Formulas to calculate the required power output of a radiator for a room of a specific size. Do they exist?

I'm no HVAC expert but I did do some work on building heat loss as part of an MSc University Project.

The CIBSE guide was very useful and if its good enough for a Master project I'm sure it will be sufficient for your needs.  The method is the same as what James Brown described, essentially the Steady State - Simple model.  There were of course Dynamic models but these are far too complex for manual calculation and require software.


As others have said why look for something overly complex?  In my field of expertise (Electrical Engineering) we often use relatively simple methods to calculate various aspects, of course more complex methods exist but outside of academia are of little use within an industrial context.  I'm sure the situaiton here is the same, why not use tried and tested simple(ish) methods that can be easily done manually and give reliable results without the need for software?  Indeed you said earlier you were not interested in software, yet what you were asking for is calling for it.

Also I'm surprised nobody else has said that some of your comments come across belittling and condescending towards trained and qualified persons - eg plumbers or HVAC Engineers.  The rules of thumb methods may work very well for individuals on site who may not have access to more detailed information at the time or have the notion to carry out calculations (even if more simple than the 'advanced' mehtods you mentioned at the start of the post).  Coming back to my own field, rules of thumb (or empirical) do have their place in science and work for on site persons, being backed up by more detailed calculaitons if required.

It is quite insulting therefore for someone who may have many years experience on site or of a practical nature and be well qualified to then read this post by someone that it appears has less knowledge than they do, does not really seem to know what they are asking for but is yet dismissing their tried and tested methods as irrelevant.

I'm no HVAC expert but I did do some work on building heat loss as part of an MSc University Project.

The CIBSE guide was very useful and if its good enough for a Master project I'm sure it will be sufficient for your needs.  The method is the same as what James Brown described, essentially the Steady State - Simple model.  There were of course Dynamic models but these are far too complex for manual calculation and require software.


As others have said why look for something overly complex?  In my field of expertise (Electrical Engineering) we often use relatively simple methods to calculate various aspects, of course more complex methods exist but outside of academia are of little use within an industrial context.  I'm sure the situaiton here is the same, why not use tried and tested simple(ish) methods that can be easily done manually and give reliable results without the need for software?  Indeed you said earlier you were not interested in software, yet what you were asking for is calling for it.

Also I'm surprised nobody else has said that some of your comments come across belittling and condescending towards trained and qualified persons - eg plumbers or HVAC Engineers.  The rules of thumb methods may work very well for individuals on site who may not have access to more detailed information at the time or have the notion to carry out calculations (even if more simple than the 'advanced' mehtods you mentioned at the start of the post).  Coming back to my own field, rules of thumb (or empirical) do have their place in science and work for on site persons, being backed up by more detailed calculaitons if required.

It is quite insulting therefore for someone who may have many years experience on site or of a practical nature and be well qualified to then read this post by someone that it appears has less knowledge than they do, does not really seem to know what they are asking for but is yet dismissing their tried and tested methods as irrelevant.