BREEAM Daylight Factor Analysis

[Anonymous]

Hi,

I would like to assess Daylight Factor for BREEAM assessment.  I need to know if a floor plate can achieve 2% daylight factor over 80% of floor area.  

Settings I selected for this Analysis are;

Analysis: Illuminance Analysis

Environment: Daylight Factor Sky

Illuminance Settings: 200 to 500 Lux

Analysis Plane Height: 32 inches above floor

I ran the analysis, and tried to create a new Analysis Display styles with Daylight Factor.

However, there is no flexibility of adding a range or no way of knowing what the units of representation are.

I only get one colour and I am not able to add more ranges.

Could anyone help with setting to determine 2% daylight factor?

Brenda

[rds3000 · Accepted solution]

DF sky yields values in the range of 0-100 (%).  The values are represented in LAR/Revit as 'lux', but the 'lux' values are simply what is returned by the analysis engine.  We are workiung on a native DF analysis type, but all it would do it label the results as '%' rather than 'lux', not change any results from the engine.

The thing you need to do is to set the threshold to '2' (even though it is labeled as 'lux' the values are in '%').  Then in the Analysis Display style, change the color thresholds to values between 0 and 100.  You can use decimal values in the Analysis Display Styles to get better resolution.

As we are working on a DF analysis type, feel free to share your workflow needs and output suggestions here.  It will help our development work.

David

[Anonymous]

Thank you, David.

The setting seems very confusing.  I tried three different settings;

1- Lux threshold 200-500

2- Lux threshold 0-100 (assuming it's 0-100 %)

3- As per your suggestion, 0-2

It was interesting to see the results were very similar to each other.

The max lux(or %) were 49, 48, 46 respectively. this is what was shown on the legend bar in 3D view. (Max values are shown differently on Analysis Results Settings for some reason closer to 20s)

On floor plan display, the results appear to be very similar.  I had to change the colour range from 0-100 to lower values below 50 with smaller increments to see the colour ranges on plan.  Would these values you put in the colour mapping be the percentages value of Daylight Factor?

If so, I can then figure out how much of areas can achieve better than 2% DF.

Also, the threshold values in the setting perhaps doesn't seem to affect the result so much?  Would this be because I selected Daylight Factor Sky which automatically works out with default sky light level?

Brenda

[rds3000 · Accepted solution]

Sounds like you have it working.
To confirm the results, for your comfort, it's a good idea to put a small
Floor object far outside the building on a Level you are analyzing. The
values on that Floor should be near 100.

If 2% is your minimum threshold, use '2' when you run a new analysis. If
you want to see the summary of areas above another threshold, use that
value for the maximum. Thresholds are only used to process the results in
the Schedules and Summary results, and they don't affect the Analysis
Display Style right now. You'll have to create a custom style to visualize
the thresholds.

The DF sky is not affected by time/date or solar values, as it is a
standard CIE Overcast sky which has the same luminous distribution any
time, and the global luminance is set to give 100 lux no matter what the
solar settings.

David

[Anonymous]

Thanks David!

Great help!  Much appreciated.

Kind regards,

Brenda