SHR (Sensible Heat Ratio) Calculator

| Added in Construction

What is Sensible Heat Ratio (SHR)?

The Sensible Heat Ratio (SHR) measures how much of the heat load in an HVAC system is used for sensible heating versus total heating. Total heat combines sensible heat and latent heat.

Sensible heat changes temperature without changing the phase, like pure heating or cooling of air. Latent heat is associated with phase changes, like dehumidification where water vapor condenses.

Why does SHR matter? It plays a crucial role in designing and sizing HVAC systems efficiently. By understanding the ratio, you can ensure your system is well-balanced to maintain comfortable temperature and humidity levels, saving energy and costs in the process.

How to Calculate Sensible Heat Ratio

The SHR calculation is straightforward once you know the sensible heat load and total heat load.

Formula:

[\text{SHR} = \frac{\text{Sensible Heat Load (kW)}}{\text{Total Heat Load (kW)}}]

Where:

  • Sensible Heat Load is the power used specifically for cooling or heating the air
  • Total Heat Load is the combined power considering both sensible and latent heats

Calculation Example

Let's work through a real-world example with an HVAC system:

Given:

  • Sensible Heat Load: 80 kW
  • Total Heat Load: 100 kW

Steps:

  1. Identify the Sensible Heat Load: 80 kW
  2. Identify the Total Heat Load: 100 kW
  3. Apply the Formula:

[\text{SHR} = \frac{80 \text{ kW}}{100 \text{ kW}} = 0.8]

The SHR is 0.8 or 80%, meaning 80% of the heat load is for sensible cooling while 20% handles latent cooling (dehumidification).

Quick Tips

  • Always double-check your numbers
  • Make sure both heat loads are in the same units before calculating
  • Use SHR to optimize HVAC for comfort and efficiency
  • Typical comfort cooling SHR values range from 0.6 to 0.9

By getting your SHR right, you're not just ensuring comfort but also getting the most efficient use of your HVAC system's capacity.

Frequently Asked Questions

The Sensible Heat Ratio (SHR) measures what fraction of total heat load in an HVAC system is used for sensible cooling versus latent cooling. Values range from 0 to 1.

Sensible heat changes temperature without phase change, like cooling air. Latent heat involves phase changes like dehumidification, where water vapor condenses without temperature change.

SHR helps size HVAC equipment properly. A higher SHR means more capacity needed for temperature control, while a lower SHR indicates significant dehumidification requirements.

No, SHR cannot exceed 1 since sensible heat is always part of total heat. The ratio is always between 0 and 1, with typical values ranging from 0.6 to 0.9 for comfort cooling.