by Maria Vincelli

Dorel Feldman officially retired from Concordia’s Department of Building, Civil and Environmental Engineering in 1996, but he’s still working on several projects, among them the search for a building material that can increase the energy efficiency of your home.

Dr. Feldman, now a professor emeritus, is involved in at least three research projects, supervises several graduate students, and offers the occasional reading course to students needing to brush up on their knowledge of polymers, a topic on which he’s published books in Romanian and English.

Chief among his accomplishments is finding and developing an organic phase-change material (PCM) that can be applied to ordinary wallboard to make it 20 to 25 per cent more energy efficient. He has been working on the project since he was hired by the then Centre for Building Studies in 1978. More than 20 years later, Feldman and his research associate, Dorina Banu, are looking for commercial partners.

It works like this. The PCM absorbs heat as it melts at 23° C. The heat is stored in the wall until the temperature dips below a comfortable room temperature. Then the PCM solidifies, releasing the same amount of heat that it had previously absorbed.

Though the researchers initially found many organic materials that absorbed and released energy during melting and crystallization, “the first problem was finding materials that melt and solidify at the temperature we need to have in our living rooms,” Feldman said.

The next step was to make sure that the mixture would keep its thermal properties over years of melting and crystallizing. After testing it for over 10,000 cycles, the researchers were able to confirm this. Though Feldman’s team has also worked with tiles and concrete blocks, the wallboard was easiest to prepare and work with in the laboratory setting, so the initial tests have been with that material. Once they successfully tried several methods of applying the PCM to the gypsum, they were ready to present their product to building materials companies.

It’s heavier than ordinary gyproc, but Feldman’s treated wall board has no odour, is easy to paint and plaster, and, after months of testing in a specially built room, does not appear to release any toxic gases.

Why isn’t it on the market yet? First, more work needs to be done to make the treated wallboard less flammable, and the team has been working on a solution that would make its flammability equivalent to or less than that of treated plywood, an industry standard.
Second, according to Feldman, who keeps a folder full of requests for information about the project from researchers around the world, the commercial interests have backed down.

Initially, Domtar participated in measuring the energy savings, but when the pulp and forest products company sold its gypsum division in 1996, it pulled out. Westroc, another producer of wallboard, also co-operated for some time, but is reluctant to produce it commercially because the technology for applying the PCM involves drying the board in an oven for one or two minutes at 200° C.

“They’re afraid of an explosion or fire,” said Feldman, who does not agree that it is a big concern. “We dried some ourselves in an oven and found that the surface of the board was only 100° C. It doesn’t have the time to take the temperature of the air.”

Now Feldman, who has received funding for the project from the federal and provincial governments and NSERC, is hoping that the companies that produce the chemicals in the PCM will fund the completion of the project. If they do, he says that the provincial government will probably match their funds.

Feldman, who taught polymer technology at a polytechnic institution for more than two decades before emigrating to Canada, also talks energetically about his other projects.

In addition to developing energy-efficient wall boards, he’s involved in a $1-million project to examine how air quality in buildings is affected by building materials and is developing synthetic materials for reinforcing concrete.