Print this page Passive Cooling Systems
A. Bhatia, B.E.
Course Outline
Buildings are major consumers of energy insofar as their construction, operation and maintenance are concerned. It is estimated that almost 50% of the global energy demand is due to buildings. Thus, the energy conscious architecture has evolved to address these issues. It involves the use of eco-friendly and less energy intensive building materials, incorporation of passive cooling techniques in building design and integration with cooling technologies without or little use of any intermediate electrical drivers.
This 4-hour course will introduce you to the passive cooling systems and is intended to be used as guidelines to choose technologies that are suitable to different situations.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
Learning Objective
Following completion of the course readers will:
- Explain the factors having greatest impact on summer cooling loads;
- Understand the mechanisms of heat gain control by intervening solar radiation, vegetation, ventilation and internal heat gains;
- Learn passive and low-energy cooling techniques and understand how these can be combined to achieve optimum benefits;
- Explain the principles of natural ventilation design for nocturnal cooling;
- List the design factors for stack and wind driven ventilation;
- Understand the basic principles of direct and indirect evaporative cooling systems;
- Understand the factors affecting evaporation rate and cooling;
- Understand the principles of desiccant cooling and dehumidification;
- Understand the functioning and application of an absorption chiller systems;
- Understand the factors influencing radiative cooling process and application of various radiant cooling strategies;
- Understand the fundamentals of direct ground cooling systems and geothermal heat pumps; and
- Understand the fundamentals and applications of thermoelectric heat pumps.
Intended Audience
This course is aimed at students, mechanical engineers, architects, facility managers, environmentalists, energy auditors and anyone who wants a basic understanding of cooling systems.
Benefit to Attendees
This course will help readers gaining a basic understanding of how to minimize, isolate, ventilate, eliminate, and radiate heat out of the buildings.
Course Introduction
Passive Cooling: What is it?
Passive cooling is a technique that uses natural forces for cooling and heat sinks for dumping heat. Passive cooling relies on two primary strategies:
First and foremost, prevent heat from getting into the building! If it does not come in, we don’t need to get rid of it.
Second, get rid of unwanted heat that comes into the building by use of various heat sinks and climate influences to decrease heat.
Passive cooling systems differ from mechanical systems in that they rely on natural heat sinks to remove heat from a building. By definition, they derive cooling directly from evaporation, convection, and radiation without the use of any intermediate electrical devices or drivers. This course discusses some of the passive cooling techniques that are low on energy consumption:
- Ventilation and Night Cooling
- Radiant Cooling
- Evaporative Cooling
- Dehumidification
- Vapor Absorption Systems
- Earth Coupling and Heat Pumps
Course Content
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Course Summary
Passive cooling systems use simple, low-cost techniques to provide summer comfort in warm climates for people and animals in buildings. The simplest and most effective passive cooling technique is to keep the sun's heat from entering a building. This is accomplished primarily by creating a cool microclimate to discourage heat buildup.
The simplest form of passive cooling is the use of landscaping. Vegetation shading western and southern walls helps reduce solar heat. Trees, shrubs, various plants, and earth absorb the brunt of the afternoon sun without increasing the thermal mass of the building.
Nocturnal coolingis the least expensive and most energy-efficient way to cool buildings. It reduces indoor air and surface temperatures, essentially precooling the building for the next day. Today, natural ventilation is not only regarded as a simple measure to provide fresh air for the occupants, necessary to maintain acceptable air-quality levels, but also as an excellent energy-saving way to reduce the internal cooling load of the building. Depending on ambient conditions, natural ventilation may lead to indoor thermal comfort without mechanical cooling being required.
Other techniques include radiant cooling, evaporative cooling, desiccant dehumidification, absorption systems and earth coupling. The selection of appropriate methods for every situation, depend primarily on the climatic conditions of a region, the cultural context, and the materials available locally. Availability of passive cooling also depends on such factors as climate, cloud cover, night sky conditions, and availability of water. In arid climates for instance where water is available, evaporative cooling is a low-cost method of providing comfort in high temperatures. Yet, this approach is of little value in humid climates where the air is already saturated with moisture; in such climates dehumidification may be needed to provide comfortable passive cooling. Thus, passive cooling differs in different places and situations.
Studies prove that taking advantage of cost-free natural resources can significantly reduce the expense of air conditioning in most of residential, commercial and industrial buildings.
Quiz
Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.
DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.
