Daylight Autonomy & BREEAM Visual Comfort credits

Hi guys,

I am here to ask if someone in the community has carried out Daylight Autonomy analyses to demonstrate compliance with the BREEAM Visual Comfort credits ?

In fact both Daylight Factors and Daylight Autonomy calcs are accepted by the BRE.
However the definition of the target for daylight autonomy is a bit ambiguous and differs from the other schemes (WELL, HQE, LEED) which are all relying on the sDA metric.

Indeed, (e.g. for an office space) it is requested to demonstrate that the “Average Daylight Illuminance” (averaged over entire space) exceeds 300 lux for 2000 hours or more.

My understanding is that this is not a straightforward output from HB+. Calculating the hourly average illuminance using the hourlyValues component is very demanding when dealing with hundreds of test points and ca. 4000 daylit hours.

Is that something for which we should wait for the MySQL link between the results file and the GH post-processing to be released ?
Is anyone aware of any program that would easily output this metric (hourly average illuminance) ? I would be a bit surprised that this made it through the BREEAM criteria if there was no easy way to calculate it :slight_smile:

Thanks in advance for your feedback,


@OlivierDambron and @Byron should be able to tell you more on this topic.

Hmm. If you use the Annual Recipe and not the DC HB[+] doesn’t load the results to memory. You still need to develop a script to post process the results but you shouldn’t have any issues with calculating the values.

Hi @JocelynUrvoy,
attached a postprocessing definition for HB legacy ,if you´re interested, for the BREEAM “funny” visual comfort credit (495.9 KB)

Peter Z


Hi Peter, Mostapha,

Thanks for your comments.

I hadn’t thought of combining the Ladybug_Fly + Data recorder on the average illuminance, but it actually works nicely (simply the time to loop through a slider equal to the number of tested hours. Approx 1 min for the full year on my machine).
This way I avoid loading millions of hourly lux levels at once through the hourlyValues component.

I’ve scripted it with HB+, I’ll tidy it up and share it here.

Thanks again,



Hi Jocelyn,

Any updates on this?

Would appreciate it if you could share the HB+ script :slight_smile:

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Hi Jocelyn,

Could you share the script?