Building a foundation
of trust with open source

We believe that open source methodologies, software and collaboration are key to developing the foundational weights and measures required to bring demand flexibility to market.
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Why we believe in open source

Transparent measurement

Transparent measurement builds the trust markets need to facilitate transactions that all parties can agree on.

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Replicable methods

Standard inputs combined with replicable methods provide reproducible results, giving public and private entities confidence that their calculations will be consistent with other third parties.

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Available without restriction

Anyone can download, modify and use open source software. This prevents vendor lock in and enables a transparent and collaborative development process.

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Open stakeholder development

Nearly 100 experts representing utilities, regulators, implementers, evaluators and academic researchers have helped develop the open source methods and code.

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Markets Need Transparent Standard Weights and Measures

The OpenEEmeter implements the CalTRACK methods to support transparent market transactions. Both the OpenEEmeter and CalTRACK are supported by the Linux Foundation, one of the largest open source foundations in the world.

FLEXmeter logo - FLEXmeter is Recurve's umbrella brand for our suite of open-source tools

FLEXmeter integrates Recurve’s suite of open-source tools, including the CalTRACK OpenEEmeter, GRIDmeter, and Energy Differential Privacy, to provide a unified framework for the revenue-grade measurement of energy efficiency and demand response.

Through our groundbreaking work in partnership with the CAISO, Utilities, CCAs, and Demand Response Providers, we proved that even during extreme grid stress, such as the 2020 heat wave pictured to the right, FLEXmeter provides accurate measurement of demand response events.

FLEXmeter is CAISO tariff compliant for settlement of demand response and is also utilized by utilities for long-term energy efficiency load shaping. This new approach integrates energy efficiency and demand response to enable a consistent system for all behind-the-meter virtual power plants.

screenshot of graph from measurment

CalTRACK specifies a set of empirically tested methods to standardize the way normalized meter-based changes in energy consumptionCalTRACK specifies a set of empirically tested methods to standardize the way normalized meter-based changes in energy consumption are measured and reported. Methods include monthly, daily and hourly calculations.  

When CalTRACK is implemented through open source software, these methods can be used to support the procurement of energy efficiency, electrification, and other distributed energy resources. 

CalTRACK is developed through an empirical, multi-stakeholder public and collaborative process under an open-source charter.
are measured and reported.


The OpenEEmeter is a Python-based open-source software tool that implements the CalTRACK methods to calculate changes in energy consumption for energy efficiency and demand flexibility projects and portfolios, normalized for weather and occupancy and on an hourly basis when smart meter interval data is available.

The OpenEEmeter is licensed under Apache 2.0 and is available to all parties without restriction through the Linux Foundation Energy (LF Energy), the oldest and most respected


Non-routine exogenous changes must be accounted for to achieve settlement-quality measurement of demand flexibility. COVID, "the mother of non-routine events," is an example of a massive exogenous event that renders traditional M&V impossible. However, factors such as changes in the economy and decarbonization policy, or extreme weather events, also profoundly affect energy use.

The GRIDmeter™ methods apply stratified sampling to identify non-participant comparison groups that can adjust for exogenous factors on an hourly basis and have been proven accurate through empirical testing for residential and commercial applications.

 Learn more at

When you want to share statistics about a population without compromising the privacy of individuals, differential privacy is the very best way to do it.

Differential privacy has emerged as the gold standard for privacy-preserving statistical analysis. ​Energy Differential Privacy™ (EDP™) applies these methods to energy use cases.Recurve has published an open-source code base that can be used to run Energy Differential Privacy™ methods at scale. 


A critical problem facing demand flexibility programs and markets is a lack of an accurate price signal for the long-term value of changes in energy consumption and the ability to track and optimize for cost-effectiveness.

The FLEXvalue™ engine democratizes the value of projects to the grid and cost-effectiveness for regulators and decision-makers.

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Posted on May 15, 2019

Recurve Joins Linux Foundation Energy and Contributes the OpenEEmeter

Read the press release

We are proud to be founding members of LF Energy and to have contributed both the OpenEEmeter and the Energy Market Methods Consortium (EM2) to the organization.

Following CPUC ruling (D.12-05-015) in 2012, energy efficiency industry leader Matt Golden began assembling a team to develop open source methods and software to enable standard measurement of energy savings.

In 2015, Matt founded Recurve (then OpenEE). Recurve has dedicated itself to the development of the open source CalTRACK methods and OpenEEmeter software. See the full history at

The History of OpenEEmeter & CalTRACK

World wide adoption of CalTRACK and the OpenEEmeter

Across the world State agencies, Utilities and Implementers are using CALTRACK and the OpenEEmeter in over 20 commercial implementations.

How the OpenEEmeter works

The OpenEEmeter calculates, in a consistent and replicable way, how an intervention changes a building's metered energy consumption.

CalTRACK 2.0

Hourly Methods

The CalTRACK Hourly method models building energy use as the interaction between the building’s temperature dependence, the occupancy status and the time of week.


Learn How Data-Driven Targeting Can Optimize Program Impacts

Want to lean how your program can identify the highest-impact customers? Contact us for a targeting demo.

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