Step 3 - Implement RETS-Compliant Green MLS Fields


Overview: RETS-Compliant Green MLS Fields
Third-Party Verified Fields
Specific/Technical Fields
Green Search/Marketing Fields


Overview: RETS-Compliant Green MLS Fields 

Early adopters of green MLS were charting new territory with limited resources.  The best option often was to convene a working group over many months to come up with a plan for green MLS fields. But MLSs interested in implementing or updating green MLS fields today find that much of the design choices are already clearly defined and working successfully in other MLS markets.

The Real Estate Standards Organization (RESO) is the entity that manages and maintains RETS. As a resource to support compliance, the RETS Data Dictionary provides common definitions for real estate data. The Data Dictionary standardizes over 500 data terms and values that define the most common descriptions of property attributes in the United States as used by real estate brokers, multiple listing services, and software developers who create applications for consumers and REALTORS®.  

Every version of the Data Dictionary has included green MLS fields.  These green MLS fields in the RETS Data Dictionary are briefly described on this webpage.  MLS technology staff can find additional details in the Data Dictionary or the Green MLS Implementation Guide.

The starting point for any MLS considering green fields must be the Real Estate Transaction Standard (RETS) Data Dictionary.  (See image for more information on the importance of the Data Dictionary.)

The benefit of using RETS-compliant green MLS fields include:

•    Ensures high-quality, consistent data
•    Designed to reduced agent liability for data entered in green fields
•    Reduced development time and cost by starting with fields already vetted by RESO and familiar to MLS system vendors

The green fields in the RETS Data Dictionary are broken into three categories:

•    Third-Party Green Verified Fields (certifications, labels and scores)
•    Specific/Technical Fields 
•    Green Search/Marketing Fields  (unverified)

NAR’s Green MLS Implementation Guide further defines these three categories of fields from the Data Dictionary so that the technology staff of an MLS or their software system vendor can implement them effectively and efficiently.  

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Third-Party Verified Fields (certifications, labels and scores)

Third-party verified fields capture information about certifications, labels, ratings and scores that have been awarded to a new or existing home based on completing a defined process for green building or energy efficiency remodeling.  

The RETS Data Dictionary defines six fields Third-Party Verified Field as repeating elements. This means each field can be used more than once on a property. This is because properties may complete requirements in one or more programs. For example, ENERGY STAR New Homes and USGBC LEED for Homes.  The six fields are designed to be used together with programming rules to maintain the integrity of the data captured while protecting users from unnecessary liability.  These six fields are also defined to have the flexibility so that future or local certifications can be added.  Finally, these fields can be defined to require supporting documentation to ensure accuracy of the data reported.  Step 2 – Manage Risks has more information on supporting documentation.

Section 4a of the Green MLS Implementation Guide further defines these fields for MLS technical staff and/or staff of their system software vendors.  

From the perspective of addressing liability concerns for agents, the most essential green fields are Third-Party Verified Fields.  The following six RETS-Compliant green MLS fields should be the basis for any MLS offering green fields.


RETS Data Dictionary Definitions - Third-Party Verified Fields


•    Green Verification Program (See Green MLS Implementation Guide for recommended pick list)--The name of the verification or certification awarded to a new or pre-existing residential or commercial structure. (i.e. LEED® for Homes, HERS, ENERGY STAR®, National Green Building Standard).  This is a repeating element.

•    Green Verification Body (See Green MLS Implementation Guide for recommended pick list)--The name of the body or group providing or sponsoring the verification or certification named in the green verification program field.

•    Green [Program] Year Verified (numeric field)--The version year used for verification or certification. This is important, since building codes and certification program change regularly. It is possible that a home considered energy efficient five years ago may not be energy efficient enough today to meet basic code requirements.  In many cases the version year will not be the same as the year built.

•    Green [Program] Verification Rating (open text field or See Green MLS Implementation Guide for recommended pick list)--Many verifications or certifications have a rating system that provides an indication of the extent of green features.  Commonly expressed as a name, such as Gold or Silver. This field is defined in RETS Data Dictionary as an open text field or MLSs may wish to extend beyond the RETS definition and offer a standardized pick list. 

•    Green [Program] Verification Metric (numeric field) -- A final score indicating the performance of energy efficiency design and/or performance in the home as tested by a third-party rater. Points achieved to earn a certification in the Green [Program] Verification Rating field do not apply to this field. HERS Index Score is the most common metric, especially with new homes. HERS runs with a lower number being more efficient. Home Energy Score is a new tool for existing homes and runs with a higher number being more efficient. Local scores may be available. 

•    Green [Program] Verification URL (open text field) – Many green verification bodies now provide a custom, property-specific URL address with details about green construction or scores achieved.  For example, on how certification points where achieved and how, or specific test scope and results. USGBC is beginning to offer a custom URL for participating homes that have completed the LEED for Homes program.  RESNET is beginning to offer a custom URL address for homes that have recorded a HERS Index Score.  

As a starting point, the Green MLS Implementation Guide offers a table which shows how the largest national green verification programs report the data needed for these fields.

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Specific/Technical Fields 

Various features in a home may contribute to its green qualities or performance.  Keeping a clear separation of features that "may be green" from a direct expression of "being green" tends to offer flexibility of expression and gives a clear avenue to mitigate risk for agents and brokers. Specific/Technical Fields in the RETS Data Dictionary are designed to make this separation.

The RETS Data Dictionary defines nearly 25 fields that capture the specific/technical features of a green or high-performance home.  The fields shown below provide an ample starting point for any MLS seeking to offer green fields and represent the details of a green or high-performance home. These fields are fully defined in the RETS Data Dictionary and offer a RETS-Compliant starting point for green MLS fields.  Enumerations (a list of options in a field) related to green and high-performance homes are further defined in the Green MLS Implementation Guide.

Section 4b of the Green MLS Implementation Guide further defines these fields for MLS technical staff and/or staff of their system software vendors.  

These fields are implemented most successfully in conjunction with the Third-Party Step 2 – Manage Risks.  

The local green building and energy efficiency remodeling community can be a huge resource to understand how the fields listed below and defined in the national RETS Data Dictionary and the related enumerations defined in the Green MLS Implementation Guide apply locally.  They can also identify further customization or clarification required to implement them successfully.  The building industry will know how often proposed features are represented in the existing housing stock and in local new construction trends.

They can also clarify how the local climate influences which features are most important.  The building community can also help with data for a business case that allows an MLS to prioritize when to implement proposed fields and enumerations.  This approach makes the most of the technology spend, but also leads to better data in the system as users tend to make less errors with fields and enumerations that they use regularly.  


RETS Data Dictionary Definitions - Specific/Technical Fields

The RETS Data Dictionary includes over 500 residential fields.  From that, approximately 25 might be used when listing a high performance property. These fields are grouped by four categories within the Data Dictionary:



DocumentsAvailable (e.,g. green addendums, copies of green verification documents, test scores, product efficiency labels, etc.)



Implementation Tips

MLSs are advised to “intermingle” existing RETS-Compliant fields from the list above with enumerations or field values that apply to green or high-performance homes.  MLS are discouraged from forcing existing features into a "green" field or other representation of being green. As an example, a listing agent may have identified dual pane windows as a feature of a house, never intending to claim that those windows were green or efficient. But if dual pane windows suddenly are placed in a green field because of an MLS change, it potentially changes the meaning of features in existing listings. Moreover, it could create a false statement of "green" or "efficient" that the listing agent or broker was not intending at the time of input. 

These intermingled field values require more maintenance and their level of detail means they are less likely to be searched by the consumer, but their value in conveying the details of a green home should not be underestimated.

Some MLS use hover help, URL links to established resources or green highlighting to identify and clarify the enumerations or field values related to green or high-performance homes.  

See Step 3 – Ongoing Quality for suggestions on maintaining and updating green MLS fields once deployed.

Implementation Samples

The Green MLS Implementation Guide defines in detail how RETS-Compliant fields can be implemented using field values or enumerations specific to green and high-performance homes.  

The following examples demonstrate how fields might be implemented with enumerations or field values as well:

Air Source Heat Pump
Ground Source Heat Pump
Evaporative Cooling
ENERGY STAR Qualified Equipment
ENERGY STAR/ACCA RSI Qualified Installation

WaterSense labeled irrigation controller
Used WaterSense irrigation partner 
South/West Shading
North Wind breaks
Water-Smart Landscaping
Native Plants
Permeable Paving
Vegetated Swale
Certified Wildlife Landscape
Gray Water System

Low VOC paints/finishes
Low VOC wood products
Lead-free paint
KCMA ESCP Cabinetry
Pest-Resistant Materials
Regional Materials
Advanced Framing
Structured Insulated Panels
Insulated Concrete Forms
Indigenous Construction
Low VOC Insulation
Recycled/Bio-based Insulation
Batt Insulation
Blown Insulation
Spray Foam
Rigid Insulation
Insulated Exterior Duct-Work
Insulated Attic/Crawl Hatch(es)
ICAT Recessed Lighting

ENERGY STAR qualified dishwasher
ENERGY STAR qualified refrigerator
ENERGY STAR qualified freezer
Heat Pump Water Heater
Solar Water Heater
Tankless Water Heater
ENERGY STAR Qualified Water Heater
High-Efficiency/Sealed Water Heater


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Green Search/Marketing Fields

Green Search/Marketing Fields are designed to be implemented as a set, and with enumerations (or field value lists) that are also defined in the dictionary and further clarified in the Green MLS Implementation Guide. The fields and enumerations for Green Search/Marketing Fields are designed to be implemented together to ensure accuracy in how they are used.

The number of specific/technical fields and their standard enumerations can be daunting.  Also, specific features, for example dual pane windows, may not always be considered green or efficient as technologies and methods evolve.  So having the option of providing green search fields allows sellers to market these aspects in a simple way that will not require MLSs to frequently adjust fields and enumerations.

This approach also simplifies buyer searches when looking for a specific performance category, for example, an agent working with the family of an asthmatic child that is particularly interested in extensive Indoor Air Quality features.

Likewise, this approach benefits appraisers who are seeking a category of comparables. For example, instead of having to understand a number of different window types (and whether they are currently considered green), users merely need to know that they are interested in efficiency features.  

Once a green search is complete agents or appraisers can drill into the listing sheets for details on specific features.

Due to the nature of Green Search/Marketing Fields, the related enumerations or field values are stable over the long-term and do not change much by climate, housing characteristics or market practices. Enumerations provided in the Green MLS Implementation Guide are designed to be implemented as shown and with all the RETS-compliant Green Search/Market Fields listed.  

Green Search/Marketing Fields are unverified and therefore require important follow-up steps to confirm information provided. Green Search/Marketing Fields should be qualified in the context of details provided in other fields. Third-Party Verified Fields provide high-quality details on green and high-performance features from a neutral third-party.  Specific/Technical Fields provide an extra level of detail on individual attributes.  Green Search/Marketing Field values should be used only when clarified against the context of Third-Party and/or Specific/Technical Field values.

Section 4c of the Green MLS Implementation Guide further defines these fields for MLS technical staff and/or staff of their system software vendors.  

RETS Data Dictionary Definitions – Implementation Design for Green Search/Marketing Fields
Green Search/Marketing Fields defined in the RETS Data Dictionary and further clarified in the Green MLS Implementation Guide are:

Green Energy Efficiency
Home Energy Management 
Incentives & Other

Green Energy Generation
PV solar array(s) 3rd-Party Owned 
PV solar array(s) Direct ownership 
Pre-wired for PV solar 
Wind turbine(s)
Pre-wired for wind turbine(s)
Net-Metering Renewable Energy Credits 

Green Sustainability
Conserving Methods
Regionally-Sourced Materials
Recycled Materials
Renewable Materials
Salvaged Materials
Onsite Recycling Center

Green Water Conservation
Water-Smart Landscaping
Green Infrastructure
Water Recycling
Efficient Hot Water Distribution 
Low-Flow Fixtures 

Green Indoor Air Quality
Contaminant Control 
Moisture Control
Integrated Pest Management

Green Location
Walkable Location
Public Transit

Walk Score® (numeric field)

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Green MLS Implementation Guide

RESO Gets a Little Greener
Real Estate Standards Organization Green MLS standard fields

Green Building Glossary
View the Green Building Glossary here

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Next: Step 4 - Design for On-Going Quality/Continuous Improvement