Updating E+ to 22.1 fixed this bug. After that, I created a new issue which is here : https://unmethours.com/question/72

Has anyone managed to reproduce this bug or does anyone have a clue to explain it ? Thanks, your answers will help us a

Has anyone managed to reproduce this bug or does anyone have a clue to explain it ? Thanks, your answers will help us a

Has anyone managed to reproduce this bug? Does anyone have a clue to explain it? Thank you for your help !

Has anyone managed to reproduce this bug? Does anyone have a clue to explain it?

Cooling limit capacity exceeded (with ZoneHVAC:IdealLoadsAirSystem object) Hello, I tried to put a cooling limit capac

Cooling limit capacity exceeded (with ZoneHVAC:IdealLoadsAirSystem object) Hello, I tried to make a cooling limit capa

Cooling limit capacity exceeded (with ZoneHVAC:IdealLoadsAirSystem object) Hello, I tried to make a cooling limit capa

Cooling limit capacity exceeded (with ZoneHVAC:IdealLoadsAirSystem object) Hello, I tried to make a cooling limit capa

I model a single storey building with a big surface (15 744m²) heated to 15°C. The building has the following insulation: floor: 0.24 K.m²W-1; walls: 2.98 K.m²W-1; roof: 6.07K.m².W-1.

I use Kiva foundations with the following parameters:

Foundation:Kiva,
    Slab Details,             !- Name
    15,                       !- Initial Indoor Air Temperature
    ,                         !- Interior Horizontal Insulation Material Name
    ,                         !- Interior Horizontal Insulation Depth
    ,                         !- Interior Horizontal Insulation Width
    ,                         !- Interior Vertical Insulation Material Name
    ,                         !- Interior Vertical Insulation Depth
    ,                         !- Exterior Horizontal Insulation Material Name
    ,                         !- Exterior Horizontal Insulation Depth
    ,                         !- Exterior Horizontal Insulation Width
    ,                         !- Exterior Vertical Insulation Material Name
    ,                         !- Exterior Vertical Insulation Depth
    ,                         !- Wall Height Above Grade
    ,                         !- Wall Depth Below Slab
    ;                         !- Footing Wall Construction Name

Foundation:Kiva:Settings,
    1.8,                      !- Soil Conductivity
    3200,                     !- Soil Density
    836,                      !- Soil Specific Heat
    0.9,                      !- Ground Solar Absorptivity
    0.9,                      !- Ground Thermal Absorptivity
    0.03,                     !- Ground Surface Roughness
    40,                       !- FarField Width
    GroundWater,              !- DeepGround Boundary Condition
    10;                       !- DeepGround Depth


SurfaceProperty:ExposedFoundationPerimeter,
    PLANCHER +00_+00_+00,     !- Surface Name
    ExposedPerimeterFraction,    !- Exposed Perimeter Calculation Method
    ,                         !- Total Exposed Perimeter
    1,                        !- Exposed Perimeter Fraction
    ;                         !- Surface Segment 1 Exposed

The simulation gives 87MWh of heating over the whole year(ie. 5.4kWh/m²/year).

Secondly, I simulate the same building but with fixed ground temperature with the monthly median of the inside face temperature of the floor of the previous Kiva simulation (taken in the middle of the building). The simulation gives 100 MWh of heating over the whole year(ie. 6.35kWh/m²/year).

I expected the contrary because the second simulation takes the inside face temperature as the ground surface temperature (moreover on the center of the building floor). It seems that the comportement is worse when I use the procedure but with 18°C for the temperature set point.

Details: 192m x 82m (a surface of 15 744m²) with 3 meters of height. The building got 10 x 5 parts (19.2m x 8.2m each).

IDF and EPW:

https://drive.google.com/drive/folder...

Udated

It's like there is less exchanges when I use the Kiva model for the ground. Please look at the graph representing the floor surface conduction heat transfert: In the fixed ground temperature IDF there is to material layers for the floor: concrete + Insulation, but in the Kiva IDF I just put one layer with the insulation because the slab is already the concrete layer.

Finally, if I take the maximum of the "Surface Inside Face Temperature C" for each month in the Kiva solution for the second approach, results give me 83.5MWh. That's less than 2% above the Kiva solution.

Updating E+ to 22.1 seems to have fixed this bug. Thanks to @shorowit for this suggestion.

I model a single storey building with a big surface (10 000 m²) heated to 15°C. The building is well insulated on the walls and the roof but not on the floor.

I use Kiva foundations with the following parameters:

Foundation:Kiva,
    Slab Details,             !- Name
    15,                       !- Initial Indoor Air Temperature
    ,                         !- Interior Horizontal Insulation Material Name
    ,                         !- Interior Horizontal Insulation Depth
    ,                         !- Interior Horizontal Insulation Width
    ,                         !- Interior Vertical Insulation Material Name
    ,                         !- Interior Vertical Insulation Depth
    ,                         !- Exterior Horizontal Insulation Material Name
    ,                         !- Exterior Horizontal Insulation Depth
    ,                         !- Exterior Horizontal Insulation Width
    ,                         !- Exterior Vertical Insulation Material Name
    ,                         !- Exterior Vertical Insulation Depth
    ,                         !- Wall Height Above Grade
    ,                         !- Wall Depth Below Slab
    ;                         !- Footing Wall Construction Name

Foundation:Kiva:Settings,
    1.8,                      !- Soil Conductivity
    3200,                     !- Soil Density
    836,                      !- Soil Specific Heat
    0.9,                      !- Ground Solar Absorptivity
    0.9,                      !- Ground Thermal Absorptivity
    0.03,                     !- Ground Surface Roughness
    40,                       !- FarField Width
    GroundWater,              !- DeepGround Boundary Condition
    10;                       !- DeepGround Depth



SurfaceProperty:ExposedFoundationPerimeter,
    PLANCHER +00_+00_+00,     !- Surface Name
    ExposedPerimeterFraction,    !- Exposed Perimeter Calculation Method
    ,                         !- Total Exposed Perimeter
    1,                        !- Exposed Perimeter Fraction
    ;                         !- Surface Segment 1 Exposed
.... [identical for all zones]

Heating needs increase with the number of zones without stabilization. The following graph shows the maximum power and the total heating energy for this building depending on the number of zones:
First results

The idf has as many BuildingSurface:Detailed for the floor as Zone objects and each surface use the same construction so I used only one Kiva object for the whole building (cf. https://bigladdersoftware.com/epx/doc...).

What makes me think the problem is with Kiva? When the floor is insulated, the heating needs remain unchanged regardless of the number of zones.

I'm using EnergyPlus 9.22.

Thank you for your help.

Updated

After modifying the value of the Exposed Perimeter Fraction parameter for all SurfaceProperty:ExposedFoundationPerimeter objects, using 1 when there is only one zone, 0.5 when the zone is in a corner, 0.25 when the zone is along one face of the building and 0 when the zone is in the middle of the building:

Results after modifying Exposed Perimeter Fraction parameters

There is still an increase up to 7.7%.

To complement these results, the graph below shows the results when the floor is very well insulated (this is the only thing that has been changed):

Results after modifying Exposed Perimeter Fraction parameters with good insulation for the floor

This time there is an increase up to 2.6%.

@rraustad I split the building with n x n blocks: 2 x 2 will give this construction: |x|x| |x|x|, 3 x 3 : |x|x|x| |x|x|x

@rraustad I split the building with n x n blocks: 2 x 2 will give this construction: |x|x| |x|x|, 3 x 3 : |x|x|x| |x|x|x

@rraustad I split the building with n x n blocks: 2 x 2 will give this construction: |x|x| |x|x|, 3 x 3 : |x|x|x| |x|x|x

@rraustad I split the building with n x n blocks: 2 x 2 will give this construction: |x|x| |x|x|, 3 x 3 : |x|x|x| |x|x|x

Thank you for your help. I changed the Exposed Perimeter Fraction parameter, using 1 when there is only one zone, 0.5 wh

Why heatings needs increase when the number of zones increase (for the same total surface) using Kiva model for the grou

Why heatings needs increase when the number of zones increase (for the same total surface) using Kiva model for the grou

Why heatings needs increase when the number of zones increase (for the same total surface) using Kiva model for the grou

Why heatings needs increase when the number of zones increase (for the same total surface) using Kiva model for the grou

Why heatings needs increase when the number of zones increase (for the same total surface) using Kiva model for the grou

Thank you for your help. I change the Exposed Perimeter Fraction parameter, using 1 when there is only one zone, 0.5 whe

Thank you for the aswers! I will try. @Aaron Boranian, yes it is related to my comment.

@Aaron Boranian that's correct !

Why heatings needs increase when the number of zones increase (for the same total surface) using Kiva model for the grou

Why heatings needs increase when the number of zones increase (for the same total surface) using Kiva model for the grou

Why heatings needs increase when the number of zones increase (for the same total surface) using Kiva model for the grou

Results changed a lot with this update, thank you for this advice! I wonder about this results: when I model the buildin

Why Kiva results seems to reduce heat needs I model a single storey building with a big surface (15 744m²) heated to 15°

If I take the maximum of the "Surface Inside Face Temperature C" for each month in the Kiva solution for the second appr

Why Kiva results seems to I model a single storey building with a big surface (15 744m²) heated to 15°C. The building ha