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WELLBEING REPORT

Published 2026. Text © Waugh Thistleton Architects. Images © Waugh Thistleton Architects, unless otherwise stated. All rights reserved. No part of this publication may be reproduced without the written permission of the publisher or copyright owner. Co-Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Research Executive Agency (REA). Neither the European Union nor the granting authority can be held responsible for them.

CONTENTS

INTRODUCTION

1.1

Why Health Matters Now Defining Health Architecture and Health

8 12 14

1.2 1.3

1.10

Designing for Health 16 Neuroarchitecture 18 Physical Conditions 22 Psychological Response 26 Physiological Response 30 Results and Limits 34 Design Checklist 38

CASE STUDIES

APPENDIX

3.1

Evidence 50 Interviews 62 Glossary 64 References 70

1.4 1.5 1.6 1.7 1.8 1.9

3.2 3.3 3.4

1. INTRODUCTION What happens when we stop measuring buildings by what they consume and start measuring them by what they support? A growing body of research is exploring how the built environment can actively improve health. The pandemic reset our relationship with the spaces where we live and work, confirming what researchers have argued for decades: that buildings shape physical and mental health. This recognition has now begun to shape policy, investment, and design culture as a user expectation. Timber is central to this emerging research agenda. One of the oldest building materials in human use, it is now its effects on the people who inhabit spaces built from it which is of increasing interest. Current research suggests a promising connection between timber and wellbeing, but the evidence remains fragmented. Most studies are small and too short in duration to support definitive conclusions. SCOPE AND OBJECTIVES The scope and objectives of this study are outlined within the Timberhaus project proposal. This task provides a definition of healthy construction and guidelines for integrating material choices, spatial design and environmental considerations into a holistic design process, intended to improve the quality of residential, institutional (healthcare and educational) and commercial buildings. A literature study is conducted on the relationship between the built environment and health, with a focus on the design of public and private spaces, alongside specific strategies and material choices, for example the relation between wood and wellbeing.

It draws on both qualitative data (subjective, psychological variables such as warmth, cosiness and comfort, and cultural factors that shape preferences for wood) and quantitative data (objective measures such as emissions and volatile organic compounds (VOCs), and building data such as temperature and humidity). In addition to the literature review, key experts are interviewed using a semi-structured methodology. The findings are shared in a summary report on the physiological and psychological benefits of wood in buildings, including case studies. The report includes clear and concise design guidelines to help inform design choices on material specification, spatial configuration, and environmental optimisation across residential, institutional, and commercial typologies. HYPOTHESIS We hypothesise that exposure to timber surfaces supports the long-term positive health and wellbeing of building occupants through multisensory stimulation, with psychological and physiological impacts being more pronounced than those of a physical nature.

Figure: The Black & White Building under construction. A mass timber office development demonstrating what timber can do for both carbon and occupant health.

INTRODUCTION

1.1

W H Y H E A LT H M AT T E R S N O W

C U LT U R E

DEMAND

People are making consciously healthy choices about how they live - in food, lifestyle and increasingly in the buildings they choose to inhabit. A building’s appeal is now consequently evaluated not only on location and cost, but on the health promoting aspects it can deliver for occupants.

As shown in the figure on the right, wellness driven buildings are a growing component of the broader wellness economy, valued at €400 billion in 2023 and projected to reach €1 trillion by 2029 (Global Wellness Institute, 2025). This category spans a wide range of project types, from fitness facilities to health-oriented hospitality and certified commercial and residential developments. Health

In industrialised nations, people spend around 90% of their time indoors (Klepeis et al., 2001). Everyday factors, including light, air quality, acoustics and materials, accumulate over a lifetime, shaping physical and mental wellbeing in ways that are gradual and largely invisible.

credentials are increasingly in demand from tenants and the general public across the built environment.

The pandemic made this visible. It demonstrated that buildings shape health not only through exposure to potential sources of illness, but through their capacity to support recovery, flexibility and social connection. It also showed that remote working was viable for many professions, giving employees more say and forcing employers to justify the office on new terms. Health and wellbeing became a commercial advantage. POLICY The policy context across Europe is moving in the same direction. Doughnut Economics (Raworth, 2017) challenges GDP growth as an adequate measure of societal progress, arguing instead that human activity should be assessed by how well it sustains people’s wellbeing within planetary boundaries. Amsterdam, Barcelona, and Copenhagen have all formally adopted versions of the framework to rethink their social and ecological impacts at city level (Rogers et al., 2024). In that context, a building designed to support positive health carries a different kind of long-term asset value that existing financial metrics only partially capture.

The construction industry has navigated this transition before. Sustainability followed a clear arc: research led to certification, which led to regulation. Sustainability certified buildings now command rental premiums of 4-8% (CBRE, 2023; JLL, 2023). Health is following the same path, but human experience is harder to measure. WELL certification, launched in 2014, formalised the market for buildings designed around physical, mental and social wellbeing. Early indications show health certified buildings commanding rental premiums of 7.7% per m2 and greater tenant retention (IWBI, 2025). The proposed EU Social Taxonomy includes occupant health and wellbeing as an explicit objective, bringing health credentials into the same focus as carbon. TECHNOLOGY Measurement tools for physical and physiological health have developed rapidly. Markers such as heart rate variability (HRV) can now be monitored continuously through ordinary wrist worn devices (Li et al., 2023), making data that was once confined to clinical settings much more widely available. This presents an opportunity to record the cumulative impact on the body across weeks and months of building use. If this were to be combined with psychological frameworks such as Diener’s Flourishing Scale (Diener et al., 2010), a holistic measure of health feels within reach.

GLOBAL WELLNESS ECONOMY €5.5 TRILLION IN 2023

Figure: The global wellness economy in 2023, valued at USD 6.3 trillion (Euro 5.47 trillion), spans diverse sectors from personal care and healthy eating to wellness tourism and real estate.

Figure: The Black & White Building, Waugh Thistleton Architects. Photography: Jake Curtis

WHY TIMBER

B U I LT E X A M P L E S

Timber’s sustainability credentials are established: lower embodied carbon, renewable, regenerative and a longterm carbon store. These benefits brought timber into the mainstream, however, developers and clients are now citing something beyond carbon as a reason for considering its use.

Despite these challenges, as more mass timber buildings are completed, evidence is growing that the material also positively affects the health and wellbeing of the people who occupy them. A 2025 study led by dRMM, Edinburgh Napier University and the Quality of Life Foundation assessed five completed UK mass timber buildings spanning education, infrastructure, worship, residential and workplace use. Occupants across all five reported feeling calmer and more connected to their surroundings.

The same pattern is emerging across different building sectors. Timber is explored in education contexts due to its impact on learning outcomes, in commercial due to increases in productivity and lower absenteeism, and in residential projects due to the character and of the homes

These findings are echoed in the experiences shared with us by developers and clients who are building extensively

created. (Kerz, IWBI)

in timber - as evidenced within the quotes opposite.

The difficulty is that these benefits largely sit outside what regulation and certification currently measure. The mechanisms are not yet fully understood, and there is not yet an established framework that captures timber’s contribution to occupant health in a consistent way.

The research is still catching up with reported experiences of timber buildings. Where this is acknowledged, occupant response is increasingly a factor in the case for timber, influencing demand across housing, workplace and education. But while these benefits sit outside standard certification and valuation frameworks its impact will largely be limited to innovative projects with conscientious clients.

Figure: 6 Orsman Road, Waugh Thistleton Architects. Photography: Ed Reeve

CRAWFORD WRIGHT DEPARTMENT FOR EDUCATION “GenZero presented an opportunity for us to rethink standards for school building and instinctively we felt that timber should be a part of that right from the outset. The rationale of timber’s alignment with modern methods of construction and low carbon credentials were actually secondary to our intuitive sense that timber would just create a better learning environment for schools. It felt like the counterpart to classrooms delivered under the standards to date; technically safe, well-functioning spaces but missing a certain intangible quality which would encourage and promote children’s learning.”

Figure: Cederhusen, Hagastaden, Stockholm. Developed by Folkhem. Photo: Emil Nordin

ANNA ERVA ST FOLKHEM “Our ambition has always been to bring craftsmanship back into large-scale housing. Used in the right places, such as common spaces and details, wood is able to add to the quality and the feel of a space. People notice, and they tell us it is surprisingly easy to make it feel like home.” Figure: 6 Orsman Road, London. Waugh Thistleton Architects. Photo: Ed Reeve.

Figure: Hartlepool Free School Gen Zero Pod. Photo by Bowmer + Kirkland

D E F I N I N G H E A LT H

AL WELLBE

community integration A

WELLBEING

physiological

Psychological

function and

balance and

the absence of illness

cognitive resilience

Figure: A conceptual model based on the WHO definition, illustrating that health requires the integration of physical, mental, and social wellbeing.

ALTH

PHYS

Optimal

T O G E NE

PROMOTION OF POSITIVE HEALTH

Mental health has also begun to be placed on a par with physical health, reflected in instruments such as the UK government’s No Health Without Mental Health strategy and parallel policy developments across Europe (Department of Health, 2011).

connection and

Figure: Transition from pathogenesis to salutogenisis

Meaningful social

TREATMENT OF ILL HEALTH

and treatment of illness, has driven medical research and shaped how healthcare is organised across Europe. More recently, frameworks such as the NHS approach to prevention recognise that the conditions sustaining health, including physical activity, sleep and nutrition are as significant as the availability of medical treatment (NHS, 2024).

G E N

For most of medical history, the focus has been on the negative end of that spectrum. Pathogenesis, the diagnosis

The World Health Organization defines health as a state of complete physical, mental and social wellbeing, not merely the absence of disease (WHO, 1948). This definition positions health as an active, positive condition shaped by everyday environments and behaviours, not merely available medicines and treatments.

1.2

Salutogenesis sits at the opposite, positive end of the spectrum. While positive physical health is a concept largely understood, positive mental and social wellbeing have taken longer to define. The term ‘Flourishing’, formalised by psychologist Diener, tries to define this across eight themes: purpose, supportive relationships, engagement, contribution to others, competence, selfacceptance, optimism and feeling respected (Diener et al., 2010). Professor Felicia Huppert later defined this more succinctly as “feeling good and functioning well”. This expanded definition of health, including social and personal welfare as a resource for living, broadens the responsibility for public health beyond the medical profession. The influence of sectors beyond healthcare on positive wellbeing goes largely unrecognised. The built environment may well be the sector with the greatest opportunity to make a positive impact.

1.3

A R C H I T E C T U R E A N D H E A LT H

Architecture and health have always been connected, but as the definition of health has shifted over time, so too has its relationship to architecture. What began as survival became hygiene and safety, and more recently that definition has expanded to include psychological and social resilience. Each era widened the health brief from the one before. The emergence of new technologies with greater resolution on our health is changing this dynamic again. H E A LT H A S S U R V I VA L Before industrialisation, buildings mediated directly between people and climate. Health was practical and immediate. Form, orientation and material regulated exposure to light, air, moisture and temperature. Ventilation and daylight were conditions for living, not design features to be optimised. Early timber construction, often framed in architectural theory through the primitive hut, acted as an environmental moderator, buffering wind, rain, heat and cold while maintaining breathable interiors. Timber was the dominant material not for aesthetic reasons but because it was available, workable and effective. It could be shaped to fit a site, a climate and a way of living. The relationship between material and health was direct and unselfconscious. Health in this period was ecological and embodied, emerging from continuous interaction between people, material and environment (Rykwert, 1972; Banham, 1969). H E A LT H A S N O T G E T T I N G S I C K Industrial cities brought crowding, pollution and disease. Health became defined by the absence of illness and architecture followed (Tulchinsky, 2014). The shift was profound. Density, contaminated water, poor ventilation and insufficient light created the conditions

for tuberculosis, cholera, and typhoid to spread rapidly through urban populations. The built environment responded and buildings became hygienic instruments. Modernist architects adopted germ theory as a design logic, treating light, air and order as defences against infection. Le Corbusier’s machine for living, Aalto’s sanatoria, and the Lovell Health House all prioritised ventilation, daylight, and ease of cleaning above other considerations (Le Corbusier, 1923; Campbell, 2005). White walls, smooth surfaces and open plans were a medical response. H E A LT H A S F LO U R I S H I N G Recent decades have broadened the brief again. Health is now understood to include mental and social dimensions alongside physical ones, and research in medicine, psychology and environmental science has made the case for measuring its impact on building occupants (WHO, 1948; Fisk, 2000). Building frameworks such as WELL have formalised categories covering comfort, mind and environment alongside the physical parameters already embedded in regulation (IWBI, 2014). The concept of biophilia has brought nature and natural materials into design thinking as active contributors to health, with evidence that exposure to natural elements reduces physiological stress levels and supports attention recovery (Kellert et al., 2008; Ulrich, 1984). Neuroarchitecture has begun to map how spatial experience affects emotion, attention and stress at a physiological level (Eberhard, 2009; Steemers, 2015). Choice architecture, developed in behavioural economics by Thaler and Sunstein, has shown that the way environments are designed can nudge behaviour and decision making in ways people are largely unaware of (Thaler and Sunstein, 2008).

PRE-INDUSTRIAL

INDUSTRIAL

FUTURE

Figure: 1) Traditional log cabin. Photo: LeFever Moe, US Fish & Wildlife Service 2) Paimio Sanatorium, Finland. Alvar Aalto, 1933. Photo: Eva and Pertti Ingervo Alvar Aalto Foundation. 3) The Black and White Building, London. Waugh Thistleton Architects.

1.4

D E S I G N I N G F O R H E A LT H

Considering how to design spaces that promote health must begin with an understanding of the spatial qualities and design features that shape occupant health and wellbeing. The tools available to designers lie across a broad spectrum with three main areas: the physical conditions a building creates, the psychological experience it shapes, and the physiological responses it generates in the body. These conditions interact continuously, with most design decisions affecting several aspects of occupant experience at once. PHYSICAL,PSYCHOLOGICAL AND PHYSIOLOGICAL CONDITIONS Physical conditions are the most familiar territory. Air quality, temperature, humidity and light levels can be measured, modelled and assessed against established healthy ranges. Regulation has developed around this understanding over time, driven by evidence of harm. Ventilation standards emerged in direct response to the relationship between humidity, mould and respiratory health. This is where the evidence is most mature and where designers have the most established tools. Psychological conditions are less well understood. Material character, spatial sequence, visual complexity and personal agency over the environment all act on occupants in ways that are real but harder to quantify. Most research to date has relied on self-reporting, asking occupants how a space makes them feel and concluding that a given feature is beneficial, without always establishing why. That approach can identify positive design attributes but it does not yet tell designers which features to prioritise, what combinations are necessary, or whether findings apply equally across different people and contexts. Translating this into regulatory thresholds remains a significant challenge.

Physiological responses lies somewhere in between. The body registers conditions before the mind consciously interprets them. On exposure to environmental stimuli, parts of the brain activate automatically, releasing hormones, shifting heart rate and narrowing attention. These responses can be measured through biomarkers such as cortisol levels and heart rate variability, but interpreting them requires care. Elevated markers are not inherently negative. What matters is not any single measurement but the pattern over time, whether activation is followed by adequate recovery. Self-reporting remains valuable but is insufficient alone, and while physiological measurements, such as heart rate variability, cortisol and blood pressure provide a biological counterpart, collecting them at scale remains technically and ethically complex. INDIVIDUALITY We must also consider that health outcomes from the built environment are not uniform. People respond differently to the same conditions based on biology, background and circumstance. Temperature illustrates this well, as shown in the figure on the right. Acceptable ranges can be regulated but individual perception varies based on long-term factors such as climate of origin, and shortterm factors such as recent physical activity. In addition, personal control over the environment, opening a window or adjusting lighting, has consistently been shown to improve comfort and reduce stress beyond what physical measurement alone would predict. The same seemingly applies to psychological responses. Sensitivity to material character, spatial density and sensory stimulation varies across individuals and shifts across the day as mood, fatigue and context change. However, the significance of individuality on occupant response to timber specifically is not yet fully understood, with further research and investigation required.

Spatial Quality Heart Rate Variability (HRV)

Temperature

Variety

Agency (Adaptive Comfort Theory)

Air Quality (VOC, PM and Co2) Body Temperature Light Levels

Infection Control

Activity Encouraged (Nudge) Respiratory Rate Electroencephalogram (EEG)

Humidity

PHYSIOLOGICAL

PHYSICAL

Biophilia

Social Connection

PSYCHOLOGICAL

Figure: A spectrum of design parameters shapes occupant health across physical, physiological, and psychological dimensions. Physical conditions such as air quality and temperature feature established regulatory metrics. Physiological and psychological conditions, including autonomic responses and spatial sequence, represent developing fields lacking equivalent measurement methods and regulatory frameworks.

I’m Cold

I’m Warm

Figure: Our response to interior environments spans both the physical and psychological. Occupant response is shaped by a range of individual factors including age, background, sensitivity and personal preference, and varies across the course of a day as mood, fatigue and agency shift.

1.5

NEUROARCHITECTURE

BUILDINGS AFFECT ON THE BODY

A C T I VAT I O N A N D R E C O V E RY

Neuroarchitecture traces the ways spatial conditions influence brain and body function (Eberhard, 2009; Sternberg and Wilson, 2006). The responses it describes fall into two categories.

In physiology, stress or arousal describe the body’s necessary response to demand. When a task requires focus or effort, physiological systems activate: heart rate adjusts and cortisol is released. This is normal and useful. Up to a point, performance actually improves as stress activation increases. This is known as the Yerkes-Dodson curve: too little stimulation evades focus, too much and it

Conscious: spaces produce thoughts, emotions, and feelings we are aware of, although often coloured by associations and memories we may not explicitly recognise (Sussman and Hollander, 2015; Damasio, 1994). Unconscious: on exposure to environmental stimuli, parts of the brain activate automatically, preparing the body to respond before any conscious decision is made (Valentine, 2023; Schuller et al., 2025). The stimuli that trigger these responses include everything the senses can detect: sight, sound, smell and touch, as well as qualities the body registers without conscious attention, such as temperature, humidity and air quality. Physical conditions and psychological experience are not separate channels. They form a single regulatory system.

overwhelms. The body manages this through allostasis, the continuous process of adjusting to meet changing demands. Every time the body responds to a stressor, it spends something, and when demands persist without resolution the body never gets the chance to settle. This physiological cost accumulates over time as allostatic load, the longterm wear on a system that is permanently partiallyactivated (McEwen, 2007). Left unresolved, that strain shows up in the body: elevated blood pressure, impaired immune function, disrupted sleep and increased risk of cardiovascular disease.

Figure: The Yerkes-Dodson curve illustrates the relationship between arousal and performance. Too little stimulation and attention wanders; too much and the system becomes overwhelmed. Spatial conditions that support the middle range create the conditions for sustained cognitive function.

It is clear that our surroundings influence this physiological cycle, however there are three possible mechanisms through which architecture could act. Firstly, it may lower the baseline, maintaining a calmer starting state so the body begins each demand from a lower point of activation. Secondly, it may dampen the peak, reducing the magnitude of our response when an independent stressor occurs.

REDUCING THE PEAK

And finally, it may accelerate or enable the return, helping the body recover more quickly after activation. This recovery cycle is most critical during sleep, when much of the body’s physiological restoration and cellular repair takes place. Physical activity is also vital for stress regulation, as movement helps clear circulating stress hormones and regulate blood glucose. Spatial layouts that encourage rest, movement and circulation can therefore function directly as health interventions. Ultimately, healthy buildings are defined by their capacity to support the body’s transition between physiological effort and recovery throughout the day.

ENABLING RECOVERY

LOWER BASELINE Figure: Lower the baseline, dampen the peak, and accelerate recovery - sustained across a day, these three possible mechanisms of influence reduce allostatic load over time.

Figure: Allostatic load accumulates when the body’s stress and recovery cycle is persistently disrupted. Each demand placed on the system has a physiological cost. When activation is not followed by adequate recovery, that cost compounds over time, showing up as elevated blood pressure, impaired immune function and increased risk of chronic disease

THE EVOLUTIONARY CONTEXT The built environment has evolved faster than our biology. Our cities are modern, but it takes time for our nervous system to adapt. For 300,000 years, most of human evolutionary history, the sensory environment comprised savannah, woodland, and forest (Richerson and Boyd, 2005). Natural textures, materials and living systems provided the backdrop against which human neurobiology developed. It was only in the last 10,000 years, with the emergence of settled agriculture and early timber construction, that built environments began to replace natural ones. And only in the last 200 years that industrialised cities became the dominant habitat for a significant proportion of the human population (Morris, 2010). Contemporary urban environments have replaced sensory conditions with surfaces and stimuli our bodily systems have no deep framework for reading, and it is hypothesised that this unfamiliarity maintains the body in

a state of chronic low-level alert (Valentine, 2025). The consequences accumulate quietly, across hours, days and years, in ways that standard environmental measurement does not capture (McEwen, 2007). Natural materials reintroduce sensory information the body already knows how to process. This is evidenced through exposure to natural elements reducing physiological stress markers, supporting attention recovery, and lowering baseline arousal compared to equivalent synthetic environments (Kaplan, 1989; Ulrich et al., 1991). Natural materials do not resolve the broader conditions of urban life. But they are one of the more direct ways of closing the gap between the environments we have built and the one our bodies evolved to inhabit. Research relating to this evolutionary context theory has largely focussed on visual processing, however it is likely that the impact is multisensory.

DEEP HISTORY

AGRICULTURAL

INDUSTRIAL

3,000,000 BCE

10,000 BCE

1850 CE

Figure: The transition from natural to built environments has occurred across a timeframe too compressed for meaningful biological adaptation. The human nervous system continues to respond to contemporary spaces as it evolved to respond to the natural world.

1.6

PHYSICAL CONDITIONS

Regulations typically govern building parameters for which measurement tools and threshold values exist. For physical conditions, measurable parameters and subsequent regulatory frameworks are extensive, robust and wellunderstood. This is in part due to knowledge which evolved as a result of the need to overcome Sick Building Syndrome. The condition, formally named by the World Health Organisation in 1983, described a cluster of symptoms, including fatigue, headaches, poor concentration and respiratory irritation, that appeared in occupants of certain buildings and resolved when they left (WHO, 1983). The response was regulation of various physical parameters to prevent the poor quality internal environment which had caused this ill health. EN 16798-1:2019 now sets baselines for thermal comfort, air quality, lighting and acoustics across residential and commercial buildings (CEN, 2019). W H AT C U R R E N T M E A S U R E S CAPTURE Thermal comfort is monitored through smart building systems that track temperature and humidity continuously across occupied spaces. Acoustic performance is measured against reverberation time targets. Lux levels capture lighting quantity. Particulate matter captures airborne particles affecting respiratory health, and VOC concentrations are measured by air sampling against established limits. The equipment used for these different measurements is widely available and standardised. What is not yet routinely captured is occupant response to conditions in real time. Combining building-level environmental monitoring with physiological measurement across full occupancy periods is where the field is moving (Whyte et al., 2024; Kumpulainen et al., 2024).

TIMBER AND THE EVIDENCE Our literature review has examined myriad studies which have measured the physical parameters of timber buildings and we have conducted interviews with various experts within this field. These studies have shown that timber buildings are generally able to achieve the same regulated levels of performance across these various criteria as other buildings using more conventional materials. Through discussion with MEP engineers, typically responsible for the design for internal environments, we have established that their design process does not take the presence of timber into account. An exception being lighting, where the reflectance of timber surfaces has to be factored into analysis of a given space alongside other internal finishes. As such, the often-quoted ability of timber to buffering of temperature and humidity, while real, is not significant enough in scale to enable a step change in design methodology or ventilation strategy, and as such should not be a primary design consideration. The physical evidence is the most mature in this review and the most consistent across study quality assessment under the GRADE quality metrics. Studies draw on a mix of real occupied buildings and controlled laboratory conditions. Some findings are specific to timber; others reflect general building performance in which timber was the structural material. The table to the right presents findings grouped by parameter. The measurement column indicates the instruments and methods typically used to assess each parameter. Notes on study quality, methodology and limitations are referenced in the appendix.

P H Y S I C A L PA R A M E T E R S PARAMETER

LITERATURE REVIEW SUMMARY –

– Air quality –

–

– Thermal comfort and humidity –

–

Acoustics

Lighting

–

TYPICAL MEASUREMENTS

Timber buildings perform within accepted parameters across all measured indoor environmental quality conditions. (Stenson, Calautit and Tien, 2020) Wooden interior materials perform well across IEQ, thermal measurements. (Alapieti et al., 2020) Reviews across multiple typologies confirm timber buildings meet or exceed performance requirements on all regulated parameters. (Burnard and Kutnar, 2015)

Continuous air quality sensors, paticulate monitoring, IEQ monitoring across full occupancy periods

Timber performs to standard on thermal comfort. Hygroscopic properties allow timber to absorb and release moisture, moderating humidity fluctuations in occupied spaces. (Hameury, 2005) Wood surfaces feel closer to ambient temperature on contact due to lower thermal conductance than metal, glass, or stone. This registers as non-threatening in the body’s sensory system. (Ikei et al., 2017) Identical physical temperature conditions produce different psychological outcomes depending on whether the occupant has environmental control. (Dorizas et al., 2024; Nicol and Humphreys, 2002)

Temperature and humidity sensors, smart building monitoring, perceived comfort surveys

Exposed timber surfaces absorb and scatter sound differently from glass or concrete, altering reverberation time and background noise character. (Harrington, C. 2019 ;Yin, J., & Ai, X, 2024) Reviews across residential, commercial, education, and healthcare confirm timber performs consistently on acoustic dimensions. (Burnard and Kutnar, 2015; Alapieti et al., 2020)

Reverberation time measurement, background noise levels, speech ineligibility testing

Warm reflectance of exposed timber surfaces produces a softer visual environment. (Kwak & Choi, 2025; Fell, 2010)

Lux level measurement, reflectance calculations.

SOLID SPRUCE SOLID SPRUCE

Primary VOCs: Terpenes, Alpha-pinenes, aldehydes Primary VOCs: Terpenes, Alpha-pinenes, aldehydes

GLUE-LAMINATED TIMBER GLUE-LAMINATED Primary VOCs: Formaldehyde, TIMBER pMDI

Primary VOCs: Formaldehyde, pMDI

ORANGES

HOUSEHOLD CLEANER HOUSEHOLD CLEANER

Primary VOCs: Limonene, Myrcene

Primary VOCs: Ethanol, Benzene

Primary VOCs: Limonene, Myrcene 3000

Primary VOCs: Ethanol, Benzene

2000

3000

550

300

ORANGES

2000

550

300 Months

Months

Figure: The types,Months concentrations and half-life of VOCs emitted Months from engineered timber products as comparedMonths to an orange and a typical household cleaningMonths product, illustrating the level of variation and challenges presented by measuring only TVOCs.

ON VOCS VOCs are airborne chemicals released by building materials, furnishings, cleaning products, and occupants. They are present in every indoor environment and are managed primarily through material specification and ventilation. Currently, most certification frameworks (such as WELL) evaluate total VOC (TVOC) concentrations as a single, aggregate metric. This methodology treats benign terpenes and hazardous formaldehyde as chemically equivalent, despite drastically different health implications. Timber emits naturally occurring terpenes, the aromatic compounds responsible for it’s characteristic scent, which are generally considered to be harmless. Once timber is processed, these terpene concentrations also decay rapidly. Levels in finished buildings fall well below those found in natural forest environments. Initial VOC spikes, significantly above the TVOC concentrations targeted in frameworks such as WELL, are a universal phenomenon across all modern construction at 24

the point of furniture fit-out. The emissions from furniture are not typically regulated and generally dwarf those from the base build with significant research needed in this area. Despite this, emissions levels in newly built homes drop sharply within the first six to eight months, to well within compliance limits in properly ventilated buildings (Fürhapper et al., 2017). Engineered timber products, such as cross-laminated timber (CLT) and glulam, use adhesives that can release formaldehyde-based compounds during the early postinstallation period. Varnishes and synthetic coatings can also introduce VOC loads independent of the timber product itself. Like most materials used in construction further work is needed to reduce the need for VOC emitting substances while not reducing the various performance requirements of the products in question. The timber industry has already begun the shift toward lowemission alternatives to address this. Structural products are increasingly specified to strict E0 and E1 emission classifications under EU standards, offering a clear route to managed regulatory compliance (CEN; AgBB; ECHA).

VOC SUMMARY SOURCE

LITERATURE REVIEW SUMMARY –

Timber VOC emissions –

–

Adhesives and coatings

–

TVOC measurement

–

Positive effects from VOCs (forest bathing)

Untreated timber emits naturally occurring terpenes. At building concentrations these are not harmful. Emissions peak in the first 6–8 months after installation and stabilise in ventilated buildings.(Fürhapper et al., 2017; Jensen et al., 2001) In a CLT model room, TVOC concentration decreased by 64 per cent over 23 weeks, from 115 to 41 μg/m(Hollbacher et al., 2014) Engineered timber products use adhesives that can release formaldehyde during the early post-installation period. Of the common structural adhesive systems, MUF carries the highest formaldehyde emission risk; PRF also contains formaldehyde but emits it at substantially lower levels. PUR systems are formaldehyde-free. Heavy varnishes and synthetic coatings introduce VOC loads independently of the timber. (CEN; AgBB; ECHA; Harb et al., 2018)

TYPICAL MEASUREMENTS

TVOC (μg/m³)

TVOC (μg/m³) EN 717 and related CEN standards

Many certification frameworks use total VOC concentration as a single aggregate metric. This approach does not distinguish between compound classes: terpenes emitted naturally by timber are weighted identically to formaldehyde from adhesive resins. Some schemes apply individual substance limits alongside the TVOC threshold, but the aggregate figure remains the primary compliance trigger in practice. (Andersson et al., 1997; Ohlmeyer, 2024)

TVOC (μg/m³)

Forest bathing research documents have been observed at terpene concentrations substantially higher than those recorded in finished timber buildings, where indoor monoterpene levels typically range from 20–90 µg/m³. Whether equivalent effects occur at indoor concentrations remains untested; the beneficial-effects literature does not extend to building interiors. (Li et al., 2007; Li, 2010; Park et al., 2010)

TVOC (μg/m³)

1.7

PSYCHOLOGICAL RESPONSE

Buildings shape psychological health through the conditions they create and the behaviours they encourage. A well designed space can support occupants in feeling and performing at their best across the day through the accumulation of small conditions that add up over time.

WELL’s Mind concept includes occupant survey requirements covering stress, restoration and cognitive engagement, with its 2025 Performance Rating moving toward demonstrated outcomes rather than design intent (IWBI 2020).

Psychological response is complex due to its individuality. Variation in response to environmental conditions is well established, what registers as positive for one person may not for another, and is shaped by background, activities and context (Humphreys and Nicol, 2002)

Approaches are increasingly being informed by emerging methods that bring greater precision to psychological measurement. EEG measures of neural response sit at

When people can adjust their environment, they feel better and perform better regardless of what the physical conditions measure. Buildings can shape behaviours below conscious awareness and also promote physically healthy activities (Thaler and Sunstein, 2008). W H AT C U R R E N T M E A S U R E S CAPTURE Measuring psychological response to buildings is harder than measuring physical conditions. The field currently relies heavily on self-reporting, asking occupants to evaluate their own experience. Tools such as Diener’s Flourishing Scale (Diener et al. 2009) and the Perceived Stress Scale or Plutchik’s Wheel of Emotions can provide a structure against which questions or responses can be framed (Plutshik 1980, Cohen, Kamarck, and Mermelstein 1983). Post-Occupancy Evaluation Frameworks provide a yet more structured process and guidance against possible bias which may be created through leading questions or participant knowledge of the survey aims. For example BS 40101 provides a British Standard framework for building performance evaluation including occupant satisfaction (BSI 2022).

the boundary between psychological and physiological evidence and appear in some studies reviewed here, however their practical requirements typically limit their use. TIMBER AND THE EVIDENCE The psychological evidence base is the broadest in this review and the most methodologically varied, drawing on controlled experiments, cross-cultural surveys and observations in occupied buildings. Some findings are specific to timber interiors; others reflect responses to natural materials and biophilic environments more broadly (Bowler et al., 2010; Augustin and Fell, 2015). Most studies rely at least in part on self-reporting; however, the stronger studies use controlled conditions and support their findings with physiological measurements. Despite variation in study qualities, timber environments are perceived as warmer and calmer than conventional equivalents across countries and building types (Fell, 2010; Burnard and Kutnar, 2015; Li et al., 2021). The table overleaf presents findings grouped into four areas: emotional state and affect, cognitive performance, connection and belonging, and productivity.

optimism

love serenity

interest aggressiveness

trust

submission

ecstasy vigilance

annoyance anger

admiration

rage

terror

loathing contempt

acceptance

joy

anticipation

disgust boredom

fear

apprehension

amazement grief sadness

surprise

awe

distraction

pensiveness remorse

disapproval

PLUTCHIK WHEEL OF EMOTION Figure: The Plutchik Wheel of Emotion, a psychological framework developed by Robert Plutchik in 1980 that maps human emotions and how they relate to each other.

MEMORY

SEASONAL LIVING

CULTURE

ACTIVITY

Figure: The diagram highlights how our conscious and unconcious psychological state and emotion is influenced by our unique experiences and context, making generalisations challenging.

PSYCHOLOGICAL EVIDENCE PARAMETER

Emotion and affect

LITERATURE REVIEW SUMMARY –

Timber interiors perceived as warmer, calmer, and more comfortable than mineral or synthetic equivalents across countries, building types, and age groups. (Fell, 2010; Burnard and Kutnar, 2015; Alapieti, 2020; Mamic and Domljan, 2023)

–

Positive perception among younger adults in Finnish and Japanese residential contexts. ( Hayrinen et al., 2020, Sun et al., 2020)

–

Significantly lower anxiety in timber room. RCT with 61 office workers. (Ojala et al., 2023)

–

Higher positive affect, lower negative affect, lower breathing rate in timber room vs resin plaster reference. Real occupied space. (Kumpulainen et al., 2024)

–

Wood as restorative material in healthcare: evidence across stress reduction, relaxation, and cognitive recovery. (Augustin and Fell, 2015; Nyrud, Bringslimark and Bysheim, n.d.)

–

Natural environments associated with lower levels of tension, confusion, anger, and depression. (Bowler et al., 2010)

–

Psycho-physiological relaxation responses from wood odour across multiple species. (Matsubara et al., 2020; Chen et al., 2015)

–

Natural surfaces rated more positively on emotional touch than varnished equivalents. 20 participants, eight pine and oak surfaces. (Bhatta et al., 2017) Consistent psychological responses to wood surface coverage across Japan, Canada, and UK. Effect is not culturally specific. (Li et al., 2021)

–

TYPICAL MEASUREMENTS

Self report

PSYCHOLOGICAL EVIDENCE –

Visual exposure to wood associated with positive affect and improved cognitive performance across residential, office, education, and healthcare settings. Systematic review of randomised trials. (Lipovac and Burnard, 2021 Shen et al., 2020)

–

Natural wood produced highest task accuracy (93%) and clearest neural relaxation on EEG across four material environments: natural wood, processed wood, concrete, metal. (Ceylan and Erkan, 2025)

Thinking and focus

Connection and belonging

Accomplishment and productivity

–

Cognitive and physiological performance in biophilic indoor environments measurably better than in conventional ones. (Yin et al., 2018)

–

Natural wood produced highest cognitive task accuracy (93%) and clearest neural relaxation on EEG across four material environments. (Ceylan and Erkan, 2025)

–

Majority of occupants across five UK mass timber buildings reported feeling more relaxed and connected to nature. Two-year study. (Scott et al., 2025)

–

Workplace biophilia studies confirm stronger connection to nature and higher overall satisfaction in timber buildings. (Lei, Lau, Gou and Zhang, n.d.)

–

Workers in mass timber office showed self-reported improvements in productivity alongside decrease in hair cortisol over 3 months. (Whyte et al., 2025)

–

Relocating to a green-certified building produces measurable improvements in wellbeing and productivity over time. Longitudinal before-after study. (Thatcher and Milner, 2014)

Task performance / outcomes

Observation

Self report

1.8

PHYSIOLOGICAL RESPONSE

The mind and body responds to its environment physiologically as well as perceptually. How a space is interpreted triggers two response systems that operate in parallel. The hormonal system releases cortisol in response to perceived demand, a slower process that accumulates over weeks and months and leaves a measurable record in the body. And the autonomic system regulates heart rate, breathing, and blood pressure moment to moment, shifting between activation and recovery in response to environmental demand. When these systems are repeatedly activated without adequate recovery, the cumulative physiological cost is allostatic load (McEwen, 2007). W H AT C U R R E N T M E A S U R E S CAPTURE Three measurements are typically used to make these responses visible, each capturing a different dimension of the body’s regulatory state. Combining two measurements produces a more complete picture of the autonomic and hormonal systems, since they can respond independently (Cacioppo and Tassinary, 1990) Heart rate variability (HRV) measures the natural variation between heartbeats. Higher variability indicates parasympathetic nervous system activity, associated with rest and recovery. Lower variability indicates sympathetic dominance, associated with activation and stress. HRV can now be tracked continuously with a wearable device across a full working day without disrupting normal activity. However, accessing these data for research still presents practical challenges, and to date we are not aware of a study that has utilised this real-time data in the context of timber’s impact within the built environment. Cortisol can be measured in two ways. Salivary cortisol reflects hormonal activity over the previous twenty to thirty minutes, capturing acute responses during a test scenario. Hair cortisol captures cumulative hormonal load over 30

weeks to months by analysing the cortisol deposited in the hair shaft as it grows. Hair cortisol is the only measure that can speak to long-term physiological impacts rather than a single acute response, which is important due to the timeframes in which we inhabit built environments. However, isolating the impact of a specific space or building within this long-term reference still poses challenges Electroencephalography (EEG) records the brain’s electrical activity through sensors on the scalp. Higher alpha wave activity indicates a calm, recovered state. Higher beta activity indicates active cognitive effort. EEG shows how much processing effort is occurring in the brain moment to moment. However it can be challenging to pin point a single cause of such activity. For the full explanation of physiological measurement tools, see Appendix: Mind and Body. TIMBER AND THE EVIDENCE The impact of timber on our physiological state is unlikely to be directly causal but instead related to a multi sensory experience, which is in turn influenced by past experience and context. The table overleaf summarises the physiological findings across four channels of stimulation: visual, haptic, acoustic, and sustained occupancy. Where individual studies carry specific limitations they should be read as indicators of where the evidence is still developing. The general evidence on noise and physiological arousal is well established. The specific contribution of timber as a material to acoustic health outcomes has not yet been isolated from overall room acoustic design, and the table reflects that gap. For the full neurophysiological evidence review, see Mind and Body.

HAIR CORTISOL ANALYSIS HAIR CORTISOL ANALYSIS

SALIVARY CORTISOL ANALYSIS SALIVARY CORTISOL ANALYSIS

HAIR CORTISOL ANALYSIS HAIR CORTISOL ANALYSIS

TIMESCALE: WEEKS AND MONTHS TIMESCALE: WEEKS AND MONTHS

SALIVARY CORTISOL ANALYSIS SALIVARY CORTISOL ANALYSIS

HRV ANALYSIS HRV ANALYSIS

TIMESCALE: HOURS

EEG ANALYSIS

TIMESCALE: HOURS

EEG ANALYSIS

HRV ANALYSIS

CONTINUOUS AUTOMATIC MONITORING

HRV ANALYSIS

CONTINUOUS AUTOMATIC MONITORING

TIMESCALE: WEEKS AND MONTHS TIMESCALE: WEEKS AND MONTHS

TIMESCALE: HOURS TIMESCALE: HOURS

CONTINUOUS AUTOMATIC MONITORING CONTINUOUS AUTOMATIC MONITORING

REAL TIME DETECTION REAL TIME DETECTION

Figure: Three physiological measurement time scales; Hair cortisol (months) · Salivary cortisol (hours) · HRV / EEG (real-time)

EEG ANALYSIS

REAL TIME DETECTION

EEG ANALYSIS

REAL TIME DETECTION

Electroencephalography (EEG)

Figure: Andrew Waugh performs an EEG recording during tactile stimulation . Electroencephalography (EEG) measures real-time electrical activity in the brain via scalp electrodes here captured during a wood-touching task as part of psycho-physiological research

PHYSIOLOGICAL EVIDENCE PARAMETER

LITERATURE REVIEW SUMMARy –

45% wood coverage produced highest comfort ratings and significant diastolic blood pressure decrease. 90% coverage reduced alertness. (Tsunetsugu et al., 2007; 2002)

–

Grain and knot patterns attract and hold visual attention without demanding sustained interpretation, supporting directed attention recovery. (Nakamura and Kondo, 2007; 2008)

–

Knotty and naturally varied surfaces produce greater parasympathetic activation than uniform clear-grain surfaces. (Ikei, Nakamura and Miyazaki, 2020)

Visual

Haptic

Blood pressure, HRV, EEG, eye tracking, computational visual stress analysis

–

Vertical vs horizontal timber arrangements produce different physiological responses relevant to facade and interior design. (Nakamura, Ikei and Miyazaki, 2019)

–

Cross-national replication of wood coverage and physiological response across China, Canada, and UK. (Li et al., 2021)

–

Systematic review of randomised trials: visual exposure to wood associated with positive affect, lower physiological arousal, and improved cognitive performance across typologies. (Lipovac and Burnard, 2021)

–

Wood contact has physiological and progressive blood pressure reduction over time. Synthetic surface contact produces sustained blood pressure elevation. (Sakuragawa et al., 2008; Morikawa et al., 1998)

–

Palm contact with white oak reduced prefrontal cortex activation and increased parasympathetic activity compared with marble, Blood pressure, HRV, EEG, , tile, and stainless steel. (Ikei et al., 2017) eye tracking, computational Foot contact with hinoki cypress produced parasympathetic visual stress analysis activation and reduced sympathetic activity compared with tile. (Ikei et al., 2018)

–

Heavy varnish weakens physiological effect. Lightly finished surfaces produce stronger autonomic responses.(Ikei et al., 2017; Bhatta et al., 2017)

–

RCT with 61 office workers: significantly lower anxiety in timber room. (Ojala et al., 2023)

–

Natural sound environments support physiological recovery more effectively than urban noise or artificial masking. (Ulrich et al., 1991) HRV, stress markers, concentration measures Timber lined spaces alter acoustic character in ways that may bring rooms closer to natural acoustic conditions. (Haapakangas et al. 2008)

Acoustic –

MEASURED

PHYSIOLOGICAL EVIDENCE

Sustained occupancy

–

Workers relocating from conventional office to mass timber building showed decrease in hair cortisol over 3 months alongside wellbeing and productivity improvements. Cortisol levels decreased but requires larger sample size and more variables to be monitored (Whyte et al., 2025)

–

Significantly higher HRV in timber interiors than conventional ones in cross-over studies conducted in real occupied spaces, not laboratories. (Kumpulainen et al., 2024)

–

Multi-measure study across 50 participants in oncology waiting room: HRV improved and cortisol decreased in timber condition. EEG subset was 4 participants. (Kotradyova et al., 2019)

Hair cortisol, HRV, EEG, ECG, blood pressure, salivary cortisol, self-report

1.9

R E S U LT S A N D L I M I T S

W H AT T H E E V I D E N C E S H O W S

W H AT T H E G R A D I N G R E V E A L S

On physical environmental performance, timber buildings meet regulatory requirements across air quality, thermal comfort, acoustics and lighting.

Most studies occupy lower tiers of the clinical evidence hierarchy. They are characterised by short-term laboratory experiments, small sample sizes frequently below thirty participants, reliance on single sensory channels and a restricted range of physiological indicators (Burnard and Kutnar, 2015; Fell, 2010; Lipovac and Burnard, 2021). A systematic review confirms that

On psychological response, occupants in timber buildings report lower anxiety and better cognitive performance than occupants in equivalent conventional buildings. The evidence spans residential, office, education, healthcare and infrastructure typologies. On physiological response, blood pressure is lower, heart rate variability is higher, and cortisol decreases over months of occupancy in timber buildings. The analysis of methodology and findings presented here focuses on the psychological and physiological effects documented in empirical studies, identifying research gaps, methodological limitations and potential negative outcomes.

fragmentation across protocols, participant cohorts and wood products renders cross-study comparison unreliable (Cavaliere et al., 2025). By clinical research standards, most findings grade as preliminary: sufficient to justify further investigation, but insufficient to support evidence-based design or health-positive policy. This reflects the difficulty of studying the built environment. Isolating timber within a system as complex as an operational building occupied by individuals over months and years presents logistical challenges due to environmental and behavioural variability. Current research is restricted to identifying immediate resultant signals to build a case for more rigorous, long-term study.

THE QUALITY OF THE EVIDENCE: M E T H O D O LO G I C A L L I M I TAT I O N S The preceding chapters demonstrate a consistent record: timber-rich environments are associated with reduced physiological stress, improved self-reported wellbeing and measurable shifts in autonomic function. What the current literature cannot yet support is precise design guidance or confident causal claims. The primary limitation is not the absence of physiological signals, but the statistical strength, duration and comparability of the evidence, alongside the challenge of isolating individual material factors from confounding variables. Applying a standard evidence-quality framework to this body of work reveals a pattern. The findings are promising, yet the studies producing them share methodological limitations. These deficiencies must be addressed through larger sample sizes and longitudinal research designs. 34

Five core recurring challenges have been identified: 1. Confounding factors: Modern timber buildings are typically also of high design quality, with good daylighting, optimised acoustics and generous spatial volumes. Each of these parameters independently supports occupant wellbeing, so when all are present, isolating the specific contribution of biophilic timber surfaces becomes problematic. For instance, a pilot study at T3 Collingwood tracked hair cortisol and self-reported wellbeing over three months, yet failed to pair this data with continuous, localised physical environmental measurements (Whyte et al., 2025).

4. Baseline variance: Allostatic load and baseline physiological stress differ between individuals based on history, sleep, mental health and broader life context. Population averages may conceal strong positive signals within specific groups while producing no net effect overall. No study to date has been designed with a sufficient sample size or participant stratification to control for this variance.

2. Novelty bias and adaptation effects: In urban environments dominated by concrete and plasterboard, exposed structural timber is visually unusual. Positive physiological responses may reflect short-term novelty rather than a sustained material-specific effect. It is possible that these responses reduce over time through psychological adaptation, no study has tracked occupants across a full tenancy period to test the long term effects.

5. Quantity and placement: Physiological benefits do not necessarily scale linearly with quantity of material. Internal responses appear to peak at moderate timber surface coverage, with diminishing returns or elevated cognitive simulation reported beyond approximately 45% coverage (Tsunetsugu et al., 2007). The precise influence of wood species, chemical finishes, grain distribution and spatial placement remains poorly defined.

3. Temporal limitations: The allostatic load pathways operate across weeks, months and years (McEwen, 2007). In contrast, almost all existing studies measure human responses over minutes or hours. While theoretical frameworks for architectural allostatic overloading have been established (Valentine and Steemers, 2023, 2024), the empirical bridge between acute autonomic response and long-term endocrine or regulatory change remains unbuilt.

Natural pattern Warmth

Natural Natural Natural pattern pattern pattern

Warmth Warmth Warmth Evokes

Individuality Individuality Individuality Individuality

Evokes Visual Visual Evokes Evokes memory memoryVisual Visual interest interest memory memory interest interest

Olfactory

Olfactory Olfactory Olfactory

Acoustic

Acoustic AcousticAcoustic

Figure: Timber’s impact is multisensory, unlikely to be directly causal or linear, but multifaceted.

P O T E N T I A L N E G AT I V E PSYCHOLOGICAL EFFECTS While the literature emphasises positive or neutral outcomes from exposure to timber, there are also psychological and environmental risks which remain under-researched: Aesthetic monotony: Timber’s natural patterns used across floors, walls and ceilings can have feelings of visual monotony. The lack of visual contrast and texture variation can lead to sensory under-stimulation or psychological aversion over sustained occupancy, as is the case in other spaces designed without variety. Visual distraction: Highly figured or knot-heavy timber species can introduce visual noise to a space. For some, this complex visual information can act as a distraction, disrupting sustained attention for those sensitive to intense patterns. Acoustic design: Timber elements alone are typically not adequate to address reverberation needs within a space and therefore can present acoustic challenges if other surfaces, materials and furniture are not designed with reverberation times in mind. Excessive reverberation or echoes can otherwise cause cognitive fatigue and triggering of the sympathetic nervous system. However it should be noted that this would also be the case, and to a much greater degree, for buildings constructed with conventional materials such as concrete, which is highly acoustically reflective. Associations: While for many, wood carries deeply ingrained associations with nature, calm and warmth, as well as secondary associations with craftsmanship. Negative associations of timber within any given building population are also possible and must not be overlooked. These associations can be conscious or subconscious but will, whether positive or negative, still have bearing on a user’s multisensory experience of timber exposure. Moderating the level of timber within a space and providing variety are ultimately critical to ensuring choice and flexibility where preferences may differ.

WHERE THE GAPS LIE The evidence establishes that timber-rich, well designed environments correlate with reduced physiological stress and improved self-reported wellbeing across diverse sensory channels and building types. It does not yet support: – Clear causal attribution to the chemical or material properties of wood independent of design quality. – Quantifiable design thresholds (eg precise surface area-to-volume ratios for specific use cases). – Verified long-term health outcomes resulting from sustained, multi-year occupancy. Developers, occupiers and institutional investors cannot currently calculate the precise value or health returns of the specific use of timber within a space. Despite this, the resulting increased rental evidenced by forerunners such as The Black & White Building, demonstrate the financial case and justify further investigation and research towards that aim. PROPOSED GUIDANCE The evidence has steered us to establishing five principles for how to design spaces which support our psychology and physiology. These five areas: variety, spatial quality, biophilia agency and nudge, are broad and not specific to timber. We believe it is important for designers to understand the holistic ways in which they can design to support the wellbeing of building occupants before considering where timber sits within this framework. The diagram opposite gives an indication as to the types of design tools which can be considered under each heading. Specific, quantified requirements are not realistic at this stage, but a heightened awareness of this spectrum of considerations and the potential for their effects to be multiplied when combined can hopefully go some way towards the level of recognition required to inform regulation. We are sure that this list will not be conclusive and invite feedback and critique as part of the design process. These points are elaborated within the following section.

Different spatial conditions VARIETY

Different materials & colours Change Height / volume Light conditions

SPATIAL QUALITY

Materiality Natural materials Nature in a space

BIOPHILIA

effects +++ multipliedeffects

mult iplied

Views of nature Manually operable controls AGENCY

Flexible layouts Options / choices Physical activity promoted

NUDGE

Social interaction promoted Variety promoted

COMPOUNDING EFFECTS Figure: The five proposed psychological design principles as well as initial design tools for consideration within each. Timber sits most notably within biophilia, as set out across our analysis

DESIGN TOOLS USED IN COMBINATION CAN MULTIPLY THEIR EFFECT

of the research, however it is clear that its effect is hugely influenced by many other design parameters.

PHYSICAL

PSYCHOLOGICAL

PSYCHOLOGICAL Temperature Variety

Humidity

PHYSICAL

Temperature

PSYCHOLOGICAL

Variety

Nudge

Light Levels Humidity

PHYSICAL Temperature Nudge

Light Levels

PHYSICAL

Agency over our environment

Air quality (VOC, PM & CO2 levels)

PSYCHOLOGICAL

PSYCHOLOGICAL Variety

Humidity Agency over our environment

Temperature Spatial quality

Air quality (VOC, PM & CO2 levels) Light Levels

Nudge

Variety

Humidity

Temperature Variety

Air quality (VOC, PM & CO2 levels)

Humidity Nudge

Light Levels

Air quality OC, PM & CO2 levels)

Biophilia

Spatial quality

Agency over our environment

Nudge

Light Levels

U S Biophilia E / ACTIVITY 1 Spatial quality Air quality (VOC, PM & CO2 levels)

Agency over our environment

USE / ACTIVITY 2

Agency over

Spatialquantity quality environment Biophilia Figure: Whatourwe have not aimed to outline through this publication is what of these different design principles might be needed in any given space. We hypothesise that what our

minds need for different activities, undertaken in different spaces, will likely differ and so too should the architectural means of supporting this.

Spatial quality

Biophilia

37 Biophilia

Temperature

PHYSICAL Variety

PSYCHOLOGICAL

PHYSICAL

Humidity

1.10 DESIGN CHECKLIST

PSYCHOLOGICAL

Nudge Temperature

Variety

Light Levels Humidity Agency over our environment

Air quality (VOC, PM & CO2 levels)

Temperature Variety

PHYSICAL Light Levels PHYSICAL

Nudge

PSYCHOLOGICAL

Humidity

PSYCHOLOGICAL Nudge

Spatial quality

Air quality (VOC, PM & CO2 levels)

Temperature Biophilia Humidity

Air quality AgencyHuman over (VOC, PM & CO2 levels) interaction our environment encouraged Light Levels

Temperature Infection Control

Activity Variety

Agency over our environment

Agency over Biophilia our environment

Variety

encouraged Air quality Spatial quality (VOC, PM & CO2 levels)

Humidity

PHYSICAL

PSYCHOLOGICAL

Light Levels

Nudge

Nudge Biophilia

PHYSICAL

Spatial quality

PSYCHOLOGICAL

Lightinternal Levels surfaces is typically plasterboard, whose thermal

Temperature

T E M P E R AT U R E – Air temperature – Radiant temperature Variety – Air flow

response is similar to timber, as such the presence of an exposed timber surface is unlikely to change the thermal Biophilia Agency over design strategy unless it our is environment compared with extensive Air quality of exposed concrete. (VOC, PM amounts & CO2 levels) Temperature

Regulations typically define internal air temperature Humidity targets based on the intended use of a space; however, it is important to remember that Nudge true thermal comfort is influenced not only by air temperature but also radiant heat, airflow and humidity, as well as occupant specific Light Levels factors such as familiar climate, current season and activity level. Agency over our environment

Air quality When designing with timber, consider that it has lower (VOC, PM & CO2 levels)

thermal conductivity than high-mass materials such as concrete, meaning it quickly adapts to the ambient air temperature. Conversely high Spatial mass quality materials store and re-emit heat (or cold) stored within the material long after the air temperature has changed, acting as a radiant temperature source. There are positive and negatives to each of these temperature responses, meaning it is Biophilia critical for the design approach to take the thermal mass (or absence of thermal mass) of exposed surfaces into account. In modern buildings, the current default for 38

Variety

Humidity

HUMIDITY Spatial quality – Relative humidity – Absolute humidity

As with temperature, regulations typically Nudge define a relative humidity range for different types of spaces, which is set Biophilia high enough to prevent dry eyes, skin and respiratory Light Levels issues, but low enough to prevent humidity being a barrier to perspiration (the body’s natural Agency overthermoregulating our environment system). It is for this reason that humidity is also a relevant Air quality in levels) the overall perception of thermal comfort. In (VOC,factor PM & CO2 addition, overly high relative humidity has also been linked with mould growth, with consequent negative health Spatial quality implications, and can cause structural and/or aesthetic issues with some building materials. When designing with timber, consider that while it is true that as a hygroscopic material exposed Biophilia uncoated timber surfaces have the ability to buffer moisture, the rate and

Temperature Variety

Humidity Nudge

PHYSICAL

PSYCHOLOGICAL Light Levels

scale of impact of this buffering is comparatively minimal AIR QUALITY and is therefore unlikely to lead to any step change in the – Carbon dioxideAgency over our environment design approach required to achieve the target criteria. – VOCs Air quality Considering the above can liberate the use of surface (VOC, PM & CO2 levels) – Particulate matter Temperature Variety treatments and coatings for timber to enhance other performance criteria without concern around the loss of In modern buildings, where the envelope is designed to Spatial quality significant humidity benefits. be highly airtight, internal air quality is typically regulated Humidity by ventilation requirements which dictate a number of L I G H T L E V E L SNudge air changes per hour. This ventilation can be achieved – Illuminance naturally, mechanically or via a combination of both. The Daylight and glare control idea is to replace stale internalBiophilia air with fresh air from Light Levels – – Light quality and colour outdoors in order to control levels of CO 2 and moisture produced by building inhabitants, as well as VOCs and Agency over environment Illuminance levels for differentour room types and tasks are particulate matter which can originate from internal

Air quality by regulation. Usually, a combination (VOC,typically PM & CO2 defined levels)

of natural and artificial light is required to achieve these levels, with secondary illumination via light reflected Spatial quality from interior surfaces also taken into account as a significant contributing factor. Consideration of the colour temperature, colour rendering index and brightness of artificial lights can help to emulate the qualities of natural light to support our circadian cycle and avoid sources of Biophilia eye strain. When designing with timber, its specific light reflectance must be used to assess the overall impact of reflected light on illuminance levels. Timber surfaces generally have lower LRV compared to the default baseline of a white painted plasterboard wall, however the exact value varies based on wood species and applied surface treatments. Consideration should be given to ensure adequate light levels in spaces with extensive exposed wood, particularly in deeper parts of a space. The impact of wood aging, where for many species the material becomes darker and more yellow over time, typically results in a decrease in LRV which should also be factored into analysis. It is possible to somewhat counteract this with the application of surface treatments, for example a translucent whitewash, which can retain a lighter tone.

surfaces, furniture and daily activities such as cooking and cleaning. Mechanical ventilation systems can incorporate heat recovery (MVHR) to increase energy efficiency, as well as filtration which can help in areas where external air quality does not meet necessary criteria, for example due to heavy vehicle traffic. When designing with timber, consider that while natural untreated timber does emit VOCs, these are biogenic and generally considered to have neutral or even positive impacts on human health. Once a log is cut, the rate at which VOCs are emitted also deteriorates very rapidly, meaning that in many cases by the time the product has been through manufacturing and reached the building in question the level of VOCs is already very low. Care and attention should be given to the known health damaging VOCs which can be present in some of the adhesives and surface treatments that are commonly applied to timber and are also regularly emitted by many materials used in construction. In general, designers should request EPD certificates and look for innovative products from the market, which is holistically working to improve levels of harmful VOCs in all construction products. Ultimately levels of VOCs (both good and bad) are controlled via a building’s ventilation system and the impact of VOCs from internal surfaces in all buildings is currently dwarfed by that of furniture and daily activities such as cleaning, so concerns around VOCs should not discourage use of timber.

PHYSICAL

Air quality (VOC, PM & CO2 levels)

ACOUSTICS – Sound insulation – Sound reflection / reverberation Humidity – Sound absorption

Temperature Infection Control

PSYCHOLOGICAL

Human interaction encouraged

Agency over our environment

INFECTION CONTROL – Airborne particle control Biophilia Variety –Activity Cleanability encouraged – Antimicrobial surfaces

Regulations define a series of acoustic criteria designed to adequately control sound transmission from outside, between spaces and within a given room to achieve comfort. The insulation level required can therefore vary based on site conditions, spatial function, consequent noise level and sensitivity to noise ingress. This is typically controlled through the selection of build-ups comprising dense or high-mass materials and acoustically isolated or decoupled materials to resist the passage of sound.

for infection control generally LightKey Levelsdesign considerationsNudge

The need to control or manipulate reverberation and echo, for example to support speech intelligibility rather than the enjoyment of music, requires carefully positioned absorptive and reflective materials within a given space.

moisture and dirt, providing areas for bacteria and viruses to thrive which are difficult to clean. As well as the surface properties of a material its ability to withstand cleaning and disinfectant products without degrading should be taken into account. Some materials have natural antimicrobial properties which can inhibit or even destroy pathogens which they encounter.

When designing with timber, consideration should be given to its comparative low density and low mass compared with concrete and masonry. To avoid the need to add mass through wet screeds and concrete toppings, which run counter to timber’s circularity benefits, it is essential to reconsider the acoustic principles driving the proposed build-ups to focus on acoustic isolation through the ‘mass-spring-mass’ concept rather than the inclusion of mass alone. Within a space, while timber is marginally more acoustically absorptive than other materials such as concrete and steel, it is still predominantly reflective compared with specifically absorptive materials such as felt, and therefore typically would not be adequate to deal with reverberation in isolation. However, when sound is reflected from a fibrous unfinished timber surface it scatters, diffusing the sound waves, which helps prevent harsh echoes and affords timber spaces the natural acoustic warmth often quoted as a positive attribute by inhabitants of timber buildings.

comprise measures that prevent the transfer of pathogens from one person to another, either via the air or droplets. Airborne particles are largely controlled via adequate ventilation, but also through spatial design which can provide separation and distancing. When it comes to surfaces, touchless technology can be most impactful, followed by key properties of surface materials. Porous materials and those with textures and seams readily trap

When designing with timber, where ease of cleaning and infection control are key requirements, surface coatings can be applied to create a barrier that prevents pathogens from colonising the timber surface and protects the timber from cleaning products. Freshly cut timber has antimicrobial properties of its own, however these quickly deteriorate meaning surface coatings are required in areas where infection control is a particular concern. Consideration should also be given to the location where timber is proposed, for example floors will be much more susceptible to pathogen build-up requiring better infection control performance and much more frequent cleaning than ceilings.

PHYSICAL

Humidity

PSYCHOLOGICAL

Nudge

PHYSICAL

PSYCHOLOGICAL

Light Levels

Temperature Agency over our environment Temperature

Variety

Air quality (VOC, PM & CO2 levels)

DESIGN CHECKLIST Humidity

Variety

Nudge

Spatial quality Humidity

Light Levels Nudge

PHYSICAL Air quality (VOC, PM & CO2 levels)

Agency over our environment

Biophilia

Light Levels

Air quality (VOC, PM & CO2 levels) Agency over our environment

PHYSICAL PSYCHOLOGICAL

PHYSICAL

PSYCHOLOGICAL

Spatial quality

Spatial quality Temperature

Temperature Variety

Biophilia

Temperature Variety Humidity

Biophilia

Humidity

PSYCHOLOGICAL AGENCY Light Levels – – – Air quality Variety (VOC, PM & CO2 levels)

Humidity

Nudge

levels of timber exposure or the ability to mask timber with Light Levels Nudge

Manually operable controls Light Levels Flexible layouts Agency over Options/choices our environment

furnishings, curtains or screens can ensure users feel in Agency over control of their surroundings our environment

Air quality (VOC, PM & CO2 Agency levels) over

quality As sentient beings, the knowledge Air that we are able to (VOC, PM & CO2 levels) influence our environment is likely even more beneficial to our wellbeing and stateSpatial of quality mind than any actual Nudge adjustments we can make. Having manual controls for some of the systems designed to control the physical parameters of the internal environment, such as windows, allow for Biophilia these not only to be tailored to the complex interrelated Agency over factors outlined above but also to provide the occupants our environment with agency. This aspect is closely linked to variety and spatial quality as these two components provide building users with choice as to which types of spaces they occupy Spatial quality based on how they feel or the task at hand. Flexibility of internal layouts also allows and encourages users to engage with and change their surroundings preventing frustration against limitations and perceived oppression. Biophilia

When designing with timber, we should be aware that people’s preferences and associations with timber, whether conscious or subconscious, will differ. Considering the extent of timber within a given space as well as use of varied timber species, colours and patterns can help to mitigate any negative association and ensure spaces feel balanced. Providing users with a choice between spaces with timber and those without, or spaces with differing 42

Variety

S PAT I A L Q UA L I T Y – Height/volume Spatial quality – Light conditions. – Materiality

our environment

Spatial quality

The proportions of a space, its scale in relation to the Biophilia spaces around it, as well as how its design guides users to flow through and inhabit it, have a profound impact on how a building’s occupants feel. As well as geometry and Biophilia layout, factors such as light, surfaces and materials are critical to the overall perception of the space and can be employed carefully to enhance the overall impact. When designing with timber, consider how timber surfaces contribute towards the intended quality of each space, at which scale the timber is experienced and through which senses. This may help to inform which parts of a timber structure would be most impactful to expose, compared to which could be concealed if regulation or performance restricts the extent of exposed timber surfaces. Additionally, consider how use of different timber products and species can complement each other as well as other materials, how applied treatments or coatings will influence the multisensory perception of the timber and how it may interact with other aspects such as light.

Nudge

Agency over our environment

VARIETY – Different spatial conditions – Different materials and colours quality –Spatial Change Inhabiting spaces of different types and qualities provides interest and stimulation Biophilia throughout the day and can equally importantly also offer spaces which enable respite and PHYSICAL retreat from over-stimulation. Within a given space, different surfaces, light levels and furniture configurations can also create variety. While buildings are essentially permanent objects, opportunities for change throughout the day, week, season or year should also be considered Temperature and promoted where possible.

PSYCHOLOGICAL

When designing with timber, consider how materials Humidity of different species and with different qualities can be used to support the creation of varied spaces for different occupant needs as well as opportunities for Light Levels For example, timber Varietyto enhance any changing features. naturally changing light patterns throughout the day could complement the experience of an exposed timber surface. Air quality (VOC, PM & CO2 levels)

B INudge OPHILIA – Natural materials – Nature in a space – Views of nature Agency over our environment

The positive impact of exposure to nature on myriad aspects of our psychological and physiological wellbeing has been widely evidenced. Many theories attempt to propose and outline rationale and mechanisms for this Spatial quality effect. Most in some way draw on the fact we evolved in nature and therefore have an evolutionary connection to its characteristics, which we do not to urban environments that have rapidly developed at a rate which outstrips Biophilia our biological evolution. Within the built environment, the presence of plants, natural materials and views out to nature all have a measurable impact on our emotional psychological state and on our physiological stress profile. When designing with timber, our innate biophilic response to its surface as a natural material should be a primary consideration, encouraging its exposure wherever regulation and other performance requirements permit.

Consideration should also be given to the species, colour, grain, cut and surface finish all of which can impact the extent of biophilic response. Timber could be prioritised in areas where multisensory interaction is possible or necessary, for example, where elements of the building will be both seen and touched. Opportunities for timber to be used alongside other biophilic design features such as plants can help to enhance its positive impact. It is also critical to consider the impact of other key design PSYCHOLOGICAL parameters. For example, a room’s light and spatial quality may affect a user’s ability to perceive the surface grain, texture and pattern of timber, potentially enhancing the biophilic response when well designed. Variety NU DGE

– – –

Physical activity promoted Social interaction promoted Variety promoted

Nudge

The spaces we inhabit have the ability to subconsciously encourage actions and activities which can support other aspects of holistic health and wellbeing. Well designed Agency over with views out to nature can encourage their staircases our environment use over lifts, high quality changing facilities enable sports and active commuting, and the design of canteens and restaurants can influence our food choices. Similarly, the design Spatial quality of communal spaces and circulation within a building can influence our levels of social interaction and activity. We also understand that physical activity is the primary means for resolving the physiological stress cycle through Biophilia metabolic processing, therefore encouraging even micro levels of movement or activity can have a proportionally greater impact on our health. When designing with timber, look for opportunities to use the natural beauty and intrigue of timber surfaces to encourage movement, changes in posture, gathering and interaction. Think about what types and species of timber are most likely to have this effect and in what context, also remember that the impact of a timber surface on occupant behaviour is heavily linked to the other design parameters identified within this guidance.

2. CASE STUDIES

T3 COLLINGWOOD

THE BLACK & WHITE BUILDING

Summary: T3 Collingwood is a mass timber office tower in central Melbourne, completed in 2023 by Jackson Clements Burrows for the developer Hines. It is fifteen storeys, the upper ten built as an exposed glulam frame with CLT floor slabs, built above a concrete podium. Across the office levels the columns, beams and ceilings are exposed timber.

Summary: The Black & White Building in London is a mass timber office development designed around biophilic principles, exposing its structural CLT and LVL to prioritise occupant wellness. A tulipwood louvred facade and a central light well optimise daylight distribution while controlling solar gains and preventing glare, significantly reducing eye strain. Through a variety of work settings,from private focus booths to light filled communal lounges, the architecture nudges occupants to move, connect and control their environment. This BREEAM Excellent workspace demonstrates how environmental

Study: A pilot study followed staff who moved in from a conventional office, using hair cortisol, a marker of stress built up over weeks, measured before and after the move. The results showed that stress fell and the workers reported feeling more comfortable and productive, though the authors treat this as an early signal rather than proof, given the small group.(Whyte, S et al. 2025) The study referenced that the effect of the exposed timber is warm and tactile, with people tending to reach out and touch the columns. They highlight the softer light given to the floorplate by the timber and a steadying calm, set off by generous daylight and open views.

sustainability and human wellness can be synthesised to attract progressive tenants. Self Report: “Since working here, I personally noticed a real improvement in my own health, I don’t get unwell as frequently as I used to. I think working in the Black and White Building plays a part in this. I am surrounded by natural light, plants and timber itself that makes a difference” -Reshma Begum, Member Experience Host, Fora

Figure: T3 Collingwood. Architect: Jackson Clements Burrows Architects. Photography: Tom Blachford.

Figure: The Black and White Building, interior. Architect: Waugh Thistleton Architects.

KINDERGARTEN IN SILZ

Summary: The kindergarten in Silz sits below forested mountains and is built almost entirely from wood. A ventilated facade of timber slats wraps the exterior. Inside are classrooms, a lunch room, an auditorium and a room for active play which are all made from timber finished in natural oil. Large square openings and skylights bring daylight into every room and enhance the occupants’ connection with nature. Study: A one-year study of classrooms was conducted across Austrian schools. The study compared the physiological effects on pupils in an environment dominated by wood with a classroom finished in standard plasterboard. The results showed that the pupils were calmer and their self-reported stress levels were lower in

N AT I O N A L O N C O LO GY WAITING ROOM

INSTITUTE

Summary: The waiting room at the National Oncology Institute in Bratislava was renovated and lined throughout in timber. The biophilic design approach include solid pine panels covering the walls and ceilings, while the seating is made from larch. The lighting has been adjusted to a warm white tone, creating a calmer atmosphere. Hospital waiting rooms are among the most stressful places to visit, the hope being that integration of these timber materials would have a positive impact on visitor experience. Study: A study conducted in the space measured physiological biomarkers in a sample of occupants before and after the renovation. The results indicated reduced signs of stress following the introduction of the

timber classrooms like that of the Kindergarten in Silz. (Kelz)

timber materials and improved environmental conditions (Kotradyova, V. et al.).

Figure: Kindergarten Silz. Architect: Armin Neurauter. Photography: Günter Richard Wett.

Figure: National Oncology Institute, Bratislava, Slovakia

3. APPENDIX

3.1 HOW TO ENTRIES

EVIDENCE READ

THE

EVIDENCE

GRADE (Grading of Recommendations, Assessment, Development and Evaluation) is a standard framework developed in the early 2000s to rate the quality of evidence across studies of different types and quality. It was originally designed for clinical guidelines and has been adapted here to fit architectural and environmental research, where randomised controlled trials are rare and much of the evidence comes from controlled lab experiments and observational studies. It does not judge whether a study is good or bad. Instead it asks: how certain can we be that this result reflects reality, rather than a quirk of the sample or method? A flat list of citations would obscure the difference between a systematic review and a single-lab experiment with 18 participants. The scores make that difference visible. All grading frameworks assess how a study was conducted, not whether its findings matter for design practice. That interpretive step is left to the reader.

THE FIVE CRITERIA The Overall GRADE summarises five criteria. It should be read alongside the summary column. A score alone does not indicate what a study found or its relevance to practice. Study Design: What kind of research is it? A randomised controlled trial carries more evidential weight than a case study or self-report survey. This is the most important criterion. Risk of Bias: Could the result have been shaped by something other than the variable being tested? Industry funding, absence of a control group or participant awareness of their assigned condition all introduce risk. Consistency: Has the same finding been replicated across different research groups, countries and building types? Directness: Was the study conducted in a real occupied building or in a laboratory using photographs and material samples?

THE FOUR LEVELS High: Consistent findings across multiple independent studies and populations. Moderate: Credible direction of finding, from small studies, laboratory conditions or limited populations. Most timber-and-health research sits here. Low: Suggestive findings only. Small samples, single cultural contexts, industry funding without independent replication, or results untested outside a laboratory setting. N/A: Theory, standards, policy documents, expert consultation. Not empirically graded.

Precision: How large was the sample? Small samples score lower regardless of study design quality.

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3.2

INTERVIEWS

INTERVIEWS Name

Organisation

Ulrich von Hundhausen

NTI (Norwegian Institute of Wood Technology)

VOC and timber moisture buffering research

16/06/2025

Kat Scott

Hackney Council (ex dRMM)

MMT study; post-occupancy evaluation

16/05/2025

Mental health and healthcare work

06/05/2025

Neuroarchitecture; health and wellbeing; built environment research

03/06/2025 12/09/2025

Building services; MEP; environmental engineering

29/04/2025

GER

Wood VOC emissions; indoor air 11/08/2025 quality; timber material science

Building services; VOC testing; healthy buildings

28/07/2025

Built by Nature Wood and Wellbeing project

04/08/2025

Architectural neuroimmunology; visual stress; façade patterns

30/01/2026 (Lecture) 04/03/2026

Clinical psychology: Predictors of Quality of Life and Cognitive Processing

12/03/2026

Palo Alto University

Michaela Mitrovic

Oxford AI Neuroar- UK chitecture Lab

Neuroarchitecture; emotions in architecture; spatial cognition

30/01/2026 (Lecture)

Mohamed Khalil

Cambridge (Neurocivitas)

Neurobiophilia; BDNF; neurogenesis; biophilic design index

06/02/2026 (Lecture)

Sophie Schuller

TU Eindhoven and Cambridge

Posture; embodied stress; propri- 06/02/2026 (Lecture) oception; office design 12/03/2026

Paul Kenny

University College Dublin

Neurodiversity and architecture; sensory design

Matthew Trobridge

IWBI / University of US Virginia School of Medicine

Built environment and public 21/11/2025 health; WELL Building Standard; physician and researcher

Tamar Krishnamurti

Associate Professor UK of Medicine, University of Pittsburgh

Wellbeing research methodology; evidence quality

30/04/2025 27/01/2026

Multiple speakers

Wood for Health EU project

Suitability and benefits of timber use in healthcare settings

11/06/2025 (Webinar)

Karen Flatt Koen Steemers

Peter Hazzard & Stuart Hawkes Martin Ohlmeyer Lydia Tew

Arcadis University of Cambridge Cundall Thünen Institute Max Fordham

Country

Gijs Bruggink

Brothers Architecture

Cleo Valentine

HKS / RISE / Cam- UK / US bridge

Induni Wickramasinghe

Multiple

Specialism

Meeting Date(s)

12/03/2026

INTERVIEWS Name

Organisation

Mike Burnard

InnoRenew CoE / University of Primorska

Reshma Begum

Fora

Anna Ervast Öberg

Country

Department for Education

Meeting Date(s)

EU (SI)

Human health in the built environment; timber and health research network; COST action

08/01/2026

Member Experience Host at The Black & White Building

22/05/2026

Timber residential development; CLT at scale; project and business development

05/06/2026

Head of Architecture and Design 08/06/2026 (Schools and Colleges); net zero schools; mass timber in education

Folkhem Crawford Wright

Specialism

3.3

GLOSSARY

Affect

Emotional states, positive or negative, capturing experienced wellbeing in the moment or over a period. (Diener et al., 2010)

Allostasis

The process by which the body achieves stability by changing its internal state in response to demand. Unlike homeostasis, which maintains a fixed set point, allostasis involves continuous adjustment. When those adjustments accumulate without recovery, the cost is allostatic load. (McEwen, 2007)

Allostatic Load

The cumulative physiological wear and tear from chronic stress; the long-term cost of repeated or prolonged neural or neuroendocrine response. (McEwen, 2007)

Amygdala

A limbic structure that processes emotional salience, especially fear and threat. Activates hypothalamic signalling and modulates autonomic and endocrine stress responses. (LeDoux, 2000)

Autonomic Nervous System (ANS) The division of the nervous system that regulates involuntary physiological processes including heart rate, digestion and respiratory rate. Central to the body’s stress and recovery response. (Marieb & ; Hoehn, 2018) Biomarker

A measurable physical indicator of a biological state or process. In health and building research, common biomarkers include cortisol levels, heart rate variability and blood pressure. Biomarkers provide objective data about how a body is responding to its environment, independent of what the occupant reports. (Cacioppo and Tassinary, 1990)

Biophilia / Biophilic Design

Biophilia is the innate human tendency to seek connection with nature and other living systems. Biophilic design applies this principle to the built environment, incorporating natural materials, daylight, planting, views to nature and organic patterns to support occupant health and wellbeing. (Kellert et al., 2008)

BREEAM

Building Research Establishment Environmental Assessment Method. The dominant building sustainability certification in the UK and across much of Europe. BREEAM covers energy, materials, water, ecology, and health and wellbeing. It does not reference timber as a material with specific health properties but awards credits for acoustic performance, embodied carbon and indoor environment quality that a well-designed timber building can readily achieve. (BRE Group, n.d.)

Burnout

A syndrome resulting from chronic workplace stress that has not been successfully managed, characterised by exhaustion, mental distance or cynicism and reduced professional efficacy. (WHO ICD-11, 2022)

CLT (Cross-Laminated Timber)

A structural timber panel made by layering solid wood boards at right angles and bonding them together under pressure. The cross-lamination gives CLT strength and stability in multiple directions, making it suitable for floors, walls, and roofs in multistorey construction. It is the most widely used mass timber product in the buildings covered by this review. (WoodWorks, 2021)

Cortisol

A steroid hormone produced by the adrenal cortex; central to the body’s stress response and regulated through the HPA axis. (Kirschbaum & Hellhammer, 1994)

DGNB

Deutsche Gesellschaft für Nachhaltiges Bauen (German Sustainable Building Council). Germany’s primary building certification system. Covers environmental, economic and sociocultural criteria including thermal comfort, acoustics and indoor air quality, with a broader scope of subjective and objective criteria than BREEAM or LEED. (DGNB, 2023)

E0-rated

A classification for engineered wood products that emit negligible formaldehyde. E0 is the most stringent category under European emissions standards, sitting below E1 and E2. Specifying E0-rated CLT, glulam and LVL is the primary way to manage formaldehyde risk in timber buildings seeking health certification. (EN 717-1, 2004)

EEG (Electroencephalography)

A method of recording the brain’s electrical activity through sensors placed on the scalp. In built environment research it is used to show how much cognitive processing effort a space requires. Spaces that are easy for the brain to interpret produce patterns associated with relaxed attention; visually complex or unfamiliar spaces produce patterns associated with higher mental effort. (Eberhard, 2009)

Flourishing

A state of self-perceived success across important areas such as relationships, self-esteem, purpose and optimism. Measured via the Flourishing Scale. (Diener et al., 2010)

Glulam (Glued Laminated Timber) A structural timber product made by bonding multiple layers of dimension lumber together with the grain running parallel. Glulam beams and columns can span long distances and carry heavy loads, and are commonly left exposed in timber buildings. (WoodWorks, 2021) GRADE Rating

A systematic framework for rating the certainty of evidence. Used to assess the quality of evidence in clinical and environmental research. (Guyatt et al., 2008) 65

Health

A state of complete physical, mental and social wellbeing and not merely the absence of disease or infirmity. (WHO, 1948)

Heart Rate Variability (HRV)

The variation in time between each heartbeat, controlled by the autonomic nervous system. Used as an indicator of stress regulation in environmental studies. (Task Force, 1996)

Homeostasis

The maintenance of stable physiological conditions within the body through regulatory mechanisms that keep variables within a set range. (Hardy, 1965)

Indoor Air Quality (IAQ)

The air quality within and around buildings, especially as it relates to the health and comfort of occupants. Key metrics include CO2, PM2.5, TVOC and ventilation rate. (U.S. EPA, 2023)

Indoor Environment Quality (IEQ) The perceived overall indoor experience, encompassing conditions that affect comfort, health and performance including air quality, thermal conditions, acoustics and lighting. (ASHRAE, 2017) LEED

Leadership in Energy and Environmental Design. The principal building sustainability certification in North America, administered by the US Green Building Council. Covers similar ground to BREEAM. For UK and European projects, BREEAM and WELL are the more commonly applicable frameworks. (USGBC, 2019)

Longitudinal Study

A research design that follows the same participants over an extended period, months or years rather than hours. Longitudinal studies are essential for understanding how buildings affect health over a tenancy, as most physiological effects accumulate gradually and cannot be captured in short laboratory experiments. (Cavaliere et al., 2025)

LVL (Laminated Veneer Lumber)

An engineered timber product made from thin wood veneers bonded together with the grain running in the same direction. LVL has high and consistent structural properties and is used for beams, headers, and other load-bearing elements. (WoodWorks, 2021)

Mental Health

A state of wellbeing in which every individual realises their own potential, can cope with the stresses of life, can work productively, and is able to make a contribution to their community. (WHO, 2022)

Neuroarchitecture

A field of research that examines how the built environment affects brain function and body response. It draws on neuroscience, psychology, and architecture to understand how spatial conditions including light, materials, scale, and layout produce measurable physiological and psychological effects in occupants. (Eberhard, 2009; Sternberg and Wilson, 2006)

Nudge / Choice Architecture

A nudge is a design decision that steers behaviour in a particular direction without restricting options or requiring conscious decision-making. Choice architecture refers to the broader practice of structuring environments so that the default or most natural path supports a desired outcome. In buildings, this includes stair placement, circulation routes, and spatial sequences that encourage movement, social interaction, or rest. (Thaler and Sunstein, 2008)

Parasympathetic Nervous System The branch of the autonomic nervous system associated with rest and recovery. When active, heart rate slows, breathing deepens, and the body moves out of a state of alert. Often described as “rest and digest” in contrast to the sympathetic “fight or flight” response. Higher parasympathetic activity is generally associated with lower stress and better recovery. (Marieb and Hoehn, 2018) Psycho-physiological

Relating to the interaction between psychological states and physiological responses. In environmental research, refers to capturing bodily responses to a spatial or material stimulus. (Cacioppo and Tassinary, 1990)

Quality of Life (QoL)

An individual’s perception of their position in life in the context of the culture and value systems in which they live, relative to their goals, expectations, standards and concerns. (WHOQOL Group, 1995)

Randomised Control Trial (RCT)

A type of scientific experiment designed to evaluate the efficacy or safety of an intervention by minimising bias through the random allocation of participants. (Schulz et al., 2010)

Sick Building Syndrome (SBS)

Situations in which building occupants experience acute health and comfort effects linked to time spent in a building, without a specific illness or cause being identified. (WHO, 1984)

Stress

A state of worry or mental tension caused by a difficult situation. A central pathway linking the built environment to physiological and wellbeing outcomes. (WHO, 2023)

Subjective Wellbeing (SWB)

Self-reported evaluations and experiences of life used to quantify wellbeing impacts of environments. (Diener et al., 1999)

Sympathetic Nervous System

The branch of the autonomic nervous system that prepares the body for action. It increases heart rate, raises blood pressure, and sharpens attention in response to a perceived demand or threat. Necessary and useful in short bursts; sustained activation without recovery accumulates as physiological wear on the body. (Marieb and Hoehn, 2018)

Terpenes

Naturally occurring organic compounds produced by trees and plants. In timber buildings they are responsible for the characteristic smell of fresh or 67

exposed wood. Terpenes are classified as VOCs but have no established harmful effects at the concentrations found in buildings. Some studies suggest they may have mild physiological calming effects. (Matsubara and Kawai, 2014) Thermal Comfort

The condition of mind which expresses satisfaction with the surrounding thermal environment, assessed by subjective evaluation. (ASHRAE Standard 55, 2017)

TVOC

(Total Volatile Organic Compound concentration) A single aggregate measurement of all organic compounds detected in the air of a building. Used by most certification schemes as a first-pass air quality check. The limitation for timber buildings is that TVOC treats harmless terpenes and potentially harmful compounds such as formaldehyde as equivalent, which can produce misleading readings in newly completed timber interiors. (WHO, 1983; Wolkoff, n.d.)

WELL

A building certification standard focused on occupant health and wellbeing rather than environmental sustainability. Introduced in 2014 by the International WELL Building Institute (IWBI), it covers ten areas including air, light, materials, movement, thermal comfort, and mind. WELL is the certification scheme most directly relevant to timber’s health credentials, with biophilic design and restorative spaces among its compulsory requirements. (IWBI, 2026)

Wellbeing

A positive state experienced by individuals and societies; it is a resource for daily life and is determined by social, economic and environmental conditions. (WHO, 2022)

Yerkes-Dodson Curve

A well-established relationship between arousal and performance. At low arousal, attention wanders and performance is poor. As arousal increases, performance improves up to an optimal point. Beyond that point, further arousal degrades performance. The curve is relevant to building design because environments that keep occupants in the middle range support sustained cognitive output; those that push them toward either extreme do not. (Yerkes and Dodson, 1908)

3.4

REFERENCES

A Adamova, T., J. Hradecky, and M. Panek. 2020. “VOCs from Wood and Wood-Based Panels: Methods for Evaluation, Potential Health Risks, and Mitigation.” Molecules.

Results of a Holistic, Multi-Level Analysis.” Building and Environment. Bejder, A. n.d. “Aesthetic Qualities of Cross-Laminated Timber.” Forest Research Journal.

AgBB (Ausschuss zur gesundheitlichen Bewertung von Bauprodukten). 2021. Evaluation Procedure for VOC Emissions from Building Products. Dessau-Roßlau: German

Bhatta, S. 2020. Looking at Wood through the Skin. Unpublished manuscript.

Federal Environment Agency (Umweltbundesamt).

Bhatta, S. R., K. Tiippana, K. Vahtikari, M. Hughes, and M. Kyttä. 2017. “Sensory and Emotional Perception of Wooden Surfaces through Fingertip Touch.” Frontiers in Psychology.

Alapieti, T., R. Mikkola, P. Pasanen, and H. Salonen. 2020. “The Influence of Wooden Interior Materials on Indoor Environment: A Review.” European Journal of Wood and Wood Products. Allen, J. G., P. MacNaughton, U. Satish, S. Santanam, J. Vallarino, and J. D. Spengler. 2016. “Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers.” Environmental Health Perspectives. Andersson, K., J. V. Bakke, O. Bjørseth, C.-G. Bornehag, et al. 1997. “TVOC and Health in Non-Industrial Indoor Environments.” Indoor Air. Appleton, J. 1975. The Experience of Landscape. London: Wiley. Augustin, S., and D. Fell. 2015. Wood as a Restorative Material in Healthcare Environments. Vancouver: Forestry Innovation Investment. B Banham, Reyner. 1969. The Architecture of the WellTempered Environment. London: Architectural Press. Barrett, P., F. Davies, Y. Zhang, and L. Barrett. 2015. “The Impact of Classroom Design on Pupils’ Learning: Final 70

Bowler, D. E., L. M. Buyung-Ali, T. M. Knight, and A. S. Pullin. 2010. “A Systematic Review of Evidence for the Added Benefits to Health of Exposure to Natural Environments.” BMC Public Health. Browning, W. D., and C. O. Ryan. 2020. Nature Inside: A Biophilic Design Guide. London: RIBA Publishing. Browning, W. D., C. O. Ryan, and C. DeMarco. 2022. The Nature of Wood. New York: Terrapin Bright Green. Browning, W. D., C. O. Ryan, and J. O. Clancy. 2014. 14 Patterns of Biophilic Design. New York: Terrapin Bright Green. BSI (British Standards Institution). 2022. BS 40101:2022 Building Performance Evaluation for Offices and Other Workplace Buildings. London: BSI. Burnard, Michael D., and Andreja Kutnar. 2015. “Wood and Human Stress in the Built Indoor Environment: A Review.” Wood Science and Technology.

Cacioppo, John T., and Louis G. Tassinary. 1990. “Inferring Psychological Significance from Physiological Signals.” American Psychologist.

D’Amico, A., L. Pompei, M. Pompei, G. Mochi, and A. Ridolfi. n.d. “Modelling VOC Emissions from Building Materials for Healthy Building Design.” International Journal of Environmental Research and Public Health.

Campbell, Margaret. 2005. “What Tuberculosis Did for Modernism: The Influence of a Curative Environment on Modernist Design and Architecture.” Medical History. CBRE. 2023. Sustainability-Certified Buildings Rental Premium Research. London: CBRE.

Damasio, Antonio. 1994. Descartes’ Error: Emotion, Reason, and the Human Brain. New York: Putnam. Department of Health. 2011. No Health Without Mental Health: A Cross-Government Mental Health Outcomes Strategy for People of All Ages. London: HM Government.

CEN (European Committee for Standardisation). 2019. EN 16798-1:2019 Energy Performance of Buildings: Indoor Environmental Input Parameters. Brussels: CEN.

Deutsche Gesellschaft für Nachhaltiges Bauen (DGNB). 2023. About the DGNB System. Stuttgart: DGNB.

Center for Active Design. 2020. Fitwel Reference Guide: Community. New York: Center for Active Design, Inc.

Diener, Ed, Robert Wirtz, William Tov, Chu Kim-Prieto, Dong-won Choi, Shigehiro Oishi, and Robert BiswasDiener. 2010. “New Wellbeing Measures: Short Scales to Assess Flourishing and Positive and Negative Feelings.” Social Indicators Research 97 (2): 143–156.

Ceylan, M., and I. Erkan. 2025. “Mental Worlds Shaped by Neuroarchitecture: Effects of Indoor Materials on Brain Activity.” Conference paper. Chen, C.-J., K. J. S. Kumar, Y.-T. Chen, et al. 2015. “Effect of Hinoki and Meniki Essential Oils on Autonomic Nervous System Activity and Mood States.” International Journal of Environmental Research and Public Health.

Dorizas, V., C. Duvier, E. Elnagar, et al. 2024. Healthy Buildings Barometer 2024. Brussels: Buildings Performance Institute Europe (BPIE). E

Clear, James. 2018. Atomic Habits: An Easy and Proven Way to Build Good Habits and Break Bad Ones. New York: Avery.

Eberhard, John P. 2009. Brain Landscape: The Coexistence of Neuroscience and Architecture. Oxford: Oxford University Press.

Cohen, Sheldon, Tom Kamarck, and Robin Mermelstein. 1983. “A Global Measure of Perceived Stress.” Journal of Health and Social Behavior 24 (4): 385–396.

Englund, Folke. 1999. Emissions of Volatile Organic Compounds (VOC) from Wood. SP Report 1999:15. Borås: SP Swedish National Testing and Research Institute.

Corbey, Stephen. 2018. Timber and Healthy Buildings: Indoor Air Quality. High Wycombe: TRADA.

Ernst Basler + Partners. 2011. Assessment with Respect to Ecology and Health: Overview of Glue Types and Formaldehyde Emissions. Zurich: Ernst Basler + Partners.

Cundalls. 2024. Expert communication on indoor terpene concentrations in timber buildings. Unpublished.

European Chemicals Agency (ECHA). 2023. Formaldehyde and Formaldehyde Releasers: Substance Information. Helsinki: ECHA.

European Commission. 2023. EU Social Taxonomy: Occupant Health and Wellbeing as a Reporting Objective. Brussels: European Commission. Evans, Gary W., and Dana Johnson. 2000. “Stress and Open-Office Noise.” Journal of Applied Psychology 85 (5): 779–783. F Fell, David R. 2010. “Wood in the Human Environment: Restorative Properties of Wood in the Built Indoor Environment.” PhD thesis, University of British Columbia. Fisk, William J. 2000. “Health and Productivity Gains from Better Indoor Environments and Their Relationship with Building Energy Efficiency.” Annual Review of Energy and the Environment 25 (1): 537–566. Fromm, Erich. 1964. The Heart of Man: Its Genius for Good and Evil. New York: Harper and Row. Fürhäpper, C., D. Stratev, C. Habla, and A. Teischinger. 2015. “Living Conditions in Timber Houses: Emission Trends and Indoor Air Quality.” Forests 6 (9): 3080–3094. Fürhäpper, Christina, Elisabeth Habla, Daniel Stratev, Martin Weigl, and Karl Dobianer. 2020. “Living Conditions in Timber Houses: Emission Trends and Indoor Air Quality.” Frontiers in Built Environment 5: 151. G Global Wellness Institute. 2025. Global Wellness Economy Monitor. Miami: GWI. Granström, Karin. 2003. “Emissions of Volatile Organic Compounds from Wood.” Journal of Wood Science 49 (1): 67–73. Guo, H., F. Murray, and S. C. Lee. 2002. “Emissions of Total Volatile Organic Compounds from Pressed Wood Products in an Environmental Chamber.” Building and Environment 37 (11): 1117–1126.

H Haapakangas, A., R. Helenius, E. Keskinen, and V. Hongisto. 2008. “Perceived Acoustic Environment, Work Performance and Wellbeing: Survey Results from a Finnish Office Building.” Ergonomics 51 (7): 1096–1110. Hameury, S. 2005. “Moisture Buffering Capacity of Heavy Timber Structures Directly Exposed to an Indoor Climate: A Numerical Study.” Building and Environment 40 (10): 1400–1412. Harb, Paul, Nadine Locoge, and Frédéric Thévenet. 2018. “Emissions and Treatment of VOCs from Wood-Based Construction Materials.” Chemical Engineering Journal 354: 641–652. Hollbacher, Evelin, Cornelia Rieder-Gradinger, Daniel Stratev, and Ewald Srebotnik. 2014a. “Measuring VOC Emissions from Wood-Based Building Products under Real Room Conditions in Idealised Model Rooms.” International Wood Products Journal 5 (3): 132–138. Hollbacher, Evelin, T. Ters, C. Rieder-Gradinger, et al. 2014b. “Emissions of Indoor Air Pollutants from a CLT Room: A 23-Week TVOC Decay Study.” Journal of Occupational and Environmental Hygiene 12 (2): 97–104. Hollbacher, Evelin, Tobias Ters, Cornelia Rieder-Gradinger, Daniel Stratev, and Ewald Srebotnik. 2017. “Emissions of Indoor Air Pollutants from Six User Scenarios in a Model Room.” Atmospheric Environment 150: 389–394. Huang, H., and F. Haghighat. 2002. “Modelling of Volatile Organic Compounds Emission from Dry Building Materials.” Building and Environment 37 (12): 1349–1360. Humphreys, Michael A., and J. Fergus Nicol. 2002. “The Validity of ISO-PMV for Predicting Comfort Votes in EveryDay Thermal Environments.” Energy and Buildings 34 (6): 667–684. Hutmacher, F. 2019. “Why Is There So Much More Research on Vision Than on Any Other Sensory Modality?” Frontiers in Psychology 10: 2246.

Häyrinen, L., A. Toppinen, and R. Toivonen. 2020. “Finnish Young Adults’ Perceptions of Health, Wellbeing and Sustainability of Wooden Interior Materials.” Silva Fennica 54 (5). I Ikei, H., M. Nakamura, and Y. Miyazaki. 2020. “Physiological Effects of Visual Stimulation Using Knotty and Clear Wood Images.” Journal of Wood Science 66: 7. Ikei, Harumi, Chorong Song, and Yoshifumi Miyazaki. 2017a. “Physiological and Psychological Relaxing Effects of Touching Wood.” International Journal of Environmental

VOC Emissions from Wood and Wood-Based Materials.” Indoor Air 11 (3): 182–190. Jensen, P. L., P. Sandøe, and E. Jastrup. n.d. Healthy Workplaces: What We Know and What Else We Need to Know. Helsinki: Stora Enso (Wood House Effect). Jimenez, M. P., N. V. DeVille, E. G. Elliott, J. E. Schiff, et al. 2021. “Associations between Nature Exposure and Health: A Review of the Evidence.” International Journal of Environmental Research and Public Health 18 (9): 4790.

Research and Public Health 14 (7): 801.

Jones Lang LaSalle (JLL). 2023. The Commercial Case for Making Buildings More Sustainable. Chicago: Jones Lang LaSalle Research.

Ikei, Harumi, Chorong Song, and Yoshifumi Miyazaki. 2017b. “Physiological Effects of Touching Coated Wood.” International Journal of Environmental Research and Public Health 14 (7): 801.

Joo, S., S. Han, J. Gu, and J. Kim. 2025. “Comparative Analysis of Indoor VOC Levels in an Office under Varying Occupancy and Ventilation Conditions.” Building and Environment.

Ikei, Harumi, Chorong Song, and Yoshifumi Miyazaki. 2018. “Physiological and Psychological Effects of Walking on Foot with Timber Flooring.” International Journal of Environmental Research and Public Health 15 (11): 2395.

International Living Future Institute. 2019. Living Building Challenge 4.0: A Visionary Path to a Regenerative Future. Seattle: ILFI. International WELL Building Institute (IWBI). 2014. WELL Building Standard v1. New York: IWBI. International WELL Building Institute (IWBI). 2024. WELL v2 Standard. New York: IWBI. International WELL Building Institute (IWBI). 2025. Global WELL Adoption: Six Billion Square Feet Milestone. New York: IWBI. J Jensen, Lars K., Anders Larsen, Lars Mølhave, Morten K. Hansen, and Bent Knudsen. 2001. “Health Evaluation of

Kaplan, Rachel, and Stephen Kaplan. 1989. The Experience of Nature: A Psychological Perspective. Cambridge: Cambridge University Press. Kaplan, S. 1995. “The Restorative Benefits of Nature: Toward an Integrative Framework.” Journal of Environmental Psychology 15 (3): 169–182. Kellert, Stephen R., and Edward O. Wilson, eds. 1993. The Biophilia Hypothesis. Washington, DC: Island Press. Kellert, Stephen R., Judith Heerwagen, and Martin Mador. 2008. Biophilic Design: The Theory, Science and Practice of Bringing Buildings to Life. Hoboken: Wiley. Kelz, Christine, Verena Grote, and Maximilian Moser. 2011. “Interior Wood Use in Classrooms Reduces Pupils’ Stress Levels.” In Proceedings of the 9th Biennial Conference on Environmental Psychology. Eindhoven: Eindhoven Technical University.

Kim, J., and R. de Dear. 2013. “Workspace Satisfaction: The Privacy-Communication Trade-Off in Open-Plan Offices.” Journal of Environmental Psychology 36: 18–26. Klepeis, Neil E., William C. Nelson, Wayne R. Ott, John P. Robinson, Andy M. Tsang, Paul Switzer, Joseph V. Behar, Stephen C. Hern, and William H. Engelmann. 2001. “The National Human Activity Pattern Survey (NHAPS): A Resource for Assessing Exposure to Environmental Pollutants.” Journal of Exposure Analysis and Environmental Epidemiology 11 (3): 231–252. Kotradyova, V., E. Vavrinsky, B. Kalinakova, D. Petro, K. Jansakova, M. Boles, and H. Svobodova. 2019. “Wood and Its Impact on Humans and Environment Quality in Health Care Facilities.” International Journal of Environmental Research and Public Health 16 (18): 3496. Kumpulainen, S., M. Kilpiäinen, J. Koski, and A. J. Pesola. 2024. “Wooden Interiors Improve Heart Rate VariabilityDerived Psychophysiological Wellbeing: An Acute CrossOver Study.” Environment and Behavior. L Langer, E. J. 1983. The Psychology of Control. Beverly Hills: Sage Publications. Le Corbusier. 1923. Vers une architecture. Paris: Éditions Crès. Lei, Q., S. S. Y. Lau, Z. Gou, and J. Zhang. n.d. “PostOccupancy Evaluation of Biophilic Design in the Workplace.” Buildings 12 (2): 163. Li, J., J. Wu, F. Lam, C. Zhang, J. Kang, and H. Xu. 2021. “Effect of Degree of Wood Use on Visual Psychological Response of Wooden Indoor Spaces.” European Journal of Wood and Wood Products 79 (6): 1581–1594. Li, Ke, Cynthia Cardoso, Angel Moctezuma-Ramirez, Abdelmotagaly Elgalad, and Emerson Perin. 2023. “Heart Rate Variability Measurement through a Smart Wearable Device: Another Breakthrough for Personal Health

Monitoring?” International Journal of Environmental Research and Public Health 20 (24): 7146. Li, Qing, Kanehisa Morimoto, Akifumi Nakadai, Hirofumi Inagaki, Maiko Katsumata, Takeshi Shimizu, Yukiyo Hirata, et al. 2007. “Forest Bathing Enhances Human Natural Killer Activity and Expression of Anti-Cancer Proteins.” International Journal of Immunopathology and Pharmacology 20 (2 Suppl. 2): 3–8. Li, Qing. 2010. “Effect of Forest Bathing Trips on Human Immune Function.” Environmental Health and Preventive Medicine 15 (1): 9–17. Lipovac, D., and M. D. Burnard. 2021. “Effects of Visual Exposure to Wood on Human Affective States, Physiological Arousal and Cognitive Performance: A Systematic Review of Randomised Trials.” Indoor and Built Environment 30 (8): 1021–1041. M Mamic, D., and D. Domljan. 2023. “Positive Aspects of Using Solid Wood in Interiors on Human Wellbeing: A Review.” Drvna Industrija 74 (1): 17–32. Matsubara, Eri, and Shuichi Kawai. 2014. “VOCs Emitted from Japanese Cedar Interior Walls Induce Physiological Relaxation.” Building and Environment 72: 125–130. Matsubara, Eri, Naoyuki Matsui, and Tatsuro Ohira. 2020. “Evaluation of the Psychophysiological Effects of the Cupressaceae Family Wood Odour.” Wood Science and Technology 54: 269–286. McEwen, Bruce S. 2007. “Physiology and Neurobiology of Stress and Adaptation: Central Role of the Brain.” Physiological Reviews 87 (3): 873–904. Messmer, Adrian. 2015. “Life Cycle Assessment of Adhesives Used in Wood Constructions.” MSc thesis, ETH Zurich.

Morikawa, T., Y. Miyazaki, and S. Kobayashi. 1998. “TimeSeries Variations of Blood Pressure Due to Contact with Wood.” Journal of Wood Science 44 (6): 495–497.

Research on Plants and Stress in Healthcare Settings.” HERD: Health Environments Research and Design Journal. O

Morris, Ian. 2010. Why the West Rules: For Now. London: Profile Books. Munir, M. T., H. Pailhories, F. Aviat, D. Lepelletier, P. Le Pape, L. Dubreil, M. Irle, et al. n.d. “Hygienic Perspectives of Wood in Healthcare Buildings: A Systematic Review.” Hygiene 3 (2): 12. N Nakamura, M., and T. Kondo. 2007. “Characterization of Distribution Pattern of Eye Fixation Pauses in Observation of Knotty Wood Panel Images.” Journal of Physiological Anthropology 26 (2): 129–133. Nakamura, M., and T. Kondo. 2008. “Quantification of Visual Inducement of Knots by Eye-Tracking.” Journal of Wood Science 54 (1): 22–27. Nakamura, M., H. Ikei, and Y. Miyazaki. 2019. “Physiological Effects of Visual Stimulation with Full-Scale Wall Images of Wooden Elements.” International Journal of Environmental Research and Public Health 16 (3): 486. NHS England. 2024. NHS Long Term Plan: Prevention. London: NHS England. Nicol, J. F., and M. A. Humphreys. 2002. “Adaptive Thermal Comfort and Sustainable Thermal Standards for Buildings.” Energy and Buildings 34 (6): 563–572. Norberg-Schulz, Christian. 1980. Genius Loci: Towards a Phenomenology of Architecture. New York: Rizzoli. Nyrud, A. Q., and T. Bringslimark. 2010. “Is Interior Wood Use Psychologically Beneficial? A Review of Psychological Responses toward Wood.” Wood and Fiber Science 42 (2): 202–218.

Ohlmeyer, Martin [materials scientist, Thünen Institute, Germany]. 2024. Expert communication on timber VOC profiles and adhesive chemistry. Unpublished. Ojala, A., J. Kostensalo, J. Viik, H. Matilainen, I. Wik, L. Virtanen, and R. Muilu-Mäkelä. 2023a. “Psychological and Physiological Effects of a Wooden Office Room on Human Wellbeing: Results from a Randomised Controlled Trial.” Journal of Environmental Psychology 89: 102059. Ojala, Ann, Liisa Tyrväinen, Kalevi Korpela, Marjo Lanki, Timo Laukkanen, and Timo Partonen. 2023b. “Effects of Indoor Nature (Plants, Wood and Views of Nature) on Physiological Stress Recovery.” Frontiers in Psychology 14. Orians, Gordon H. 1986. “An Ecological and Evolutionary Approach to Landscape Aesthetics.” In Landscape Meanings and Values, edited by E. C. Penning-Rowsell and D. Lowenthal, 3–25. London: Allen and Unwin. P Paciuk, M. 1990. “The Role of Personal Control of the Environment in Thermal Comfort and Satisfaction at the Workplace.” In Coming of Age, Proceedings of the Annual Conference of the Environmental Design Research Association 21: 303–312. Park, Bum-Jin, Yuko Tsunetsugu, Tamami Kasetani, Takahide Kagawa, and Yoshifumi Miyazaki. 2010. “The Physiological Effects of Shinrin-yoku (Taking in the Forest Atmosphere or Forest Bathing): Evidence from Field Experiments in 24 Forests across Japan.” Environmental Health and Preventive Medicine 15 (1): 18–26. Plutchik, Robert. 1980. Emotion: A Psychoevolutionary Synthesis. New York: Harper and Row.

Nyrud, A. Q., T. Bringslimark, and K. Bysheim. 2010. “Do Elements of Nature Have a Healing Effect? A Review of 75

Pollinate and University of Canberra. 2018. Workplaces, Wellness and Wood. Prepared for Forest and Wood Products Australia. Canberra: University of Canberra.

Schuster, A., K. Koller, M. Schuller, J. Uhr, and H. Rüden. 2006. “How Hygienic and Useful Is Wood in Patient Rooms?” Krankenhaushygiene und Infektionsverhütung 28 (6): 183–187.

Q Quality of Life Foundation. n.d. Quality of Life Framework. London: Quality of Life Foundation. R Raworth, Kate. 2017. Doughnut Economics: Seven Ways to Think Like a 21st-Century Economist. London: Random House. Richerson, Peter J., and Robert Boyd. 2005. Not by Genes Alone: How Culture Transformed Human Evolution. Chicago: University of Chicago Press. Rogers, Ben, Nuno F. da Cruz, Francesco Ripa, and Imogen Hamilton-Jones. 2024. “Prosperity Beyond Growth: An Emerging Agenda for European Cities.” Journal of City Climate Policy and Economy 2 (2): 124–146. Rovelli, Sabrina, Silvia Fustinoni, Andrea Cattaneo, et al. 2019. “VOC Measurements in Residential Buildings.” International Journal of Environmental Research and Public Health 16 (7): 1125. Rykwert, Joseph. 1972. On Adam’s House in Paradise: The Idea of the Primitive Hut in Architectural History. New York: Museum of Modern Art. S Sakuragawa, S., T. Kaneko, and Y. Miyazaki. 2008. “Effects of Contact with Wood on Blood Pressure and Subjective Evaluation.” Journal of Wood Science 54 (2): 107–113. Schuller, S., L. Bergefurt, Y. de Kort, and R. AppelMeulenbroek. 2025. “The Influence of Physical Office Environments on Physiological Stress: A PRISMA Systematic Scoping Review.” Journal of Environmental Psychology 105: 102642.

Scott, K., F. Charleson, dRMM, Edinburgh Napier University, and Quality of Life Foundation. 2025a. Measuring Mass Timber. London: Built by Nature. Scott, Laura, et al. 2025b. “Occupant Wellbeing in UK Mass Timber Buildings: A Two-Year Post-Occupancy Study.” Building and Environment (forthcoming). Shen, J., X. Zhang, and Z. Lian. 2020. “Impact of Wooden vs Non-Wooden Interior Designs on Office Workers’ Cognitive Performance.” Building and Environment 185: 107390. Son, Y. S., W. K. Jo, and J. C. Kim. n.d. “Characteristics of VOCs Emitted from Building Materials: Natural VOCs.” Building and Environment. Steemers, Koen. 2015. “Architecture for Wellbeing and Health.” Daylight and Architecture 23: 6–27. Stenson, J., J. K. Calautit, and P. W. Tien. 2022. “Monitored Indoor Environmental Quality of a Mass Timber Office Building.” Buildings 12 (1): 44. Sterling, P. 2004. “Principles of Allostasis: Optimal Design, Predictive Regulation, Pathophysiology and Rational Therapeutics.” In Allostasis, Homeostasis, and the Costs of Physiological Adaptation, edited by J. Schulkin, 17–64. Cambridge: Cambridge University Press. Sterling, P., and J. Eyer. 1988. “Allostasis: A New Paradigm to Explain Arousal Pathology.” In Handbook of Life Stress, Cognition and Health, edited by S. Fisher and J. Reason, 629–649. Chichester: Wiley. Sternberg, Esther M., and James Wilson. 2006. “Neuroscience and Architecture: Seeking Common Ground.” Cell 127 (2): 239–242.

Sumitomo Forestry Co. / Tsukuba Research Institute. n.d. The Results of Our Research on Wood and Greenery. Tokyo: Sumitomo Forestry.

Tulchinsky, Theodore H. 2014. “John Snow, Cholera, the Broad Street Pump: Waterborne Diseases Then and Now.” In Case Studies in Public Health. Amsterdam: Elsevier.

Sun, M., T. Nakashima, Y. Yoshimura, A. Honden, T. Nakagawa, H. Saijo, Y. Watanabe, et al. 2020. “Effects and Interaction of Interior Material Treatment and Personal Preference on Psychological and Physiological Responses in a Living Environment.” Journal of Interior Design 45 (1).

Sussman, Ann, and Justin Hollander. 2015. Cognitive Architecture: Designing for How We Respond to the Built Environment. London: Routledge.

Ulrich, Roger S., Robert F. Simons, Barbara D. Losito, Evelyn Fiorito, Mark A. Miles, and Michael Zelson. 1991. “Stress Recovery during Exposure to Natural and Urban Environments.” Journal of Environmental Psychology 11 (3):

201–230.

Tew, Lucy. 2023. “Terpenes and Forest Bathing in Built Environments.” PhD thesis, University of Cambridge.

US Environmental Protection Agency (EPA). 2025. Indoor Air Quality. Washington, DC: US EPA.

Thaler, Richard H., and Cass R. Sunstein. 2008. Nudge: Improving Decisions about Health, Wealth, and Happiness. New Haven: Yale University Press.

US Green Building Council. 2024. LEED v5 Rating System. Washington, DC: US Green Building Council.

Ulrich, Roger S. 1984. “View through a Window May Influence Recovery from Surgery.” Science 224 (4647): 420–421.

V Thatcher, A., and K. Milner. 2014. “Changes in Productivity, Psychological Wellbeing and Physical Wellbeing from Working in a Green Building.” Work 49 (3): 381–393. Tsunetsugu, Y., Y. Miyazaki, and H. Sato. 2002. “The Visual Effects of Wooden Interiors in Actual-Size Living Rooms on the Autonomic Nervous Activities.” Journal of Physiological Anthropology and Applied Human Science 21 (6): 297–300. Tsunetsugu, Y., Y. Miyazaki, and H. Sato. 2007. “Physiological Effects in Humans Induced by the Visual Stimulation of Room Interiors with Different Amounts of Wood.” Journal of Wood Science 53 (1): 11–16. Tsunetsugu, Yuko, Bum-Jin Park, Hideki Ishii, Hideki Hirano, Takahide Kagawa, and Yoshifumi Miyazaki. 2007. “Physiological Effects of Shinrin-yoku (Taking in the Atmosphere of the Forest) in an Old-Growth Broadleaf Forest in Yamagata Prefecture, Japan.” Journal of Physiological Anthropology 26 (2): 135–142.

Valentine, C. 2023. “Architectural Allostatic Overloading: Exploring a Connection between Architectural Form and Allostatic Overloading.” International Journal of Environmental Research and Public Health 20 (9): 5637. Valentine, C., A. J. Wilkins, H. Mitcheltree, O. Penacchio, B. Beckles, and I. Hosking. 2025a. “Visual Discomfort in the Built Environment: Leveraging Generative AI and Computational Analysis to Evaluate Predicted Visual Stress in Architectural Facades.” Buildings 15 (13): 2208. Valentine, C., H. Mitcheltree, I. A. K. Sjovall, and M. H. Khalil. 2025b. “Architecturally Mediated Allostasis and Neurosustainability: A Proposed Theoretical Framework for the Impact of the Built Environment on Neurocognitive Health.” Brain Sciences 15 (2): 201. Valentine, C., I. Hosking, A. J. Wilkins, H. Mitcheltree, C. Smith, E. Butters, and O. Penacchio. 2026. “Impact of Architecture Facade Design on Neurophysiological Stress

Using Functional Near-Infrared Spectroscopy and Heart Rate Variability.” Buildings 16 (4): 885.

World Health Organisation (WHO). 1983. Indoor Air Pollutants: Exposure and Health Effects. Copenhagen: WHO Regional Office for Europe.

Valentine, C., T. Steffert, H. Mitcheltree, and K. Steemers. 2024. “Architectural Neuroimmunology: A Pilot Study Examining the Impact of Biophilic Architectural Design on Neuroinflammation.” Buildings 14 (5): 1292.

World Health Organisation (WHO). 2010. WHO Guidelines for Indoor Air Quality: Selected Pollutants. Geneva: WHO.

Wang, H., W. Lu, S. Huang, and H. Zhang. 2024. “LongTerm Emission Characteristics of VOCs from Building Materials.” Building and Environment.

Yi, X., D. Zhao, R. Ou, J. Ma, Y. Chen, and Q. Wang. 2017. “Comparative Study of Wood-Plastic Composites and Typical Substrates as Heating Floor Considering Thermal Comfort and Physiological Responses.” BioResources 12

Whyte, S., R. Kaburagi, V. Gan, C. Candido, B. Avazpour, D. Fatourehchi, et al. 2024. “Exploring Benefits of Mass Timber Construction in the Workplace: A Novel Primer for Research.” Buildings 14 (7): 2072.

(4): 8395–8416.

Whyte, Sarah, Kathryn Skillington, Christhina Candido, Yimin Zhang, Dorsa Fatourehchi, Sabine Finlay, Ho Fai Chan, Ryo Kaburagi, Katie J. McDonnell, Mateus R. Viana, and Zoltan Sarnyai. 2025. “Understanding the Effects of Timber-Rich Workplaces on Occupants’ Perceived Productivity and Health: A Pilot Study.” Scientific Reports 15 (1): 39480.

Yin, J., S. Zhu, P. MacNaughton, J. G. Allen, and J. D. Spengler. 2018. “Physiological and Cognitive Performance of Exposure to Biophilic Indoor Environment.” Building and Environment 132: 255–262. Yu, C. W. F., and J. T. Kim. 2012. “Long-Term Impact of Formaldehyde and VOC Emissions from Wood-Based Products on Indoor Environments.” Indoor and Built Environment 21 (1): 13–23. Z

Willis, K. 2024. Good Nature: Why Seeing, Smelling, Hearing and Touching Plants Is Good for Our Health. London: Bloomsbury / Pegasus Books. Wilson, E. O. 1984. Biophilia. Cambridge, MA: Harvard University Press. Wingfield, J. C. 2003. “Control of Behavioural Strategies for Capricious Environments.” Animal Behaviour 66 (5): 807–816. Wolkoff, Peder. 1998. “Impact of Air Velocity, Temperature and Humidity on Long-Term VOC Emissions from Building Products.” Indoor Air 8 (Suppl. 4): 1–37. World Health Organisation (WHO). 1948. Constitution of the World Health Organization. Geneva: WHO.

Zhang, X., Z. Lian, and Y. Wu. 2017. “Human Physiological Responses to Wooden Indoor Environments.” Indoor and Built Environment 26 (8): 1038–1051. Zhong, L., F. Haghighat, P. Blondeau, and J. Kozinski. 2017. “VOCs in Conventional and High-Performance School Buildings in the US.” Building and Environment 124: 46–55. Zhong, W., T. Schröder, and J. Bekkering. 2022. “Biophilic Design in Architecture and Its Contributions to Health, Wellbeing, and Sustainability: A Critical Review.” Frontiers of Architectural Research 11 (1): 114–141.

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