WEFOUNDPsychrometrics


Many young engineers, or engineers in training, don’t possess a good understanding of psychrometrics and how it impacts HVAC, or drying system design and operation, controls, or diagnosis of client comfort and system complaints. Let’s look at why young engineers might lack the motivation to learn psychrometric skills and some ideas that might provide the motivation to acquire these skills. The final part of this article recommends helpful ASHRAE resources to help all engineers expand their knowledge of psychrometrics.

Until the 1980s the psychrometric chart was the tool of choice for (1) determining state point properties, (2) graphically using space conditions, sensible heat ratio, and outdoor air requirements to determine (and then specify) cooling coil entering and leaving air state points and system air quantity, and (3) providing a visualization of the complete cycle of the individual processes that link to form the air-conditioning cycle.

Computers and graphical psychrometric software programs have taken over Tasks 1 and 2. Using a psych chart for Task 3 is so useful for detecting design problems as well as finding alternative opportunities, but in too many cases is an outstanding, but underused visualization/diagnosis tool.

Psychometrics is the approximation of latent psychological processes by means of stochastic analysis at both the individual and population levels. 

Galton, F. (1879). Psychometric experiments.  Brain: A Journal of Neurology, 11 , 149-162.
Guilford, J.P. (1936). Psychometric Methods . New York, NY: McGraw-Hill Book Company.  

Humidity - or moist - is the water vapor present in air where commonly used terms are Absolute, Specific and Relative Humidity

Online calculator, figures and tables showing density and specific weight of air at temperatures ranging -100 to 1600 °C (-140 to 2900 °F) at atmospheric and higher pressure - Imperial and SI Units

Figures and tables showing dynamic (absolute) and kinematic viscosity of air at temperatures ranging from -100 to 1600°C (-150 to 2900°F) at standard atmospheric pressure - SI and Imperial Units

Many young engineers, or engineers in training, don’t possess a good understanding of psychrometrics and how it impacts HVAC, or drying system design and operation, controls, or diagnosis of client comfort and system complaints. Let’s look at why young engineers might lack the motivation to learn psychrometric skills and some ideas that might provide the motivation to acquire these skills. The final part of this article recommends helpful ASHRAE resources to help all engineers expand their knowledge of psychrometrics.

Until the 1980s the psychrometric chart was the tool of choice for (1) determining state point properties, (2) graphically using space conditions, sensible heat ratio, and outdoor air requirements to determine (and then specify) cooling coil entering and leaving air state points and system air quantity, and (3) providing a visualization of the complete cycle of the individual processes that link to form the air-conditioning cycle.

Computers and graphical psychrometric software programs have taken over Tasks 1 and 2. Using a psych chart for Task 3 is so useful for detecting design problems as well as finding alternative opportunities, but in too many cases is an outstanding, but underused visualization/diagnosis tool.

Psychometrics is the approximation of latent psychological processes by means of stochastic analysis at both the individual and population levels. 

Galton, F. (1879). Psychometric experiments.  Brain: A Journal of Neurology, 11 , 149-162.
Guilford, J.P. (1936). Psychometric Methods . New York, NY: McGraw-Hill Book Company.  

Many young engineers, or engineers in training, don’t possess a good understanding of psychrometrics and how it impacts HVAC, or drying system design and operation, controls, or diagnosis of client comfort and system complaints. Let’s look at why young engineers might lack the motivation to learn psychrometric skills and some ideas that might provide the motivation to acquire these skills. The final part of this article recommends helpful ASHRAE resources to help all engineers expand their knowledge of psychrometrics.

Until the 1980s the psychrometric chart was the tool of choice for (1) determining state point properties, (2) graphically using space conditions, sensible heat ratio, and outdoor air requirements to determine (and then specify) cooling coil entering and leaving air state points and system air quantity, and (3) providing a visualization of the complete cycle of the individual processes that link to form the air-conditioning cycle.

Computers and graphical psychrometric software programs have taken over Tasks 1 and 2. Using a psych chart for Task 3 is so useful for detecting design problems as well as finding alternative opportunities, but in too many cases is an outstanding, but underused visualization/diagnosis tool.

Psychometrics is the approximation of latent psychological processes by means of stochastic analysis at both the individual and population levels. 

Galton, F. (1879). Psychometric experiments.  Brain: A Journal of Neurology, 11 , 149-162.
Guilford, J.P. (1936). Psychometric Methods . New York, NY: McGraw-Hill Book Company.  

Humidity - or moist - is the water vapor present in air where commonly used terms are Absolute, Specific and Relative Humidity

Online calculator, figures and tables showing density and specific weight of air at temperatures ranging -100 to 1600 °C (-140 to 2900 °F) at atmospheric and higher pressure - Imperial and SI Units

Figures and tables showing dynamic (absolute) and kinematic viscosity of air at temperatures ranging from -100 to 1600°C (-150 to 2900°F) at standard atmospheric pressure - SI and Imperial Units

Psychometrics is a field of study concerned with the theory and technique of psychological measurement . As defined by National Council on Measurement in Education (NCME), psychometrics refers to psychological measurement. Generally, it refers to the field in psychology and education that is devoted to testing, measurement, assessment, and related activities. [1]

The field is concerned with the objective measurement of skills and knowledge, abilities, attitudes, personality traits , and educational achievement . Some psychometric researchers focus on the construction and validation of assessment instruments such as questionnaires , tests , raters' judgments, and personality tests . Others focus on research relating to measurement theory (e.g., item response theory ; intraclass correlation ).

Practitioners are described as psychometricians. Psychometricians usually possess a specific qualification, and most are psychologists with advanced graduate training. In addition to traditional academic institutions, many psychometricians work for the government or in human resources departments. Others specialize as learning and development professionals.

Many young engineers, or engineers in training, don’t possess a good understanding of psychrometrics and how it impacts HVAC, or drying system design and operation, controls, or diagnosis of client comfort and system complaints. Let’s look at why young engineers might lack the motivation to learn psychrometric skills and some ideas that might provide the motivation to acquire these skills. The final part of this article recommends helpful ASHRAE resources to help all engineers expand their knowledge of psychrometrics.

Until the 1980s the psychrometric chart was the tool of choice for (1) determining state point properties, (2) graphically using space conditions, sensible heat ratio, and outdoor air requirements to determine (and then specify) cooling coil entering and leaving air state points and system air quantity, and (3) providing a visualization of the complete cycle of the individual processes that link to form the air-conditioning cycle.

Computers and graphical psychrometric software programs have taken over Tasks 1 and 2. Using a psych chart for Task 3 is so useful for detecting design problems as well as finding alternative opportunities, but in too many cases is an outstanding, but underused visualization/diagnosis tool.

Many young engineers, or engineers in training, don’t possess a good understanding of psychrometrics and how it impacts HVAC, or drying system design and operation, controls, or diagnosis of client comfort and system complaints. Let’s look at why young engineers might lack the motivation to learn psychrometric skills and some ideas that might provide the motivation to acquire these skills. The final part of this article recommends helpful ASHRAE resources to help all engineers expand their knowledge of psychrometrics.

Until the 1980s the psychrometric chart was the tool of choice for (1) determining state point properties, (2) graphically using space conditions, sensible heat ratio, and outdoor air requirements to determine (and then specify) cooling coil entering and leaving air state points and system air quantity, and (3) providing a visualization of the complete cycle of the individual processes that link to form the air-conditioning cycle.

Computers and graphical psychrometric software programs have taken over Tasks 1 and 2. Using a psych chart for Task 3 is so useful for detecting design problems as well as finding alternative opportunities, but in too many cases is an outstanding, but underused visualization/diagnosis tool.

Psychometrics is the approximation of latent psychological processes by means of stochastic analysis at both the individual and population levels. 

Galton, F. (1879). Psychometric experiments.  Brain: A Journal of Neurology, 11 , 149-162.
Guilford, J.P. (1936). Psychometric Methods . New York, NY: McGraw-Hill Book Company.  

Humidity - or moist - is the water vapor present in air where commonly used terms are Absolute, Specific and Relative Humidity

Online calculator, figures and tables showing density and specific weight of air at temperatures ranging -100 to 1600 °C (-140 to 2900 °F) at atmospheric and higher pressure - Imperial and SI Units

Figures and tables showing dynamic (absolute) and kinematic viscosity of air at temperatures ranging from -100 to 1600°C (-150 to 2900°F) at standard atmospheric pressure - SI and Imperial Units

Psychometrics is a field of study concerned with the theory and technique of psychological measurement . As defined by National Council on Measurement in Education (NCME), psychometrics refers to psychological measurement. Generally, it refers to the field in psychology and education that is devoted to testing, measurement, assessment, and related activities. [1]

The field is concerned with the objective measurement of skills and knowledge, abilities, attitudes, personality traits , and educational achievement . Some psychometric researchers focus on the construction and validation of assessment instruments such as questionnaires , tests , raters' judgments, and personality tests . Others focus on research relating to measurement theory (e.g., item response theory ; intraclass correlation ).

Practitioners are described as psychometricians. Psychometricians usually possess a specific qualification, and most are psychologists with advanced graduate training. In addition to traditional academic institutions, many psychometricians work for the government or in human resources departments. Others specialize as learning and development professionals.

I have a confession to make: I've fallen in love with psychrometrics! After water itself, moist air has got to be the most interesting substance in building science. And the psychrometric chart, in all its many manifestations and with its multitudinous quantities, is a thing of beauty. Well, at least it is to me, and maybe it will be to you, too, after you get to know it a bit better.

One of the problems with learning this subject is that a lot of people jump straight into the chart without understanding exactly what psychrometrics is. Unless you're an engineer, physicist, or meteorologist, your first encounter with the field of psychrometrics may have been the psych chart itself, with a little explanation of how it relates dry bulb temperature, relative humidity, dew point temperature, and "absolute humidity." (I put that last term in quotes for a reason. You'll find out why in part 2 of this series.)

My purpose here is to define the basic terms and put the field of psychrometrics in its proper context for you. The bible of psychrometrics, on which I'm basing a lot of what I'm telling you here, is the book, Understanding Psychrometrics by Don Gatley . Here's his definition of psychrometrics:


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