Chris Rush
July 2021

Collaborating on assessment, design and management

environmental SCIENTIST | Improving indoor air quality | June 2021

Chris Rush emphasises that for the best indoor air quality coordinated input is needed at all stages of a building project.

The quality of the environment inside the buildings in which we live, play and work is governed by a host of interacting factors. The air is one part of the broader indoor environmental quality (IEQ) package and is influenced by a range of disciplines throughout the design process and then during the operation of the building. Architects, building services engineers, building managers and air quality consultants are some of the people who have a role to play in how the quality of the air we breathe in these indoor spaces is taken into account in the design and subsequent operation of a building.

Overview of the current process

Recently, indoor air quality services have seen a surge in interest, fuelled by the health and wellbeing agenda and, more recently, the Covid-19 pandemic. The consultation on the Future Homes Standard1 that included changes to Approved Document F1 of the Building Regulations2 is one example of how indoor air quality is being given greater consideration in the design process. In parallel to this, there is growing recognition of the benefits of moving beyond compliance to voluntary accreditations, such as the WELL Standard.3 In some cases, developers have assembled bespoke criteria for indoor air quality that will be of most benefit to their end users – employees, tenants or buyers, for example.

The increased focus on indoor air quality across various disciplines is evidenced in the new guidance and notes that are being released, such as the Technical Memorandum series on operational performance from the Chartered Institution of Building Services Engineers (CIBSE).4,5 The requirement for expertise of disciplines from professional bodies such as CIBSE in working towards this common goal of improved indoor air quality means that an interdisciplinary approach is absolutely essential.

Reaching this goal is further complicated as the amount and type of specific expertise required varies with the stage of a project. For example, detailed input will be required from a competent and suitably experienced air quality professional (the air quality expert) at the start of a project, so as to identify and understand the air quality climate. Input from mechanical building services engineers is required to a greater extent during the subsequent detailed design stages when specification of filtration and how it integrates with other design considerations is required. Over the life of a project, the input for indoor air quality can be split into two high-level areas: identifying and understanding the issues, followed by adapting to and mitigating them.

Identification and understanding

Having a firm grasp of the issue at hand and the science of air quality is the first step in moving towards a building with the desired indoor air quality. This means that identifying and understanding both the outdoor and indoor air quality in terms of the sources of pollution as well as the pollutants’ chemistry and behaviour in the environments is necessary in order to inform other professionals in the group, such as the architect and the building services engineer. This allows for effective design and subsequent operation.

To realise the full potential of air quality technical expertise, it cannot be provided in isolation. Having an appreciation of the wider policy setting, existing and upcoming guidance, legislation and regulation involved in applying this science to real-world situations and how this integrates with other disciplines is critical. The role of the air quality expert at this stage is pivotal – as well as providing the understanding of the science and its application, the air quality expert can help support the project team on how air quality guidance and policy should be applied and at which stage. Setting out options and providing a roadmap by which the building design can develop with air quality as a principal consideration is a key deliverable at this stage, and it can take the form of a project-specific air quality plan.

Adaptation and mitigation

Buildings play a role in influencing the outdoor and indoor air quality from the design stage: the ventilation strategy includes intake locations, filtration options, air change rates etc, along with fit out and furniture specification. The role of architects and building services engineers at this stage is key in harnessing the information around the poor air quality and actioning it appropriately as part of the design. Effectively adapting the building design and applying mitigation as appropriate to address and account for the prevailing and projected quality of the air sits largely with the mechanical engineers and architect, and they will have been and should continue to be guided by the air quality expert.

As with the identification and understanding stage, to realise the full potential that indoor air quality can offer, adaptation and mitigation should not be progressed in isolation – and the role of the air quality expert is to support the mechanical engineer and architect in the interpretation of the impacts of design decision on air quality.

Beyond design and moving forward into the operation of a building, the principal parties responsible for indoor air quality must ensure that any embedded mitigation and the long-term responsibility transfers to the building managers and users of the building. The maintenance of the existing building services and operations must remain consistent with design parameters to ensure the long-term integrity of indoor air quality for all end users and occupants.

This is a rapidly evolving field, so during the operational phase, accreditation bodies (such as WELL) and building performance engineers help to maintain compliance with the design as well as highlighting opportunities for improvements, taking into account any recent guidance and knowledge. This expertise again helps to bolster the building management organisations and building users to ensure indoor air quality is maintained.

As part of any design and operation there is also a need for collaboration with other parties beyond those mentioned previously – such as sustainability consultants with regards to design considerations to avoid overheating and excessive energy usage. In addition to the more established parties as part of the standard design and operation team for a building, input from experts in the field of virology may be one area from which we will see growing input to improve indoor air quality as the ongoing effects of the Covid-19 pandemic continue to be felt.

The importance of collaboration

The complexity of the indoor environment, with different disciplines interacting, collaborating and influencing indoor air quality outcomes, means that air quality experts are integral at the identification and understanding stage, so that the various other disciplines can build and develop designs on an informed footing.

Continued dialogue throughout the adaptation and mitigation process is key, to allow for the benefits of indoor air quality to be carried through the project and be truly realised by the end user. Having a solid scientific basis on which to build is critical and means that this expertise acts as an identifiable point of reference for a project team to help navigate the growing complexities and opportunities in this evolving topic in the later design stages. This allows for a truly robust design and operation. To fully realise the opportunity that indoor air quality offers in terms of the value to the individual user, collaboration and engagement by all parties is required throughout the processes of design, build and beyond.

Chris Rush is the Air Quality Group Lead at Hoare Lea, a committee member of the IAQM and a member of the CIBSE Air Quality Working Group. He is a Chartered Environmentalist and has an MSc in air pollution management and control. His diverse experience includes air quality works from initial feasibility through planning to construction and operation. He is involved in the testing and assessment of indoor air quality and furthering understanding of how building design contributes to indoor air quality in the detailed design stages and operation.


  1. Ministry of Housing, Communities & Local Government (2021) The Future Homes Standard: changes to Part L and Part F of the Building Regulations for new dwellings consultation. (Accessed: 28 May 2021).
  2. Ministry of Housing, Communities & Local Government (2010 with 2013 amendments) Ventilation Approved Document F: ventilation. (Accessed: 28 May 2021).
  3. International WELL Building Institute (2021) Home page. (Accessed: 28 May 2021).
  4. CIBSE (2020) TM61: Operational Performance of Buildings. (Accessed: 28 May 2021).
  5. CIBSE (2020) TM64: Operational Performance: Indoor Air Quality. (Accessed: 28 May 2021).

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