What the 2025 Buildings XVI Conference Reveals About High-Performance Homes
By John Peavey, PE
Published Thursday, December 18, 2025
Five Key Insights from the 2025 Buildings XVI Conference
Introduction: Research Driving Emerging Building Science Trends
This week, I attended the Buildings XVI Conference, organized by ASHRAE and Oak Ridge National Laboratory. Held every three years, this conference focuses specifically on the building envelope and brings together product manufacturers, research organizations, academia, builders, designers, architects, and consultants to share research, discuss emerging building science trends, and explore solutions to major building envelope challenges. This work closely aligns with the applied research and industry guidance supported by Home Innovation.
The research presented was impressive, and many of the technical findings can be applied to both new construction and remodeling projects. With that in mind, I want to highlight five key insights from the conference that have direct implications for high-performance residential construction: air tightness, advanced windows, bio-based construction materials, the Building Science Advisory Tool, and occupant behavior.
Air Tightness and Energy Performance
Why Airtightness Matters for High-Performance Homes
Air tightness plays a critical role in heat transfer through the building envelope due to convection and is a key factor in overall building energy performance. In many buildings, air leakage can account for 30–50 percent of total heating and cooling energy losses, making air sealing one of the most cost-effective strategies for energy reduction. Improved air tightness also enables designers to rely on controlled ventilation systems, which are essential to maintaining indoor air quality with far less energy penalty.
Emerging Tools for Air Leakage Detection
Air leakage detection tools on smartphones are now available, some more effective than others, making air tightness measurements faster, more accessible, and less dependent on specialized equipment. Multiple presentations highlighted new apps that use built-in cameras to detect air leakage. While these tools have limitations, they complement blower door testing at relatively low cost and may help expand access to airtightness diagnostics, support field verification, and improve air sealing practices.
Advanced Windows and Building Envelope Performance
Window Performance and Energy Efficiency
Windows have a significant impact on building envelope performance. For years, research has focused on improving window U-factor, which measures heat transfer through the entire assembly, and Solar Heat Gain Coefficient (SHGC), which measures how much incident solar radiation enters a building through a window. Because windows directly affect peak energy loads, HVAC sizing, occupant comfort, and resilience during extreme weather, they remain a critical design variable for high-performance homes. As a result, window performance remains one of the most influential components of a high-performance building envelope.
New Window Technologies and Retrofit Applications
New window technologies offer improved performance, often at increased cost. Lightweight triple-pane windows, for example, use thinner glass, advanced spacers, and low-conductivity gas fills to achieve very low U-factors while reducing weight, making them more practical for retrofits and high-performance construction.
Dynamic window technologies further enhance performance by actively or passively adjusting SHGC and visible transmittance in response to sunlight, temperature, or control signals. Presentations highlighted electrochromic and thermochromic glazing systems that can reduce cooling demand during peak solar periods while preserving daylight and views. Retrofit projects have also noted meaningful reductions in sound pollution. Although some of these technologies are not new, wider adoption depends on demonstrated performance, cost reductions, and energy rebate support.
Bio-Based Construction Materials
Research into Hemp-Lime and Other Bio-Based Materials
Research into bio-based construction materials featured prominently at the conference, including insulation, bio-based caulking, and non-carcinogenic fireproofing materials. One presentation examined hemp-lime insulation, often referred to as hempcrete, and described extensive durability testing underway by the National Research Council Canada. Preliminary results are promising, with the added benefit of carbon-neutral or carbon-negative performance depending on life-cycle analysis.
In addition to durability, hemp-lime insulation provides acoustic dampening, fire resistance, and vapor-open properties, making it a compelling option for high-performance envelopes.
Barriers to Broader Adoption in North America
Hemp-lime insulation products are available today; however, achieving broad adoption in the U.S. and Canada will require comprehensive testing for thermal performance, mechanical properties, fire resistance, and failure modes across North American climate zones. Clear and consistent code pathways—such as ICC-ES or CCMC approvals—are essential to provide confidence for designers, builders, and regulators.
Market adoption could also be accelerated through education, energy-code recognition, and low-carbon incentives. Alignment with programs such as the National Green Building Standard (NGBS) can further support adoption by providing recognized evaluation and compliance frameworks.
Building Science Advisory Tool (BSA)
Decision-Support for Residential Wall Assemblies
Oak Ridge National Laboratory has launched the next version of the Building Science Advisor (BSA), a web-based decision-support tool designed to help building professionals evaluate the performance and durability of residential wall assemblies, with a strong emphasis on moisture risk and energy efficiency.
How the BSA Supports Early Design Decisions
Users define a proposed wall system by selecting climate location, construction type, and key assembly components such as cladding, sheathing, insulation, and air and vapor control layers. The tool applies rule-based logic informed by validated hygrothermal modeling and field experience to assess risk and performance. Results are presented as qualitative ratings with clear recommendations, helping users identify moisture concerns, durability risks, and opportunities to improve thermal performance.
The BSA is particularly valuable for builders, designers, manufacturers, energy program managers, and housing agencies seeking rapid, science-based feedback without running complex models such as WUFI. While it does not replace advanced building science expertise, it reflects the broader effort by Home Innovation to translate building science research into practical, actionable guidance.
Occupant Behavior and the Performance Gap
Why Buildings Don’t Always Perform as Modeled
In building research, a well-documented performance gap exists between modeled and actual energy use. Even well-designed envelopes and high-efficiency systems can underperform when occupant behavior conflicts with design assumptions. The conference offered new insights into why occupants behave differently than researchers expect, highlighting the importance of incorporating human behavior into future building science research and performance modeling.
Real-World Examples from the Field
One researcher shared an example where, after advanced windows were installed, the occupant refused to close them so her cats could freely come and go. In another case, an occupant left the cooling system off to avoid a perceived increase in utility costs, even after efficient equipment and windows were installed.
Looking Ahead to Future Building Science Research
In closing, deeper research into occupant behavior will benefit future building envelope research by refining assumptions around comfort, system use, and real-world performance. I am looking forward to Building Conference XVII in 2028.
Frequently Asked Questions About Building Science Trends
What are the most important building science trends for high-performance homes in 2025?
Key trends include improved air tightness, advanced window technologies, increased use of bio-based construction materials, decision-support tools like the Building Science Advisor, and growing research into occupant behavior and its impact on building performance.
Why is airtightness so important for building energy performance?
Air leakage can account for 30–50 percent of heating and cooling energy losses. Improving airtightness reduces energy demand, supports controlled ventilation, and improves indoor air quality.
How do advanced window technologies improve building performance?
Advanced windows reduce heat transfer, manage solar gain, improve occupant comfort, and enhance resilience during extreme weather, while newer technologies such as dynamic glazing can further optimize performance.
What are bio-based construction materials and why are they gaining attention?
Bio-based materials, such as hemp-lime insulation, offer durability, fire resistance, vapor permeability, and lower carbon impact. Ongoing research is helping validate their performance and support broader adoption.
What is the Building Science Advisory Tool (BSA)?
The BSA is a web-based decision-support tool developed by Oak Ridge National Laboratory to help building professionals evaluate residential wall assemblies for moisture risk, durability, and energy efficiency.
Why does occupant behavior matter in building science research?
Occupant behavior can significantly influence actual energy use and comfort, contributing to the performance gap between modeled and real-world building performance.
These questions reflect common themes emerging from current building science research and practice. For additional context, supporting data, and real-world examples, refer to the full article above.