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Relax leaf area index (LAI) range for the IndoorLivingWall module #11451

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mitchute merged 7 commits into from
Mar 14, 2026
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Merged

Relax leaf area index (LAI) range for the IndoorLivingWall module #11451

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c6471c7
Remove the constraint of leaf area index (LAI) for indoorlivingwall m…
LipingWang Mar 6, 2026
ab09e04
format update for references
LipingWang Mar 7, 2026
5f8ecf4
update format for references
LipingWang Mar 7, 2026
4a1de65
update format for references insert final newline
LipingWang Mar 7, 2026
3bc0a8a
Clang-format
LipingWang Mar 7, 2026
e71d6aa
Update the limit for leaf area index
LipingWang Mar 11, 2026
00374d6
I/O reference update
LipingWang Mar 12, 2026
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14 changes: 8 additions & 6 deletions ...neering-reference/src/simulation-models-encyclopedic-reference-003/indoor-living-wall.tex
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Expand Up @@ -171,14 +171,16 @@ \subsection{Evapotranspiration from indoor living wall}\label{evaporation-from-i

\subsection{References}\label{references-indoorlivingwall}

Wang, L. and M.J. Witte (2022). Integrating building energy simulation with a machine learning algorithm for evaluating indoor living walls’ impacts on cooling energy use in commercial buildings. Energy and Buildings 272, p. 112322.

Monteith, J.L. (1965). Evaporation and environment. in Symposia of the society for experimental biology. Cambridge University Press (CUP) Cambridge.
Ball, J.T., I.E. Woodrow, and J.A. Berry (1987). A model predicting stomatal conductance and its contribution to the control of photosynthesis under different environmental conditions, Photosynthesis Research, Springer. p. 221-224.

Graamans, L., et al. (2017) Plant factories; crop transpiration and energy balance. Agricultural Systems. 153, p. 138-147.

Wang, L., E. Iddio, and B. Ewers (2021). Introductory overview: Evapotranspiration (ET) models for controlled environment agriculture (CEA). Computers and Electronics in Agriculture 190, p. 106447.

Jarvis, P. (1976). The interpretation of the variations in leaf water potential and stomatal conductance found in canopies in the field.Philosophical Transactions of the Royal Society of London. Series B, 273(927), p. 593-610.

Ball, J.T., I.E. Woodrow, and J.A. Berry (1987). A model predicting stomatal conductance and its contribution to the control of photosynthesis under different environmental conditions, in Progress in photosynthesis research, Springer. p. 221-224.
Monteith, J.L. (1965). Evaporation and environment. in Symposia of the society for experimental biology. Cambridge University Press (CUP) Cambridge.

Wang, L., L. Norford, M. J. Witte (2025). Modeling Thermal Impacts of Indoor Living Plants in the Built Environment. Energy and Building. 2025. Volume 346, 116113.

Wang, L. and M.J. Witte (2022). Integrating building energy simulation with a machine learning algorithm for evaluating indoor living walls’ impacts on cooling energy use in commercial buildings. Energy and Buildings 272, p. 112322.

Wang, L., E. Iddio, and B. Ewers (2021). Introductory overview: Evapotranspiration (ET) models for controlled environment agriculture (CEA). Computers and Electronics in Agriculture 190, p. 106447.
2 changes: 1 addition & 1 deletion doc/input-output-reference/src/overview/group-internal-gains-people-lights-other.tex
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Expand Up @@ -2381,7 +2381,7 @@ \subsubsection{Inputs}\label{inputs-indoorlivingwall}

\paragraph{Field: Total Leaf Area}\label{field-total-leaf-area-indoorlivingwall}

This field is the estimated one-sided leaf area {[}\si{\area}{]} of an indoor living wall. Based on the users’ input, leaf area index (LAI) is calculated as the ratio of the total leaf area and the partition wall area. Typical LAIs are 1.0 for grass and 3.0 for bushes and shrubs. The maximum LAI is 2.0 for the IndoorLivingWall module in EnergyPlus. If the calculated LAI is greater than 2.0, the maximum value of 2.0 is used for LAI in the simulation.
This field is the estimated one-sided leaf area {[}\si{\area}{]} of an indoor living wall. Based on the users’ input, leaf area index (LAI) is calculated as the ratio of the total leaf area and the partition wall area. Typical LAIs are 1.0 for grass and 3.0 for bushes and shrubs.

\paragraph{Field: LED Nominal Intensity}\label{field-led-nominal-intensity-indoorlivingwall}

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48 changes: 24 additions & 24 deletions src/EnergyPlus/IndoorGreen.cc
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Expand Up @@ -410,27 +410,27 @@ namespace IndoorGreen {
// SUBROUTINE PARAMETER DEFINITIONS:
static constexpr std::string_view RoutineName("ETModel: ");
auto &lw = state.dataIndoorGreen;
Real64 ZonePreTemp; // Indoor air temperature (C)
Real64 ZonePreHum; // Indoor humidity ratio (kg moisture / kg dry air)
Real64 ZoneNewTemp; // Indoor air temperature (C) after ET
Real64 ZoneNewHum; // Indoor humidity ratio (kg moisture / kg dry air) after ET
Real64 ZoneSatHum; // Saturated humidity ratio
Real64 ZoneCO2; // Indoor zone co2 concentration (ppm)
Real64 ZonePPFD; // Indoor net radiation (PPFD)
Real64 ZoneVPD; // vapor pressure deficit (kpa); local variable
Real64 Timestep; // s
Real64 ETTotal; // kg
Real64 rhoair; // kg/m3
Real64 Tdp; // dew point temperature
Real64 Twb; // wet bulb temperature
Real64 HCons; // enthalpy (J/kg)
Real64 HMid; // enthalpy 3rd point (J/kg)
Real64 ZoneAirVol; // zone air volume (m3)
Real64 LAI; // leaf area index, the ratio of one-side leaf area per unit plant growing area, maximum LAI =2 if LAI_cal>2.0
Real64 LAI_Cal; // calculated leaf area index based on users's input on total leaf area
Real64 OutPb; // outdoor pressure (kPa)
Real64 vp; // actual vapor pressure of the air (kpa)
Real64 vpSat; // saturated vapor pressure at air temperature (kpa)
Real64 ZonePreTemp; // Indoor air temperature (C)
Real64 ZonePreHum; // Indoor humidity ratio (kg moisture / kg dry air)
Real64 ZoneNewTemp; // Indoor air temperature (C) after ET
Real64 ZoneNewHum; // Indoor humidity ratio (kg moisture / kg dry air) after ET
Real64 ZoneSatHum; // Saturated humidity ratio
Real64 ZoneCO2; // Indoor zone co2 concentration (ppm)
Real64 ZonePPFD; // Indoor net radiation (PPFD)
Real64 ZoneVPD; // vapor pressure deficit (kpa); local variable
Real64 Timestep; // s
Real64 ETTotal; // kg
Real64 rhoair; // kg/m3
Real64 Tdp; // dew point temperature
Real64 Twb; // wet bulb temperature
Real64 HCons; // enthalpy (J/kg)
Real64 HMid; // enthalpy 3rd point (J/kg)
Real64 ZoneAirVol; // zone air volume (m3)
Real64 LAI; // leaf area index, the ratio of one-side leaf area per unit plant growing area
Real64 LAI_Cal; // calculated leaf area index based on users's input on total leaf area
Real64 OutPb; // outdoor pressure (kPa)
Real64 vp; // actual vapor pressure of the air (kpa)
Real64 vpSat; // saturated vapor pressure at air temperature (kpa)
Timestep = state.dataHVACGlobal->TimeStepSysSec; // unit s
for (int IndoorGreenNum = 1; IndoorGreenNum <= lw->NumIndoorGreen; ++IndoorGreenNum) {
auto &ig = lw->indoorGreens(IndoorGreenNum);
Expand All @@ -444,10 +444,10 @@ namespace IndoorGreen {
ig.ZVPD = (vpSat - vp) * 1000; // Pa
LAI_Cal = ig.LeafArea / state.dataSurface->Surface(ig.SurfPtr).Area;
LAI = LAI_Cal;
if (LAI_Cal > 2.0) {
LAI = 2.0; // maximum LAI=2.0 in the surface heat balance
if (LAI_Cal > 10.0) {
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@mitchute mitchute Mar 12, 2026

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Field limits should be enforced through the IDD. In this instance, you can add \maximum 10 on this field. That change will cause a slight adjustment to this block.

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@LipingWang LipingWang Mar 12, 2026

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LAI or LAI_Cal is not an input but calculated value at this point based on leaf area.

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@mitchute mitchute Mar 12, 2026

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In that case, it would be good to edit the docs for the Total Leaf Area field to note that only LAI up to 10 are allowed.

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@LipingWang LipingWang Mar 12, 2026

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Great thanks! Updated.

LAI = 10.0;
ShowSevereError(state,
EnergyPlus::format("Maximum indoor living wall leaf area index (LAI) =2.0 is used,calculated LAI is {}", LAI_Cal));
EnergyPlus::format("Maximum indoor living wall leaf area index (LAI) =10.0 is used,calculated LAI is {}", LAI_Cal));
}
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@rraustad rraustad Mar 9, 2026

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Seems like there should be some maximum. Maybe 5 or 10?

Typical LAIs are 1.0 for grass and 3.0 for bushes and shrubs.

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@LipingWang LipingWang Mar 10, 2026

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Thank you for your comments. Currently, EnergyPlus requires that each living wall be attached to a partition wall. Relaxing the leaf area index (LAI) limit in the model can conceptually represent a larger living wall area within the space. So, users can define a relatively small partition wall, while assigning a larger LAI to represent the total leaf area present in the space. In this approach, the LAI parameter therefore represents the total leaf surface area included in the simulation, rather than the strict physical leaf area index.

switch (ig.lightingMethod) {
case LightingMethod::LED: {
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