Next steps
The next stage of the project is to finish collecting field data for the two retrofit scenarios demonstrated with ORNL’s two-story Flexible Research Platform. The field data will be evaluated to identify the best practice retrofit recommendation.
This project identified two top-performing wall retrofit recommendations for commercial buildings with masonry construction based on a multi-stage evaluation process. While the project is still ongoing, the selection of the two scenarios is based on the performance results achieved up to the current stage of the project.
The polyiso foam board scenario evaluated as a retrofit installed over existing assembly was identified as the most cost-effective retrofit scenario, as it provided HVAC energy savings of 30 percent at a payback of 14 years. However, this scenario depends on the condition of the existing insulation and is applicable only when the insulation is in effective condition to be retained. Increased steps in the installation (e.g. taping of board seams, and sealing junctions or sealing boards to wall surface) require vigilant inspection onsite to ensure quality installation.
The closed-cell SPF scenario was identified as the most energy-efficient retrofit, providing HVAC energy savings of 41 percent. However, this strategy requires the teardown of existing insulation within the assembly, which can be an added cost in terms of time and labor, resulting in a payback of 16 years. The spray application method by a single trade (i.e. certified sprayfoam contractor) can help ensure installation quality onsite.
The evaluation conducted through the project compared the two integrated retrofit solutions based on cost, energy performance, and constructability. This information will provide the industry with guidelines for best practice retrofit recommendations and help building owners and design professionals make informed decisions regarding the most suitable option for their buildings.
André Desjarlais is the program manager for the Building Envelope Research Program at the Oak Ridge National Laboratory (ORNL). He has been involved in building envelope and materials research for more than 40 years, specializing in building envelope and material energy efficiency, moisture control, and durability. Desjarlais is the past chair of ASTM Committee C16 and was awarded Fellowship in the association. He chairs ASTM’s committee on Technical Committee Operations (COTCO), and has also been a member of American Society of Heating, Refrigeration, and Air-conditioning Engineers (ASHRAE) since 1991. Desjarlais can be reached at desjarlaisa@ornl.gov.
Amy Wylie is the buildings and transportation platform leader for Covestro LLC’s public sector and business growth services division. She has vast experience in various material science disciplines and functions including coatings, plastics, and polyurethane materials. Wylie is a principal investigator dedicated to the Consortium for Building Energy Innovation (CBEI). She can be reached at amy.wylie@covestro.com.
Mugdha Mokashi was a building science specialist with Covestro at the time of this article, analyzing value-added propositions for integrated envelope retrofits for commercial buildings. Her primary responsibilities included performing energy modeling and providing retrofit recommendations specific to the Northeast United States.
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