Merge pull request #10732 from NREL/revert-10548-extendedHI

Revert "Adopt the Extended Heat Index calculation in zone resilience"

doc/engineering-reference/src/special-modules-reporting/resilience-metrics.tex

@@ -66,17 +66,69 @@ \subsubsection{Heat Index}\label{heat-index}
 \end{tabular}
 \end{table}
 
-Before version 24.2, the computation of the heat index is a refinement of a result obtained by
+The computation of the heat index is a refinement of a result obtained by
 multiple regression analysis carried out by Lans P. Rothfusz and described in a
-1990 National Weather Service (NWS) Technical Attachment (SR 90-23) [4-5].
+1990 National Weather Service (NWS) Technical Attachment (SR 90-23) [4-5]. The
+calculation is based on degree Fahrenheit.
 
-Starting from version 24.2, the heat index calculation adopts the extended heat
-index method developed by Lu \& Romps [17]. The previous heat index gives
-unrealistic results for very hot and humid or very cold and dry conditions. The
-extended index extends the domain of the heat index calculation to all
-combinations of temperature and relative humidity and gives a more realistic heat
-index for the extreme conditions. The implementation in EnergyPlus is based on
-the released Python code by Lu and Romps [18].
+The regression equation of Rothfusz is
+\begin{equation}  \label{eq:rm-1}
+HI = c_1 + c_2T + c_3R + c_4TR + c_5T^2 + c_6R^2 + c_7T^2R + c_8TR^2 + c_9T^2R^2
+\end{equation}
+
+where
+
+HI = heat index (expressed as an apparent temperature in degrees Fahrenheit),
+
+T = ambient dry-bulb temperature (in degrees Fahrenheit),
+
+R = relative humidity (percentage value between 0 and 100),
+
+$c_1$ = -42.379,
+
+$c_2$ = 2.04901523,
+
+$c_3$ = 10.14333127,
+
+$c_4$ = -0.22475541,
+
+$c_5$ = -0.00683783,
+
+$c_6$ = -0.05481717,
+
+$c_7$ = 0.00122874,
+
+$c_8$ = 0.00085282,
+
+$c_9$ = -0.00000199.
+
+If the RH is less than 13\% and the temperature is between 80 and \IP{112}{\fahrenheit}, then
+the following adjustment is subtracted from HI:
+
+\begin{equation}  \label{eq:rm-2}
+HI = (13 - R) / 4 * ((17 - |T - 95|) / 17)^{0.5}
+\end{equation}
+
+Otherwise, if the RH is greater than 85\% and the temperature is between 80 and
+\IP{87}{\fahrenheit}, then the following adjustment is added to HI:
+
+\begin{equation}  \label{eq:rm-3}
+HI = (R - 85) / 10 * (87 - T) / 5
+\end{equation}
+
+The Rothfusz regression is not appropriate when conditions of temperature and
+humidity warrant a heat index value below about \IP{80}{\fahrenheit}. In those cases, a simpler
+formula is applied to calculate values consistent with Steadman's results:
+
+\begin{equation}  \label{eq:rm-4}
+HI = 0.5 * (T + 61.0 + (T - 68.0) * 1.2 + (R * 0.094))
+\end{equation}
+
+In practice, the simple formula is computed first based on the temperature and
+humidity. If this heat index value is \IP{80}{\fahrenheit} or higher, the full regression
+equation along with any adjustment as described above is applied. The Rothfusz
+regression is not valid for extreme temperature and relative humidity conditions
+beyond the range of data considered by Steadman.
 
 The Heat Index Hours (accumulated hours for a space) and Heat Index
 OccupantHours (accumulated hours for the sum of all occupants in a space) of
@@ -464,11 +516,3 @@ \subsection{References}
 
 {[}16{]} ACGIH, Threshold Limit Values (TLVs) and Biological Exposure Indices
 (BEIs), 2012. doi:10.1073/pnas.0703993104.
-
-{[}17{]} Lu, Yi-Chuan, and David M. Romps. ``Extending the heat index''. Journal
-of Applied Meteorology and Climatology 61, no. 10 (2022): 1367-1383.
-doi:10.1073/pnas.0703993104.
-
-{[}18{]} Lu, Yi-Chuan, and David M. Romps. ``Lu and Romps, Extending the heat index, JAMC, 2022'',
-Physics of Climate, February 23, 2023.
-https://romps.berkeley.edu/papers/pubs-2020-heatindex.html.

src/EnergyPlus/CMakeLists.txt

@@ -262,8 +262,6 @@ set(SRC
     EvaporativeFluidCoolers.hh
     ExhaustAirSystemManager.cc
     ExhaustAirSystemManager.hh
-    ExtendedHI.cc
-    ExtendedHI.hh
     ExteriorEnergyUse.cc
     ExteriorEnergyUse.hh
     ExternalInterface.cc