Daylight Simulation and Solar Radiation

Considering glazing, shading and layout alongside light

Enlarging a window can increase the light entering a space; the same decision can also change direct sun exposure and shading needs. Our daylight and solar radiation studies examine these effects through design options. AECO calculates how façade and interior decisions relate to natural illumination and provides comparable results for the design team.

The service can support new-building design, façade development and improvements to existing spaces. Offices, educational spaces and exhibition areas have different visual needs. We begin by identifying the areas to assess and the design decisions the findings will inform.

Daylight simulation requires the preparation of geometry, orientation, surrounding obstructions, glazing properties and shading elements. Internal surface reflectances and local climate data are also considered. The method may assess specific sky conditions or changing conditions throughout the year. Inputs are defined at the level of detail appropriate to the design question.

Results show where illumination is concentrated and where daylight penetration is limited. Window arrangements, glazing, shading and interior layouts are compared using the same assumptions. We explain findings through maps and graphics that the team can use for façade and spatial decisions.

IES LM-83 provides methods for Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE). sDA examines access to sufficient daylight during occupied hours; ASE assesses high levels of direct sunlight exposure under defined conditions. The report states the area, time and calculation assumptions used.

Where visual comfort requires a glare assessment, an appropriate evaluation is undertaken separately. Daylight distribution, sunlight exposure and the user's viewing conditions can then be addressed through their respective criteria. For certification work, the assessment method is connected with the requirements of the relevant system.

Solar radiation analysis assesses the sunlight reaching surfaces alongside orientation, surroundings and shading conditions. Exposure on façades or roof areas can be compared across different periods, and the effects of shading options can be examined. Findings support solar control and envelope decisions.

Incident solar radiation and indoor illuminance are different metrics. Considering these studies together provides a clearer assessment of the façade's relationship with light and sun. Where heating or cooling implications are to be assessed, findings can be connected with an energy modelling study.

Deliverables include input and method explanations, illuminance or radiation maps, option comparisons and design recommendations. Implications for lighting energy are considered alongside use and controls. Translating analysis findings into implementation decisions is the central purpose of the work. For background, see our daylight simulation article; for site conditions, see our testing and measurement service.