Windows / Doors

Energy codes and standards play a significant role in the United States construction market by influencing the design of commercial buildings, as designers and contractors frequently turn to the U.S. Department of Energy (DOE) International Energy Conservation Code (IECC) code and the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) 90.1 standard to assist in creating project specifications. In fact, many building permits depend on it. While it is beneficial to promote energy efficient buildings, the DOE’s lofty long-term vision is to achieve net-zero commercial construction by 2025. This will drive significant changes to energy codes over the next decade, most of which will require higher performance from fenestration products.

Image 1 – Prescriptive requirements of commercial fenestration products

One of the most recent examples of tightening energy codes can be found in the 2012 IECC, which mandates prescriptive performance requirements that are close to current green codes and standards (see Image 1). These increasingly strict codes indicate that the commercial fenestration industry will need to evolve standard designs to meet the market’s future thermal performance needs.

Fenestration’s Role in Building & Thermal Envelopes

Fenestration provides natural light into an occupied space, so maximizing the amount of fenestration on the building envelope is typically a key strategy. However, it typically presents a weak point in the thermal envelope. Thankfully, we have moved on from the exceptionally inefficient monolithic glazing and non-thermally-broken aluminum framing systems to aluminum framing systems. Most commercial construction projects today use aluminum framing systems due to its versatility and durability. But unfortunately, aluminum is also a good conductor of energy – an undesirable characteristic in framing materials. That is why thermal barrier technologies have been used for decades to minimize heat loss by interrupting energy flow. Polyamide strips and polyurethane cavities are commonly found in standard aluminum framing materials to help resist energy flow; these products have the ability to meet current codes with standard glazing and they also allow for more efficiency by incorporating high performance glazing to meet today’s green codes. However, they are not robust enough to meet the increasingly tough energy codes of the future.

Fenestration’s New Baseline for Energy Efficiency

Image 2 – Advanced fenestration products establish a new baseline of performance for greater energy efficiency

There is good news, though! Recently-introduced fenestration products significantly improve the thermal performance of the whole product and establish a new baseline of performance (see Image 2). Simulation tools such as Therm and Windows 5.0 – developed with funding from DOE – allow manufacturers to simulate the thermal performance of various designs prior to production. Designers now have the capability to not only analyze the placement of thermal barriers, but also to analyze the extrusion design to minimize heat flow through the profile assemblies. This process helps close the thermal performance gap between the framing system and the glazing system and yields an overall product with superior thermal performance. The result is a new generation of framing systems that have greatly improved thermal performance attributes and provide a more comfortable interior environment. Surface temperatures of the frame are raised and improve human comfort when in close proximity to the fenestration systems; this higher surface temperature also improves condensation resistance, which is an equally important performance metric in commercial construction.

Image 3 – Advanced framing design incorporating a double polyurethane thermal barrier to significantly reduce heat transfer

These advanced products incorporate multiple thermal barriers (see Image 3). Furthermore, they are capable of achieving current energy-efficient building requirements as well as future energy codes with readily available glazing infills. This concept is important because it lowers the overall price point in achieving this level of performance. By integrating high performance glazing with the advanced framing, architects are able to continually achieve performance more stringent than code.

Helping Designers and Contractors Meet the Codes

But the question remains, how can designers and contractors ensure the correct product combination is specified to meet their requirements? Fortunately, the fenestration industry has developed tools to communicate the energy performance of whole products. The American Architectural Manufacturer’s Association (AAMA) released AAMA 507, a standard practice for determining the thermal performance of fenestration systems. By utilizing the same simulation standards defined by the National Fenestration Rating Council (NFRC), AAMA 507 allows architects to quickly understand the whole product’s performance. It provides a fast and accurate analysis of how different insulating glass systems will perform within the framing system. AAMA 507 thermal certificates are readily available from fenestration manufacturers to demonstrate compliance to specifications and codes.

NFRC, which is known for its residential window certification program, recently released a program- the Component Modeling Approach (CMA) program- to independently certify the thermal performance of commercial fenestration products. Similar to the concepts deployed in the AAMA 507 standard, the CMA program allows whole product energy performance ratings for commercial projects. The concept behind component modeling is performance data from the three primary components – frame, glass and spacer assemblies. These three systems are combined on a project-by-project basis to generate the overall product performance rating.

The Future of the Commercial Fenestration Industry

Advanced framing systems being developed by fenestration manufacturers will be able to meet and exceed current and future energy codes. Designers and contractors now have design flexibility throughout all categories within the building envelope including entrance doors, storefronts, curtain walls, balcony doors, operable windows and sun control devices. The continued research and development of new products by the commercial fenestration industry will ultimately lead to more energy and cost efficient buildings across the U.S.

Written by Michael Turner, Vice President of Marketing at YKK AP America Inc.