Glare Control and Partitions

A common unpleasant side effect of daylighting is glare caused by high ratio of illuminance, especially near the perimeter. In the spirit of occupant comfort in a green building, it becomes important to reduce glare by providing external shades, blinds or glazing treatment. A simple user controlled blind is sufficient to meet this requirement.

For NC projects, furniture is not included for IEQ 8.1 Daylight. They are to be taken into account for NC IEQ 8.2 VIews and CI IEQ 8.1 and 8.2.

Brittany,
It is possible to exclude not only north direction facing glass, but also any direction facing glass from glare control requirement. It will depend on what type of glass will be used and where the location of the glass is.

In most cases, you may need to add luminance, not illuminance, study as your supporting documentation.

Brittany,
Basically, you need to provide glare study or luminance study. Just FYI, in case you don't know, luminance is different than illuminance. Glare is a function of luminance ratio. You can ask a daylight consultant or expert to provide glare study. If, based on the study, the glare will occur, you can choose the glass that has lower VLT value. I hope it can clarify my previous answer.

Eddy
we are considering on-site measurements for daylight factor calculation. we cannot take measurements at equinox 9am and 3pm. can we take measurements at any time during the day on a 10ft grid? does the grid have to cover all regularly occupied areas or only that falls within 2H daylight zone?
what is the best software if we go for simulation? can ECOTECT be used without RADIANCE?

thanks

Ruffina,
There is no specific requirement for the measurement so you can take any time. Grid should cover all regularly occupied areas. For the software, as long as, it can run per LEED requirement then it will be good. You can check these softwares: Ecotect+Radiance,IES VE(Radiance based engine), and AGI32. Additionally, I heard DesignBuilder just added radiance engine in its daylight simulation. There is also SPOT (Radiance Based engine) if you have a simple room only.
For Ecotect only, there are only two sky models that you can choose on Ecotect such as uniform and overcast, while LEED uses clear sky.

If using Ecotect the export to Radiance is very simple. The most critical part is assigning and naming the file where the results are going. I usually setup a file on my server with just two letters or numbers because the path name is short. The more complicated the path and the name of the folder, the more likely there will be an error. Once you setup the folder just follow the steps in the calculation wizard. When the results are done it will ask if you want to import the Radiance results, just hit yes. Sometimes it will not import and you have to go into the grid management tab in the analysis gird section of Ecotect. Hit Manage grid Date, import data, select file and OK. You may have to play with the data scale to get the right contours showing.

You can also use the help command, export to Radiance section and it will give you step by step instructions. Hope this helps.

Glare control requirements for the north are not as crazy as you think when you consider 24 hour facilities, especially in the more northern latitudes. I would suggest that you outline your facilities use hours and and if they are during hours when direct light doesn't enter, you can state that the building itself is glare control for those windows.

I will also add my usual comment regarding simulation tools. All daylighting simulation tools (with the exception of maybe SPOT) have a sizable learning curve to them not only in the software, but in the interpretation and verification of results. They can also be quite costly. Unless you plan on doing daylighting simulation on a regular basis (10 or more projects a year), I stand behind my assertion that you will get a far greater value for your time and money by hiring a daylighting consultant. Not only will they do the simulations but they will teach you a lot about the practical application of daylighting and human perception mechanisms.

If I had my way, this forum would not be used for specific questions about daylighting simulation because it implies that these software programs are easy and complete ways to evaluate daylighting and they are not.

The questions for daylighting simulations would be best discussed on each software's forum, through IBSPA or the building simulation forum. Email me if you would like the addresses to any of these forums.

Jill i agree and disagree with your statement about simulation tools but that discussion is for another place ans too many assumptions can be made in forums or blogs.

I agree that many do not have the experience to correctly interpret the outputs or verify the inputs are correct.

I will say that In today;s climate things have gone in house and project teams are not able to hire specialists. So there are alot of people out there trying to do the right thing the best they can. I don;t believe that someone posting a simulation question goes against what this forum is about or for. Further, i don;t see how answering those questions implies that all these programs are simple or they are complete ways to evaluate daylighting.

I would sooner have people ask questions about simulations than try and post questions about using the prescriptive method to evaluate or document daylight performance but they do.

Why don;t you post those links to those forums on this thread? Thats one of the purposes of LEED users, to share with others to help create a better built environment. IBSPA and building sim are more for energy modelers. DAYSIM forum is good if you are using DAYSIM. Autodesks Ecotect forum is hit or miss on some topics but it has gotten better since it bought from Square one, at least someone answers the questions, sometimes.

I don't have any problems posting the links, I am just away from my desk right now, so I will put them up here when I get back.

I would feel better about posting answers about simulation questions if I knew the backgrounds of those asking the questions. For me, it would be similar (although this is an extreme analogy) as if this forum was for health and people were asking questions on what type of x-ray machines to use and how to use them. The x-ray tech could say, "push buttons A and B while holding down lever K". But if the questioner doesn't know the machine causes birth defects and that it doesn't show cartilage, they don't know not to use it on pregnant woman and that it might not show them what they need to know. If the info came with these disclaimers I would feel better. I guess I just feel it is a little risky to give the inexperienced the tools without the wisdom. It seems that there are more and more of these questions are on this forum and that fewer people are searching the forum before they ask questions and it is hard to keep repeating the disclaimer.

True, this may not happen on the software user's forums either, but at least if the questioner signs up for them, they are exposed to the questions that other users have.

As for this climate turning things to in-house operations, I stand by my original statement. These things can get accomplished a lot more cheaply via a consultant who already has paid for one or more software programs and already has put in the hours to learn them. And, there are plenty of consultants available.

Simulation is definitely preferred over the prescriptive method. I also think the credit itself doesn't do a good job of expanding the interest or knowledge of great daylighting or superior visual environments.

Thanks for your thoughts on this.

AGI32 User Forum
http://www.agi32.com/forums/

AGI32 Knowledgebase
http://www.agi32.com/kb/index.php?category=7

Radiance Forum
http://www.radiance-online.org/mailman/listinfo/radiance-general

Ecotect AUGI forum
http://forums.augi.com/forumdisplay.php?f=964

DesignBuilder
http://www.designbuilder.co.uk/component/option,com_forum/Itemid,25/page...

Rayfront
http://www.schorsch.com/en/software/support/

I'm certain this is not a complete list.