How To Calculate Heating Requirement For Marquee Sizes?

  Posted by: Chief Editor, Selmore - Marquee Hire, on July 26, 2017 11:07 am Leave your thoughts
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Calculate Heating Requirement for Marquee

Need to choose the right heater for an event tent? Lean how to calculate heating requirement for marquees.

When staging a marquee event in cold weather, an effective portable space heater will be required to keep your event guests comfortable.

As was the focus our previous articles on marquee heaters tips, we introduced the professionally recommended options using currently available technology, for heating a marquee space effectively and safely.

Each type of heater which is suitable for operating within such an enclosed environment, uses its own method of generating and distributing the heat, and therefore has its own unique merits.

There still however, remains the question though of "what scale or power of portable marquee heater do I need to competently maintain my desired temperature for the duration of the event?"

What are the contributory factors involved in calculating heat requirement for marquee events?

Firstly, the measurement for the heat power itself can be expressed in a variety of unit measures. Depending on preference you can use one rather than another. Also, there are equivalent figures for converting from one unit type to another.

Common measures of heat power:

  • British Thermal Unit (BTU/h) - traditionally used throughout industry & defined as...

    • 'the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit in one hour'
  • Kilocalorie Per Hour (Kcal/h) - is a measure equal to 3.97 BTU/h, and defined as...
    • '1 kcal/h can raise 1000 cc of water 1 degree C in 1 hour, or 2000 cc of water 1 degree in 1/2 hour, or 1000 cc 2 degrees in 1 hour or 2000 cc 4 degrees in 1/8 of an hour, etc.'

Volume of space:

  • Cubic Metres (m3) - measure by which to determine how large a space you need to heat in your marquee...
    • marquee width in metres x marquee length in metres x marquee height in metres

Temperature gradient:

  • Difference between temperatures (degrees C) - difference between external temperature & desired marquee temperature
    • desired internal temperature minus external temperature

Dispersion Coefficient:

  • Characterising the function of heat dispersion (k) through the marquee roof and walls materials
    • for marquee tents the dispersion is approximated to be 4

What is the formula by which we calculate the power requirement using the above factors?

The equation which is most readily available and quoted by industry professionals for calculating the heating requirement for your marquee event is as follows:

Volume (V) x Temperature Difference (Delta T) x Dispersion Coefficient (k) = Kcal/h

Once you have this final Kcal/h figure, you now have a technical benchmark to use as reference for making enquiries with heater hire manufacturers, distributors or hire firms for your proposed marquee event.

[Remember: if your heater provider has the figures for their machine power published in BTU/h, then simply multiply the number that you arrive at in the equation above by the conversion rate 3.97 to reach the equivalent power value in British Thermal Units per Hour.]

And's one we prepared earlier...

A Selmore tutorial-based blog post would be complete if we didn't include a working example for you to walk through yourself.

Example calculation of heating requirement for a marquee event tent

A marquee hire contractor has received an enquiry for a rare December marquee winter wedding reception in Aberdeen (Scotland, UK). The planned layout will be traditional dining set-up with guests seated, 10-per round table. The expected numbers are 50.

In December, the record low temperatures in Aberdeen can dip to -18.1 degrees C, with snow fall of course.

A comfortable internal temperature planned for guests will be 23 degrees C.

The marquee planned by the contractor for use will be a PVC, Clearspan structure with the following dimensions:

  • 6m width x 9m length x 3m height
    • 54 metres squared floor space
    • 162 cubic metres volumetric space

Guest for the event are scheduled to arrive on-site and will be ushered into the marquee tent at 11am.

The organiser wants all things prepared and read for guests by 10am - thus leaving an hour spare to resolve any last minute issues, should they arrive.


If our marquee contractor was to use an indirect portable oil heater for this job, what power output will be required to achieve his desired internal room temperature if the external temperature expected on the day is 2degrees C? And what time will the heater need to be operational from to meet the organiser's needs?


V x Delta T x k = Kcal/h

162 x 21  x 4 = 13, 608 Kcal/h (or 54,023.76 BTU/h) is needed to heat the event. The heater will need to be operational contiuously from 9am at the earliest.

Need to see some marquee heaters which could pull off a job like the one in the above example?

Selmore Marquee Hire is a event hire broker specialising in connecting hire customers with top quality hire professionals in their area. For more information on how we might be able to help you, contact us.

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