AnnualLoads explanation

Hi @chris,
i’ve noticed this new component and the example.
Just wanted to ask if you can tell what is it running? When i run the example i expected to see the Command window showing the E+ developing simulation. But no command opened and the simulation ended super quick. So i’m wondering how it works. Have to say that i didn’t know about the existence of this “quick” simulation.

Hey @AbrahamYezioro ,

The component icon gives it away. It’s 100% EnergyPlus but it’s using two things that make it an order of magnitude faster than the OpenStudio component:

  1. It’s using honeybee’s direct-to-idf translators and completely bypasses OpenStudio. This saves at least 7 seconds per simulation (or up to 30 seconds on larger models) but it means that detailed HVAC and the AFN cannot be modeled with it (you’ll get an exception if you try to do so).
  2. It’s using some of the coarsest settings that EnergyPlus offers that are ONLY suitable for simulation of annual loads. Notably, the default timestep it uses is 1 and this should never be used for a simulation with detailed HVAC since the timestep isn’t fine enough to resolve certain controls and feedback loops in the HVAC. It also shouldn’t be used for thermal comfort studies or studies of natural ventilation since, again, the timestep isn’t good enough to resolve how occupants might open and close the windows. Nor should it be used to accurately estimate HVAC size since you are likely to smooth out the peak time with the 1-hour timestep. It’s for this reason that I limited the things you can get out of the component to just loads so that people don’t end up abusing it for things they shouldn’t be using it for.

But, as long as annual loads are the only thing that you are interested in and you are ok with the fact that the results at a timestep of 1 can have an error of up to 5% from the finer timesteps, then you are good to go and the methods E+ is using are already much better than other fast means of assessing thermal loads like the ISO model. I found the real-time nature of it particularly helpful to explain how different the various programs of a hospital are from one another in their energy use (hence the program slider in my example).

Thanks for the explanation @chris!!
Get it. Many of the simulations i do are related to loads calculations. So i’ll give it a shot.

You’re welcome!

If the component ends up being popular and people don’t abuse it, I think I will add an option to output the monthly energy balance. I’m realizing that the real-time nature of the component has a lot of educational value to quickly show people how different programs and geometries have their loads driven by different factors. It also provides a quick sanity check before adding in real HVAC systems or detailed natural ventilation strategies since I’m sure we all have experienced the case of waiting several minutes for a simulation only to see that we made a dumb mistake and need to re-run it.

Given how I structured the component, it seems it would be tough for people to simulate a case that it wasn’t intended for and I just added a warning for the one remaining case where I can see some potential for abuse. So, at this point, I think the only area where it could be misused is in people’s interpretation of the results. For example, if people start referring to the “load intensity” output as “end use intensity” or EUI. Or if people think that modeling loads is all that they ever need to to do to inform design decisions about energy efficiency.

So let’s see how it does in the wild!


Hi @AbrahamYezioro! I love how you find these components as soon as they are out! :grinning: Thank you for all your help during the early access.

Oh, you are very welcome … i check daily. I was/am trying to see if i can move this semester class to the LBT, but i see that i can’t. There are 2 important components missing: Psychrometric chart and Solar Envelopes. Hopefully for the next semester. It is a basic class on Climate and it’s influences in design/architecture.
But as you know, i’m always happy to test all new developments.

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You’ll see in " Missing Legacy Features Targeted for the Next Stable Release" section of the release notes I just posted that Psych chart and other Ladybug visuals are at the top of my list. The Psych chart should only take me half a week to implement now that all of the visualization and comfort functions are in the core libraries. The solar envelope that Boris contributed is also really straightforward to convert to LBT. Now that I know that it’s a top priority for you, I’ll move it up on my list.

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Thanks @chris,
Looking forward to it. Following those, the comfort mapping will be more than welcomed … :slight_smile: :wink: