Print this page HVAC Thermal Comfort – Concepts & Fundamentals
A. Bhatia, B.E.
Course Outline
Thermal comfort is a condition of mind that expresses satisfaction with the thermal environment. If you're designing a system strictly to maintain a temperature and humidity range without any consideration to human comfort, then that's not HVAC system design, that's refrigeration system design as in a refrigerated warehouse or such, and that's a whole different topic. Designing residential and/or commercial HVAC systems is nothing more that learning a series of principles of physics, combined with an understanding of certain real-world mechanical application concepts.
This 6 -hour course provides the basic concepts of human comfort, temperature - humidity relationships, the principles of psychrometrics and modes of heat transfer you need to design new HVAC systems and/or to retrofit existing systems. It also covers the methodology of heat loss/heat gain calculations and the concepts of noise and acoustic treatment.
This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.
Learning Objective
At the conclusion of this course, the reader will:
- Understand the environmental factors influencing thermal comfort;
- Understand how to determine and prioritize system design objectives;
- Understand the basic principles of temperature, humidity and air motion in relation to air conditioning;
- Understand the terminology such as mean radiant temperature, wind chill factor, heat index, operative temperature, effective temperature and comfort zone;
- Understand how to use simple psychrometric charts;
- Understand the relationship of wet bulb temperature, dry bulb temperature and dew point temperatures;
- Understand the 4 air-conditioning processes viz. mixing; sensible cooling and heating; cooling with dehumidification; and humidification;
- Understand the concept of cold air distribution;
- Understand the modes of heat transfer through solids and air;
- Understand the terminology and relationships between conductivity, conductance, resistivity, U-factors etc.;
- Understand how to calculate the heat transfer through the materials;
- Understand the basic concepts to determine cooling load;
- Understand the various types of internal and external loads and learn how to find and use local climate data and effects of air infiltration and ventilation;
- Understand the concept of balance point temperature and heating and cooling degree days in determining annual energy costs; and
- Understand the established noise criteria for HVAC system and ways to reduce unwanted noise.
Intended
Audience
This course is aimed at mechanical and HVAC engineers, facility managers, environmentalists, H &S professionals, O & M personal, safety engineers, industrial hygienists, and engineers responsible for the design, purchase or upkeep of heating, ventilation and air conditioning systems.
Benefit to Attendees
Attendee of this course will get to know more about the factors influencing human comfort, temperature - humidity relationships, the principles of psychrometrics and modes of heat transfer that are needed to design new HVAC systems and/or to retrofit existing systems. The course will be extremely helpful to the amateur engineers who desire to build on their design experience and the skilled professionals who have learnt the trade informally on the job.
Course
Introduction
The aim of Heating, Ventilation and Air Conditioning (HVAC) system is to provide COMFORT environmental conditions for the spaces in which we work, relax or do our business. The main criterion for comfort is temperature, humidity, air quality and sound level with the importance changing as per type of occupancy and business priorities.
To meet these requirements we carry out heat load computations to arrive at system requirement and system selection is based on outdoor conditions which will depend on location of facility to be air conditioned and indoor air conditioned which is specific requirement of client. The heat load calculations take in to consideration the structural load, glass area load, occupancy, equipment load and similar other factors to arrive at total load to be offset by the HVAC system.
This course is designed to explore the common aspects of HVAC/R technology. Discussion will be in five modules which cover: thermal comfort, basic psychrometerics and definitions, modes of heat transfer, heat gain and heat loss in building and HVAC noise and vibrations.
Course Content
This course is in the following PDF document:
HVAC Thermal Comfort – Concepts & Fundamentals
Please click on
the above underlined hypertext to view, download or print the document for your
study. Because of the large file size, we recommend that you first save the
file to your computer by right clicking the mouse and choosing "Save Target
As ...", and then open the file in Adobe Acrobat Reader. If you still experience
any difficulty in downloading or opening this file, you may need to close some
applications or reboot your computer to free up some memory.
Course Summary
HVAC helps keep people comfortable and healthy by maintaining good indoor air quality, humidity and comfortable temperatures. Designing for comfort requires integrated knowledge of human physiology, heat transfer, psychrometrics, and mechanical systems. Most professionals don't learn this stuff in school or on the jobsite, but are expected unrealistically to meet your physiological needs and wants for indoor environmental quality based predominantly on the skills of assembling building components. This is the #1 reason why over 50% of occupants are unsatisfied with their thermal environments.
Major factors affecting thermal comfort have been found to include:
- Metabolic rate: occupant activity level
- Clothing insulation: how the occupant is dressed
- Air temperature: temperature of the air around the occupant
- Radiant temperature: temperature of the surfaces around the occupant
- Air speed: regardless of direction, the rate of airflow across the occupant
- Humidity: moisture content of the air around the occupant.
Recommended Reading
The second part of this course “HVAC Components and Systems”, which focuses on HVAC heating and cooling equipments, air and hydronic distribution schemes, is separately listed.
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.
