Course Description

Why is this topic so important? Consider two scenarios. If you oversize an air conditioner, the unit short-cycles-it runs for only a few minutes at a time, never dehumidifying properly, and it wastes energy every time it starts. That also means higher capital cost for equipment you don't need. On the other hand, if you undersize the system, it will run continuously on the hottest day and still not maintain the setpoint, leading to occupant discomfort and complaints. Proper load calculation ensures that indoor temperature, humidity, and air quality meet design standards. It is mandated by ASHRAE Standard 183 and by most building codes. Furthermore, accurate load calculations feed directly into energy models for LEED and other green building certifications. In short, load calculation is not just a technical exercise-it is the foundation of good HVAC design.

What you'll learn in this course?

• Differentiate between cooling load, heat gain, and heat extraction in HVAC systems.

• Identify the key sources of cooling loads in a building, including external and internal sources.

• Explain fundamental heat transfer mechanisms: conduction, convection, and radiation.

• Understand the concept of solar radiation through fenestration and opaque surfaces.

• Describe thermal properties of building materials such as U-value, R-value, thermal mass, and time lag.

• Apply the principles of radiant time series (RTS) and heat balance (HB) methods for load calculation.

• Manually calculate cooling load components for walls, roofs, windows, people, lighting, and equipment.

• Use safety factors and design criteria as per ASHRAE standards.

• Interpret psychrometric relationships affecting sensible and latent loads.

• Avoid common errors in cooling load estimation and select appropriate HVAC equipment.

Prerequisites

• Basic knowledge of HVAC systems, heat transfer, psychrometrics, and engineering calculations

• Familiarity with building envelopes, ventilation, and load terminology is helpful