Building Envelope Strategies

Energy codes are minimum energy-efficiency requirements and building design specifications for all new and substantially renovated buildings. Codes are updated over time to require increased energy efficiency for building envelope components, assemblies, and installation techniques.

To maximize efficiency, aim for a higher standard of envelope performance than the latest energy code requirement—but be sure to balance efficiency with your building’s appropriate humidity levels and occupant comfort.

Strategies to surpass minimum code compliance:

• Review local and state energy codes (e.g., ) to inform performance and materials specifications.
• Review other standards, guidance, and benchmarking systems such as New York City's 2020 Energy Conservation Code , ASHRAE 90.1 , LEED , Passive House , and ENERGY STAR® . They provide frameworks for assessing the energy consumption of building designs.
• Create energy models to help you evaluate designs and materials against these standards and consider all opportunities to reduce the building energy footprint and optimize performance, and to understand the tradeoffs on cost and performance.

Tightly sealed construction reduces energy losses, maintains indoor thermal comfort, preserves indoor air quality, and minimizes drafts. Caulking, weatherstripping, and air barriers all help minimize air leakage.

You can verify the integrity of the building envelope through blower door testing, infrared thermography, and smoke testing. These methods can help identify and quantify air leakage pathways by measuring pressure differentials and temperature variations caused by air infiltration.

Air infiltration or leakage typically occurs at joineries between roofs, walls, windows, floors, and doors. Multiple techniques can control moisture and prevent or minimize air leakage across the building envelope, including ensuring a continuous air barrier.

Strategies to minimize air leakage:

• Install high-performing windows which can achieve U-values and solar heat gain coefficients (SHGC) that align with or outperform energy code standards when they are tailored to the climate zone and building orientation. Triple glazing, argon gas, thermally broken frames, and low-emissivity (low-e) window coatings also significantly enhance thermal resistance, limit solar heat gain, and reduce air infiltration.
• Install high-performance doors that have insulated cores, airtight seals, and thermally broken construction. They work seamlessly with wall assemblies to prevent moisture and maintain the integrity of the envelope.

Effective insulation reduces heat loss through roofs, walls, floors, and doors, which improves overall energy efficiency by reducing heating and cooling loads.

Strategies to reduce heat loss:

• Use continuous insulation to extend across all structural components, effectively addressing heat loss caused by thermal bridging. Systems such as exterior insulation finishing systems (EIFS) and insulated sheathing ensure consistent thermal resistance across the entire envelope while reducing the risk of condensation.
• Opt for thick layers of dense insulation to enhance thermal performance.
• Improve R-values and U-values. Thermal bridging can occur anywhere in the envelope, from wall penetrations by screws, nails, and other types of anchors to metal window frames. Insulation performance standards are dictated by code requirements and are measured by metrics called U-values and R-values. When improving envelope construction, increase the R-value of insulation and increase insulation thickness to improve the resulting U-value.

Again, make sure that retrofit applications improve upon minimum code requirements (e.g., ASHRAE 90.1 , International Energy Conservation Code , local codes) to maximize efficiency.

Control Solar Heat Gain

In new construction, building orientation and design make a significant difference in how sunlight and wind play a role in heating and cooling a building naturally. Proper shading reduces cooling needs in summer while allowing beneficial sunlight in winter, improving comfort and efficiency.

Several strategies can help to control solar heat gain:

• Opt for window glazing which includes technologies such as tinted or reflective glass, varying pane thicknesses, multiple glazing layers, and air- or gas-filled cavities—can significantly impact solar heat gain. When replacing windows, high-performance models with a long life expectancy offer the best savings over time. Alternatively, window films are a lower-cost solution.
• Consider Internal shading such as roller shades and louver blinds, which can be combined with external solutions to allow the occupant to tailor individual shading and lighting needs depending on the time of day.
• Consider external shading solutions such as overhangs, horizontal louvers, vertical fins, and other creative architectural features, which can serve as creative visual features.
• Choose reflective roofing materials to minimize solar heat gain, resulting in substantial energy savings in hot climates by reducing cooling loads. They are also effective in mitigating the urban heat island effect in densely built environments. In colder climates, reflective roofing materials may help heat buildings during the winter months, but this impact is insignificant when compared to the impact of additional insulation. Prior to installing reflective roofing materials in northern climates, it is important to evaluate factors such as roof insulation levels, the extent of conditioned areas, occupancy patterns, anticipated cooling energy savings, and potential heating energy penalties.
• Consider installing a building automation system, which can dynamically adjust internal and external shading to changing sunlight conditions to increase energy efficiency, reduce glare, and maintain natural daylighting.