Finer TimeSteps Do Not Work in HB+

[AMIRTABADKANI]

Dear Community,

I have a problem regarding using finer timesteps when I use HB+

I am trying to use 3 timesteps for daylighting calculations, while it seems there is still a problem for reading the results file; there were many similar reported issues on this matter and I have checked them all, and what @mostapha recommended. I have installed the latest verison of Radiance (5.1 or 5.2) in the C:/Radiance, and every time I removed the previous results folder, but still I get the same error.

I also paused the batch file that HB generated but I couldnt find any clue why this happens.

It works fine when I do the simulation for the whole year without any timesteps (on hourly basis) or for a single hour, but when I use finer timesteps (3 in my case) I get the error.

Cheers
Amir

[AMIRTABADKANI]

It seems HB+ still cannot analyze finer timesteps smaller than one hour for annual simulations

[mostapha]

Yes. This is a limitation of the current implementation. Mainly because of the results visualization and post processing.

[soham1205]

Is this limitation still the case or in the newer versions one can use lower timesteps? I am planning to use HB + for a 10 min time step and am getting an error too. Is there a workaround this?

Thanks
Soham

[AMIRTABADKANI]

@soham1205
There is actually a workaround I used for my research last year. You need to manually create the .wea in finer time steps and load the direct and diffuse solar radiation manually for each time step and simulate the PIT through HB Legacy which takes the DC method, not HB+, and do the post-processing manually at the end through customized algorithms.

[chris]

Or you could just use the latest LBT 1.4 plugin. The HB Annual Irradiance recipe over there is perfectly capable of handling Wea’s at finer timesteps. If you need sub-hourly illuminance instead of broadband solar irradiance, I’m willing to add a tweak to the recipe that will support this if you ask for it here:

Sub-annual daylight simulation with timestep other than 1

Hi @OlivierDambron , This is intentional because all of the methods that perform postprocessing on the illuminance matrices to produce DA and UDI rely on the analysis being at a timestep of 1 in order to have the illuminance values correctly aligned with the occupancy schedule. I was thinking that I would eventually add support for running the annual daylight recipe at a finer timesteps but it requires a significant refactor of these postprocessing methods and so it would take some time. So I …

[letmegraduate]

sorry to bother you guys,@chris , i am wondering if lbt now support sub-hourly illuminance simulation, i really hope lbt can do sub hourly daylighting simulation. Many thanks for your time

[chris]

Hi @letmegraduate ,

Yes, we do support sub-hourly illuminance studies but only though the HB Annual Irradiance recipe. You see that there is now a visible_ input for the recipe, which will change the recipe to compute the irradiance in just the visible part of the spectrum, which has a direct relationship with illuminance.

From there, you just need to multiply the irradiance values by 179, which is the luminous efficacy noted in many Radiance discussions like this one and the irradiance will be converted to illuminance.

[letmegraduate]

@chris Thank you .Your method is helpful and i will try it later