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Use a collaborative design process
Access to daylight inside buildings makes for healthier and more comfortable occupants—and is also linked with greater productivity. When designed with proper glare control and minimized solar heat gain, daylighting provides high-quality light while reducing energy use for lighting and for cooling. Increased daylight through increased vision glazing can help projects earn IEQc8.2 for access to views. Realizing the benefits of daylighting requires a collaborative design process.
Balance other design goals
Keep in mind that daylighting strategies must balance with other design goals. For example, you will want to provide enough glazing area for lighting, and plan for open spaces that allow for light transfer, but not at the expense of too much heat...
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42 Comments
Option 2 - Prescriptive
Hi!
I'm trying to get IEQ C8.1 by the prescriptive option, but I'm having problems with the calculation of the window areas.
Its a residential building and the project contains plenty of balconies and not much windows. Could I consider the areas of the glass doors from the balconies? To calculate these areas, should I use the window head height minus 30 inches or the height of the balcony's sill? And the obstruction of the ceiling of the balcony, should I use the 63-degree angle from the vertical to modify the height?
Thanks!
Use the glass from the doors minus the 30 inches. There is nothing that i have read that has this situation that requires the height of the rail to be used instead of the typical height. You get really technical with that if the rail was solid and went the whole way around the balcony and argue that a rail higher than 30 is blocking daylight. If its not within a few feet i would just use the 30 inches.
Draw the 63 angle from the end of the balcony above. Reason being is that the angle in the prescriptive method is considering the floor space which has access to the sky dome.
Thanks a lot, Todd!
One more question... should we consider the balcony as a regularly occupied space? It will have a barbecue grill and it's usually used as a space to hang out..
Thanks again!
The balcony is an outdoor space so it would not have to be considered in your regularly occupied space calculations.
Tenant Lease Agreement compliance path for glare control IEQc8.1
Has anyone used the Tenant Lease Agreement compliance path for glare control in LEED CS projects where the automated shades are being required by the developer but provided by the tenant?
Sarah, I could be wrong, but I think that since IEQc8.1 is not listed in CS Appendix 4, this approach could not contribute to this credit.
No VLT available
Hello,
for our CS project we would like to implement option 2. The difficulty I have is that the building was constructed in the early 90ties and only little information on the existing parts is available. Unfortunately I have no proven VLT for the calculations. In addition windows literally run all around the house on every storey, but they all do have blinds on the outside, which can be operated individually.
Would it still be possible to achieve the ICQc 8.1 via option 2 or would we be forced to measure the whole building?
Thanks.
You will need a reliable source for the VLT value in order to use option 2. It might take some time, but if you can research any of the drawings, specifications, permits, payment receipts, or paperwork from the original construction that could help. If you can determine the manufacturer of the windows, they may have a record of the installation or product data from that time.
Use a good light meter. Take a reading on the inside of the window, about a foot away. Then immediately take a reading outside the window. Simple math will give you the VLT. It is not as scientific as the NFRC method, but it is close enough to get you what you need for the calcs.
Do not take readings of direct sun. Take readings at windows where there is just clear sky. Be careful of reflectances from surrounding objects and the glass itself. Turn off the interior lights.
I did not know that that would be sufficient.
Thanks a lot!
The other option which is also acceptable for EAc 1 is to use table A8.2 in ASHRAE. This gives a VLT and other properties to use if it is unknown. Not the best properties, but it is a referenced standard and accepted method.
My project is in a high rise, built in the early 90's, so I cannot take a reading outside. I wonder what kind of success people have had using the default VLT's in the ASHRAE table.
Common Areas
My project is a residential building, and I am seeking certification for Core & Shell, then the areas that I will consider only the rooms / spaces located in the common areas?
Or should I consider the areas of the apartment residents as well?
Thank you!
Joaquim, you do need to consider all the spaces in the building.
Glare control in CS projects
Hello,
We would like to clarify some questions regarding the credit EQc8.1 – Daylighting for buildings pursuing LEED 2009 Core&Shell certification in Brazil.
When it comes to Core&Shell buildings, we apply the Tenant Sales and Lease Agreement compliance path for any device that will not be installed in the building by the end of construction stage. EQc8.1 credit requests the use of glare control devices for all options and do not accept the Tenant Sales and Lease Agreement compliance path.
Glare control devices are usually considered by architectural design in Brazil including ceiling and fenestration projects. Even though glare control devices are not delivered by the contractor, they are always installed during interior fit-out by the tenant. Due to the daylight availability in tropical climates such as Brazil and their consequent frequently exacerbated discomfort and disability glare problems, tenants are naturally forced to install glare control devices as to provide minimum comfort conditions for the occupants.
According to this scenario above, we would like to know what would be a possible path to comply with credit requirements. Considering that is not possible to use, in this situation, the Tenant Sales and Lease Agreement, how can we proceed to get the credit compliance?
Hi Anderson,
In my opinion, the only possibility is to include the glare control as a part of architecture feature such fritted glazing or shading device.
Additionally, You may do your glare study if you have low transmittance value to prove that there is no glare in your building.
About Option 3: Measurement
Hello,
If one decides to use option 3 to show compliance with this credit, should the light measurements have to be done in a specific time of the day? This doesn't seems to be the case, but we want understand each option's specifications before deciding with one to use.
Thank you very much
There is no specific time. It is recommended that they are conducted as close to solar noon as possible and under clear skies.
Shopping Mall - walkways
Hello,
We are currently preparing a daylight simulation on a shopping malls. The retail stores are tenanted areas and are therefore excluded from the simulation. However, can we consider interconnecting walkways (between one store and another) as regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. given that:
1) Many shoppers will be using these walkways
2) cleaners and security personel will be working along these corridors
3) There will also be Owner's helpdesks along these corridors to answer visitor's queries
Your opinions are much welcome !
Thanks,
George
I've never seen a space denied being regularly occupied when you are providing daylight to that space, even if it is a corridor. But, depending on how much these corridor spaces are helping you earn the credit or not, may determine if the reviewer accepts your argument.
Typically, corridors and other circulation spaces are not, but static spaces within these corridors can be considered regularly occupied.
Since there are help desks in the corridors, the area around the desk is regularly occupied. The rest of the corridor would not be even though cleaning staff and security is moving through the space. The key is static and dynamic, placing permanent seating in the corridor creating rest areas could be a strategy used that would allow you to use more of the corridor spaces.
Many thanks for the answer Todd. It seems to me from the uestions and answers below that regularly occupied tenanted areas must also be considered in the calculations. Can you please confirm that this is the case?
Thanks,
CS project: How do I know the regularly occupied spaces?
Do I need to work with the tenants and base our calculations on their interior fit-out design to evaluate whether we're meeting 75% of all regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building.?
Susan,
No you do not need to work with the tenants with their layout to determine whether it will meet the 75% for 8.1. All that is needed is the areas that could be regularly occupied. Core areas such as elevator lobbies, mechanical spaces do not need to be included.
I would say that it is good practice to involve your tenants so that they can maximize the daylight. Even tenant guidelines could be used.They may not know what was done to provide daylight in the space and could hurt the effort by placing enclosed offices at the window wall and open office in the interior.
If attempting 8.2, you will need to provide possible tenant layout and count. In that case i would use it for 8.1 also for consistency.
Hi Todd and Suzan,
From what I understand, Tenanted areas should not be included in the daylight simulation. Indeed, the guidance states on p 554 that daylighting in tenanted areas is a LEED for Commercial Interior credit and is therefore not considered in LEED CS. Do you agree ?
George,
Are you attempting CS? You have a mall, is it already occupied with tenants? Or is it just the shell? Is it occupied? The space which will be tenant fit out areas would have to be included. Without digging through CIRs (which the new library for CIRs is terrible) I don;t know of why this space would be excluded.
Some projects just cannot earn some credits. When you start looking to attempt LEED and even daylight after schematic design. then it is search for compliance and not actually designing and building for compliance and performance.
George, I did 4 LEED CS projects within the last year. Here is how we did it and what the reviewers advised us on. You have to establish a "potential tenant design". This is not necessary, what the tenants actually build. This design has to be consistent throughout the credits/prerequisites. So while developing the tenant design keep in mind that you will also have to consider views IEQ 8.2, comfort controlls IEQ 6, etc.. You than determine the regular occupied areas based on the same definition as for LEED NC. Also you have to include the tenant space into your calculations. You can make assumptions like having offices along the windows and a hallway in the middle, while all walls (Office-hallway) are made of glass. So basically you will show that the building allows for 75% daylight area based on the core & shell and a possible tenant layout.
Option 2 prescriptive
Hi, I’m working with a CS project and we have chosen to go for Option 2, the prescriptive path. My issue is that the project consists of an 8 story square building with a large skylight and atrium in the center. I have completed the D&V calculations for the offices which are located around the perimeter of the building; however, when it comes to the offices located on the atrium side, I’m not sure how to calculate the daylighting factor. At the moment, I’m not able to complete the simulation option so I’m how to incorporate the daylighting of these rooms from the atrium and whatever reaches them from the exterior windows through the glass parti-walls.
Sofia,
I believe you can't use option 2 for your case. The available options for you are option 1 and option 3.
Option 3 - Measurement
Hello,
Using this option, the LEED guidance requires to demonstrate through records of indoor light measurements that a minimum daylight illumination level of 25 fc1. A footcandle (fc) is a measure of light falling on a given surface. One footcandle is defined as the quantity of light falling on a 1-square-foot area from a 1 candela light source at a distance of 1 foot (which equals 1 lumen per square foot). Footcandles can be measured both horizontally and vertically by a footcandle meter or light meter. 2. The non-metric measurement of lumens per square foot, one footcandle is the amount of light that is received one foot from a light source called a candela, which is based on the light output of a standardized candle. A common range for interior lighting is 10 to 100 footcandles, while exterior daytime levels can range from 100 to over 10,000 footcandles. Footcandles decrease with distance from the light source. The metric equivalent of a foot candle is 10.76 lux, or lumens per square meter. has been achieved in at least 75% of all occupied areas.
Does anybody know if we also need to demonstrate that the illuminance levels do not exceed the maximum threshold of 500 fc such as in Option 1? It does not seem to be the case ...
Many thanks,
I agree, this does not seem to be the case. As a best practice, though, you'd want to check that this is the case, so that occupants don't suffer from glare and cover up the windows—negating your careful daylighting plan.
Glare Control for CS project
Has anyone had any luck requiring the tenant to provide interior shading devices (interior blinds or shades) in order to achieve this requirement of the credit? I have a base building where the developer is not including that element in the CS scope. A tenant is already selected for the entire space and will provide interior shades to control glare. Therefore, would it be acceptable to pursue an alternative compliance path as the building will have glare control devices (although supplied by the tenant) in order to earn the credit? Any help is appreciated!
Hi Michelle,
I believe you do not need to pursue an alternative compliance. A letter from the tenant or a copy of the contract that mentions a tenant that uses entire space of your building provides the glare control, is sufficient.
Glare control in CS projects
Wwe are working on several CS projects that have good daylight illumination levels. Nevertheless, there are some spaces that go over the 500 fc1. A footcandle (fc) is a measure of light falling on a given surface. One footcandle is defined as the quantity of light falling on a 1-square-foot area from a 1 candela light source at a distance of 1 foot (which equals 1 lumen per square foot). Footcandles can be measured both horizontally and vertically by a footcandle meter or light meter. 2. The non-metric measurement of lumens per square foot, one footcandle is the amount of light that is received one foot from a light source called a candela, which is based on the light output of a standardized candle. A common range for interior lighting is 10 to 100 footcandles, while exterior daytime levels can range from 100 to over 10,000 footcandles. Footcandles decrease with distance from the light source. The metric equivalent of a foot candle is 10.76 lux, or lumens per square meter. limit.
In the LEED form for IEQ8.1 it's obvious that if you don't install glare control you can't get the credit but that doesn't make sense to me. If I have 100,000 sqft of offices and I go over the 500fc limit in only a couple of spaces totaling 1,000 sqft I can't get the credit? Or should I simply deduct that area from the area that complies?
Thanks.
Hi Jana,
I believe you can deduct the area that does not comply. In addition, I would suggest to take a look your building design, High illuminance level usually means that your room will receive direct sunlight.
Regarding glare control, you may provide luminance/glare study and try to prove that the glare will not be a problem in your space. There are many glare control strategies, outside common strategies mentioned in LEED reference.
In this credit, LEED actually wants to address 2 issues in daylight design such as illuminance level issue and luminance issue. The glare requirement is to address luminance issue, while your simulation/calculation is to address illuminance level issue.
Hope it helps...
About Design of IEQc8.1
I am working on core and shell project, building a data center. in order to get this credit, i need to have vision glazing or skylight in occupied space. for example a console room, which does not require any natural light or whatsoever. any suggestions
The credit requirements focus on regularly occupied spaces—areas where workers are seated or standing as they work. It sounds like your console room might not be a regularly occupied space, and thus not included under this credit.
Option 2 prescriptive
Hello,
I'm working on a core&shell project and it'll go with option 2, prescriptive.
I can type "Total daylight requlary occupied gross area, determined throught prescriptive calculations" in the blank on the template, but don't know where I should type "Total regularly occupied gross area" to calculate percentage.
Anybody knows it?
Hi Jiwon,
Could you check: PI FORM 3: OCCUPANT AND USAGE DATA? You may need fill in the information in there.
About simulation of IEQc8.1
Hello
I want to get IEQc8.1 through simulation, but I have some problem.
1. There are internal shades in the building, such as blinds, In simulation, Can I use internal shades in the location where direct sunlight will fall. If I don't use internal shades, many illumination values will exceed 500fc.
2. Are rests and corridors in retail regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building.?
3. How much feet is the high of simulated work plane?
Thanks
In the reference guide for LEED NCv2009, p 556 they identify shades - see bullet 3
"If the project uses automated shades, the maximum footcandle level does not apply."
This implies that with manually operated shades the maximum level does apply - e.g. you cannot assume that they'll always be operated optimally to minimize glare. A number of studies on daylighting bear this out - most people do not change their blinds frequently, so they end up more closed than open - defeating daylight entry.
The reference guide also discusses regularly occupied spacesRegularly occupied spaces are areas where one or more individuals normally spend time (more than one hour per person per day on average) seated or standing as they work, study, or perform other focused activities inside a building. - I defer to others with more retail experience on corridors, but restrooms are not considered regularly occupied.
What happens if we have fixed louvers on an open circulation hallway used to connect the spaces? do i need to take into account that space? it is not an interior space, it will be more as a terrace.
Hello Juan,
Are you asking if you need to include the hallway space? If so, the answer is no because it is not classified as a regularly occupied space.
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