Energy Savings

The idea of using insulated panels to regulate temperature is older than you might think. In the 1820’s Frederic Tudor made his ice houses from double timber panels filling the interior gap with cheap and easily obtainable sawdust. While the R-value couldn’t have been wonderful, the design allowed for ice to be stored in the heat of Havana. The sawdust gave the panels minimal additional structural strength and the studs which held the panels apart created a thermal bridge, further decreasing the insulation value.   On the structural front, the US Forest Products laboratory conducted experiments in the 1930’s using stress skinned timber panels with paperboard/tar paper insulating cores to find an alternative way building houses using less wood. Building timber was seen as a scarce resource. An early example was visited and praised by Eleanor Roosevelt, showing just how much importance was attached to this initiative. Frank Lloyd Wright, the famous American architect, understood the structural strength of these panels, the two skins being compared to the flanges of a steel H beam and the filling being the web, and designed larger structures with minimal internal framework. He also passed the idea on to a student, Alden B Dow. Alden was a member of the Dow Chemical family and realized the advantages of using Dow’s trademark “Styrofoam” to replace the paper core. Styrofoam vastly improved the insulation and durability of SIPs or structural insulated panels, as they came to be known. Indeed, there is a continuing trend toward the use of SIPs in US residential house construction. Polystyrene, from which Styrofoam derives, was discovered by Eduard Simon, a Berlin apothecary, in 1831. He isolated Styrol (what is now known as Styrene) from Storax resin which can come from the tree Styrax Officinalis. Storax resin was traded in ancient times primarily as an ingredient of incense.   Replacing storax with erethhylene and benzine, the German IG Farben company used industrially produced polystyrene during the early 1940’s to replace heavier zinc castings in many applications, but it was only in the 1954 that Dow Chemical and the Kopper company of Pittsburgh started producing “Stryofoam” and “Dylite” using Otis Ray McIntire’s process of mixing styrene and isobutylene under pressure. This “foamed” polystyrene was 30 times lighter than the original and 98% air while having structural strength and a low thermal conductivity. It is said McIntire discovered Styrofoam by accident while attempting to develop a flexible insulator for electrical cables as natural rubber was in short supply during the war.     So, by the late 1950’s SIPs were manufactured using Styrofoam/Dylite as the filler. The first known use of SIPs in cold storage construction occurred in Australia. During the late 1950’s, Australia was increasing its food exports, primarily mutton, beef and frozen vegetables and needed bigger, more efficient and acceptably sanitary cold stores to hold this frozen produce prior to export. Michael Rudnev, a Russian immigrant who had settled in Brisbane, was manufacturing SIPs panels for residential housing.   During 1960, Rudnev with the assistance of CSIRO, (Commonwealth Scientific and research Organisation), experimented on ways of sticking thin metal, plastic and other materials instead of wood on either side of Styrofoam. He presented his new product using steel skins at the Commonwealth Cold Storage Conference held near Brisbane in 1962, but most delegates thought that SIPs would never replace standard cold store construction methods using brick with internal cork layers.   But Frank Vale, MD of Woodmasons, now part of the Swire Group, needed to build a new cold store in Dandenong outside Melbourne. Vale quickly saw that Rudnev’s product could significantly reduce building costs, while giving his freezer chambers sufficient height and space for forklifts. Cork insulation was problematic as it couldn’t satisfy the requirements of the USDA 191 regulations for export Meat Plants or the Codex Alimentarius. Neither would the normal wood or OSB skinned SIPs.     Rudnev’s metal skinned panels could be longer, possessed structural strength and had a high R-value. The non-corrosive easily cleaned and bacteria resisting metal skins would satisfy the health requirements. By the late 1960’s Woodmason’s Dandenong store design was being replicated globally as the old brick cold stores simply couldn’t compete. Michael Rudnev then opened SIPs businesses in other countries including South Africa, where he entered into partnership with Durban’s Southey company in 1971. Rudnev panels are still a brand to be reckoned with in the South African market.     Shortly after joining I&J (Irvin & Johnson) in 1991, I was put in charge of their five Cape Town freezer stores. One of them, now Auckland Cold Store in Paarden Eiland, was an early South African example of the Woodmason’s design using SIPs insulated panels from Rudnev’s South African company. Without knowing any of this history, I am glad to say that I closed three of the brick and cork stores, moving the stock to Auckland Cold Store, which is still very much in operation.   Insulated Cold Store Panel History written by James Cunningham