HB Model To OSM - appropriate simulation time?

I have model of an 8 story 30,000 sqm office building; it has…
64 core rooms
11 non-core rooms
14 ceiling plenums
808 apertures
42 shades

Does 2 hours for an energy simulation seem correct or super long. Notes below…

HB MODEL TO OSM method

11:40 begin

12:00 solar calculations initializing

1:00 calculation of heat

really slow on periods

cancelled after 2+ hours

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HB ANNUAL LOADS method
takes about 5 minutes

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(restructured code to run rooms, glazing and shades parallel into HB MODEL component instead of in series into HB MODEL component)

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HB ANNUAL LOADS method

2:10 begin
2:15 done

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HB MODEL TO OSM method

2:17 begin

2:20 solar calculation initializing

hung up on calculating sky diffuse exterior solar reflection factors

2:40
these 7x each
Beam-to-Diffuse Exterior Solar Reflection Factors
Beam-to-Beam Exterior Solar Reflection Factors
warming up

2:47 Sizing Period #1

2:51 Sizing Period #2

2:54 Sizing Period #3

up to Sizing Period #7?

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3:35 Starting simulation at 01/01/2006 for run Period 1, looks like its monthly…

4:15 done!

The Annual Loads component will always be significantly faster than the Model To OSM component because:

  1. The Annual Loads component runs at 1 timestep per hour by default, which is only suitable for modeling monthly loads and it CANNOT be used to model detailed HVAC energy use, natural ventilation, or peak load/HVAC size. Conversely, the “Model To OSM” component runs at 6 timesteps per hour by default, which is suitable for modeling all of these cases.
  2. The Annual Loads component uses FullExterior solar distribution by default while the Model To OSM component uses FullExteriorWithReflections by default.
  3. The HVAC system in the Annual Loads component is always Ideal Air and so there are no sophisticated HVAC controls to be computed.

So your difference in simulation time does not seem that unreasonable, especially if your model has a detailed HVAC system.

Also, your description here does not sound quite correct:

You should only be plugging rooms and shades into this “HB Model” component when setting up an energy simulation. If you are plugging in glazing (Apertures) to the HB Model component, then you are likely duplicating the geometry that is being sent off to the OSM.

Thank Chris,

This is what I mean by parallel…


The only place that glazing is integrated into the algorithm into the Apertures input of HB Model.

Your screenshot is mostly correct except your are not adding the apertures correctly. You should be assigning the Apertures to your Rooms and then there is no need to connect the Apertures to the HB Model component. You should probably just watch this series here to get accustomed to the model creation workflows of the LBT plugin.

Chris,

I have been through that whole series and it was very helpful. I rewired it as shown below for both a plenum version and non-plenum version of my design, ran HB Annual Loads for a quick look and got much closer results (270 vs 273). So the problem was that HoneyBee was angry with my bad wiring…Will run HB Model To OSM later to verify.


Sorry about the slow response…been camped out at my 90yr old fathers house looking after some health issues. Algo and dad both doing better.