Dec. 20, 2021
Toray Industries, Inc.
Toray Develops Advanced Total Heat Exchange Element Sheets
that Can Save Energy and Enhance Ventilation Comfort and Hygiene

Tokyo, Japan, December 20, 2021 – Toray Industries, Inc., announced today that it has de-veloped a heat exchange sheet that delivers advanced heat transfer, moisture permeabil-ity, gas shielding, and water and anti-viral resistance performance. This new offering could significantly enhance the energy savings, comfort, and ventilation hygiene of total heat exchange ventilation systems. The company aims to commercialize this sheet in 2022 for elements in total heat exchange ventilation systems, for which demand is rising in view of intensifying measures worldwide to combat COVID-19 infections. A total heat exchange ventilation system saves energy by exchanging temperature (sensi-ble heat) and humidity (latent heat) between air from outdoors and interior exhaust air, reducing room temperature and humidity changes during ventilation. This lowers air con-ditioning system loads and improves comfort. Heat exchange sheets are inside system el-ements, so heat transfer properties and moisture permeability are necessary for the sheets to transfer temperature and humidity. Gas shielding is vital to keep carbon dioxide and odors in exhaust air out of supplied air. Generally, heat exchange sheets employ paper membranes. However, it was difficult to completely shield gas with porous paper, as well as to clean and remove dirt accumulating on elements after long-term use. Toray responded to this situation by creating a new heat exchange sheet comprising a unique thin porous film laminated with a functional resin layer that only lets humidity through. The sheet is about one-fifth the thickness of conventional paper counterparts and has excellent heat transfer properties. It is around 1.2 times more moisture permeable and delivers more than 20-fold better gas shielding, retaining that performance even after cleaning with water or a neutral detergent.  Used in total heat exchange systems, the sheet delivers a total heat exchange efficiency (see Glossary note 1) of at least 80% and an effective ventilation rate (Glossary note 2) of 99% or more, even after cleaning. These results are from a Toray assessment in accord-ance with JIS B8628, with an air volume of 150 cubic meters per hour. Also, tests for anti-bacterial (JISZ2801:2010), antifungal (JISZ2911:2018), and virus barrier (ASTM F1671) per-formance demonstrated the solid performance of Toray’s sheet. The COVID-19 pandemic has heightened the importance worldwide of good ventilation. Toray will continue striving to help materialize comfortable, safe, and secure lifestyles by offering high-quality materials in keeping with its corporate philosophy of contributing to society by creating new value.

Figure 1: Airflow for total heat exchange ventilation in winter
Figure 2: Heat exchange sheet heat transfer, humidity transmission, and gas shielding
Figure 3: Heat exchange sheet cross-section
1. The total heat exchange efficiency is the rate at which all heat in the air, including temperature (sensible heat) and humidity (latent heat) are exchanged.
2. The effective ventilation rate is the proportion of outside (fresh) air pumped indoors.