RTS Cooling Load Calculation Course

Learn how to calculate cooling load using the Radiant Time Series method through a step-by-step process with an Excel calculator — including walls, roofs, windows, doors, internal heat gains, and 24-hour load profile analysis.

110+ Enrolled
1–2 Hrs
English
Beginner Level
25 Lessons
Not Available
Self-Paced
Certification
One-time purchase: $49.99
Enroll in RTS Cooling Load Calculation Course

Also included in Pro Membership from $20/month or $220/year.

Compare Membership Plans
RTS Cooling Load Calculation Course Product Image Final

Cooling Load Calculation Is Hard When You Only Use Rules of Thumb

You know that cooling load affects equipment sizing, but still struggle to calculate it properly using a structured method instead of rough BTU/hr per square foot estimates.

1

You Rely Too Much on Rule of Thumb

You know common sizing shortcuts, but still feel unsure whether the selected equipment capacity is technically justified.

2

Solar Heat Gain Feels Complicated

You struggle to understand how sun position, solar irradiance, wall orientation, roof exposure, glass, blinds, and overhang shades affect cooling load.

3

Heat Gain and Cooling Load Feel Disconnected

You know that walls, roofs, windows, people, lighting, and equipment add heat, but still feel unsure how those heat gains become cooling load over time.

4

Peak Load Timing Is Not Clear

You calculate individual loads, but still struggle to plot a 24-hour load profile and identify when the actual peak cooling load occurs.

Who This Is For

Student

Junior HVAC Engineers

For engineers who need to calculate or review cooling load for HVAC equipment sizing.

Engineer

HVAC Design Learners

For learners who want to understand proper cooling load calculation instead of relying only on sizing rules of thumb.

Company

Business Owners and Team Leaders

For companies that want their technical team to acquire a proper cooling load calculation skill.

Technician

Project Engineers and Site Engineers

For project personnel who want to understand whether equipment capacity, load assumptions, and sizing decisions are reasonable.

Project

Contractors and Technical Teams

For contractors who want to improve design understanding and communicate better with consultants, engineers, or clients.

This Course May Not Be for You If…

  • You are looking for only a quick BTU/hr per square foot shortcut.
  • You do not want to work through calculations or Excel-based examples.
  • You are looking for a full building energy simulation course.
  • You want someone to calculate your actual project cooling load instead of learning the method.
  • You are completely new to HVAC and still do not understand basic air conditioning systems.

New to HVAC? Start with the HVAC Beginner Course first.
Need project-specific design support? View HVAC Engineering Services.

What You Will Learn in This Course

01

RTS Calculation Workflow

Understand the Radiant Time Series method, the overall procedure, and how the cooling load calculation process is structured.

02

Solar and Envelope Heat Gain

Learn how sun position, solar irradiance, sol-air temperature, wall heat gain, roof cooling load, and interior wall/floor loads are calculated.

03

Window and Door Cooling Load

Learn beam and diffuse solar heat gain, conduction heat gain, window cooling load, overhang shade effect, and door cooling load.

04

Internal Heat Gains

Learn how people, lighting, equipment, system gains, sensible load, latent load, usage profile, diversity factor, and standby equipment heat gains affect cooling load.

05

Excel Calculator Application

Learn how to use the provided Excel calculator, copy tabs, customize inputs, and apply the calculation workflow to more surfaces.

06

24-Hour Load Profile and Peak Load

Learn how to summarize the calculation, plot a 24-hour load profile, and identify the peak cooling load for equipment sizing.

Course Outline

This course takes you through a practical chilled water system design workflow using a high-rise sample project. You will start with project requirements and drawings, then move through load calculation, AHU/FCU selection, fresh air system design, chiller and cooling tower sizing, piping design, pump sizing, air distribution, and bonus system design topics.

This section will first let you download an Excel calculator. Then, we’ll quickly brief through what is RTS and how’s the RTS procedure. A few key elements of the RTS method will be pointed out to give you an overview of the calculation process.

Lessons:

  • RTS Cooling Load Calculator
  • RTS Method

In this section, we’ll calculate how much solar energy is present at a specific design month and time. With that, we can calculate the solar energy actually hitting on these surfaces. Then, we’ll follow the RTS method to apply the appropriate CTS and RTS factors to calculate the cooling load from these surfaces.

Lessons:

  • Sun Position
  • Solar Irradiance
  • Design Temperature
  • Surface and Sky Irradiance
  • Ground Reflected Irradiance
  • Sol-Air Temperature
  • Wall Heat Gain
  • Wall Cooling Load
  • Custom Wall CTS
  • Exercise and Quiz
  • Roof Cooling Load
  • Interior Wall and Floor

Windows and doors have a different calculation than walls and roofs. So, in this section, we’ll calculate three solar heat gains and then convert them into cooling load. We’ll take into account any blinds and overhang shades that might reduce the cooling load.

Lessons:

  • Beam and Diffuse Solar Heat Gain
  • Conduction Heat Gain
  • Window Cooling Load
  • Overhang Shades
  • Door Cooling Load

In this section, we’ll calculate the cooling load due to internal heat gains. We’ll break them into sensible and latent load. The usage profile and diversity factor will be demonstrated here and for equipment, we’ll also account the heat gains from appliances in standby mode. The heat gain of various types of equipment will also be provided.

Lessons:

  • People
  • Lighting
  • Equipment
  • System

In this section, you’ll know how to use the Excel calculator and add more tabs to account for more surfaces. As a summary/conclusion, I’ll show you an example of how to plot a 24 hours load profile and identify the peak cooling load for equipment sizing.

Lessons:

  • How to Copy a Tab
  • Summary

What You Get Inside This Course

25 Self-Paced Lessons

Learn online at your own pace. You can complete one module per day or move faster depending on your schedule.

RTS Excel Calculator

Use the included Excel calculator to follow the calculation and apply the workflow to your own learning examples.

24-Hour Load Profile

Learn how to plot a 24-hour load profile, identify peak cooling load for equipment sizing and discover cost reduction opportunities.

Practical Working Example

Learn by working through an example instead of only reading formulas.

Certificate of Completion

Learners receive a certificate upon course completion.

Access to Course Platform

Lessons are delivered online through my course platform.

By the End of This Course, You Should Be Able To…

  • Understand the basic RTS cooling load calculation workflow.
  • Use the RTS Excel calculator.
  • Understand how sun position affects cooling load.
  • Determine design temperature inputs.
  • Calculate wall, roof, floor heat gain and cooling load.
  • Calculate solar heat gain and window/glass cooling load.
  • Estimate internal heat gains from people, lighting, equipment, and system loads.
  • Understand sensible and latent internal loads.
  • Use building load profiles and diversity factors.
  • Summarize the calculation and identify peak cooling load from a 24-hour load profile.

Preview the Learning Journey

This course teaches chilled water system design through a full project workflow. You will see how drawings, calculations, Excel files, equipment selection, piping layout, pump sizing, ductwork, and control decisions connect in one design process.

Enroll in RTS Cooling Load Calculation Course

Choose How You Want to Learn

Buy This Course

$49.99

one-time purchase

Best if you only want to learn the RTS method and prefer a focused one-time course.

Included:

  • RTS Cooling Load Calculation Course
  • 25 lessons
  • RTS Excel calculator
  • Practical calculation example
  • 24-hour load profile summary
  • Self-paced access
Enroll in Chilled Water System Course

Join Pro Membership

$20

per month

or

$220

per year

Best if you want RTS cooling load calculation plus the full HVAC design learning path.

Included:

  • RTS Cooling Load Calculation Course
  • Psychrometric Analysis Course
  • Duct Design Course
  • Chilled Water System Design Course
  • HVAC Beginner Course
  • Pro resources and references
  • Exclusive Pro Zone community
View Membership

Should You Buy the Course or Join the Membership?

Choose this

Best if

Buy RTS Cooling Load Calculation Course

You only want to learn RTS cooling load calculation and prefer a one-time purchase.

Join Pro Membership

You want access to multiple HVAC design courses and continuous learning resources.

Start with HVAC Beginner Course

You are still new to HVAC and need stronger fundamentals first.

Recommendation: If you only want to learn cooling load calculation, buy this course. If you want to build a broader HVAC design foundation, Pro Membership is the better learning path because cooling load calculation connects closely with psychrometrics, duct design, chilled water system design, equipment sizing, and system selection.

How Cooling Load Calculation Fits Into HVAC Design

Cooling load calculation is one of the starting points of HVAC design. It affects:

  • equipment capacity
  • supply airflow
  • AHU and FCU sizing
  • duct design
  • chilled water flow rate
  • chiller sizing
  • energy efficiency
  • system operation strategy
  • peak load and part-load behavior

The RTS method helps you go beyond rule-of-thumb sizing by showing how different heat gains occur throughout the day and how they affect the final cooling load.

Learn from Practical HVAC Field Experience

This course is taught by Yu Chang Zhen, founder of aircondlounge. The teaching approach is based on practical HVAC experience across design, installation, operation, maintenance, commissioning, troubleshooting, and technical content development.

MBOT Professional Technologist

MASHRAE Independent CxS

HRD Corp TTT Certified Trainer

10+ Years HVAC Field Experience

“My goal is to help learners understand HVAC in a practical, structured, and field-relevant way, not just memorize theory.”

Hero Section Real photo of me explaining at site 2

What Learners Say

  • Very good course, explanations were very good and matched the spreadsheet.
    Mitchell Sklar
  • This course was very thorough. The Excel Calculator is easy to use and goes into a lot of detail.
    Kenrick Mohammed
  • This is a well structured course that teaches HVAC engineers how to use the RTS method.
    Vinicius Romualdo
  • Gathering all the Information in a easy way to understand the deep HVAC Subject
    Dia Ousmane
  • I can now compare the data more accurately between the RTS and the Heat Balance method used by the prominent software in the HVAC industry.
    Erween Joseph
  • There are many workshops so I can learn the calculations.
    Ghon. K

FAQ

Yes. The course was made with a beginner mindset, using easy language and step-by-step explanation. Still, basic HVAC knowledge will help you understand the design context faster. 

This is a self-paced online course. You can access the lessons online and learn at your own pace.

The course covers the RTS method, Excel calculator, sun position, solar irradiance, design temperature, sol-air temperature, wall heat gain, wall cooling load, roof cooling load, interior wall and floor load, window solar heat gain, window conduction heat gain, overhang shades, door cooling load, people, lighting, equipment, system gains, and 24-hour load profile summary.

Yes. The RTS method is one of the methods outlined in the ASHRAE Handbook. 

Yes. The course includes an Excel calculator and teaches you how to use it.

The course includes tables for selecting inputs such as wall type and glass U-factor, and also includes a lesson on using customization functions when the default input does not match your project. 

Yes. This course is included in Pro Membership.

Buy this course if you only want RTS cooling load calculation. Join Pro Membership if you want access to multiple HVAC design courses and continuous learning resources.

Start Learning RTS Cooling Load Calculation Step by Step

If you want to understand how to calculate cooling load using the Radiant Time Series method, this course gives you a structured path to learn the process through an Excel calculator, practical examples, and 24-hour load profile analysis.

Enroll in RTS Cooling Load Calculation Course

Compare Membership Plans