# Sensible Heat Ratio - SHR

The Sensible Heat Ratio - SHR - is used to describe the ratio of sensible heat load to total heat load and can be expressed as:

SHR = q_{ s }/ q_{ t }

= q_{ s }/ (q_{ s }+ q_{ l }) (1)

where

SHR = sensible heat ratio (ratio of sensible heat load to total heat load)

q_{ s }= sensible heat load (kW, Btu/hr)

q_{ t }= total heat load - sensible heat and latent heat (kW, Btu/hr)

q_{ l }= latent heat load (kW, Btu/hr)

For an air flow * (1) * can be modified to:

SHR = c_{ p }(t_{ o }- t_{ i }) / (h_{ o }- h_{ i }) (2)

where

c_{ p }= specific heat air (1.005 kJ/kg^{ o }C, 0.240 Btu/lb^{ o }F)

t_{ o }= outlet air temperature (^{ o }C,^{ o }F)

t_{ i }= inlet air temperature (^{ o }C,^{ o }F)

h_{ o }= outlet moist air enthalpy (kJ/kg, Btu/lb)

h_{ i }= inlet moist air enthalpy (kJ/kg, Btu/lb)

### Example - SHR for a room

The inlet temperature to a room with some people is * 20 ^{ o } C * . The relative moisture of the inlet air is

*50%*. From the Mollier chart the enthalpy of the inlet air is

*37 kJ/kg*.

The outlet temperature is * 26 ^{ o } C * and the relative moisture of the outlet air is

*40%*. From the Mollier chart the enthalpy of the outlet air is

*47 kJ/kg*.

The Sensible Heat Ratio can be calculated as

* SHR = (1.005 kJ/kg ^{ o } C ) (( 26 ^{ o } C ) - ( 20 ^{ o } C ) ) / (( 47 kJ/kg ) - (3 7 kJ/kg )) *

* = 0.6 *

* 60% * of the load provided to the room heats the air (sensible load) and * 40% * of the load provided humidifies the air (latent load).

### Example - SHR for a evaporator

If the SHR value for an evaporator is * 75% (0.75) - 75% * of the load cools the air (sensible load) and * 25% * of the loads dehumidifies the air (latent load).

### General Design Values

- Auditoriums, Theaters - SHR : 0.65 - 0.75
- Apartments - SHR : 0.80 - 0.95
- Banks, Court Houses, Municipal Buildings - SHR : 0.75 - 0.90
- Churches - SHR : 0.65 - 0.75
- Dining Halls - SHR : 0.65 - 0.80
- Computer Rooms - SHR : 0.80 - 0.95
- Cocktail Lounges, Bars, Taverns, Clubhouses, Nightclubs - SHR : 0.65 - 0.80
- Jails - SHR : 0.80 - 0.95
- Hospital Patient Rooms, Nursing Home, Patient Rooms - SHR : 0.75 - 0.85
- Kitchens - SHR : 0.60 - 0.70
- Libraries, Museums - SHR : 0.80 - 0.90
- Malls, Shopping Centers - SHR : 0.65 - 0.85
- Medical/Dental Centers, Clinics and Offices - SHR : 0.75 - 0.85
- Motel and Hotel Public Areas - SHR : 0.75 - 0.90
- Motel and Hotel Guest Rooms - SHR : 0.80 - 0.95
- Police Stations, Fire Stations, Post Offices - SHR : 0.75 - 0.90
- Precision Manufacturing - SHR : 0.80 - 0.95
- Restaurants - SHR : 0.65 - 0.80
- Residences - SHR : 0.80 - 0.95
- Retail, Department Stores - SHR : 0.65 - 0.90
- Other Shops - SHR : 0.65 - 0.90
- School Classrooms - SHR : 0.65 - 0.80
- Supermarkets - SHR : 0.65 - 0.85

## Related Topics

### • Air Conditioning

Air Conditioning systems - heating, cooling and dehumidification of indoor air for thermal comfort.

### • Air Psychrometrics

Moist and humid air - psychrometric charts, Mollier diagrams, air-condition temperatures and absolute and relative humidity and moisture content.

## Related Documents

### Cooling and Heating Equations

Latent and sensible cooling and heating equations - imperial units.

### Cooling Load - Latent and Sensible Heat

Latent and sensible cooling loads to consider when designing HVAC systems.

### Great Sensible Heat Factor - GSHF

The Great Sensible Heat Factor is the ratio sensible to total heat in a cooling coil.

### Heat Index

Equivalent heat index vs. air temperature and relative humidity - in degrees Fahrenheit and Celsius.

### Heat Recovery Efficiency

Classification of heat recovery efficiencies - temperature efficiency, moisture efficiency and enthalpy efficiency - online heat exchanger efficiency calculator.

### HVAC Abbreviations

Commonly used HVAC abbreviations.

### Indoor Relative Humidity vs. Outdoor Relative Humidity and Temperature

Recommended indoor relative humidity vs. outdoor relative humidity and temperature.

### Latent Heat Flow

Latent heat is the heat when supplied to or removed from air results in a change in moisture content - the temperature of the air is not changed.

### Room Sensible Heat Factor - RSHF

Room Sensible Heat Factor - RSHF - is defined as the sensible heat load divided by the total heat load in a room

### Sensible Heat Flow

Sensible heat is dry heat causing change in temperature but not in moisture content