Skip to content

Fix 10168 zone multiplier incorrectly applies to water heater tank losses #11240

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
mitchute merged 9 commits into from
Jan 9, 2026
+53 −0
Merged

Fix 10168 zone multiplier incorrectly applies to water heater tank losses #11240

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
9 commits
Select commit Hold shift + click to select a range
29c3ec0
Adjust space gain fraction multipliers for tank losses
kevin-moos Sep 24, 2025
7b98b35
Merge branch 'develop' into Fix-10168-Zone-multiplier-incorrectly-app…
kevin-moos Sep 24, 2025
246ebef
Add comment to new array
kevin-moos Sep 24, 2025
9e22697
Merge branch 'develop' into Fix-10168-Zone-multiplier-incorrectly-app…
kevin-moos Sep 30, 2025
888dfa9
Merge branch 'develop' into Fix-10168-Zone-multiplier-incorrectly-app…
kevin-moos Oct 1, 2025
6eea128
Moved space gain fraction adjustment logic to SetupSpaceInternalGain
kevin-moos Oct 1, 2025
e03f243
Merge branch 'develop' into Fix-10168-Zone-multiplier-incorrectly-app…
kevin-moos Oct 23, 2025
0491289
Merge branch 'develop' into Fix-10168-Zone-multiplier-incorrectly-app…
kevin-moos Nov 6, 2025
c89787f
Merge branch 'develop' into Fix-10168-Zone-multiplier-incorrectly-app…
mitchute Jan 9, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
9 changes: 9 additions & 0 deletions src/EnergyPlus/HeatBalanceInternalHeatGains.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -154,6 +154,15 @@ void SetupSpaceInternalGain(EnergyPlusData &state,

thisIntGain.device(thisIntGain.numberOfDevices).CompObjectName = UpperCaseObjectName;
thisIntGain.device(thisIntGain.numberOfDevices).CompType = IntGainCompType;

// Tank losses should be distributed across multiplied zones/spaces - adjust the space gain fraction to account for this
if (std::find(AdjustTankLossMultipliers.begin(), AdjustTankLossMultipliers.end(), IntGainCompType) != AdjustTankLossMultipliers.end()) {
const int zoneNum = state.dataHeatBal->space(spaceNum).zoneNum;
const int multiplier = state.dataHeatBal->Zone(zoneNum).Multiplier * state.dataHeatBal->Zone(zoneNum).ListMultiplier;
if (multiplier > 1) {
spaceGainFraction /= multiplier;
}
}
thisIntGain.device(thisIntGain.numberOfDevices).spaceGainFrac = spaceGainFraction;

// note pointer assignments in code below!
Expand Down
7 changes: 7 additions & 0 deletions src/EnergyPlus/HeatBalanceInternalHeatGains.hh
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -83,6 +83,13 @@ void SetupSpaceInternalGain(EnergyPlusData &state,
int RetNodeNum = 0 // for return air heat gains
);

// Tank losses should be distributed across multiplied zones/spaces - these are the internal gains that need adjust for this
static constexpr std::array<DataHeatBalance::IntGainType, 4> AdjustTankLossMultipliers = {
DataHeatBalance::IntGainType::WaterHeaterMixed,
DataHeatBalance::IntGainType::WaterHeaterStratified,
DataHeatBalance::IntGainType::ThermalStorageChilledWaterMixed,
DataHeatBalance::IntGainType::ThermalStorageChilledWaterStratified};
Comment on lines +87 to +91
Copy link
Contributor

@mjwitte mjwitte Sep 30, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

If I'm following this correctly, any gain that comes from HVAC, electrical, refrigeration, etc. (anything other than the zone gains like lights, people, etc) should be included in this list. @shorowit ?

Copy link
Contributor Author

@kevin-moos kevin-moos Oct 1, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I did it this way so we could easily add/remove other gains as needed, but beyond water heaters I wasn't sure what to add.

Copy link
Collaborator

@mitchute mitchute Oct 24, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I guess this is because the tanks have an ambient zone specified, right?

Doing a quick search for "Ambient Temperature Zone Name" in the IDD shows the following components:

Chiller:Electric:ASHRAE205
WaterHeater:Mixed
WaterHeater:Stratified
ThermalStorage:ChilledWater:Mixed
ThermalStorage:ChilledWater:Stratified
ThermalStorage:HotWater:Stratified
Pipe:Indoor

Searching "Ambient Zone Name" shows these:

ZoneHVAC:ForcedAir:UserDefined
AirTerminal:SingleDuct:UserDefined
Coil:UserDefined
PlantComponent:UserDefined
Duct:Loss:Conduction

Do these get handled here too?

Also, we can put a 📌 in this, but we should probably unify these.

Copy link
Contributor Author

@kevin-moos kevin-moos Oct 27, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'll try to test these out and see if any should be added to the list.

Copy link
Contributor Author

@kevin-moos kevin-moos Dec 12, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Opened #11365 to address other components with ambient temperature zones

Copy link
Collaborator

@tanaya-mankad tanaya-mankad Dec 15, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@mitchute , we'd like to prevent this PR from expanding in complexity more than the Issue it was created to resolve, so there's a new issue documenting your concerns so we don't lose track of them. In the meantime, this particular set of changes is ready to finalize.

Copy link
Collaborator

@mitchute mitchute Dec 16, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@tanaya-mankad that works. Thanks.


struct HeatBalInternalHeatGainsData : BaseGlobalStruct
{

Expand Down
37 changes: 37 additions & 0 deletions tst/EnergyPlus/unit/WaterThermalTanks.unit.cc
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -6721,6 +6721,43 @@ TEST_F(EnergyPlusFixture, MixedTank_PVT_Per_VolumeSizing_PerSolarCollectorArea)
EXPECT_DOUBLE_EQ(0.0, Tank.AmbientZoneGain); // Didn't define on/off cycle losses
}

TEST_F(EnergyPlusFixture, WaterThermalTankData_AdjustTankLossMultipliers)
{
constexpr int ZONES = 1;
constexpr int SPACES = 5;
constexpr int FLOOR_AREA = 1000;
constexpr int MULTIPLIER = 10;

state->dataHeatBal->Zone.allocate(ZONES);
state->dataHeatBal->Zone(ZONES).numSpaces = SPACES;
state->dataHeatBal->Zone(ZONES).FloorArea = FLOOR_AREA;
state->dataHeatBal->Zone(ZONES).ListMultiplier = MULTIPLIER;
state->dataHeatBal->Zone(ZONES).Multiplier = MULTIPLIER;
state->dataHeatBal->Zone(ZONES).spaceIndexes.allocate(SPACES);

state->dataHeatBal->space.allocate(SPACES);
state->dataHeatBal->spaceIntGainDevices.allocate(SPACES);

for (int spaceNum = 1; spaceNum <= SPACES; spaceNum++) {
state->dataHeatBal->Zone(ZONES).spaceIndexes(spaceNum) = spaceNum;
state->dataHeatBal->space(spaceNum).FloorArea = static_cast<Real64>(FLOOR_AREA) / SPACES;
state->dataHeatBal->space(spaceNum).zoneNum = ZONES;
}

WaterThermalTanks::WaterThermalTankData tank;
tank.Name = "Water Heater";
tank.WaterThermalTankType = DataPlant::PlantEquipmentType::WtrHeaterMixed;
tank.AmbientTempZone = ZONES;
tank.setupZoneInternalGains(*state);

Real64 spaceGainFracTotal(0);
for (int spaceNum = 1; spaceNum <= SPACES; spaceNum++) {
spaceGainFracTotal += state->dataHeatBal->spaceIntGainDevices(spaceNum).device(1).spaceGainFrac * state->dataHeatBal->Zone(ZONES).Multiplier *
state->dataHeatBal->Zone(ZONES).ListMultiplier;
}
EXPECT_NEAR(spaceGainFracTotal, 1, 0.001);
}

TEST_F(EnergyPlusFixture, thermalStorageTankInputReading_Autocalculate)
{
// Test for #11282
Expand Down
Loading