daylight autonomy and useful daylight illuminance

[ellie]

Can we simulate daylight autonomy and useful daylight illuminance with IES VE PRO?
I have read the post about daylight autonomy simulation, but I still didn't get it.
I would appropriate your help
thanks

[ZapBran]

i don't think you can do this easilly - you'll need to extrapolate your results from a sensor (Radiance) calc so perhaps use another tool like daysim in sketchup for that. never used myself but have heard through the grapevine (t'internet) it's quite good.
http://daysim.ning.com/

maybe someone with more daylighting knowledge will have a better answer than me for this? John and Marc are usually s**t hot.

[Marc Jensen]

Thanks Zap,

Well I will give you a bit of an explanation that I have found that can be of use:

Daylight Autonomy (DA) was the first of a string of annual daylight metrics, now commonly referred to as ‘dynamic daylight metrics’. It is represented as a percentage of annual daytime hours that a given point in a space is above a specified illumination level. It was originally proposed by the Association Suisse des Electriciens in 1989 and was improved by Christoph Reinhart between 2001-2004. It is a major innovation since in considers geographic location specific weather information on an annual basis. It also has power to relate to electric lighting energy savings if the user defined threshold is set based upon electric lighting criteria. The user is free to set the threshold above which Daylight Autonomy is calculated. For the graphs above, we selected a Daylight Autonomy threshold of 300 lux (DA300). The graphical percent values represent the percentage of the floor area that exceeds 300 lux for at least 50% of the time.

http://patternguide.advancedbuildings.n ... t-autonomy

Now In IES as far as I know if you want to do some DA, you will require the Radiance module then you will need to put sensors in your room in 6m zones from your windows and then program the sensors to let you know / turn on your lights when the light drops below day 300lux. Now you know what rooms and what times your lights turn on in Vista. From that you can then calculate the utilization of your lighting and get your useful daylight illuminance....

Now to program your light sensors create a dimming profile with the following equation ramp(e1,0,1,300,0.01) (you can replace the 0.01 with whatever percentage brightness you want the lights to operate at when the daylight illuminance in your room is above 300lux... Such as 30% brightness 0.3 etc) From the 1% light usage or even 0%(not sure if 0 works) you can find out when your lights are on etc....

Good luck!

[PCully]

the IES development team are looking at providing some Daylight Autonomy analysis options within RadianceIES but it's a fairly new area (I'm not advanced with lighting at the best of times) so I can't give much more information than that at the moment or say really when it will be available but it's certainly something we are looking to introduce as the demand for this kind of study grows.

Phil