C.A. Ikutegbe, M.M. Farid
University of Auckland,
Keywords: housing poor insulation, energy-efficient materials, PCM- polyurethane foam composite, encapsulation, peak load shifting
Summary:The poor insulated homes and on-going increase in the cost of electricity are driving poor health outcomes globally. Energy-efficient materials can provide active management for the indoor environment creating warm homes in winter and comfortable in summer with minimal operating costs. To this end, thermal energy storage systems such as phase change materials (PCMs) can effectively moderate the variation in the indoor air temperatures of buildings if they are properly implemented and contained. They can contribute to reducing energy demand of buildings, improve indoor thermal comfort, and reduce environmental footprint. Thus, we have patented an innovative method to fabricate thermally stable PCM- polyurethane foam composites of high latent heat storage capacity. The PCM foam composite can be directly injected, coated, or sprayed on wallboards, using conventional foam applicator. The technique relies on the ability of the polyurethane to encapsulate at least 50 wt.% of PCM during the polymerization reaction. Through this approach, the commonly used, capital-intensive, and non-environmentally friendly technology of microencapsulation is not required. The PCM-foam composite was tested in our laboratory for thermal stability at 50oC over one year showing less than 1% mass loss. Our developed material was tested using two identical office-size constructions, one with conventional building materials, while the other has 10 mm PCM foam layer applied to its walls and ceiling. An advanced CompactRIO / LABVIEW system was implemented for an efficient thermal energy storage control strategy. The results of 22 winter days in the year 2021 showed that the use of the PCM foam composite resulted in an accumulative energy and cost savings of 22% and 46.6%, respectively. The extra cost saving was achieved through peak load shifting, utilizing the price-based electricity available by some power companies in New Zealand. In summer an energy-saving of about 40% in some of the days was achieved. The study revealed that the correct application of the control system could significantly improve the performance of the developed PCM foam composite in the built environment.