Designing a Passive House

energy

#1

Has anyone successfully used Ladybug/Honeybee to build a house to Passivhaus standards? Can anyone recommend learning resources or example files that would help me understand how to set up my model?

Background:
I’m currently designing and building a small house (600 ft^2 / 56 m^2) to comply or exceed PH criteria. After viewing Chris and Mostapha’s tutorials on YouTube, and building a Honeybee model, I’m running into problems and wondering if Honeybee is the right tool for the job, and if PHPP+designPH would be a better fit for my application. Or do I just need to better learn Honeybee (specifically, understanding impact of thermal mass and shading)? I’m experienced with Rhino+GH and was hoping to avoid purchasing & learning new tools, but I’m willing to do so if it’s necessary.

Any thoughts are greatly appreciated.


#2

Hi Steven,

Yes I’ve used Honeybee to model a Passivhaus project in the past and while it can be done, a couple things to keep in mind:

  1. There are some significant differences between the Energy+ model and the PHPP (ISO 13790) model protocols and defaults. These include, amongst others, the occupancy schedules, the reference floor areas, the usage (load) schedules and levels, the way windows are modeled, the way thermal bridges are handled, the boundary conditions (set points inside and out) and the way items like ventilation are handled. While E+ can be made to work the same (ish) as the PHPP, you need to build out quite a few schedules and additional items in order to get it to align to the PHPP methods (if that is what you are after).

  2. You’ll never get exactly the same result from Honeybee as PHPP since they simulate heat flow (and heat storage) very differently. So while you can get close, you’ll never get 100% alignment.

  3. For Passivhaus ‘certification’, if that is what you are after, be aware that for PHI only PHPP can be used and for PHIUS only WUFI Passiv can be used (I’m pretty sure).

  4. Especially for small residential projects, the PHPP has a lot of nice defaults which work well (in my opinion) for this usage case and so yes, I’d personally recommend looking into PHPP and/or DesignPH for that sort of a project. While there aren’t a lot of great online tutorials that I know of - I think for the case you are describing this (PHPP) is an excellent tool, especially if you don’t want to spend a ton of time scheduling out the usage patterns and loads. There are some good reference books (PHPP Illustrated comes to mind) and many regional PH groups host various PHPP trainings throughout the year as well. Certainly its not as robust a user group as you’ll find for E+ or Honeybee though.

so - all that said, I think using Honeybee and checking yourself with regards to the PH criteria is a nice ‘check’ and certainly I think it’ll get your project at least pointed the right direction. I’d say the main two items to keep in mind if you are trying to compare E+ results to the those PH thresholds though are:

a) the PH threshold values are set in reference to TFA (Treated Floor Area) which is mostly just ‘net interior floor area’ - thats different than the way Honeybee shows floor area by default - so keep that in mind

b) the PH thresholds are set using an interior winter set point of 20° C (no setback) and a summer set point of 25°C (no setback). So to get ‘comparable’ results you’d need to make sure your boundary conditions are the same.

Hope that helps! best of luck with it.
-Ed


#3

Thanks so much for the detailed response, Ed. Sounds like accomplishing the task is possible but requires a deep understanding of the real-world physics and the Energy+ model.

My project is relatively simple, and my time to deep dive on modeling methods limited, so I think I’ll be going with a purpose-built Passive-House tool: either WUFI Passive Free or PHPP/designPH. I will likely still use Ladybug/Honeybee to understand weather data and the daylighting impacts of various design decisions.