Design guidelines for replacement of air-conditioning systems

Many buildings have capabilities to admit only minimal quantities of fresh air to the air-conditioning supply ducts. There are climates that have temperature and humidity ranges for months of the year during which up to 100% fresh air could be admitted for ventilation and provide thermal comfort. This would result in a number of benefits that, when carefully considered, may lead to replacement of existing air-conditioning systems and/or the introduction of new systems or subsystems to complement existing systems. Examples illustrating the use of up to 100% fresh air for all or a portion of the year, in cold, temperate, and hot climates, are reviewed. The focus of this paper is on the development of design guidelines for potential replacement of the air-conditioning systems in buildings. The guidelines were developed with the assistance of 92 design professionals in nine countries, namely the United States, Japan, Canada, Australia, the United Kingdom, Singapore, Spain, Saudi Arabia, and Kuwait.