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MEASUR-Tools-Suite v1.0.11
The MEASUR Tools Suite is a collection of industrial efficiency calculations written in C++ and with bindings for compilation to WebAssembly.
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This calculator estimates annual electricity use and associated cost for a set of electricity reduction measures identified during an energy treasure hunt or efficiency assessment. It supports four measurement methods — multimeter, nameplate, power meter, and other (direct energy) — and accumulates the results across all measures in a single pass.
The calculation follows these steps for each measure:
Relevant formulas and symbol definitions are documented below.
Total power calculated from voltage, current, power factor, and number of phases.
The multimeter method derives total power from direct electrical measurements using a clamp-on ammeter or multimeter. For single-phase loads, the power is computed as the product of supply voltage, average current, and power factor (scaled to kilowatts). For three-phase loads, the square root of three is applied to account for the phase relationship between voltages and currents.
\begin{equation}\label{eq:electricity-reduction-multimeter-1ph} P = V \cdot I \cdot \mathrm{PF} \cdot 10^{-3}\end{equation}
\begin{equation}\label{eq:electricity-reduction-multimeter-3ph} P = V \cdot I \cdot \mathrm{PF} \cdot \frac{\sqrt{3}}{1000}\end{equation}
| \(P\) | Power draw per load \([\unit{ \kilo\watt}]\) |
| \(V\) | Supply voltage \([\unit{ \volt}]\) |
| \(I\) | Average current measured by the meter \([\unit{ \ampere}]\) |
| \(\mathrm{PF}\) | Power factor (dimensionless, 0–1) \([\unit{ \unitless}]\) |
| \(10^{-3}\) | Conversion factor from watts to kilowatts \([\unit{ \watt\per\kilo\watt}]\) |
| \(\sqrt{3}\) | Phase factor for three-phase systems \([\unit{ \unitless}]\) |
Operating power estimated from motor nameplate data, load factor, and efficiency.
The nameplate method estimates operating power without direct measurement by using the rated motor power from the nameplate, adjusted for the actual load factor, the ratio of operational to line frequency (raised to the 2.5 power, representing the affinity law relationship for variable-speed drives), and the combined motor-and-drive efficiency.
\begin{equation}\label{eq:electricity-reduction-nameplate} P = P_{rated} \cdot f_L \cdot \left(\frac{f_{op}}{f_{line}}\right)^{2.5} \cdot \frac{1}{\eta}\end{equation}
| \(P\) | Estimated operating power \([\unit{ \kilo\watt}]\) |
| \(P_{rated}\) | Rated motor power from the nameplate \([\unit{ \kilo\watt}]\) |
| \(f_L\) | Motor load factor (dimensionless, 0–1) \([\unit{ \unitless}]\) |
| \(f_{op}\) | Actual operating frequency \([\unit{ \hertz}]\) |
| \(f_{line}\) | Nominal line frequency \([\unit{ \hertz}]\) |
| \(\eta\) | Combined motor and drive efficiency (decimal) \([\unit{ \unitless}]\) |
Annual energy use derived from a direct power meter reading and operating hours.
The power meter method uses a direct power reading from an installed or portable power meter. The reading is multiplied by the quantity multiplier (units) and the annual operating hours to obtain total annual energy use.
\begin{equation}\label{eq:electricity-reduction-power-meter} E = P_{meter} \cdot n \cdot t_{op}\end{equation}
| \(E\) | Annual energy use \([\unit{ \kilo\watt\hour\per\year}]\) |
| \(P_{meter}\) | Direct power reading from the power meter \([\unit{ \kilo\watt}]\) |
| \(n\) | Quantity multiplier (number of identical loads) \([\unit{ \unitless}]\) |
| \(t_{op}\) | Annual operating hours \([\unit{ \hour\per\year}]\) |
Annual energy use supplied as a direct consumption value.
The other method accepts a pre-calculated or independently determined annual energy consumption value. No power-to-energy conversion is applied; the supplied figure is used directly as the annual energy use.
\begin{equation}\label{eq:electricity-reduction-other} E = E_{other}\end{equation}
| \(E\) | Annual energy use \([\unit{ \kilo\watt\hour\per\year}]\) |
| \(E_{other}\) | Direct annual energy consumption \([\unit{ \kilo\watt\hour\per\year}]\) |
Annual energy use calculated from total power and operating hours.
For the multimeter and nameplate methods, total power is first computed and then multiplied by the annual operating hours (and by the quantity multiplier for the nameplate method) to obtain annual energy use.
\begin{equation}\label{eq:electricity-reduction-energy-use} E = P \cdot n \cdot t_{op}\end{equation}
| \(E\) | Annual energy use \([\unit{ \kilo\watt\hour\per\year}]\) |
| \(P\) | Power draw per load \([\unit{ \kilo\watt}]\) |
| \(n\) | Quantity multiplier (number of identical loads) \([\unit{ \unitless}]\) |
| \(t_{op}\) | Annual operating hours \([\unit{ \hour\per\year}]\) |
Annual energy cost calculated from annual energy use and the electricity cost rate.
Regardless of the measurement method used to determine annual energy use, the annual energy cost is obtained by multiplying the energy use by the cost per kilowatt-hour. This formula applies uniformly to the multimeter, nameplate, power meter, and other methods.
\begin{equation}\label{eq:electricity-reduction-energy-cost} C_{elec} = r_{elec} \cdot E\end{equation}
| \(C_{elec}\) | Annual energy cost \([\unit{ \dollar\per\year}]\) |
| \(r_{elec}\) | Electricity cost rate \([\unit{ \dollar\per\kilo\watt\hour}]\) |
| \(E\) | Annual energy use \([\unit{ \kilo\watt\hour\per\year}]\) |
Modules | |
| Multimeter Power Formula | |
| Total power calculated from voltage, current, power factor, and number of phases. | |
| Nameplate Power Formula | |
| Operating power estimated from motor nameplate data, load factor, and efficiency. | |
| Power Meter Energy Use Formula | |
| Annual energy use derived from a direct power meter reading and operating hours. | |
| Other Method Energy Use Formula | |
| Annual energy use supplied as a direct consumption value. | |
| Annual Energy Use Formula | |
| Annual energy use calculated from total power and operating hours. | |
| Energy Cost Formula | |
| Annual energy cost calculated from annual energy use and the electricity cost rate. | |
Files | |
| file | electricity_reduction.h |
| Declares structs, enums, and functions for the Electricity Reduction Calculator.Calculates annual electricity use and cost for electricity reduction measures using multiple measurement methods. | |
Namespaces | |
| namespace | electricity_reduction |
| Electricity reduction calculations for treasure hunt measures. | |
Classes | |
| struct | electricity_reduction::MultimeterData |
| Input data for the multimeter measurement method. More... | |
| struct | electricity_reduction::NameplateData |
| Input data for the nameplate measurement method. More... | |
| struct | electricity_reduction::PowerMeterData |
| Input data for the power meter measurement method. More... | |
| struct | electricity_reduction::ElectricityOtherMethodData |
| Input data for the other (direct energy) measurement method. More... | |
| struct | electricity_reduction::ElectricityReductionInput |
| Input data for a single electricity reduction measure. More... | |
| struct | electricity_reduction::ElectricityReductionOutput |
| Output data for an electricity reduction calculation. More... | |
Functions | |
| ElectricityReductionOutput | electricity_reduction::electricityReduction (const std::vector< ElectricityReductionInput > &input_vec) |
| Calculates total annual electricity use, cost, and power for a collection of measures. | |
| ElectricityReductionOutput | electricity_reduction::multimeterReduction (const MultimeterData &data, int operating_hours, double electricity_cost, int units) |
| Calculates annual energy use and cost using the multimeter measurement method. | |
| ElectricityReductionOutput | electricity_reduction::nameplateReduction (const NameplateData &data, int operating_hours, double electricity_cost, int units) |
| Calculates annual energy use and cost using the nameplate measurement method. | |
| ElectricityReductionOutput | electricity_reduction::powerMeterReduction (const PowerMeterData &data, int operating_hours, double electricity_cost, int units) |
| Calculates annual energy use and cost using the power meter measurement method. | |
| ElectricityReductionOutput | electricity_reduction::otherReduction (const ElectricityOtherMethodData &data, double electricity_cost) |
| Calculates annual energy cost using a directly supplied energy consumption value. | |
| ElectricityReductionOutput electricity_reduction::electricityReduction | ( | const std::vector< ElectricityReductionInput > & | input_vec | ) |
Iterates over input_vec, dispatches each measure to the appropriate single-method helper (multimeter, nameplate, power meter, or other), and accumulates the results.
| [in] | input_vec | Vector of ElectricityReductionInput structs, one per measure. |
| ElectricityReductionOutput electricity_reduction::multimeterReduction | ( | const MultimeterData & | data, |
| int | operating_hours, | ||
| double | electricity_cost, | ||
| int | units | ||
| ) |
Computes power per load from the supply voltage, average current, power factor, and number of phases, then scales to annual energy use using the operating hours and the units multiplier. Energy cost is then derived using Energy Cost Formula.
| [in] | data | MultimeterData with voltage \([\unit{\volt}]\), current \([\unit{\ampere}]\), power factor, and number of phases. |
| [in] | operating_hours | Annual operating hours \([\unit{\hour\per\year}]\). |
| [in] | electricity_cost | Electricity cost rate \([\unit{\dollar\per\kilo\watt\hour}]\). |
| [in] | units | Quantity multiplier (number of identical loads). |
| ElectricityReductionOutput electricity_reduction::nameplateReduction | ( | const NameplateData & | data, |
| int | operating_hours, | ||
| double | electricity_cost, | ||
| int | units | ||
| ) |
Estimates power per load from the rated motor power, load factor, frequency ratio, and motor-and-drive efficiency. Annual energy use is then obtained by multiplying by the operating hours and the units multiplier. Energy cost is then derived using Energy Cost Formula.
| [in] | data | NameplateData with rated motor power \([\unit{\kilo\watt}]\), load factor, operational and line frequencies \([\unit{\hertz}]\), and motor-and-drive efficiency (percent). |
| [in] | operating_hours | Annual operating hours \([\unit{\hour\per\year}]\). |
| [in] | electricity_cost | Electricity cost rate \([\unit{\dollar\per\kilo\watt\hour}]\). |
| [in] | units | Quantity multiplier (number of identical loads). |
| ElectricityReductionOutput electricity_reduction::otherReduction | ( | const ElectricityOtherMethodData & | data, |
| double | electricity_cost | ||
| ) |
Uses the energy field directly as the annual energy use without any power-to-energy conversion. Energy cost is then derived using Energy Cost Formula.
| [in] | data | ElectricityOtherMethodData with the annual energy consumption \([\unit{\kilo\watt\hour\per\year}]\). |
| [in] | electricity_cost | Electricity cost rate \([\unit{\dollar\per\kilo\watt\hour}]\). |
| ElectricityReductionOutput electricity_reduction::powerMeterReduction | ( | const PowerMeterData & | data, |
| int | operating_hours, | ||
| double | electricity_cost, | ||
| int | units | ||
| ) |
Multiplies the direct power reading by the annual operating hours and the units multiplier to obtain annual energy use. Energy cost is then derived using Energy Cost Formula.
| [in] | data | PowerMeterData with the direct power reading \([\unit{\kilo\watt}]\). |
| [in] | operating_hours | Annual operating hours \([\unit{\hour\per\year}]\). |
| [in] | electricity_cost | Electricity cost rate \([\unit{\dollar\per\kilo\watt\hour}]\). |
| [in] | units | Quantity multiplier (number of identical loads). |
1.9.8