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ASHRAE 90340

Air-Conditioning System Design Manual

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Organization: ASHRAE
Publication Date: 1 December 2019
Status: active
Page Count: 316
scope:

PURPOSE OF THIS MANUAL

This manual was prepared to assist entry-level engineers in the design of heating, ventilating, and air-conditioning (HVAC) systems. It is also intended as a design guideline reference manual for the more experienced HVAC design engineer as well as a reference design manual for those in the construction industry, e.g., mechanical-electrical field coordinators, and for building owners' capital project personnel, e.g., owner's project engineer. It can also be used in conjunction with fundamental heating, ventilating, air-conditioning, and refrigeration (HVAC&R) resource materials as a senior- or graduate-level text for a university course in HVAC system design. This manual was intended to fill the void between theory and practice, to bridge the gap between real-world design practices and the theoretical knowledge acquired in the typical college course or textbook. Courses and texts usually concentrate on theoretical calculations and analytical procedures or the design of components. This manual focuses on applications.

The manual has been organized into 13 chapters, beginning with the business of HVAC design engineering followed by the design process. Next, this design manual addresses human health, wellness, and safety in regards to HVAC design and occupants.

The user/reader should be familiar with the general concepts of HVAC&R equipment and possess or have access to the four-volume ASHRAE Handbook series and appropriate ASHRAE publications, e.g., ASHRAE Guidelines and Standards, to obtain grounding in the fundamentals of HVAC&R system design. Information contained in the Handbooks and in other publications referenced herein is not generally repeated in this design manual. There is a broad range of publications referenced at the end of each chapter, which are to be used by the designer as a list of general references to compliment this manual.

The initial difficult task in any design problem is how to begin. The entry-level professional may not have experience (or have limited experience) from past design projects to fall back on and may be at a loss as to where to start a design. To assist the reader in this task, a business plan based on sound business strategy and fundamental engineering concepts should be created as a guide for the designer to follow that takes into account the project timeline and delivery method. With an understanding of the HVAC&R system design process for the application a step-by-step sequence of design procedures is outlined as part of the design process herein. Simple rules are given, where applicable to assist the new designer in making decisions regarding equipment types and size based on the project's available budget.

Chapters 2 and 3 address the guidelines by which the HVAC designer will proceed with a business plan that accommodates the design process. These chapters will also cover the selection of the optimum HVAC system for the application, the satisfaction of occupant comfort, health, and wellness needs, the calculation of the required HVAC&R loads, and the identification of HVAC components. It also includes a discussion on the four types of HVAC systems (all-air, air-water, all-water, and special HVAC systems).

Chapter 3 goes into further detail on the difference between analysis and design. This chapter covers basic issues that are addressed during the design phases of a building project and discusses a number of factors that influence building design, such as codes and economic considerations. Health, wellness, indoor air quality, and safety and their implications for HVAC systems design, are discussed in Chapter 4. Load calculations are discussed in Chapter 5. The specifics of load calculation methodologies are not presented herein because they are thoroughly covered in numerous ASHRAE Handbook resources and are typically conducted via computer programs today.

Chapter 6 introduces the topic of decentralized HVAC systems and central cooling and heating plants. Before the design engineer can proceed with a design, the decision must be made to provide an engineered solution based on either decentralized and/or central plant servicing decentralized HVAC systems. In addition to this chapter, Chapter 1, "HVAC System Analysis and Selection," in ASHRAE Handbook-HVAC Systems and Equipment is one of the best places for a designer to start the design process.

Chapter 7 highlights the components of HVAC&R systems, e.g., refrigeration equipment, heating, equipment, and so on. Chapters 8 through 11 cover the design parameters of all-air, air-and-water, all-water systems, and special HVAC systems, respectively. A conscious effort was made here not to duplicate material from ASHRAE Handbook-HVAC Systems and Equipment, except in the interest of continuity. Its treatment of the air side of HVAC systems is equally applicable to the air side of air-water systems; thus, this information is not repeated in Chapter 9. Chapter 10 addresses all-water heating and air-conditioning systems with limited ventilation features. Chapter 11 covers a variety of special HVAC systems, including energy recovery, heat pump systems, underfloor air distribution systems, variable refrigerant, and so on.

Chapter 12 addresses controls and provides an overview of control strategy as well as building management, energy management, and HVAC security. Chapter 13, "Commissioning and Testing, Adjusting, and Balancing," covers the HVAC system requirements that must work in sync for the specific HVAC systems to achieve the design intent, demonstrate the HVAC system's performance under all conditions, and to document the as-built results of the operating conditions and basis of design.

A few words of advice: do not hesitate to make initial design assumptions. No matter how far off the specific values of a final solution they might prove to be, assumptions enable the designer to start on a project and to gradually iterate and improve a proposed design until a satisfactory solution has been obtained. Frequently, more experienced colleagues may be able to assist by giving counsel and the benefit of their experience, but do not hesitate to plunge ahead on your own. Good luck!

Document History

ASHRAE 90340
December 1, 2019
Air-Conditioning System Design Manual
PURPOSE OF THIS MANUAL This manual was prepared to assist entry-level engineers in the design of heating, ventilating, and air-conditioning (HVAC) systems. It is also intended as a design guideline...
January 1, 2007
Air-Conditioning System Design Manual
PURPOSE OF THIS MANUAL This manual was prepared to assist entry-level engineers in the design of air-conditioning systems. It is also usable—in conjunction with fundamental HVAC&R resource...

References

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