COMNET (Commercial Energy Services Network)

The COMNET Commercial Buildings Energy Modeling Guidelines and Procedures was submitted for a second public review on July 14, 2010 and will be open for 15 days. The second public review is limited to the changed sections of the manual; this document. A summary of the comments received can be viewed here.

 

 

 

 

The Commercial Energy Services Network (COMNET) is a new system for assessing and rating the energy efficiency of commercial and multifamily buildings in the United States.  It consists of a technical component focusing on development of Energy Modeling Guidelines and Procedures, and an institutional component involving quality assurance among energy rater and auditor credentialing programs.  It is designed to work with existing modeling software and build off of existing credentialing systems. The technical component provides specifications for integration with energy simulation software to serve three calculation purposes: federal tax deductions, green building ratings, and energy labels.  The institutional component provides a framework for setting standards and ensuring the quality of building professionals in the energy assessment field. 

By addressing many of the current technical and market-based challenges of creating energy models and ratings, COMNET will make it straightforward and cost-effective for building owners, designers and operators to comply with requirements for energy efficiency programs and mandates.  In the past, there has been great variation in how these calculations have been performed and no industry-wide standard for the level of knowledge and skills of energy assessment building professionals.  The technical and institutional components of COMNET will support many existing energy efficiency programs, rating systems and professional credentialing processes in the United States.  A draft of the COMNET Commercial Buildings Energy Modeling Guidelines and Procedures was submitted on April 15, 2010, for a 30-day public review and comment period.

At its meeting on February 21, 2010, the RESNET Board of Directors created a new COMNET Standing Committee chaired by Charles Eley of Architectural Energy Corporation (AEC). In the same meeting, the RESNET board elected Mr. Eley as a RESNET board member. Please contact IMT at , or Laurel Elam of RESNET at (760) 529-3630 or by emailing if you have any questions about the COMNET committee.

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COMNET TEAM

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WHAT IS COMNET DESIGNED TO WORK WITH?

Federal tax deduction for energy efficiency                                             ASHRAE Building EQ    

USGBC Energy Simulation LEED Points                                                     CA Title 24 Nonresidential Standards compliance framework

US EPA Energy Star's Target Finder                                                           US DOE EnergyPlus energy simulation software tool

ASHRAE Standard 90.1                                                                             Green Building Initiative's Green Globes System


HOW DOES COMNET WORK WITH THESE PROGRAMS?

EPA's Energy Star

COMNET is working to complement EPA’s ENERGY STAR, currently the most successful and best-established commercial building operational rating system in the United States, which can also be used during the design phase of buildings through Target Finder to generate a consistent asset rating.   COMNET can generate input data for use in the Target Finder tool.  

Federal Tax Deduction

The COMNET system will create the first truly accessible way for building owners to comply with the protocol to apply for the $1.80/sq ft federal tax deduction for energy efficient commercial buildings. 

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WHAT ARE THE CURRENT CHALLENGES THAT COMNET ADDRESSES?

  • Accounting for unregulated loads in energy models for buildings as designed
  • Being able to control variables for reference buildings
  • Lack of industry-wide standards for building professionals in the energy assessment field
  • Lack of quality control and professional accountability mechanisms
  • More information

 

Technical Challenges in Energy Modeling for Asset Ratings

Currently, during the building design process, energy modeling is typically done for code compliance, which has been proven to not necessarily produce realistic predictions on how a building performs during operation.  The main reason is that meeting code requirements involves evaluating equipment and system efficiencies but does not account for the entire energy use in buildings because unregulated loads are typically not accounted for.  Process and plug loads are considered unregulated loads in most energy codes but need to also be factored into the energy model during the design phase.  By creating guidelines for unregulated loads in the energy model, buildings can be designed with the potential to save energy as predicted.  The energy metrics for design should account for all the variables included in the operational phase of the building.  These variables include computers, process loads for cooking, and equipment and system loads for occupant comfort.  

Another issue with energy modeling for buildings as designed is generating a reference building that shows a baseline for actual performance, not just a reference specified by the energy code where variables are typically difficult to control. 

Institutional Challenges for Energy Assessors

Institutionally, there is increasing demand for the services of building professionals, particularly those who conduct energy audits and create energy models.  Therefore, the skills and ethical standards for these professionals need to be clearly defined and maintained with the rapidly changing technology related to energy efficiency.  Several agencies in the United States offer credentialing for professionals in the energy assessment field, but key issues exist.  There is a lack of uniformity among existing programs in terms of content, rigor, process, and cost and insufficient quality assurance and professional accountability, largely because of resource and staffing limitations.  Developers of energy-efficiency legislation, mandates, and programs in the United States currently perceive that these existing credentials in themselves are not legal-grade, thus leading to the need to set further requirements, such as stipulations for minimum professional experience and additional review by licensed design professionals.  These requirements add cost and complexity, slowing the implementation of energy efficiency initiatives.  Beyond these issues, the diversity in building size and type and the complexity of energy systems in commercial buildings makes it difficult to create a single uniform standard.

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HOW DOES COMNET ADDRESS THESE CHALLENGES?

Technical Components

COMNET provides rules and procedures for asset ratings, based on calculated energy use.  The asset rating is determined by modeling the building under a defined set of standard conditions of occupancy, climate, environment, and use.  In contrast, an operational rating is based on metered energy use. The metered energy consumption includes energy uses for all uses, including unregulated loads.   COMNET standardizes the calculations to provide more consistency, but also to close the gap between energy model predictions used for asset ratings and actual energy bills by requiring that assumptions on building operation, non-regulated equipment loads, and other inputs more closely match empirical data compiled from multiple sources including the Commercial Buildings Energy Consumption Survey (CBECS) and the California Commercial End-Use Survey (CEUS).  COMNET also establishes standards for defining a hypothetical reference building against which the subject building will be compared.  The COMNET rules and procedures are consistent with the Performance Rating Method in ASHRAE 90.1-2007, official guidelines on tax deduction calculations, and the EPA ENERGY STAR program.  

Another significant technical component of COMNET is a comprehensive list of simulation engine independent building descriptors, each with a detailed description of input restrictions and baseline building definitions. The building descriptors address all aspects of building energy consumption, ranging from ground reflectance and shading from adjacent buildings to details of the baseline building HVAC systems and renewable energy systems.

Institutional Components

COMNET provides an institutional framework which creates categories of commercial buildings based on size, type, and complexity; identifies types of services that stakeholders need from energy assessors for each building category; defines and standardize what skills energy assessors would need to be qualified to conduct these services; and creates a mechanism for professional accountability.  COMNET has been designed to ensure compatibility with existing credentialing processes already in place among professional societies and governmental licensing agencies and to make maximum appropriate use of existing certifications and credentials.

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COMNET MULTIMEDIA

 

 

COMNET LINKS AND RESOURCES