Architectural building products with high thermal performance are an essential part of meeting increasingly stringent Model Energy Codes for today and tomorrow. High-performance products also contribute to achieve current project’s ambitious energy-efficiency and net-zero requirements. In addition to storefront, curtainwall and window systems, commercial entrance doors also serve valuable roles in high-performing building envelopes.
Helping our clients compete and meet the requirements of energy-driven projects, Tubelite Therml=Block® architectural aluminum entrance systems have been upgraded and expanded to provide our highest thermal performance. Using a new patent-pending “poured over strut” (patent pending) thermal separation construction, Tubelite Therml=Block doors can achieve a 0.50 U-value, based on glazing with a center-of-glass 0.24 BTU/ft2-hr-°F value.
Thermally broken is better
Aluminum has consistently proven to be the material of choice for fenestration framing because it is versatile, strong, corrosion resistant, light weight, fabrication friendly, long-lasting, infinitely recyclable and can be finished in an almost unlimited choice of colors. It is also a good conductor of thermal energy.
Without a physical thermal barrier to separate the exterior and interior surfaces of an architectural aluminum product, energy will “bridge” through it. “Thermally broken” fenestration systems interrupt the energy transmission by creating a cavity and inserting an insulating barrier to reduce thermal bridging.
Our innovative process combines the benefits of the two most dependable types of thermal breaks: polyurethane pour-and-debridge (P&D) and polyamide thermal strut.
- P&D thermal barriers
- This method involves pouring a chemically cured resin into a cavity in the aluminum extrusion. After it cures, the metal bridge from the bottom of the channel is removed, or “de-bridged,” to create the thermal break. The cavity also may be lanced for an additional bond between the metal and thermal break. Double poured-and-debridged barriers utilize two poured-and-debridged cavities, further reducing the energy transfer.
- Insulating polyamide strip profiles
- Used as thermal barriers, these strips – also known as struts – are inserted between the two surfaces of the aluminum extrusion. They are reinforced with glass fibers in three axes, supporting the framing’s structural and long-term durability.
Glass gains with lower U-values
When thermally broken aluminum entrances and other fenestration are matched with high-performance glass, the system performance is further improved in all categories, including lower U-values. Tubelite Therml=Block entrance system can achieve a 0.50 U-value (frame), based on glazing with a center-of-glass 0.24 BTU/ft2-hr-°F U-value.
U-value, also known as U-factor, is a measure of:
- Conduction – heat transfer through a solid, liquid or gaseous material via molecular contact. For example, touching a hot stove. To reduce conduction in windows, add frame thermal barriers.
- Convection – the transfer of heat through the movement of liquids or gases. For example, facing into a cold, north wind. To reduce convection in windows, add enclosed air spaces.
- Radiation – the transfer of heat through space without relying on an intervening medium. For example, the heat of the sun on your face. To reduce radiation in windows, add low-e glass coatings.
U-value = BTUs / Square Foot / °F Differential / Hour – In this formula, BTUs are British Thermal Units, which is the approximate heat required to raise 1 lb. of water 1 degree Fahrenheit, such as from 59°F to 60°F. U-value allows the HVAC engineer to calculate peak loads, as well as energy consumption, for any size fenestration opening, in any climate. When comparing U-values, remember that lower is better.
The three components used to calculate U-value for fenestrations systems are:
- Center of Glass (COG) – typical value is 0.29 BTU/ft2-hr-ºF (low-e insulating glass)
- Edge of Glass (EOG) – typical value is 0.34 BTU/ft2-hr-ºF (aluminum spacer)
- Frame – typical value is 0.90 BTU/ft2-hr-ºF (thermally broken). A frame’s U-value includes heat transfer through surfaces perpendicular to the glass plane.
Be aware that COG is different than “whole system” U-value, which includes frame and EOG areas. In addition to noting total system U-values vs. COG, be cautious not to confuse U-value with R-value, commonly used in wall and roofing applications. R-value is the inverse of U-value. For instance, a U-value of 0.50 would equate to an R-value of 2.0.
Saginaw Valley State University
Finishing touches
Beyond the exceptional thermal performance of our Therml=Block architectural aluminum entrance systems, these products support a wide range of applications and aesthetic options. They are available with narrow, medium and wide stiles, and up to 10 feet tall, as well as in a broad choice of finishes.
Along with standard anodized and painted finishes, these Tubelite’s specialty finishing options include Copper and Bordeaux Anodize, textured Terra Cotta coatings and Wood Grain finishes. Tubelite Therml=Block entrances also allow for dual finishing options and different colors on the interior and exterior.
New and upgraded Tubelite entrance door products are immediately available. Please visit our entrance product webpages to learn more about the features and benefits of Tubelite Standard and Monumental Entrances, or contact your local Architectural Sales Representative for personalized assistance.