Jean Claude E Peclet, a French Physicist born in Besançon, FR, became one of the first scholars of Ecole Normale a Paris and in 1829, became professor of Physics at the Ecole Central des Arts et Manufactures. In the 1850’s he experimented with the effect of insulating using high and low emissive metals facing air spaces. He chose a wide variety of metals from tin to cast iron concluding that color and the visual reflectance were not significant determining factors in the performance of the material. He then calculated the reduction in BTUs for high and low emissive surfaces facing into the air spaces and discovered the reduction in heat transfer for a radiant barrier.
Two German businessmen in 1925 filed for reflective surface patents for use as building insulation. Thanks to technology improvements which, allowed low emissivity aluminum foil to be commercially viable and available and, no longer a protected resource, the popularity of the product soared.
This was the departure point worldwide for radiant barrier and within 15 years or so, millions of square feet were installed in the United States. Withing 30 years and, the name radiant barrier gave itself, afforded its inclusion in projects at MIT.
In the mid-1950s, Clark Beck, a U.S. Air Force engineer began working on what NASA used for their spinoff, radiant barrier technology. Beck worked on inventing and producing materials to withstand immense heat when passing through the Earth’s atmosphere. His goal was to create a material that could withstand the fluctuations in temperature created by a skip-type reentry. The craft “skips” along the surface of the atmosphere, steadily making progress sufficient for reentry. This skip-type of a reentry takes the craft from extreme heat to frigid cold every few seconds. The material would also need to withstand millions of pounds of pressure per inch of bending without twisting which, is the simulated force of reentry.
Without the reflective material, the craft would form “hot wings,” and without the required flexibility, it would break apart.
During his work, Beck discovered the fantastic properties of radiant barrier. NASA used his work for the materials that went into the space capsules, heat resistant instrument panels and together with the Air Force, an early spacecraft prototype. That prototype was the Boeing Dyna-Soar which, looks an awful lot like the Space Shuttle.
It was finished in 1962 and scheduled for 11 maned flights in 1964 with its first orbital flight for 1965. It was a reusable space vehicle with three retractable struts for landing. Oddly, on December 10, 1963 the program with Boeing was cancelled, scraping the partially completed X-20 prototype and mockup as well as, the tooling for a 10-plane production line. Meanwhile in 1961, the Air Force contracted with McDonnell Aircraft to build 6 experimental aerodynamic/elastic structures that roughly resembled the Dyna-Soar.
NASA used the thin, shiny silver material to protect the first space explorers from the harsh space environment (a range of -460 °F to 541°F). In order to protect the astronauts, standard thermal insulation would have needed to be 7-feet thick! Just a tad awkward to move in. Radiant barrier also reflected body heat back to the astronauts inside their suits keeping them warm and at the same time, reflecting radiant energy from the Sun outward to keep them cool.
The radiant barrier NASA used reflected more than 95% of radiant energy away from them and the tiny holes in the fabric, allowed moisture to escape and longer heat waves to enter. The aluminum was vacuum coated to a thin film and applied to the base of the Apollo landing vehicles. It has been used in the James Webb Space Telescope and Skylab. Radiant barrier is much more effective in space than here on Earth because outer space is a vacuum where heat transfer is ONLY by radiation. An additional benefit, making it ideal for space, was the weight; radiant barrier only weighed 17 pounds per 1,000 square feet! Radiant Barrier is a Space Foundation Certified Space Technology ™.
Radiant barrier has been in use since the Gemini and Apollo missions at NASA and on almost all its spacecraft manned and unmanned. Radiant barrier here on earth even with an effective barrier, still can have 5% to 45% of heat transfer occurring via convection and conduction.
When Skylab lost a heat shield during launch and began to overheat, NASA used the reflective barrier as an umbrella for a sunshield and saved the mission. This was groundbreaking in 1973 because, it provided the first chance for a livable, workable habitat for astronauts in space. NASA’s radiant barrier has been public domain for over thirty years.
Currently, the Hubble Space Telescope and Mars Rovers are protected with reflective barrier. NASA’s barrier is made of a strong plastic vacuum-metallized film with an infrared reflective aluminum coating applied as a vapor.
The space agency has also perfected multi-layer insulation (MLI) materials creating “blankets” for application to the exteriors of satellites, instruments inside, space suits etc., to name just a few.
The components are ultra-lightweight insulation. In the vacuum of space, there is substantial exposure to thermal radiation and these blankets furnish exceptional insulation. A typical one-foot piece of insulating material on Earth, could have an R-value of 24 to 30. An MLI blanket in space will have an R-value of 10,000. Wow!
MLI blankets are made of multiple layers of ultra-thin plastic film, coated on one or both sides with an aluminized reflective material. Typically, a NASA blanket will have 10, 20 or more layers with roughly a maximum thickness of half inch! Between these layers is a non-woven mesh separating reflective layers while preventing conduction between them. Blanket performance is directly proportional to the amount of space between layers.
Typically, a blanket works as follows: The outermost blanket layer reflects roughly 90% of the radiated heat. The next layer will reflect 90% of what has passed through the first layer and each layer after, does the same. Collectively, the multiple layers reduce radiated heat to virtually zero. This means, 10% of the radiated heat from the first layer meets the second layer. Layer II will reflect 90% of that 10%. Layer III will reflect 90% of that 1% that may have passed through until there is zero radiated heat passing.
NASA engineers tend to favor MLI blankets over other options due to the lightweight properties, dependability, and superior thermal performance. Thinner MLI blankets are most definitely in its future.
With the COVID-19 crisis this year, 2020, the global market for Radiant Barrier and reflective insulation was estimated at $1 Billion and is projected to reach a revised size of $1.7 Billion by 2027 which, is growing at a CAGR of 7.6% over the period 2020-2027. Reflective insulation, one of the segments analyzed in the report, is projected to grow at an 8.1% CAGR to reach $1 Billion in that segment alone by the end of 2027. The United States accounts for over 28.9% of the Global Market Size in 2020 and the market in the U.S. is estimated at $293.5 Million.
Radiant Barrier and Reflective Insulation are here to stay.