Unrealistic Temperatures

grasshopper honeybee-legacy
,
1

I am findings unrealistically high temperatures in a somewhat simple honeybee energy simulation and would like to get some feedback as to why this is happening. I have modeled a simple south-facing shoebox model for a dwelling in San Francisco and would like to study the effect of an “irregular” shading scheme on indoor thermal comfort.

You can see that the construction of the shoebox model uses modified EP Constructions. I edited the thickness for EP concrete for ceiling, walls, and floors and used a climate relevant EP wall construction for the exterior wall. As for the window, a self-defined glazing unit. The program type is a Mid-Rise Apartment.

When I run this model as a non-conditioned space, I get insanely high indoor air temperature values. This is most apparent in the first few hours of the year, when outdoor temperature is 15C and indoor is >30C. I reduced the loads within the space with Set EnegryPlus Zone Loads but still have temperatures between 27-30C, which just doesnt seem right.

Screenshot of the GH native line graph showing indoor temp(green) and outdoor temp (red) during the SF cooling design week (Aug 1-8th). It seems odd that the unit experiences little diurnal swing and is constantly hovering around 85F.

Can someone provide further explanation as to why an apartment in SF is experienced indoor temperatures upwards of 80F in the winter and a constant temp of 85F in the summer?

Thank you for your time and I appreciate the assistance in advance.

Kit

170619_HB_Troubleshooting.3dm (836 KB)
Comfort Analysis_HB-troubleshoot.gh (657 KB)

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Hi Kit,

I know that those temperatures seem crazy based on what we experience in our daily lives but they are actually perfectly reasonable given what you have put into the model. It would be unusual to build an unconditioned, south facing, highly-insulated shallow room without any way to open the windows (unless you are trying to build a solar oven :). As long as you use the “SetEPAirflow” component that I see is being bypassed in your GH file, your simulation will allow for operable windows and you should get temperatures that seem much more familiar.

I hope that helps,
-Chris

3

Hi Chris,

After mulling over the numbers, I find myself agreeing. I think this list of architectural and environmental factors sums up the persistent temperatures above the comfort zone:

-Only one exterior surface (all others adiabatic)

-Insulated exterior wall (R11)

-Tight construction / small infiltration

-Moderate nighttime temperature, most likely above the balance point temperature for this space. (deltaT=20-30 with nighttime lows around 50-55F)

-Significant solar energy into the space. (0.6 kWh max)

I put together a more aesthetically pleasing graph to help articulate these items. This is for a west facing space that looks at the effect of a flat scheme (no shading), shading, and then with natural ventilation added. Clearly, once the natural ventilation is introduced, the space is able to dissipate heat quickly and the discomfort issue is avoided.

Thanks again Chris.