Indoor Environments

There is mounting evidence for the impact that indoor environments have on our health, wellbeing, performance and productivity. With 65% of the developing world and 85% of the developed world predicted to be living in urban areas by 2050, providing good quality indoor environments is a growing priority – particularly for those developing, designing and operating buildings.

The consequences of poor indoor conditions can range from discomfort and irritation to more serious health effects, both physical and mental. Important factors affecting indoor environments include indoor air quality, lighting, acoustics and thermal comfort, along with often occurring combinations of these and additional, less tangible factors.

The BRE Trust has supported a wide range of research and dissemination projects to address these issues.

Health effects of indoor air quality on children and young people

The inside story

The growing evidence that respiratory problems in children can be made worse by indoor air pollution in homes, schools and nurseries, has highlighted a pressing need to improve indoor air quality (IAQ).

This is according to a report from the Royal College of Paediatrics and Child Health and the Royal College of Physicians, based on an extensive review of indoor pollution research, evidence from a wide range of practitioners and experts, and conversations with children, young people and families. It presents evidence linking indoor air pollution to childhood health problems such as asthma, wheezing, conjunctivitis, dermatitis and eczema.

Wide-ranging contributory factors detailed in the report include the materials used to construct and decorate buildings, which can be long term sources of VOCs and formaldehyde, and the design and refurbishment of buildings to be more airtight. Airtight construction can improve energy efficiency but should incorporate sufficient ventilation to prevent the build-up of pollutants.

A group of experts reviewed the evidence and formulated recommendations for action by government and local authorities, and guidance for families.

“I was very happy for the BRE IAQ team to participate (with support from the BRE Trust) in this crucial and timely report, which benefitted from the contributions of a wide range of stakeholders,” says Dr Andy Dengel, Director, BRE Environment.

“The importance of good indoor air quality for health and wellbeing is now increasingly being recognised, and in children and young people the effects of poor IAQ can be more marked due to respiratory and other bodily systems still being in development.  Now, as called for in the report, it is time for urgent action by many parties.”

Those parties include people designing, constructing, maintaining and repairing buildings, who the report says (among many recommendations) should be helped to avoid the use of harmful chemicals and pollutants with the support of clear labelling and a national system for control. Professional bodies for design and construction should provide or accredit training about indoor air quality, providing high standards for ventilation, energy efficiency, and reduction in exposure to allergens and pollutants.

The full report is freely available from the RCPCH website.

Assessing Indoor air quality sensors and monitors

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Ensuring good indoor air quality (IAQ) requires continuous monitoring, but the quality of the growing numbers of sensors and monitors available is variable and robust protocols for testing such devices are needed.

This BRE Trust supported project investigated the performance of various commercially available VOC and CO2 sensors/monitors, when challenged by realistic levels of these pollutants generated in a controlled environmental chamber at BRE.

Test protocol for standards and assessments

A key aim was to set the foundations for a robust chamber-test protocol for air quality monitors, which can be applied when developing standards against which such monitors may be certified in future. At the same time, it will enable BRE to gauge the performance characteristics that should be applied to monitors specified for use, for example, in BREEAM building assessments.


The project first identified a range of ‘commercial’ (i.e. for use on building performance assessment/verification) and ‘consumer’ (i.e. low-cost monitors, watches, etc.) devices. The team then developed a test protocol using one of BRE’s room-sized environmental chambers, designed for testing devices against Standard Methods or fully-fledged reference analysers, when challenged by real-life levels of CO2 and VOCs. This protocol was then used to test some of the devices currently available on the market.


A number of the devices with CO2 sensors performed satisfactorily, as perhaps might be expected given the length of time this type of sensor has been commercially available. However, at normal background CO2 levels some of the devices over-measured, and at higher levels (1000-2000 ppm) two types of sensor under-measured by 60-80%.

Several of the devices with TVOC (total VOC) sensors performed unsatisfactorily – with many significantly over-measuring TVOC when at ‘background’ chamber conditions, and having very varied responses to higher concentrations. During the project issues with reliability, reproducibility (although only studied here with two replicate devices), connectivity and procurement were also encountered.


It is anticipated the findings of this project will heighten awareness of the importance of obtaining good data from air quality monitors – especially where that data may be used to inform financial, reputational or personnel-based decisions.

This limited study has shown that more work is needed to assess the selectivity, accuracy, reproducibility and usability of air quality sensors, which might be used to assess the performance of buildings or to garner credits for environmental assessment schemes. It has helped to underline the very real need for Standard(s) for such air quality monitors.

Next steps

A proposal for developing a BRE Standard for air quality sensors will be submitted to the appropriate BRE teams. The test protocol developed for this project may later be applied to other IEQ parameters such as humidity, CO, NOx and particulate matter. The main findings will also be shared with the BRE Centre for Intelligent Homes team, in connection with their work on Smart buildings.

Designing for quality indoor environments for occupant health, wellbeing and productivity

BRE has used its applied research work on air quality, lighting, acoustics and other aspects of indoor environment quality, to inform its commercial proactive and reactive investigation work in this field.

To complete this knowledge feedback, findings from such investigations need to be easily accessible industry-wide for new development and refurbishment projects. To this end, the following three guides on the overall theme of ‘Quality indoor environments for occupant health, wellbeing and productivity’ have been published – and were launched at the BRE Trust supported Health, Wellbeing and Productivity: An Integrated Approach to Providing Quality Indoor Environments event hosted by BRE. They are now all available on the BRE Trust website.

Indoor air quality

Indoor air quality (IAQ) is a complex issue with many factors affecting it, including a wide range of pollutants and sources, building types, locations and decor.

The new publication – Ensuring good indoor air quality in buildings – summarises the issues that building owners, architects, designers and facilities managers face when seeking to provide good air quality. It gives an overview of the sources and types of pollutants likely to affect different indoor environments in urban areas, and summarises current regulations, standards and guidance in the UK. It also includes short case studies to illustrate strategies for improving IAQ.

Indoor lighting

The new publication, Quality indoor lighting for comfort, health, wellbeing and productivity, provides important information for building designers, owners and occupants – to make them aware of the potential benefits of careful lighting design that meets the recommendations of codes and standards, and ensures that occupants’ visual requirements are met. These recommendations address lighting design issues such as the type of activity in the building, health, visual comfort and performance – including issues such as flicker, glare and controls, individual requirements and emergency lighting.

As indoor lighting is not always designed or installed to standard recommendations – adversely affecting occupant wellbeing, comfort, health and productivity – the publication recommends specialist post-occupancy evaluation of artificial lighting. It also presents a number of case studies in which lighting problems have been identified and solutions suggested.

Acoustic design

The new guide, Acoustic design and testing for health and wellbeing, identifies the basic elements of acoustic design and the standards which are most commonly used when considering the impact of noise on residential properties.

It is intended to help housebuilders, building owners, designers/architects, planners, landlords and householders take the first steps towards understanding acoustic requirements for homes and the kind of technical data they might encounter on the way.

Overheating guidance

The increased occurrence of heat waves has been widely predicted, exacerbating the already growing number of cases where there is already a build-up of heat within buildings during ‘normal’ climatic conditions.

In response to this worsening problem of overheating in certain types of building, two BRE Trust guidance documents –outputs of a Trust funded project by the BRE Building Technology Group and Professor David Ormandy of the University of Warwick – and an academic journal paper have been produced.

The guidance document, Overheating in dwellings, was developed to help with assessing homes at risk of overheating, and to inform decisions on preventative measures. The accompanying, Assessment Protocol, document describes the assessment methodology and process in detail. The academic journal paper on chronic overheating, was the result of collaboration between BRE’s Dr Mich Swainson and Dr Rob McLeod of Loughborough University Chronic overheating in low carbon urban developments in a temperate climate. Renewable and Sustainable Energy Reviews 74, 201-220.

Other research

BRE’s Dr Ed Suttie launched a new TRADA (Timber Research and Development Association) Briefing document at the Timber Trade Journal’s Wood and Wellness Conference in February 2019. The Briefing document, The role of wood in healthy buildings, investigates and discusses the potential roles for timber in supporting health and wellbeing. Prepared by Dr Suttie with funding support from the BRE Trust, it brings together and summarises a wide range of international research on the impact of nature and natural products on health and wellbeing, and focuses on how the inherent qualities of wood can contribute to healthier buildings.

“It points towards how we as an industry can work together to fundamentally start to deliver health and wellbeing through the use of timber and timber products in buildings and construction,” said Dr Suttie. More information and access to this report is available at

Circadian rhythms control human alertness and sleep, and the release of hormones. Daytime exposure to light, especially blue light, helps synchronise the circadian clock, enabling us to feel alert during the day and sleepy at night. But many people work in poorly daylit spaces with relatively low levels of electric light, where it may be hard for their bodies to maintain their circadian rhythms.

Dynamic ‘circadian’ lighting is being marketed using dimmable, colour-tuning LEDs to give brighter, bluer light in the middle of the day, and dimmer light – with less blue – later in the day when it is time to relax. However, little or no research has been done on the best way to control this tuneable lighting under real-world conditions. Research was needed to help translate experimental knowledge into practice and investigate the effects of dynamic lighting and its timing on how people feel (i.e. their subjective assessments), and their activities and reported sleep.

For the full report on this research project visit the Knowledge Hub page.

How do we know we are designing effective spaces if we don’t measure it?

BRE has collaborated with Interface and Oliver Heath Design to develop a new guide aimed at designers, decision makers, end users and influencers in the built environment. Part-funded by the BRE Trust, Creating Positive Spaces by Measuring the Impact of Your Design explains how to assess how well your building is performing, using pre and post occupancy evaluation (POE).

The guide covers:

  • What POE is and its benefits.
  • What a POE process looks like.
  • How to get started.

It incorporates ‘Who’s doing it’ case studies, including the POE of BRE’s own B18 office refurbishment.

Download the guide for free here