Solar Engineering of Thermal Processes, 4th Edition

Chapter 22

Design of Passive and Hybrid Heating Systems

The principles underlying passive (and active) solar processes are outlined in Chapters 1 to 11, and passive heating and cooling processes and phenomena associated with them are described in Chapters 14 and 15. In this chapter we deal with questions of estimating the annual performance of several types of passive building-heating systems. The solar-load ratio correlation method developed at Los Alamos Scientific Laboratory is first introduced. The application of utilizability methods to direct-gain and collector-storage wall systems is shown. Then design methods for two hybrid systems are outlined, for active collection–passive storage systems and for systems having significant fractions of annual loads carried by both active and passive processes. This combination of methods will allow the annual performance of a wide variety of passive and hybrid systems to be estimated.

22.1 Approaches to Passive Design

Thermal design of passive buildings is closely interrelated to architectural design, as the collection of solar energy and its storage are accomplished in elements of the structure itself. There is a spectrum of methods for estimating long-term thermal performance of these buildings that range from practical experience (“do it this way in this climate and it will work”), to use of charts and tables that are based on combinations of experience and calculations, to correlation and utilizability methods that are the counterparts ...