Emerging Technologies Research and Development DRAFT Research and Development Opportunities Report for Opaque Building Envelopes May 2020 Section title (upper/lower case) i Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government, nor any agency thereof, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise, does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency, contractor or subcontract table or thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. ii Authors The author of this report is: • Chioke Harris, National Renewable Energy Laboratory With contributions from: • Nelson James, ORISE Fellow at the U.S. Department of Energy The technical manager of this report is: • Sven Mumme, U.S. Department of Energy The program manager providing overall guidance for this report is: • Karma Sawyer, U.S. Department of Energy Acknowledgments The author and technical manager would like to thank the many researchers who contributed to this report as well as the stakeholders who provided input throughout the development of this report. The authors would like to thank the following list of contributors. • Fraunhofer IBP: Florian Antretter (previously at ORNL) • Gas Technology Institute: Kaushik Biswas (previously at ORNL) • Lawrence Berkeley National Laboratory (LBNL): Ravi Prasher, Ronnen Levinson • National Renewable Energy Laboratory (NREL): Janet Reyna, Lena Burkett, Shanti Pless, Chuck Booten, Wale Odukomaiya, Jason Woods, Roderick Jackson • Oak Ridge National Laboratory (ORNL): Diana Hun, André Desjarlais, Som Shrestha, Simon Pallin • Prescriptive Data: Cindy Zhu (previously an ORISE Fellow) iii List of Acronyms ACH50 air changes per hour at an induced pressure differential of 50 Pa BEM building energy modeling BIM building information modeling BTO Building Technologies Office CFM75 cubic feet per minute of air leakage per square foot building envelope surface area at an induced pressure differential of 75 Pa (sometimes denoted CFM75/ft2) ECM energy conservation measure HVAC heating, ventilation, and air conditioning IECC International Energy Conservation Code MPC model-predictive control ORNL Oak Ridge National Laboratory PACE property-assessed clean energy programs PCM phase change materials R&D research and development TAMs thermally anisotropic materials VIPs vacuum-insulated panels VOCs volatile organic compounds iv Executive Summary BACKGROUND The opaque envelope—the barrier that helps maintain comfortable indoor conditions irrespective of prevailing outdoor conditions—is the single largest contributor to primary energy use in residential and commercial buildings. Residential and commercial buildings comprise 39% of total U.S. primary energy use [1]. The opaque envelope affects 25% of building energy use, or 10% of total U.S. primary energy use [2]. Improving the energy performance of the opaque envelope in U.S. buildings is critical to reducing total building energy use. Retrofits are crucial to realizing the energy savings potential of the opaque envelope because nearly 85% of residential and 55% of commercial buildings that exist today will still exist in 2050 [1]. Building envelope performance is also relevant to occupant comfort, productivity, health, and well-being. Residential Commercial Heating Heating Water Heating Refrigeration Cooling Lighting Ventilation Refrigeration Lighting Televisions Clothes Dryers Cooling Cooking Office Electronics (non−PC) Fans and Pumps Computers Computers Dishwashers Water Heating Freezers Cooking Clothes Washers Other Uses Other Uses 0 1 2 3 4 5 6 0 1 2 3 4 5 6 Primary Energy (quads) Primary Energy (quads) Figure ES-1: The opaque envelope affects heating, cooling, and ventilation (fans and pumps) energy use; these end uses are among the largest contributors to total primary energy use in U.S. buildings. Performance improvements in the opaque envelopes of new and existing buildings can reduce energy use in all three of these end uses. [1] Roof Residential Walls Foundation Commercial Infiltration 0 1 2 3 4 5 6 Primary Energy (quads) Figure ES-2: The breakdown of energy use by the components that comprise the opaque envelope shows that infiltration is the single largest contributor to total energy use, though all of the components represent a substantial contribution to energy use in buildings. [2] v TECHNOLOGY SOLUTIONS Novel opaque envelope technologies could dramatically reduce building energy use while simultaneously delivering additional benefits—comfort, well-being, and productivity—for building owners and occupants. This research and development (R&D) opportunities report identifies technologies that have the greatest potential to transform opaque envelope performance in new and existing buildings. This report articulates critical technology improvement needs and the R&D actions to address those needs for each of five technology focus areas. Reduce Air Improve Moisture Improve Increase R-Value Leakage Management Constructability Needs Increase Improve Enable Demand Longevity Affordability Flexibility Technology Focus Areas Needs Addressed Ultra-High Materials with a high R-value per inch of R/in thickness can enable higher insulation levels in Insulation new construction and reduce the cost and Materials complexity of retrofits of existing buildings. Envelope Technologies that can characterize the key energy Diagnostic performance-related properties of existing Technologies opaque envelopes could facilitate retrofit and Modeling adoption by quantifying the benefit of retrofits Tools and verify post-retrofit performance. Once a building envelope is complete, it is difficult Envelope to improve performance without substantial Remediation teardown and reconstruction; novel remediation- Technologies specific technologies can resolve this challenge. Tunable transport materials promise new Tunable envelope functionality, adjusting envelope Transport properties in response to electric grid needs and Materials interior and exterior conditions to minimize energy use while maximizing occupant benefits. Thermal and moisture storage can shift the timing Energy of heating and cooling energy demand, improve Storage thermal comfort by stabilizing indoor Systems temperatures, and offset energy use by taking advantage of favorable ambient conditions. vi Ultra-High R/in Insulation Materials Technology Action Plan • Develop materials and encapsulation methods that are durable and ensure long life with stable R-value • Develop high-throughput, low-capital-cost manufacturing methods for relevant materials • Develop materials and fabrication methods that yield convenient form factors for installation • Develop materials that allow for on-site modification of the dimensions of the as-delivered product while maintaining R-value and durability • Develop material formulations that achieve expected R-values at the macroscale • Develop new metrology that offers accurate measurement at low thermal conductivities (<20 mW/m-K) • Develop simulation methods that accurately represent thermal transport phenomena at multiple relevant length scales. 2040 Target (Walls) Today 2040 Target (Walls) Today 20 <18 0.64–1.91 14–17.25 R/in R/in $/ft2 area $/ft2 area Envelope Diagnostic Technologies and Modeling Tools Technology Action Plan • Develop novel diagnostic metrology suitable for year-round buildings testing conditions • Investigate virtual sensing to evaluate envelope performance and establish minimum requirements • Develop diagnostic metrology for envelope moisture performance • Develop low computational cost, accurate methods for modeling complex heat and mass transfer flows. Envelope Remediation Technologies Technology Action Plan • Develop novel materials and methods for overcladding with reduced labor effort and complexity • Investigate compatibility of high R/in insulation materials with remediation delivery systems • Develop materials and installation methods that can yield air sealing in the climate-appropriate plane without significant teardown • Develop autonomic self-healing air barrier films • Develop one-step spray- or liquid-applied air and vapor control materials. 2040 Target Today 2040 Target Today 2040 Target Today 1 1–3 0.2 0.17–1.09 1.5–2.5 2 — ACH50 ACH50 CFM75/ft $/ft2 area $/ft2 area (residential) (residential) (commercial) Tunable Transport Materials Technology Action Plan • Establish fundamental physics underlying circuit element mechanics in solid-state materials in environmental conditions comparable to the opaque envelope • Achieve dynamic resistive switching ratio (Roff/Ron) ≥ 10 with a high thermal resistance state ≥ Rair vii • Evaluate cycling durability and develop materials with minimal performance degradation over thousands of cycles • Establish viable heat sinks and sources for anisotropic systems and demonstrate operation. 2040 Target Today 2040 Target Today 50% 0.93–1.28 — — energy savings