BESS Indoor Environment Quality Guide
Indoor Environment Quality is a core BESS category addressing how proposed buildings provide daylight, ventilation, solar access and thermal comfort for occupants.
Indoor Environment Quality, commonly shortened to IEQ, is one of the categories assessed within BESS Buildings. The category does not provide a general rating of whether a building is healthy or comfortable. Instead, it applies defined credits to particular development types and requires project information or evidence to support the responses entered into the assessment.
The applicable IEQ credits change according to the project profile. An apartment development may be assessed for daylight access, natural ventilation, cross-flow ventilation and particular thermal-comfort measures. A non-residential development may instead require daylight, ventilation, shading, ceiling-fan or air-quality evidence relevant to its regular-use areas.
This guide explains how IEQ operates within BESS and what information may be required to substantiate the assessment. For the complete planning, scoring and report pathway, see the BESS Knowledge Hub.
In Brief
Natural Light
Daylight credits assess whether relevant residential rooms or non-residential regular-use areas receive adequate natural light.
Ventilation
Ventilation credits consider natural airflow, cross-flow ventilation or defined outdoor-air and carbon-dioxide control measures.
Thermal Response
Thermal-comfort credits can recognise measures such as glazing, external shading, orientation and ceiling fans where applicable.
The category is project-specific. A measure only contributes where the relevant credit applies and the required drawings, calculations or supporting evidence are provided.
Current Assessment Context
BESS does not issue a separate IEQ certification. Indoor Environment Quality is one category within the wider BESS Buildings assessment, alongside Management, Integrated Water Management, Operational Energy, Transport, Waste & Resource Recovery, Urban Ecology and Innovation.
The credits presented by the tool depend on the development type, scale and project-profile information. This means there is no single list of IEQ measures or fixed category contribution that applies identically to every house, apartment building, commercial development or mixed-use project.
The assessment output is a BESS report rather than a BESS statement or separate IEQ certificate. That report records the project responses, applicable credits, evidence requirements and category result.
Category Scope
The current BESS Buildings IEQ category includes credits relating to daylight access, winter sunlight, ventilation and thermal-comfort measures. Non-residential projects can also encounter a specific air-quality credit based on the nominated ventilation or carbon-dioxide control approach.
Not every aspect normally associated with indoor environmental quality is directly assessed by BESS. Acoustic privacy, external views and low-VOC paints, sealants or adhesives remain relevant design considerations, but they should not be assumed to earn standard BESS IEQ points unless a current applicable credit expressly addresses them.
The project should therefore be assessed against the credits shown within the relevant BESS engine rather than a generic healthy-building checklist.
IEQ Credit Families
Daylight Access
Applicable credits assess the proportion of rooms or regular-use areas achieving the nominated daylight criteria through a permitted calculation or modelling pathway.
Solar Access
Residential credits may assess whether relevant living spaces or private open spaces receive the required access to winter sunlight.
Natural Airflow
Applicable apartment credits consider natural ventilation and whether dwellings provide an effective cross-flow ventilation path.
Commercial Ventilation
Non-residential credits may recognise effective natural ventilation, increased outdoor-air provision or defined carbon-dioxide monitoring and control.
Residential Thermal Measures
Particular residential credits can recognise double glazing, external shading and orientation where they apply to the project profile.
Non-Residential Thermal Measures
Applicable non-residential credits can recognise external shading and ceiling fans as defined measures supporting thermal comfort.
Daylight Evidence
The daylight pathway depends on the development profile. For multi-unit residential projects, the current BESS framework allows the project to nominate an accepted daylight metric and assessment pathway. The same selected metric must then be applied consistently across the apartments within the project.
Depending on the selected pathway, evidence may rely on the BESS built-in calculation method, deemed-to-satisfy criteria or a separate daylight model. More complex sites, multiple-aspect rooms, close neighbouring buildings or projects using spatial daylight autonomy may require specialist modelling rather than a simplified calculation.
For non-residential projects, relevant regular-use areas may also require daylight calculations or modelling. The report should identify the methodology, assumptions and percentage of assessed floor area achieving the applicable target.
A larger window does not automatically establish that a room achieves the applicable daylight criteria. The result can also be affected by room depth, window position, visible-light transmittance, external obstruction, balconies, neighbouring buildings, light wells and internal surface reflectance.
Glazing decisions also need to be coordinated with solar control and thermal performance. Heavily tinted glazing may reduce daylight transmission, while unshaded glazing can introduce unwanted solar gain. The response should therefore be assessed against the specific credit rather than through a general assumption that more glazing will always improve IEQ.
Where a daylight report is required, its room geometry, glazing and surrounding obstructions should correspond with the planning drawings submitted with the BESS report.
Ventilation Evidence
For apartment developments, BESS can assess whether dwellings provide suitable natural ventilation and whether an effective airflow path is available between openings. The result depends on the arrangement of rooms, openings, external walls and the path available for air to move through the dwelling.
For non-residential development, the ventilation credit can respond to natural ventilation, increased outdoor-air provision or a defined carbon-dioxide control approach. The supporting evidence changes according to the pathway selected and may include marked floor plans, ventilation calculations or proposed monitoring and control information.
An operable window alone does not necessarily demonstrate that the relevant floor area is effectively naturally ventilated. The size and position of openings, room depth and airflow path must align with the applicable credit method.
Thermal Measures
BESS includes defined thermal-comfort credits, but it does not automatically perform a full dynamic thermal-comfort simulation. Depending on the development profile, the assessment can recognise particular design measures such as double glazing, external shading, orientation or ceiling fans.
These credits should not be confused with a NatHERS assessment. NatHERS models residential thermal performance and produces a separate rating. BESS records the applicable project responses and may rely on separate technical results where required.
Where a project requires a more detailed understanding of operative temperature, seasonal comfort or conditions across occupied spaces, a separate thermal comfort model may be needed. That work remains distinct from the BESS credit assessment.
The drawings and schedules should clearly identify any glazing, shading or fan commitments relied upon by the BESS report.
Non-Residential Projects
BESS includes defined ventilation and air-quality pathways for non-residential development. Depending on the applicable credit, the project may respond through natural ventilation, increased outdoor-air provision or carbon-dioxide monitoring and control.
This should not be interpreted as a complete indoor-air-quality certification. Broader matters such as all pollutant sources, filtration performance, material emissions and post-occupancy testing are not automatically assessed through the standard BESS report.
Low-VOC products may still form part of a responsible material specification, but they should not be presented as a standard BESS IEQ credit unless the relevant current assessment pathway expressly recognises them.
Supporting Documentation
Floor plans and elevations. These may need to show room layouts, window positions, opening sizes, shading devices, orientations or assessed areas.
Daylight calculations or modelling. A report may be required to identify the methodology, assumptions, assessed rooms and results achieved.
Ventilation diagrams or calculations. Plans may need to mark compliant areas, openings and airflow paths or record the proposed outdoor-air provision.
Schedules and specifications. Glazing type, external shading, ceiling fans or monitoring systems should be documented where they support a selected response.
Consistent revision information. The IEQ evidence should relate to the same design version as the BESS report and planning drawings.
Assessment Review
The assessment relies on an earlier BESS category weighting, credit list or evidence pathway rather than the engine applicable to the current project.
Noise control, views or low-VOC products are described without confirming that they correspond with an applicable BESS credit.
Window area is relied upon without assessing room depth, external obstruction, visible-light transmission or the nominated daylight metric.
A room is described as naturally ventilated without showing suitable openings, room depth or an effective airflow path.
A measure is applied across the whole development even though the credit relates only to apartments, non-residential areas or another defined project profile.
The daylight model, ventilation diagram or shading schedule reflects an earlier room layout, façade or drawing revision.
Design Refinement
The first step is to identify the actual credit creating the shortfall. A daylight issue should be reviewed through the relevant daylight pathway. A ventilation shortfall should be traced to the affected floor area, openings or airflow arrangement. A thermal measure should be checked against the specific project profile and evidence requirement.
Potential refinements may include adjusting room depth, window geometry or glazing selection; improving building separation; revising the location of openings; strengthening cross-flow opportunities; coordinating external shading; or documenting fans and ventilation systems more clearly.
The preferred response is not simply the measure producing the highest credit score. It should be spatially achievable, documented in the planning set and capable of being carried into the completed project.
Technical Boundary
BESS assesses the responses entered against the applicable IEQ credits. Where a credit requires daylight modelling, ventilation calculations or another specialist result, that work remains a separate technical assessment.
A BESS daylight result should not be treated as a full daylight-design study beyond the nominated credit. A shading credit does not replace detailed thermal-comfort modelling. A ventilation response does not automatically establish detailed mechanical-services compliance.
The separate assessment and BESS report should use consistent project geometry, assumptions and document revisions while remaining clearly identified as different scopes.
Frequently Asked Questions
IEQ means Indoor Environment Quality. In BESS, the category includes project-specific credits addressing daylight, ventilation, solar access and thermal-comfort measures, together with a defined non-residential air-quality pathway.
Is IEQ worth 16.5% of every BESS assessment?A fixed historic percentage should not be assumed for every current project. Applicable credits, available points and category contribution depend on the BESS engine, development type, scale and project profile.
Does BESS assess acoustic performance?Acoustic privacy is an important indoor-environment consideration, but it is not generally included as a standard credit within the current BESS IEQ category. Separate acoustic advice may still be required by the project or planning authority.
Do low-VOC paints improve the BESS IEQ score?Low-VOC products may support responsible material selection, but they should not be assumed to earn standard BESS IEQ points unless the applicable current credit expressly recognises them.
Is daylight modelling always required?Not for every project or daylight pathway. Some residential assessments may use deemed-to-satisfy criteria or a built-in calculation method. Other projects require separate modelling, particularly where the chosen metric, development type or site complexity requires it.
Does an operable window prove natural ventilation?Not automatically. The relevant credit may also consider opening size, room depth, the proportion of floor area served and whether an effective airflow path is available.
Does BESS replace NatHERS or thermal comfort modelling?No. BESS includes particular IEQ and thermal-measure credits, but NatHERS and detailed thermal-comfort modelling remain separate assessments with their own methodologies and outputs.
Should IEQ evidence be updated when the design changes?Yes, where changes affect room geometry, glazing, openings, external obstruction, shading or other inputs relied upon by the assessment. The BESS report and IEQ evidence should reflect the same project revision.
Related Guidance
BESS IEQ Review
Certified Energy can review the available planning drawings, project profile and existing technical information to identify the applicable BESS IEQ credits and clarify whether daylight, ventilation or other supporting evidence is required.
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