Annual Daylighting Performance Metrics, Explained

Annual Daylighting Performance Metrics, Explained
02 Jan 2021 / by admin in Design, Life, Light

One of the most photogenic and emblematic demonstrations of environmental architecture is a house interior overflowing with Daylighting . However, until recently, everybody believed how a “day-lit” room looked—and everyone’s right to identify indicators of progress as appropriate for their initiative. Not only has the lack of continuity contributed to uncertainty between planners, construction scientists, owners and tenants but reasonable distinctions between constructed conditions and design alternatives have often been ignored.

Annual Daylighting Performance Metrics


The United States in 2000 The LEED rating framework was developed by the green building council (USGBC) to standardise metrics for many primary sustainable architecture features, including daylight. However, rational comparisons of daylight quality were not feasible until 2013 when the Illuminating Engineering Society (IES) introduced and released the Lighting Message 83 Research and Measurement Guideline (LM-83) (ASE).

LM-83 is the first annual daylight indicator in the lighting sector to be implemented by IES. IS Daylight Metrics Committee (DMC) under the leadership of the energy conservation specialist has made a six-year study initiative.

SDA: Is the light of day sufficient?

The spatial daylight autonomy investigates when a room provides adequate daylight on the horizontal plane on a yearly basis within normal operating hours (8 a.m. to 6 p.m.). The sDA is determined virtually through numerical simulation with exact parameters instead of collecting data for one year in the field. It applies to a local environment file—such as a weather file for EnergyPlus from the United States. Energy Department — operates hourly lighting charts in the lighting app which provides an algorithm to approximately manual window blinds service.

ASE: A blindness and overheating proxy

The ability for light and solar heat gain comes with higher daylight levels. Annual solar exposure (ASE) is now being added. ASE is aimed at helping designers to restrict excess sunlight in a given space, to complement sDA. Whilst ASE is a crude representative for lighting phenomenon, it tests the presence of sunlight by means of annual horizontal illumination grids instead of light measures.

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As an indicator value of sunlight, a simulated 1000 lux is used by ASE but the simulated value may vary significantly from the physical environment which takes secondary bounce-off surfaces into consideration.

Sunlight analyses are often used for the manual activity of manual shields that influence the determination of sDA by using the technique for ASE measurement of the simulations with the LM-83. Consequently, areas with large ASE values will have lower sDA values since the algorithm believes the building owners cover window shutters or manually draw window shades if excess sunlight continues.


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