Insights by HIP V. HYPE — BESS-10 and the Revised Daylight Pathway: What It Means for Your Next Project

In November 2025, CASBE released an updated version of the Built Environment Sustainability Scorecard (BESS-10) introducing a new daylight compliance pathway. The update, informed by three research papers overseen by CASBE between 2019 and 2025, allows projects to use spatial daylight autonomy (sDA) as an alternative to daylight factor (DF) when demonstrating daylight access in the Indoor Environmental Quality (IEQ) category.

In practical terms, projects now have a choice: the established daylight factor method, or the new climate-responsive sDA metric.

What This Means for Sustainability Advice

BESS is a Victorian tool, used by many but not all Victorian councils as a pathway for demonstrating alignment with the sustainability requirements of local planning schemes. Daylight access is a mandatory item within the BESS framework, and one we’re responsible for assessing as the sustainability consultant on a project.

Outside Victoria, different frameworks apply. NSW projects typically use BASIX, which sets its own built environment sustainability requirements. In other states, there is no single mandated tool; daylight targets are determined by the consultant based on the project’s context, drawing on frameworks such as Green Star or the NCC performance pathway.

The Problem with Daylight Factor
Daylight factor has been the default metric for years, but it has well-documented limitations. It models an overcast sky (a uniform, worst-case scenario) rather than the actual conditions a building will experience based on its location, orientation and climate. The result is that DF consistently presents a more pessimistic picture of daylight performance than residents will actually experience. Because DF assumes a uniform overcast sky, it doesn't distinguish between orientations. A north-facing and a south-facing apartment with otherwise identical geometry will return the same DF result, despite delivering very different real-world daylight amenity. For projects with constrained façades or deep floor plates, meeting the DF thresholds in BESS has been a persistent challenge even when the real-world daylight amenity of those spaces is adequate.

How Spatial Daylight Autonomy is Different
Rather than assuming a uniform overcast sky, sDA uses annual weather data specific to a project’s location to model how much of a space receives sufficient daylight across occupied hours over the course of a year. It accounts for orientation, surrounding obstructions and seasonal variation. The sDA method also requires two requirements to be met: adequate daylight and visual acuity. Adequate daylight ensures appropriate levels of light to a portion of the space while visual acuity ensures minimal daylight levels across most of the space. For developments that have historically struggled with the DF pathway, particularly those on constrained urban sites, sDA provides a more accurate way of demonstrating daylight access.

What This Means for Architects, Developers and Project Managers

• Architects and Design Teams: For architects, the change is most immediate. sDA rewards orientation and façade design in ways that DF doesn’t, because it accounts for actual sun paths rather than a uniform sky. Design teams that understand the difference early with sustainability advice can use it to inform massing, apartment layout and glazing strategy from concept stage, rather than discovering daylight compliance issues late in the planning process.
• Developers and Project Managers: For developers and project managers, the new pathway is about de-risking compliance. Projects that were marginal under the DF method may now have a viable alternative route to meeting BESS daylight requirements, without compromising yield or requiring costly redesign. The decision about which metric to pursue should be made with sustainability advice early.
  
  

How HIP V. HYPE Can Help

We assess daylight compliance across a wide range of multi-residential projects nationally, including Victoria where BESS changes apply. The introduction of sDA into the BESS framework aligns with climate-based daylight modelling approaches we already use.

Daylight Strategy and Metric Selection: We can advise on which daylight metric, DF or sDA, is most appropriate for a given project based on its site conditions, orientation, building form and planning context. For Victorian projects assessed under BESS, we can identify whether the new sDA pathway is likely to deliver better outcomes than DF. If we are not completing daylight for BESS we usually will assess it for Green Star (using sDA) or as a performance solution for NCC (using DF).

BESS Compliance and Sustainability Management Plans: For Victorian projects, we prepare BESS assessments and Sustainability Management Plans as part of the planning permit process. With BESS-10 now live, our assessments will incorporate the new daylight pathway where it delivers better outcomes for the project without compromising the quality of the spaces being assessed.

Early-Stage Design Advice: We work with architects and design teams from concept and schematic stages to integrate daylight performance into the design process across BESS, Green Star and NCC performance pathways. Early engagement on daylight means fewer surprises at planning.

We look forward to providing further insights and are ready to provide guidance to assist with your projects. Stay informed with the latest updates by subscribing to HIP V. HYPE’s newsletter.