Honeybee Tutorial 2: Daylight Analysis with Radiance

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Important to note:

To continue with the Daylight Analysis you should have, firstly, created a HB model based on your design following the steps described in: Honeybee Tutorial 1: Creating the HB model

You can check about the general example description in: Tutorial Introduction


Step 1B: Assign the material optical properties

Before following on with the Daylight analysis, you should make sure that the relevant material optical properties are assigned to the faces of your HB model. See how you can, firstly, assign them and, secondly, check the result in:


Step 2B: Create the sensor grid for the analysis


Assigning sensor grids to the HB model

In order to be able to run a simulation a sensor grid should be assigned to the HB model that you have created.

1. Create a HB-Radiance » Basic Properties » HB Sensor Grid from Rooms component.

2. Connect the 'model' result from the HB model component to the '_rooms' input.

3. Use a Params » Input » Number Slider to define the '_grid_size' input (size of sensor grid cells). For this tutorial you should set the number slider to 0.5.

4. Use a Params » Input » Number Slider to define the '_dist_floor' input (number referring to the vertical distance between the sensor grid points and the HB room floor). For this tutorial you should set the number slider to 0.75, since the simulation should calculate the daylight conditions at a desk height in the interior.

5. Create a HB-Radiance » Basic Properties » HB Assign Grids and Views component.

6. Connect the 'model' result from the HB model component to the '_model' input.

7. Connect the 'grid' result from the HB Sensor Grid from Rooms component to the 'grids_' input.


Step 3B: Daylight Factor simulation

What is the Daylight Factor?

The Daylight Factor (DF) gives an indication of how a space performs in the ‘worst case scenario’ of overcast (i.e., very cloudy) sky conditions. Under such conditions, the DF is defined as the ratio between the indoor illuminance recorded at desk height inside a space and the outdoor horizontal illuminance under an unobstructed sky. It is therefore expressed as a percentage value.

The DF simulation uses a standard definition of such sky conditions, called the CIE Standard Overcast sky. This means that the simulation is invariant of the location of the building and the time period, so no weather data will be used as an input in this analysis.


Create & Run the Daylight Factor Simulation


Set-up of the Daylight Factor simulation

1. Create a HB-Radiance » Recipes » HB Daylight Factor component.

2. Connect the ‘model’ result from the HB Assign Grids and Views component to the ‘_model’ input. You should pay attention to this, because it would create an error if you connected the ‘model’ result directly from the HB model component!

3. Create a HB-Radiance » Recipes » HB Radiance Parameter component.

4. Use a Params » Input » Number Slider to define the type of recipe for which you want to define the radiance parameters. In the case of daylight factor, you should set the value to 0.

5. Use a Params » Input » Number Slider to define the detail level of the analysis. For this tutorial, we are going to use the 2 (high level of detail).

For further information on which detail level of radiance parameters you should choose or how you can select customized values, check the:

6. Create a Params » Input » Boolean Toggle component and connect it to the ‘_run’ input of the HB Daylight Factor component.

7. Double-click the Boolean Toggle component in order to set it to ‘True’ and run the simulation.

Important to note: It will take some minutes, so do not interrupt the simulation!


Post-processing the results


Daylight Factor visualizations (Simple & Parametric openings)

For easier comprehension, you can visualize the results as shown in:

Moreover, you can compare the acquired values with the acceptable Daylight Factor values related to the location of your project. You can check them on the EN 17037 code for Daylight in Buildings. If you are a TU Delft student, you can find it by logging in with your TU Delft account in the following page:

https://connect.nen.nl/Account/LogOn

Step 4B: Point-in-time simulation

What is a Point-in-Time simulation?

Point-in-time simulations belong to the Sunlight analyses category and are a fundamental companion to the Daylight Factor. As the Daylight Factor tests only cloudy conditions, it does not give any indication about excessive sunlight issues, which are important for a more comprehensive evaluation of a building, especially to assess the design of shading elements.

Important to note: Sunlight refers only to direct sun, whereas Daylight includes both the direct Sunlight and the indirect ambient Skylight.

Unlike the Daylight factor, the Sunlight access depends, firstly, on the location where the building is placed, since it affects the climate characteristics such as the amount and the angle of sunlight, and, secondly, on the time period for which the simulation is held.


Import the Weather data


Importing weather data for Point-in-Time simulations

You can import and extract the respective EPW weather data by following the steps in the sections of the Ladybug Light Analysis tutorial (only these sections are needed for this tutorial and not the whole Ladybug Light analysis!) :

Ladybug Light Analysis: Importing the EPW data

Ladybug Light Analysis: Extract the EPW data

Following these steps (and selecting the Amsterdam weather data in the EPW map), you should have the components as shown in the image.

It is important to make sure that the EPW file we are using is of good quality and does not miss any data. See how you can check the quality of the EPW file in:

Create the Sky for the simulation

The point-in-time Radiance standard CIE sky will be used and set to a sunny day without clouds. Regarding the time points for the analysis, it is typical to select a few specific dates and (solar) times, usually 9:00, 12:00 and 15:00 of the following days:

- 21st December(winter solstice), when the sun is at its lowest altitude.

- 21st March or 21st September(equinoxes), when day and night have the same duration.

- 21st June(summer solstice), when the sun is at its highest altitude.

In this tutorial, we are going to run the simulation for 12.00, 21st of December. However, in order to summarise the annual variation, it is advisable to run the simulation for all the 3 hours and the 3 different characteristic days.


Creating the CIE Sky for a specific time & day

1. Create a HB-Radiance » Light Sources » HB CIE Standard Sky component.

2. Connect the ‘location’ result from the LB Import EPW component to the ‘_location’ input.

3. Define the orientation of the façade. In this example, we are going to set the north vector along the positive direction of Y axis, facing the opposite direction of the aperture normal.

Create a Vector » Vector » Unit Y component and connect the ‘unit vector’ result to the ‘north_’ input.

4. Create a Params » Input » Number Slider in order to set the Sky type. By moving your mouse on top of the ‘_type_’ input, you can see the integers related to each different type. In this example, set the Number Slider to 0 (sunny sky with direct sun).


Changing the min/max & number of decimals in a Number Slider

5. Create 3 Params » Input » Number Slider components in order to set the month, day and hour for which you want to run the simulation. For 12.00 h, 21st December, we should set the first number slider to 12, the second to 21 and the third to 12 and connect them to the ‘_month_’, ‘_day_’ and ‘_hour_’ inputs respectively.

Important to note: Make sure that you set the minimum and maximum values of the Number Sliders according to the needs every time. For example, double click on the Number Slider of the months’ and set the min to 0 and max to 12.

Create & Run the Point-in-Time Simulation


Set-up of Point-in-Time simulation

1. Create a HB-Radiance » Recipes » HB Point-In-Time Grid-Based component.

2. Connect the ‘model’ result from the HB Assign Grids and Views component to the ‘_model’ input. You should pay attention to this, because it would create an error if you connected the ‘model’ result directly from the HB model component.

3. Connect the ‘sky’ result from the HB CIE Standard Sky component to the ‘_sky’ input.

4. Create a Params » Input » Number Slider in order to set the metric which you want to be computed by the recipe. By moving your mouse on top of the ‘_metric_’ input, you can see the integers related to each different metric. For this example, set the slider to 1 so as to calculate the Irradiance.

Important to note:

a. Luminance and radiance indicators are less commonly used for numerical analyses on the plane. Luminance maps are mainly used to represent the field of view and possible glare sources, therefore they will not be included in this phase.

b. It is advisable to use the Point-in-Time simulations mainly for qualitative results. If you want to get absolute values for illuminance or irradiance, it is advisable to run simulations that cover larger time periods (or even annually) as discussed in the next sections.


5. Create a HB-Radiance » Recipes » HB Radiance Parameter component.

6. Use a Params » Input » Number Slider to define the type of recipe for which you want to define the radiance parameters. In this case, set the value to 0.

7. Use a Params » Input » Number Slider to define the detail level of the analysis. For this tutorial, use a Params » Input » Number Slider and set it to 2 (High Detail Level).

For further information on which detail level of radiance parameters you should choose or how you can select customized values, check the:

8. Create a Params » Input » Boolean Toggle component and connect it to the ‘_run’ input of the HB Point-In-Time Grid-Based component.

9. Double-click the Boolean Toggle component in order to set it to ‘True’ and run the simulation.


Post-processing the results


Illuminace & Irradiance Heatmaps (Simple & Parametric model)

For easier comprehension, you can visualize the results as shown in:

Important to note:

A. Given that the results from this simulation are not percentages, you should not set the min & max values of the legend manually. On the contrary, they will be automatically set based on the range of the simulation results.

B. Regarding the title of the legend, you can check the measurement units for the metric that you are calculating by moving your mouse on top of the ‘results’ of the HB Point-In-Time Grid Based component.

Step 5B: Annual Daylight simulation

The Annual simulations refer to Daylight, including both the direct Sunlight but also the indirect Skylight conditions. They follow the ‘Daylight Coefficients’ method for performing the simulation and the most commonly used metrics related to them are:

- Daylight Autonomy (DA): Indicates the percentage of occupied hours in a year during which the indoor illuminance is over a certain threshold

- Spatial Daylight Autonomy(sDA): indicates the percentage of the analysis grid which satisfies DA requirements for more than 50% of the occupied time

- Useful Daylight Illuminance (UDI): indicates the percentage of the occupied hours in a year during which the indoor illuminance is within a range of values (e.g., 300 and 3000 lx)


Other indicators related to Useful Daylight Illuminance (UDI) are:

- UDI_low, which reflects the percentage of time that each sensor grid is below the lower threshold of the Useful Daylight Illuminance.

- UDI_up, which reflects the percentage of time that each sensor grid is above the upper threshold of the Useful Daylight Illuminance.


Import the Weather data


Importing the EPW weather data for Amsterdam

You can import and extract the respective EPW weather data by following the steps in the sections of the Ladybug Light Analysis tutorial (only these sections are needed for this tutorial and not the whole Ladybug Light analysis!) :

Ladybug Light Analysis: Importing the EPW data

Following these steps (and selecting the Amsterdam weather data in the EPW map), you should have the components as shown in the image.

It is important to make sure that the EPW file we are using is of good quality and does not miss any data. See how you can check the quality of the EPW file in:

Important to note: In case you have already imported the weather data for the Point-in-Time simulation, you can use the same component.

Converting the EPW to a WEA file

Since, the Annual Daylight Metrics do not refer to a specific condition (e.g. cloudy or sunny), the weather data will be imported directly without creating the specific sky first. In order to do that, the EPW file should be converted to a WEA object .

1. Create a HB-Radiance » Light Sources » HB WEA from EPW component.

2. Connect the panel with the EPW file path (you have created it already for the Point-in-time simulation) to the ‘_epw_file’ input.

In this example we are going to use the default setting, which is extracting the data for the whole year. However, you can see how to extract data for a specific time period in:


Create & Run the Annual Daylight Simulation


Annual Daylight Simulation

1. Create a HB-Radiance » Recipes » HB Annual Daylight component.

2. Connect the ‘wea’ result from the HB WEA from EPW to the ‘_wea’ input.

3. Connect the ‘model’ result from the HB Assign Grids and Views component to the ‘_model’ input. You should pay attention to this, because it would create an error if you connected the ‘model’ result directly from the HB model component.

4. Define the north of the location. In this tutorial, the north vector will be set along the positive direction of the Y axis, facing the opposite direction of the aperture normal. Create a Vector » Vector » Unit Y component and connect the ‘unit vector’ result to the ‘north_’ input.

5. Create a HB-Radiance » Recipes » HB Radiance Parameter component.

6. Use a Params » Input » Number Slider to define the type of recipe for which you want to define the radiance parameters. In this case, you should set the value to 2.

7. Use a Params » Input » Number Slider to define the detail level of the analysis. For this tutorial, we are going to use the 2 (high level of detail).

For further information on which detail level of radiance parameters you should choose or how you can select customized values, check the:


Format for changing the threshold values in the Annual Daylight Simulation

Important to note: In the ‘_thresholds_’ input you can change the thresholds used for DA and UDI by following the exact format mentioned when you move your mouse over the ‘_thresholds_’ input. In this tutorial we will use the default values (DA: 300 lx, lower UDI: 100 lx, upper UDI: 3000 lx).

8. Create a Params » Input » Boolean Toggle component and connect it to the ‘_run’ input of the HB Annual Daylight component.

9. Double-click the Boolean Toggle component in order to set it to ‘True’ and run the simulation.


Spatial Daylight Autonomy


Calculating the Spatial Daylight Autonomy

You can use the DA values obtained through the Annual Daylight simulation in order to calculate the Spatial Daylight Autonomy.

1. Create a HB-Radiance » Results » HB Spatial Daylight Autonomy component.

2. Connect the ‘DA’ output of the HB Annual daylight component to ‘_DA’ input.

3. Connect the ‘mesh’ result from the HB Sensor Grid from Rooms component to the ‘mesh_’ input.

Important to note: In the _target_DA input you can set the minimum DA value for which a space can be considered well daylit. In our tutorial we will use the default value (50).


Post-processing the results

For easier comprehension, you can visualize the results as shown in:

Important to note:

Spatial Daylight Autonomy - Create Heatmap

A. In the case of the Spatial Daylight Autonomy (sDA) make sure that you connect the ‘pass_fail’ result and NOT the ‘sDA’ result of the HB Spatial Daylight Autonomy component to the ‘_values’ input. This is because the information per grid point is included on the ‘pass_fail’ result.

B. Regarding the sDA Heatmap, given that each point value can be either 0(fail) or 1(pass), the min & max limits of the legend should be set to 0 and 1 respectively.

If you do not set at all the max value and none of the grid points meets the DA threshold, Honeybee will automatically set both min & max value to 0. This will give you the error:

‘Mesh must have at least one face’ in the LB Spatial Heatmap component.


Daylight Autonomy & sDA Heatmaps (Simple & Parametric model)
Useful Daylight Illuminance Heatmaps (Simple & Parametric model)

C. Given that the results from this simulation are percentages (such as DA, UDI), it is useful to set the min and max of the legend to 0 and 100 respectively so that the heatmaps are directly comparable.

As we see, in both the simple and the parametric version, no grid sensor fulfils the criteria to be considered well day-lit with the given threshold (50 lx). Going back to the first steps and changing the size of the windows, adding windows to other walls, changing the distance between the shades or their rotation angle can be just some of the steps that, if followed, they could create a space that will perform better in terms of daylight.

Other Annual indicators

You can find more Annual indicators that can be useful for your projects in:

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