How Low-E Coatings, SHGC, U-Values, and Marvin ERS Glass Can Help Meet Project Goals
When a project has specific energy performance goals, the conversation often focuses on insulation levels, air sealing, and HVAC efficiency. Yet one of the most powerful performance variables is often hiding in plain sight: the glass package.
Many architects are surprised to learn how much flexibility exists within today’s glazing options. With the right combination of Low-E coatings, glass configurations, and dual- or triple-pane construction, it’s possible to influence U-Value and Solar Heat Gain Coefficient (SHGC) more independently than many realize.
That flexibility can create opportunities to improve energy performance, meet modeling requirements, and maintain the project’s design intent—without making significant changes elsewhere in the building envelope.
At JB Sash, we work closely with architects, builders, HERS raters, and energy consultants to help identify glazing solutions that support both performance goals and architectural vision.
Start With the Performance Target
One of the first questions we ask when discussing glass options is simple:
What is the energy model looking for?
More specifically:
- What U-Value target does the project need to achieve?
- What SHGC target is required?
- Is the project pursuing a specific HERS score?
- Are there code requirements or energy modeling goals that need to be met?
Once we understand where the project needs to land, we can help identify available glazing options that support those targets.
The Biggest Misconception About Glass Performance
Two of the most important metrics in window performance are U-Value and SHGC.
U-Value measures how much heat transfers through the window assembly. SHGC measures how much solar heat passes through the glass.
One of the most common misconceptions in window specification is that these two values are locked together.
They’re not.
Modern Low-E coatings allow architects to influence thermal performance and solar heat gain independently to a meaningful degree. While adjustments to one metric may affect the other, today’s glazing technologies offer significantly more flexibility than many people realize.
This means it’s often possible to improve insulating performance without dramatically changing SHGC—or reduce solar heat gain while maintaining strong thermal performance.
For architects working through energy modeling, that flexibility can become an important design tool.
Beyond Dual-Pane vs. Triple-Pane
When projects require improved energy performance, many assume triple-pane glass is the only answer.
While triple-pane glazing can certainly achieve lower U-Values, it’s only one part of the equation.
Different Low-E coatings, gas fills, spacer systems, frame designs, and glass configurations can significantly impact performance in both dual- and triple-pane systems.
Typical performance targets often fall into ranges such as:
Likewise, SHGC values can often be tailored based on orientation, climate, and project goals.
The better question isn’t:
“Do I need triple-pane?”
It’s:
“What combination of glazing options best supports the project’s performance goals?”
Actual performance varies by manufacturer, product line, window size, operation type, frame material, and glazing package.
New Opportunities with Marvin ERS Glass
Marvin’s Enhanced Reflective System (ERS) glass represents one of the most significant recent advancements in glazing technology.
Traditionally, achieving lower U-Values often meant moving to triple-pane glass, bringing added weight, potential sizing limitations, and increased complexity.
ERS helps bridge that gap by delivering improved thermal performance while maintaining many of the benefits associated with dual-pane glazing systems.
For architects, that can mean:
- Improved thermal performance
- Reduced glass weight compared to many triple-pane alternatives
- Greater flexibility for larger window and door openings
- Fewer size limitations associated with heavier glazing packages
- Additional pathways to achieving project performance goals
ERS is a great example of how glazing technology continues to evolve. Rather than viewing performance as a choice between standard dual-pane and triple-pane, architects now have more options available to fine-tune window performance to meet the needs of the project.
Performance characteristics vary by product line and application. Consult manufacturer performance data for project-specific values.
Sometimes the Simplest Path Is Changing the Glass
When a project is being modeled, numerous variables can influence overall energy performance, including:
- Insulation levels within the building envelope
- Air sealing performance
- HVAC efficiency
- Renewable energy systems
- Window and door performance
- Adjusting any of these variables can impact the final result.
In many cases, modifying the glazing package may be one of the most efficient ways to improve modeled performance without making significant changes elsewhere in the design.
Sometimes the answer isn’t changing the wall assembly.
Sometimes it isn’t changing the HVAC system.
Sometimes it isn’t adding more solar panels.
Sometimes it’s simply a different glass package.
Why Work With a Glass Performance Expert?
The challenge isn’t a lack of available options—it’s understanding which combination of coatings, glazing configurations, and performance characteristics best supports the goals of the project.
Because every project is different, there is rarely a one-size-fits-all solution.
The right glass package depends on factors such as:
- Project location and climate
- Building orientation
- Window size and quantity
- Energy modeling requirements
- Desired U-Value and SHGC targets
- Budget and design priorities
This is where working with an experienced product specialist can make a meaningful difference. Rather than sorting through dozens of glazing combinations, architects can start with their performance goals and identify the solutions most likely to achieve them.
Let’s Talk About Your Project
Every project has different performance requirements, design priorities, and energy goals.
If you’re evaluating glazing options, working through HERS requirements, or trying to determine the right balance between U-Value and SHGC, our team can help.
Tell us where your project needs to land—and we’ll help identify the glass package that gets you there.
From product selection to performance optimization, JB Sash works alongside architects, builders, and energy consultants to help align glazing decisions with project goals.
