Designing a naturally lit interior involves more than adding glass to a façade. The team should consider where light reaches, how it changes over time and where direct sunlight becomes concentrated. Daylight simulation helps examine these relationships during design. It gives the team a basis for comparing planning and façade decisions beyond a coloured results map.
Which questions can analysis answer?
Plan depth, window position, glass properties, neighbouring buildings, internal surfaces and shading can all influence daylight. Simulation considers these inputs under defined conditions. It can reveal areas with sufficient daylight and locations of concentrated direct sunlight. Reading the distribution across a space rather than relying on a single average makes the design question more concrete.
An area near a façade may be well lit while deeper workspaces have very different conditions. Internal partitions or a neighbouring building may change the distribution. Defining the areas of interest and the question at the start makes it easier to translate results into architectural decisions.
An annual view and a particular moment
Some analyses show illuminance at a particular time and under specified conditions; annual analyses consider climate and changes over time. These outputs answer different questions. A good result at one moment does not mean all occupied conditions throughout the year will be the same. USGBC — Daylight assessment.
The method follows the design question or the certification requirements. Exploring the distribution of daylight and documenting a particular compliance route are different purposes. Establishing that distinction helps define both the calculation scope and the meaning of the results.
What do sDA and ASE describe?
sDA is used to assess annual daylight sufficiency, while ASE addresses excessive direct sunlight exposure. Reading them together helps balance the benefits of daylight with the effects of sunlight. ASE alone is not a complete measure of glare or thermal comfort. IES — Daylight metrics.
A strong result for one indicator should not be treated as proof that the design is complete. Space use, occupant positions, shading and other comfort needs also matter. The report should explain what each indicator means and identify areas that warrant further design review.
Consider the façade and shading together
More glazing may improve daylight in some areas, while also affecting direct sunlight and energy demand. Shading, glass selection, window distribution and planning offer different responses. Comparing alternatives on a consistent basis makes their actual effects easier to understand.
If shading alone changes in an option, the team should understand why other inputs remain the same. Blind and control assumptions should follow the selected method. A comparison is more useful when the team can distinguish a design effect from a change in calculation conditions. Coordinating energy and daylight work helps with this judgement.
Turn the map into a practical decision
A useful presentation identifies the area needing attention and shows the effect of an alternative. It should explain the assessed area and changed design decision rather than show only a colour scale. Architects, engineers and owners can then discuss the same outcome and establish the purpose of the next revision.
Measurements can also support studies of existing buildings. A measurement records conditions at a particular place and time; simulation calculates results from defined building and environmental information. Where they are compared, measurement conditions should be considered. This keeps different kinds of information from being presented as the same result.
AECO's daylight simulation service defines the design question, appropriate method and reporting scope together. Sharing plans and the façade decisions under consideration helps clarify the study. Related energy questions can also be coordinated with energy modelling.