Users can document the USGBC LEED v4.0 / v4.1 - IEQ: Daylight credits using cove's Daylighting 3D Analysis.
Before we begin
Download the Daylight and Quality Views Calculator from USGBC. The forms are available for both LEED v4.1 and LEED v4.0 versions of the credit.
The analysis tool generates a spreadsheet that matches the structure of the credit documentation inputs. Users can use the analysis results in the spreadsheet to complete the LEED forms manually. Alternatively, cove also offers a consulting service to help design teams complete this credit.
Geometry Requirements for Room-By-Room Analysis
For the daylight LEED credit, users must distinguish between regularly occupied floors and non-regularly occupied floor areas (see full explanation of the definition of "regularly occupied spaces" in the FAQs).
Using the Geometry page workflow
You can export your geometry from Revit and assign occupied vs unoccupied spaces within the platform. See here for more details on that process. The benefit of using this method is the ability to exclude and include spaces for analysis without having to re-export from the 3D modeling platform.
Interior Walls
Use the Interior Walls plugin category to import all interior obstructions. Interior glass doors and interior glazing should be excluded since clear glass materials have a high visual transmittance.
Shading Devices
The plugin category of Shading Devices can be used to categorize shading devices in your geometry. This is taken into account as daylight obstructing objects in 3D Analysis.
Geometry Requirements for Floor-By-Floor Analysis
Using plugin export only
In the analysis model, a regularly occupied floor area is brought through the Floor Category export, and non-regularly occupied floor area through the Shading Device Category. Thereby only accounting for the true analysis area, but still benefiting from possible lighting strategies related to high-reflective surfaces. Only the floor area imported through the floor category will contribute directly to the final percentage daylight assessment. Verify and update, if needed, the views in your model before exporting the geometry.
Interior Walls
Use the Interior Walls plugin category to import all interior obstructions. Interior glass doors and interior glazing may be excluded to imitate clear glass materials.
Shading Devices
The plugin category of Shading Devices can be used to categorize shading devices in your geometry. This is taken into account as daylight obstructing objects in 3D Analysis.
Simulation Methodology
Our calculation method follows the guidelines required by the IES LM-83: Approved Method: IES Spatial Daylight Autonomy (sDA%) and Annual Sunlight Exposure (ASE), and the BD+C LEED v4.0 IEQ - Daylight credit for sDA% and ASE% simulations by running a full ray-tracing simulation and calibrating within 1%-5% of a Radiance simulation. Radiance is calibrated to the sun so it is very accurate.
Our method is compatible with permanently installed geometry which is typical of the vast majority of buildings. Dynamic facades, electrochromic glass, or other non-yearly fixed elements and strategies cannot pursue LEED compliance with analysis.tool's sDA and ASE Full Floorplate Daylight Analysis unless they are pre-simulated to determine their effective visual transmittance. If your project has dynamic elements reach out to us on livechat for guidance or make use of our consulting services.
Documentation Process
Step 1 - Understand the requirements of LEED Daylight Credit
According to LEED v4.0 IEQ c7. Daylight language, the following requirements must be met for Option 1:
The analysis areas must cover all regularly occupied floor areas.
The sDA and ASE calculation grids should be no more than 2 feet (600 millimeters) square and laid out across the regularly occupied area at a work plane height of 30 inches (760 millimeters) above the finished floor.
Set the following Period of Analysis: An hourly time-step analysis for a full calendar year, January 1 to December 31, from the hours between 8 A.M. and 6 P.M. local clock.
Use the nearest available Typical meteorological year data or an equivalent.
Glazing Specifications must match the final building glazing schedule.
Must include all permanent interior obstructions. Moveable furniture and partitions may be excluded.
If existing, Glare-control devices must be included (ex. Blinds/Shades Operation, and Blinds/Shades Optical Properties).
Set thresholds for the simulation to 300 lux for 50% of the annual occupied hours for sDA%, and 1000 lux for 250 hours of the annual occupied hours for ASE%.
Step 2 - Calibrate analysis.tool settings for LEED Compliance
The requirements of LEED are met in the following manner:
Set up your analysis.tool model using the instructions listed in the article here.
Change your grid size to 2 ft (0.6 m) on the bottom left-hand settings panel. The analysis plane is automatically fixed at 30 inches above the floor objects.
The period of analysis is automatically fixed for annual occupied hours: January 1st to Dec 31st, 8 am to 6 pm local time.
The weather file is based on your building location completed on the first page, which uses the latest and nearest TTY2 or TTMY3 EPW file from the DOE.
Specify your glazing's Visual Transmittance. If you have multiple glazing products with varying VT, you can use an area-weighted average for the input. If you have frit patterns in your glazing, you can explore the Frit Analysis in analysis.tool article. The frit method works for other complex facade elements or for setting the effective visual transmittance of dynamic elements.
Simulation thresholds are automatically fixed to meet sDA (300 lux/50%) and ASE (1000 lux/250 hours).
After setting these parameters, proceed to run the simulations.
Step 3 - Run 3D Analysis
After setting up the parameters, run the Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE) analysis. As the analysis is completed, levels will load one by one with their % performance.
If the percentages do not load at first, try refreshing your browser page. Before hitting the "Calculate" button, make sure your building is correctly placed and loaded (tutorial).
Step 4 - In the LEED Excel Calculator, identify the Space IDs
In the USGBC-provided Daylight and Views Calculator, begin by setting your LEED calculator to IP units.
In the Daylight tab of the Excel sheet, start listing the regularly occupied spaces in the building. Details of the Space ID, Space Description, and Total Regularly Occupied Area (sqft) should be sourced from the project drawings.
Step 5 - Analysis for sDA and ASE
Each level in the building geometry is analyzed for sDA and ASE.
The overall result of the analysis is shown in the top right-hand corner. LEED v4.0 requires an annual sDA value of at least 55%, 75% or 90% demonstrated through annual computer simulations, and an ASE of less than 10%. Next to the floor names, a percentage value is displayed for both sDA and ASE in their respective tabs.
Users can turn on one floor at a time to record the percentage value and save an image using the camera tool (in the top left corner). The legend in the right panel shows the "PASS" flag indicating the LEED passing range for each category separately.
Step 6 - Enter data for each floor level
Fill in the percentage values, for each level of the building, for both sDA and ASE.
Step 7 - Enter data for each room (skip this step if you used plugin export only)
Users can generate a LEED report for room-by-room sDA and ASE values by clicking on the "Create a LEED Report" button on the top right of the panel. You can read more about it here.
Use this report to populate data in the USGBC Excel Calculator.
Step 8 - Confirm that LEED requirements are met
LEED v4.0 requires a minimum of 55% sDA and an ASE of no more than 10% to meet the criteria. For any regularly occupied spaces with ASE greater than 10%, identify how the space is designed to address glare.
LEED v4.0 awards points for sDA based on the table below.
LEED v4.1 awards points for sDA based on the table below.
Step 9 - Compile Documentation
Export Maps for each level, and compile them into a single report. Submit these along with the calculator and narrative.
Happy Modeling!
FAQs
Q. What is the difference between regularly versus non-regularly occupied spaces?
A. According to the LEED BD+C v4.0 Handbook regularly occupied and non-regularly occupied spaces are determined by the duration of the occupancy. Regularly occupied spaces are enclosed areas where people normally spend time, defined as more than one hour of continuous occupancy per person per day, on average. Occupied spaces that do not meet the definition of regularly occupied are non-regularly occupied; these are areas that people pass through or areas used an average of less than one hour per person per day. Example areas are listed here.
Q. How do I create a LEED report with analysis.tool?
A. You need to assign occupied and unoccupied spaces for your rooms using the geometry page workflow and then go to 3D Analysis to generate the LEED report. You will be able to find the "Create LEED report button" clickable on the 3D Analysis page once you assign occupied and unoccupied spaces for your geometry on the Geometry page. For further context check out this: occupied-vs-unoccupied-rooms-and-leed-report.