What is BTU?

BTUs (British Thermal Units)

BTU, or British Thermal Unit, is a standard unit of heat which is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. One BTU is roughly the equivalent to one kilojoule of energy and is used by radiator manufacturers to determine the amount of heat needed to warm a room.

Before buying a radiator for a room, it is a good idea to work out the BTU output required for the room. This is important as it will not only mean the room is not over or under heated but will also save you money by applying the right amount of heat for the right room.

What is BTU output?

BTU output is the amount of heat given out by a radiator. This is usually found in the product description presenting BTU per hour, although this is often simply abbreviated to BTU.

How do I calculate BTU requirement for a room?

There is no failsafe way for calculating the BTU requirement for a room as there are a number of factors which can affect it such as the age of the house, insulation, windows and the climate outside. One way of checking the BTU requirement for a room is to enlist the service of a plumber.

However, you can work out the BTU requirement for a room manually. This is done by multiplying the height, width, and length of the room, and then multiplying the result by heating factors which are usually situational.

Below is a table with a simple method to help you calculate the rough BTU requirement for a room:

Room

Width(m)

x

Length(m)

x

Height(m)

=

Room size(m2)

x

Heating factors such as windows and doors

=

Total (BTU)

Bedroom

 

x

 

x

 

=

 

x

121.5

=

 

Kitchen

 

x

 

x

 

=

 

x

108

=

 

Living Room

 

x

 

x

 

=

 

x

135

=

 

Dining Room

 

x

 

x

 

=

 

x

81

=

 

Bathroom

 

x

 

x

 

=

 

x

81

=

 

Hallway

 

x

 

x

 

=

 

x

135

=

 

 

The answer is the BTU per hour for the room. It is then a simple process of matching this result with a radiator that roughly has this output. In most cases rooms will need more than one radiator to heat them so don’t worry if a room’s BTU is far higher than your average radiator’s.

What temperature do I want in a room to be?

Due to several situational factors and personal preferences there is no definite temperature any given room should be. However an average temperature between 20 and 22°C is a typically comfortable room temperature for most people.

How do I calculate BTU requirement for a house?

Calculating the BTU requirement for a house can be as simple as adding together the BTU for each room or simply filling in the criteria for length, height and width on the BTU calculator for your house instead. However to get the best result for your home it is best to do each room individually as the type of room, where it is in the house and number of windows can affect the result.