Radiant Heating and Cooling Handbook

# Section 7: RADIANT HEATING AND COOLING HYBRID SYSTEMS

Chapter 1: WHEN TO USE HYBRID SYSTEMS
Chapter 2: CONVECTIVE SYSTEMS WITH RADIANT PANELS
Chapter 3: VENTILATION WITH RADIANT HEATING AND COOLING
Chapter 4: HYBRID HEATING AND COOLING DEMONSTRATION PROJECTS

## 1.1 HEATING SYSTEM DEFINITIONS

Heating systems are used to condition and protect buildings and their contents. However, the second and most commonly identified threshold for heating system use is to provide occupant thermal comfort. Gan and Croome (1994) reported that almost 40 percent of the world s nonrenewable energy is used to achieve thermal comfort in buildings. Thermal distribution systems can use one or both of two different modes of heat transfer, convection and radiation, to deliver thermal comfort to an occupant.

Figure 1.1illustrates the difference in heating modes. The forced-air system [Fig. 1.1(b)] uses primarily convection to deliver the heat energy to the occupant. The system heats the air first. Then the air heats the occupant. With a radiant system [Fig. 1.1(c)], the occupant is first heated. Then the occupant and the other room surfaces heat the surrounding air. To accurately mathematically model a heating system and predict the thermal comfort of an occupant, it is necessary to know the relative amounts of energy transferred by each mode, called the radiative-convective split.

FIGURE 1.1: Radiant-convective heaters. ( a) Natural convection. ( b) Forced-air convection. ( c) Radiant heating panels. ( Courtesy of Morris L. Markel.)

Section 7briefly describes three major types of heating systems: in-space convective heating systems, radiant heating systems, and combination or hybrid...

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