BRE FB84 PDF

Introduction

Traditional construction relies on heavyweight structures with high thermal mass to achieve effective energy storage in the construction’s fabric. Modern, lightweight structures, with low thermal mass, can be susceptible to overheating[1, 2] due to solar heating and internal heat gains which cannot be absorbed by the structure or being too cold when external temperatures are too low. Air conditioning and heating systems are often specified to make the internal temperatures acceptable.

Phase Change Materials (PCMs), or latent heat storage materials for building applications, are an emerging technology in the UK. They offer a solution for improving the thermal performance and comfort of low thermal mass buildings currently being constructed using modern materials and techniques and also when renovating existing building stock.

PCMs can be used to provide thermal mass to buildings with low thermal mass. They can smooth the daily fluctuations in internal temperatures by lowering the peak temperatures resulting from extreme external temperature changes and can prevent overheating (Figure 1).

PCMs can reduce the capacity of mechanical heating or cooling systems. PCMs come in many physical forms and are available for different transition or operating temperatures. PCMs have now become available and incorporated into different building products.

This publication concentrates on PCMs as part of a passive/ fabric/thermal mass approach but it should be noted that PCMs can also be used as part of low energy ventilation and cooling systems and other emerging applications.

The publication provides introductory information about PCM building products and available methodologies for assessing them for specifiers, designers, approving authorities, manufacturers, fire safety risk assessors and other interested parties so they can ensure that this technology is properly considered on individual building projects.