & Wellbeing Matrix™ to understand the environmental setting and its practical characteristics.

2. Consider the interaction Use the 11 Levels of Health Restoration™ to consider the degree and form of environmental interaction appropriate to the circumstances.

3. Build realistic continuity Combine suitable environments and forms of interaction into a pattern that can be used realistically and repeatedly.

Example: apartment living

Someone living in an apartment may have access to an indoor room with natural light, a balcony, an urban park and a forest requiring substantial travel. These environments provide different levels of environmental richness.

The Matrix can help compare those settings. The 11 Levels can then help consider how environmental interaction might progress within whichever settings are realistically available.

The objective is therefore not simply to reach the highest environmental class or the highest possible level. It is to identify meaningful combinations of environment and interaction that can form part of everyday life.

Higher does not automatically mean appropriate Neither environmental class nor progression level should override personal circumstances, accessibility, weather or practical suitability.

Frequency matters practically A nearby environment that can be used regularly may play an important role even when richer environments are available less frequently.

Progression is not competition The frameworks are intended to support informed choices rather than create a hierarchy between individuals or lifestyles.

Environmental quality remains independent Changing the degree of interaction does not automatically change the A–E classification of the environment itself.

A connected NRE framework

Used together, the NRE Health & Wellbeing Matrix™ and the 11 Levels of Health Restoration™ provide two complementary perspectives: the environmental opportunity available and the way an individual may interact with that environment. This separation allows the wider NRE framework to compare environments without prescribing one universal pathway for every person.

Evidence, Interpretation & Responsible Use

The NRE Health & Wellbeing Matrix™ distinguishes between established research concerning environmental exposure and the classifications developed by NRE to organise and compare environmental opportunities.

Evidence-informed framework

The Matrix draws on broader research concerning green and blue spaces, daylight, outdoor environments, physical activity, environmental comfort, nature contact and related health and wellbeing factors. That evidence informs the framework but does not independently validate every NRE classification.

NRE classification system

The A–E Environmental Classification and the structure of individual matrices are NRE-developed analytical tools. They organise environmental characteristics into a consistent comparison framework and should be described as such.

Association is not guarantee

Research may identify associations between environmental exposure and health or wellbeing outcomes. Such findings do not mean that every individual will experience the same effect or that a particular matrix class guarantees a specific outcome.

Evidence can evolve

Scientific understanding changes as new research becomes available. The Matrix Library should therefore remain capable of documented revision where stronger evidence, better methodology or practical evaluation supports a change.

Evidence domains relevant to the Matrix Library

Depending on the subject of an individual matrix, relevant evidence may come from research concerning:

Green-space exposure
Blue-space exposure
Nature contact
Daylight and light exposure
Outdoor physical activity
Walking and active mobility
Environmental psychology
Stress and restoration research
Urban design and public health
Biophilic environments
Thermal comfort
Air quality
Noise exposure
Sleep and circadian research where relevant
Healthy ageing
Child development and outdoor activity
Accessibility and inclusive design
Occupational health where relevant

Three levels of interpretation

Research-supported principle A general principle supported by relevant external research, such as the importance of environmental exposure, daylight, physical activity or access to green space.

NRE analytical classification An A–E grade, comparison variable or framework interpretation developed by NRE to organise environmental opportunities.

Practical guidance A suggested way of using the framework to compare realistic options. Guidance should not be presented as a guaranteed medical outcome.

Claims the Matrix does not make

A Class E environment is not claimed to produce a defined percentage improvement in health compared with Class D, C, B or A.

The framework does not establish that a specific duration of environmental interaction will prevent, diagnose, treat or cure a disease or health condition.

A higher environmental class should therefore be interpreted as a richer environmental interaction opportunity within the NRE framework, not as a clinical health score.

Evidence review principle

References supporting individual matrices should be selected for relevance to the actual subject being discussed rather than added simply to increase the number of citations.

Where evidence is uncertain, mixed, emerging or indirect, that uncertainty should be reflected in the wording. The framework should distinguish between what research supports, what NRE classifies and what remains a hypothesis or area for further investigation.

Responsible interpretation

The Matrix is strongest when used comparatively. It can help identify differences between environments, recognise practical barriers, compare available options and support more deliberate environmental choices.

It should not be used to diagnose an individual, replace professional advice, promise health improvements or imply that people who cannot access higher-class environments are receiving inadequate health or wellbeing opportunities.

Quick Reference & Framework Governance

The following principles provide a concise reference for interpreting, developing and maintaining the NRE Health & Wellbeing Matrix™ Library.

Environmental class

A–E describes the relative richness and continuity of environmental interaction available within the setting. It is not a medical score.

Application variables

Accessibility, adaptability, weather, season, physical demand, recovery opportunity and similar variables are assessed separately where relevant.

Higher is not always more practical

A lower-class environment that can be used frequently and appropriately may be more useful in everyday circumstances than a richer environment that is rarely accessible.

Classification is not prescription

The framework supports comparison and informed choice. It does not prescribe one environment, activity or progression pathway for every person.

Class	Meaning	General interpretation
A	Very limited	Little or no direct interaction with daylight, fresh air, vegetation, natural surfaces, water or changing outdoor conditions.
B	Limited	Some environmental contact exists, but the setting remains substantially enclosed, built or environmentally restricted.
C	Moderate	Meaningful interaction is available through outdoor access, vegetation, gardens, managed green space or similar environmental features.
D	High	Substantial interaction is available through mature natural features, water, sustained routes, habitat diversity or meaningful separation from built surroundings.
E	Exceptional	An unusually rich, continuous and diverse environmental setting clearly exceeding the ordinary Class D range.

Core governance principles

The integrity of the Matrix Library depends on applying the same fundamental controls throughout its development.

The purpose of each matrix must be clearly defined.
The comparison axis must match the question being addressed.
Environmental class must remain separate from practical variables.
Class D and Class E classifications require additional scrutiny.
Class E should remain exceptional rather than becoming a routine top grade.
Danger does not increase environmental value.
Remoteness does not increase environmental value.
Physical difficulty does not increase environmental value.
Expense and prestige do not increase environmental value.
Reduced clothing does not independently increase environmental class.
Accessibility and adaptability should be assessed separately where relevant.
Safety and legal considerations remain separate from environmental grading.
Research-supported principles and NRE-developed classifications should not be confused.
Health outcomes should not be guaranteed from environmental classifications.
Material methodological changes should be documented through version control.
New matrices should add genuine analytical value rather than increase the library's size.

Before adding another matrix

A proposed matrix should be challenged before development. It should proceed only where it can provide a distinct and useful function within the wider library.

Does it address a genuinely different question?
Can it stand alone while remaining compatible with the wider framework?
Does it provide a useful comparison or decision-support function?
Will readers learn something that cannot already be adequately obtained from an existing matrix?
Would its absence leave a meaningful gap in the Matrix Library?

Responsible use

The NRE Health & Wellbeing Matrix™ is an educational and decision-support framework. It should not be represented as a validated clinical scale, medical diagnostic instrument, treatment protocol or guarantee of health improvement. Environmental classifications should be interpreted alongside individual circumstances, current conditions and appropriate professional or official guidance where relevant.