DGNB - Annual Light Exposure

[David_S]

Hello,
We would like to asses the Annual Light Exposure (ALE), which is a requirement of our DGNB project. To our knowledge, the IES Radiance module can produce the Annual Sunligth Exposure (ASE), Spatial Daylight Autonomy (sDA) and Useful Dayligth Illuminance (UDI) measures. As the ALE is not reported by the IES directly, is there a way how to derive the ALE out of the above data? NOTE: The ALE is reported in lux hours per year (I am sorry should that be a dumb question, but our experience covers only calculation of Dayligth Factors and Illumination levels, for which we use the FlucsDL module). Many thanks for any thougths on this

[David_S]

Just to add more specific information to the above question - the question is related to the DGNB SOC1.4 - Visual comfort (Offices 2014), Indicator 2, option 2 - Dayligth Simulation. Thank you

[PCully]

Hi,

I haven't seen annual lighting exposure before but it should be possible to output it from the calculations that radiance performs, I'll ecord the request with our product managers to consider for a future update.

In meantime do any other users have a suggestion to manually calculate this or extract from the current VE outputs?

Phil

[PCully]

Hi,

Thinking on this further you might be able to assess it for a point in a room using a Radiance sensors calculation which you can then view as e1 variable in Vistapro following an Apache simulation with Radiance link on. This gives you the lux value at that sensor point for each hour which you can then either export or manipulate using the VistaPro range tools to see number fo hours where a certain lux is exceeded and so calculate the lux-hours which is ultimately what you are after here. Similarly after a dynamic calculation within Radiance you have access to the raw data for the points on the working plane should you wish to review that

I will still record this request though to automate some of the steps if possible

Phil

[David_S]

Hi Phil,
Many thanks for your suggestions.

I have already managed to extract one week worth of data (illuminance profile -> calculate lux hrs) from the raw data for one point on the grid. But it is a very laborious and time consuming process, so some automation would indeed be great here.

I will also give it a go via the other route (Apache with Radiance link on). Do the Radiance sensors have to be positioned manually, or is it possible to arrange them into a grid automatically?
Thank you
David

[PCully]

Hi,

With Radiance sensors and linking into Apache you can only define max 2 sensors per room so you won't get a grid but I would have expected with this kind of analysis you are looking at specific points int he room anyway rather than metrics across a working plane (I may be wrong based on your previous comment here)

Radiance sensors tab has na option to place sensors in default position (one in centroid of each room either on working lane facing up or ceiling facing down) but they can be place manually and/or edited after placing at default position.

Phil

[David_S]

Hi Phil,
There is some new info regarding the DGNB SOC1.4.

We have consulted the requirements of the credit with a German colleague, who commented that the measure they actually use is the Spatial Daylight Autonomy (sDA).

While the annual light exposure is indeed specifically mentioned in the DGNB credit description, we concluded that it is probably an inaccurate translation from German to English and the expression is meant to be used as a general term, rather than a specific measure. This is where the requirement got mixed up with the ALE, which indeed is measured in lux hrs.

So, it seems that the IES VE is capable of evaluating the DGNB dayligting credit, at least in this specific case.

I apologize for the confusion. In any case, thanks a lot Phil for your replies, time & thoughts on this.
David