Supporting healthy indoor environments is a growing imperative for business

There is well-established evidence showing internal environmental quality (IEQ) in buildings, including visual comfort, indoor air quality, thermal comfort and acoustic comfort, can have a significant impact on our physical and mental health. 

Recent periods of extreme heat across the world have highlighted how difficult it can be to maintain safe and comfortable indoor environments, particularly for vulnerable groups such as children, older adults and those with existing health conditions.

Poor indoor environments can contribute to a range of physical and mental health impacts, making them an important consideration for both building occupants and employers.

Indoor air quality has a direct impact on occupant health, comfort and productivity. Photograph: iStock

Underlying these associated impacts are staff costs – which typically contribute 90% of the total financial burden associated with a building-based business. The impact on productivity, staff attraction and retention, and general employee satisfaction on the bottom line means that staff wellbeing is therefore vital to business success.
 
The Version 7 updates to BRE’s environmental assessment methodology (BREEAM), bridges the gap between a range of built environment outputs, helping build a holistic approach where the impacts of assets are understood on a lifecycle basis. In particular, the integration of health and social impacts alongside whole life performance enables asset owners and managers to respond to the growing requirements of their occupants and users. 

BREEAM is a sustainability assessment method for the built environment (i.e. buildings, like workplaces) and infrastructure. Using science-based frameworks, BREEAM assesses, validates and certifies the sustainability and whole life performance of buildings, including new build projects, refurbishment and fit-out, and buildings in everyday use.

BREEAM assesses and certifies areas of a building’s sustainability and performance (from design to operation and end of life), such as its contribution to net zero carbon, health and social impacts (i.e. impact on the health and wellbeing of occupants, visitors and the local community), circularity and resilience, and biodiversity.

Indoor air quality (IAQ)

Indoor air quality is a key component of IEQ and has a direct impact on occupant health, comfort and productivity. Poor IAQ is associated with respiratory conditions, allergies and reduced cognitive performance, making it a critical consideration for employers and building managers. Recognising this, health and wellbeing is a fundamental aspect of BREEAM, ensuring that buildings are designed and operated to support both occupants and visitors.

BREEAM supports the maintenance of good IAQ through a combination of science-based requirements and practical measures applied across the entire building lifecycle. Within the Indoor Air Quality issue of the Health and Wellbeing category, BREEAM sets out clear, evidence-based criteria that address both pollutant sources and occupant exposure.

At the design stage, the methodology prioritises early intervention, including the development of an Indoor Air Quality Plan to ensure that IAQ risks are identified and managed from concept through to construction and handover. This includes practical measures to prevent contamination during construction and to ensure that buildings are free from hazardous materials such as asbestos.

Another key focus is source control, reflecting strong evidence linking building materials to indoor air pollution. Materials can emit pollutants such as volatile organic compounds (VOCs), formaldehyde and other carcinogens, which can impact occupant health. BREEAM addresses this through strict requirements for low-emission construction materials, providing a practical and effective way to reduce pollutant loads at source.

To manage pollutants generated from both materials and occupant activities, BREEAM also requires adequate and well-designed ventilation. This ensures that buildings deliver sufficient fresh air, taking into account outdoor air quality and internal pollutant sources, to effectively dilute and remove contaminants. These requirements translate scientific understanding of exposure pathways into real, measurable improvements in indoor air quality.

Natural light has positive effects on physical and emotional wellbeing. Photograph: iStock

Once the construction or fit-out of a development is complete, BREEAM requires post-construction indoor air quality testing or a flush-out strategy, focusing on key pollutants such as VOCs and formaldehyde.

This provides assurance that design intentions are achieved in practice and that buildings are ready for safe occupation.

In BREEAM Refurbishment and Fit-Out Version 7 launching in September 2026, we extend this approach to include emissions from furniture, recognising its contribution to indoor pollution. This ensures a consistent and lifecycle-based approach to IAQ, addressing all major pollutant sources within the indoor environment.

For existing buildings, where design interventions are more limited, the forthcoming BREEAM In-Use Version 7 emphasises ongoing performance and monitoring. This includes tracking key IAQ parameters, such as temperature, relative humidity, VOCs, formaldehyde, nitrogen dioxide, ozone and particulate matter (PM₂.₅ and PM₁₀).

Advances in sensor technology enable building managers to monitor trends and take timely, data-driven action, ensuring that indoor environments continue to support occupant health and wellbeing over time.

Natural and electric light

Light is an intrinsic part of the human experience, affecting our physiological health, such as eye discomfort, migraines, alertness, and our sleep and wake cycles. Natural light in particular has positive effects on physical and emotional wellbeing, with electric lighting ensuring that visual tasks can be carried out safely, accurately and comfortably. 

BRE continues to recognise the provision of suitable visual comfort within buildings, aligning with the latest best practice, including the EN 17037 standard on the design and provision of daylight in buildings. In BREEAM Version 7, there are now three key topics: natural light, electric light and non-visual effects of light. Each of these areas helps to ensure that the indoor environment positively impacts occupant health and wellbeing.
 
Within natural light, there is a focus on ensuring accurate climate-based daylight modelling is used to reflect local climatic conditions throughout a year. For BREEAM New Construction Version 7, a new minimum standard has been set, ensuring that the top-rated buildings aiming for ‘Outstanding’ meet a minimum level of performance for daylight provision. 

The non-visual effect of light has become an established field with greater consensus and research backing. This work and BREEAM’s new criteria support lighting designers and engineers to provide science-backed strategies for their clients and building occupants. Aligned with both natural light and electric light provision, our strategy supports providing the right light at the right time. 

It also supports occupant health whilst reducing negative impacts of lighting such as flicker. 

Thermal comfort

Thermal comfort is a critical component of IEQ, as occupants are highly sensitive to temperature conditions, and perceptions of comfort can vary significantly between individuals.

Achieving good thermal comfort is therefore essential to supporting health, wellbeing and productivity within buildings. Health and wellbeing is therefore a fundamental aspect of BREEAM, ensuring that buildings are designed and operated to meet the needs of occupants and visitors under changing future conditions.

At the design stage, BREEAM requires the use of detailed thermal modelling and simulation to assess how buildings will perform under a range of conditions.

This ensures that spaces are designed to provide appropriate and optimised thermal conditions based on occupancy patterns, building use and operational requirements. By applying established thermal comfort standards and adaptive comfort models, BREEAM translates scientific understanding into practical design decisions that improve occupant comfort.

Recognising the increasing risks associated with climate change, BREEAM also requires buildings to demonstrate resilience to future weather scenarios. This includes assessing the risk of overheating and ensuring that buildings can maintain comfortable conditions under projected climate conditions.

Overheating is a growing concern, particularly in modern, energy-efficient buildings, and can have significant impacts on both occupant wellbeing and safety.

To address this, BREEAM encourages the use of passive and active design strategies. These include measures such as shading, appropriate glazing, natural ventilation, thermal mass, and efficient HVAC (heating, ventilation and cooling) systems, all of which contribute to maintaining stable and comfortable indoor temperatures while minimising energy demand.

Research also shows that occupants are more satisfied with their environment when they can adjust conditions to suit their personal preferences. As such, BREEAM promotes the provision of appropriate controls, including zoned systems, local temperature controls, and user-adjustable settings, enabling occupants to adapt their environment where feasible.

Across the building lifecycle, these measures ensure that thermal comfort is not only considered at the design stage but also delivered in practice. 

In existing buildings, operational performance, system control and occupant feedback play a key role in maintaining comfort over time.

Acoustics

Good acoustic design of a space promotes concentration and relaxation, promoting productivity. Acoustic design also has a direct impact on health conditions such as stress, hearing conditions and heart disease, with a higher risk factor for neurodivergent people. 

To promote good acoustic conditions, BREEAM focuses on three core principles: sound insulation, indoor ambient noise levels and room acoustics.

Sound insulation is the protection from noise transfer between two spaces, with the level of sound insulation dependent on the amount of noise expected in the environment and the degree of privacy required. Indoor ambient noise is the amount of noise within a space from both internal and external noise sources – for example, extract fans and road traffic.

Room acoustics describe how sound behaves in an enclosed space in terms of the reverberation time (or degree of echo), overall noise levels and speech intelligibility. These principles are applicable to all building types and guidance on appropriate standards and levels is set out within the BREEAM schemes.

Takeaways for employers 

These considerations underline the importance of combining science-based criteria with practical design and operational measures to deliver improvements in occupant wellbeing, satisfaction and productivity. People spend up to 90% of their time indoors, meaning evidence-based action that takes a view across the lifecycle of a building is essential to provide the conditions for resilient, productive and healthy building occupancy.

This does not require employers to approach buildings only through the lens of compliance, but to adopt more systematic approaches to understand how indoor spaces are experienced and perform in practice.

Regular monitoring, occupant feedback, maintenance and evidence-based interventions can help employers make better decisions about the spaces they operate. 

For organisations seeking to attract, retain and support building users, IEQ is becoming part of the wider conversation about responsible business. The most effective employers will be those that treat the workplace not simply as a cost to be managed, but as an asset that can support productive teams.

For more information see:
breeam.com
bregroup.com

Anna Buchanan is Principal consultant for health and Wellbeing,
BRE

Chetas Rana is Senior consultant for health and wellbeing,
BRE