LBNL Tasked to Develop Technical Foundation for the new Window Attachment Rating Organization (AERC)

This project provides critical technical support to AERC that includes development and validation of simulation methods to model thermal, optical and energy performance of fenestration attachments, to develop associated test methods, and to assist AERC in the development and establishment of technical documents and rating procedures. LBNL’s activities are grouped in 2 major tasks, being to develop validated simulation models and procedures, including the update and release of software modeling tools that will be used to rate window attachment products and to develop and document standardized test procedures that are used for validation of the computer simulation methods and software tools, as well as for rating products that could not be simulated in software tools.

Progress to Date

  • LBNL has actively supported the establishment and operational start of the new window attachment energy rating council, AERC, which is currently in its very first year of existence. LBNL technical expertise, its software tools and impressive window testing facilities represent technical backbone of AERC. In January, LBNL layed out detailed technical plan in support of AERC phased approach to rating window attachments. While AERC proposed 4 product classes for the first phase (venetian blinds, roller shades, cellular shades and window panels – also known as storm windows), LBNL provided technical solutions to two more classes of products (pleated shades and solar screens).
  • LBNL performed major thermal validation study this year to determine validity of existing thermal models for air flow around shading devices and through the porous shading devices. The currently used heat transfer correlations were based on ISO 15099 standard calculation method, which were not documented well in peer-reviewed literature, so there were concerns about their validity. LBNL completed testing and evaluation of air flow around shading devices, such as side gaps, top and bottom gaps in the first half of this FY, while the validation of the flow through porous shading devices is currently being completed.
  • The newly developed heat transfer correlations, as a result of this research are being documented in peer-reviewed papers and are being prepared for incorporation in LBNL window software tools. LBNL will release new versions of THERM and WINDOW (7.4) to the public in October of this year, with the intent that this version becomes AERC approved for use in fledgling rating system. Version 7.4 includes modeling support for the 6 window attachment classes mentioned earlier.
  • LBNL is currently developing technical and User’s manuals in support of planned train-the-trainers for the software tools, as well as simulation training materials. LBNL will also assist in the development of AERC simulation manual, which will be based on LBNL’s simulation manual material developed over years for NFRC simulation manual. Content and graphics will be licensed to AERC through LBNL Intellectual Property Office, with the stipulation that AERC can freely use and modify materials from LBNL’s simulation manual with the acknowledgment where the material came from and with the stipulation that AERC will grant-back rights to LBNL to use any newly developed AERC simulation manual materials in its future documentation.
  • LBNL hosted Rapid Prototyping Session (RPS) in April of this year to accelerate the development of AERC rating and certification. More than 25 participants from wide selection of fenestration attachment industries and consultants working in this space attended RPS. The event was run by professional Bay Area-based facilitators Ecotone and was a great success that will help streamline next formative and structural AERC activities.

Per Unit and Aggregate Savings Potential

This type of activity does not lend itself well to per-unit energy savings. Aggregate savings are also hard to estimate, but the potential for savings by window attachments is documented in the DOE prioritization tool <provide source> and amounts to technical potential of 0.9 quads energy savings for commercial window attachments and 1.25 quads for residential window attachments by the year 2030.