Exemplary Performance, Point 2

I did the calculations for one project, but the requirements fell just short. I can't say I've succeeded, yet. You should base the evaluation on the line of sight at 42". Refer to EQc8.1, Figure 1, of the LEED Reference Guide. Get a copy of the detailed report referred to in the LEED Reference Guide. http://h-m-g.com/downloads/Daylighting/ day_registration_form.htm The LEED Reference Guide does not tell you the report you need is the one titled "Windows and Offices: A Study of Office Worker Performance and the Indoor Environment - CEC PIER 2003." This is a free PDF download. The proper term for the views exemplary performance is "View Factor". Search for "view factor" in the PDF file.

Plants and other fauna and human activity must be within 70 feet of the window. I would suggest that to to successfully document this you need to use the the Heschong and Mahone Study, Windows and Offices as guidance. As already noted, you need to look at the section that defines how view factors are established. This is based on a the vision cone a person has, i believe its either 11 or 15 degrees. What i would do is provide a building section which also includes the exterior activity or fauna. With the upper floors, i would use the cone of vision angle to show how a person on the upper floor is able to see such items through the window. The furthest distance from the window in which the cone of vision angle allows the occupant to see the exterior items establishes the depth of compliant space. Have you looked at the other options for exemplary performance? These may be more easily attainable than this option.

As far as the distance item, it is at least, not within as i had noted. Was thinking one thing and typing another. I have not read or seen anything that would put a limit on the distance so whose to say what the limit is. It would also depend on actually what the occupants are looking at. A person could have a view of the mountains and be miles away. This would work for vegetation and object, but i could see where an occupant would not be able to clearly identify and view "human activity. Have you thought about deferring this credit until the construction phase and when the building is complete, and you can provide actual images from the spaces? A picture is worth a thousand words and would greatly reduce the amount of time and documentation needed to demonstrate compliance.

I'm a little confused -- View Factors are only referenced in the Reference Guide as part of Measure #4... Not the first three measures. In the Report, View Factors specifically refer to the fraction of a worker's field of vision that is filled with a view out a window, from a seated position inside the building. Whether or not the view includes vegetation can then improve the View Factor rating, but this seems to only apply to Measure #4, and to be separated out for the purposes of Measures 1, 2, and 3. That being said... can anyone offer input on the following? Our 3-story building is on a Unviersity Campus, and is surrounded by lawns, trees, walking paths, and other buildings (at some distance). RE: Measure #2 -- In plan view I drew a 70-foot line from exterior of the glazing in each of four directions. The view of vegetation, people, or other objects are not obstructed within 70 feet. Seems to me like this would be sufficient, since there is no mention of angles or View Factors. I also have a 45-dgree view from Google Earth that clearly shows the surrounding area. RE: Measure #3 -- Is this Measure referring to head height of glazing measured from the floor? Then the occupant must be within 3 times that distance from the window? OR, are you supposed to measure outside, from the ground level to the top of window, then the view has to be within that distance from the exterior. I'm guessing the former, given the requirements of Measure #2, and it would just make more sense. But just checking if anyone has attempted this yet. Thanks!

Erica, if you read the Heschong and Mahone report, it may help clarify the meaning of view factor. It's about the size of the view window from an occupants position rather than what is actually able to be seen. #2-Providing a site plan with the 70 foot line and labeling the items is good, along with the aerial image i sufficient. You already have to provide a plan showing the sight lines, so unless the reviewer sees and area that may not have view to twp of the items, then there is no need to provide them again. But, since this is a three story building, can the people on the third floor that are located towards the core of the building able to see people walking on the paths on campus? Tree height should not be an issue, seeing people on the ground may be hard, and if this is the tallest building in the area, objects within 70 feet might not be met. You may need to provide a section that demonstrates the areas on the upper floors do have views to one of the three items. Images of the completed space would be best the proof and if needed, you could submit the credit in the construction review so that you can get images. #3 It is the head height as measured from the finished floor, refer to page 550 in EQc8.1 but use 3H not 2H. Its about providing occupants access to vision glazing, not about what they are actually able to see. If they can see outside, good to go.

Hi Todd - Thanks for the input on #2 and #3. I've read the whole report a couple times now, and I think I have a good understanding of the View Factor. Just could not understand why View Factor terminology was being used to answer the original question in this post, RE: Measure #2. Seemed irrelevant and confusing. Thanks again!

Todd, you mention the figure on page 55 in EQc8.1 and the 2H distance, but the 3H distance for Measure #3 should extend to the exterior, not the interior, correct? So, a line should be drawn that is offset from the exterior of the window by the distance of 3H, then the % of regularly occupied space that has a view to this line is calculated. (Similar to option 3 in measure #2 except it uses a generic 70 ft.) Erica, I agree. The way the credit and Reference Guide are worded are confusing with regard to view factor and the four measures. I wonder how many of the LEED reviewers think that the measures need to apply to the Primary View? The only reason I can see this come up is the statement in the Reference Guide page 571 "Refer to page 47, for their Primary View." Primary View according to the document is a portion of the View Factor. It's unfortunate that the credits and reference guide aren't written a little more like building codes by using words like "must" and "always" instead of "refer to" and insinuating with things like "Measures determined per." Since they don't I would interpret it the way it is explicitly written with just the word “view” and determine that the requirement is met if unobstructed lines can be drawn to these items in plan and section back to the seated eye position. I should use the disclaimer that I have also tried and failed to receive this point. (Primarily due to timing and architectural mislabeling of space use.)

Jill, The 3H for measure #3 is from the interior side of the window because that is the occupied space. You can;t occupy inside the wall. Is it specifically spelled out, no; like many things missing in the reference guide. Measure 2 specifically states from the exterior edge of the glazing. Measure three deals with interior, measure 2 deals with exterior. The difference between the exterior and the exterior could be 6 inches, so if you used the outside to start your 3H, I highly doubt that a reviewer would call you on this, unless your calcs resulted in exactly 95.0%.

No, I'm not talking about taking credit for the width of the wall. The question I'm not explaining very well without drawing it out is, does the 3H extend (from the exterior of the glazing) to the exterior, or does it extend (from the interior of the glazing) to the interior. I see from your answer that you're saying it extends into the interior. So basically what Measure 3 is asking you to prove is that no more than 10% of ROS is further than 3H to the interior and that the rest of the ROS (90% plus) has a view to the exterior? I guess I thought it was the other way in that the requirement was similar to "the 70' from the exterior of the glazing" requirement in measure 2 except we are to substitute 70' with 3H. As an example, if my head height is 10', and I am meeting the requirements of measure 2, option 3 and measure 3, I would have a view of any activities within 30' from the exterior of the window and out to 70' from the exterior of the window. I feel like because they didn't state “within the interior” of the vision glazing, the reader is supposed to follow the thought of the previous statement which states exterior. Again, pretty vague wording that leaves too much interpretation up to the reader.

The purpose of Measure 3 is to ensure that 90% of the ROS is within a certain distance of a window. It follows the European standard and the older LBC requirement of having occupants within a certain distance of a window. Occupants located beyond the distance are not considered to have "View Quality or A Quality View". The windows become more like bright spots in the distance rather than an actual view portal. The smaller the window and the further away, contrast becomes more relevant making those windows just blurry light portals. The bigger the window, larger head height, the distance in which a person can actually see outside clearly increases. This is written up in the H&M report, i just don;t know off the top of my head as to exact location. It's a measure that keeps those large deep open office spaces where people are located deep in the space near the core from occurring or earning this measure. As written in the Reference Guide its not clear, but why would it have two exterior distance requirements.

That was my reasoning as well -- Measure #2 covers quality of view framed by the window, Measure #3 covers interior distance to that framed view. At first I really thought they wanted the viewed exterior objects located within 3x the window height, but that just didn't make sense given #2. Thanks Jill and Todd for all the input!

In regards to Exemplary Performance #3, is there a minimum distance? Because my 3x the head height is equal to 23' and all the ROS are a maximum of 15' deep, would those ROS would qualify for this exemplary performance measurement?

There is no minimum distance and your spaces would qualify, as long as there was nothing impeding the view within that 15 foot depth.