Heat load rules of thumb

[mechanicaldude]

Here is an easy question compared to some that have been asked. The question is...what BTU per sq. ft. of heating should I expect to be needed for a "typical" office building. Wall construction is fairly old but the windows will be new.

Thanks for your help

 

[STYMIEDPIPER]

Look at "HVAC Equations, Data, and Rules of Thumb" by Arthur A. Bell.

 

[RossABQ]

Why not do a calc? or are you trying to cross-check a calc?

I wouldn't know what a typical office building is anymore. It changes constantly! With the shift to LCD monitors and Energy Star computers, a huge chunk of load is disappearing from the typical cubical jungles that sprouted in the 90's. Add in the shift to T8 lighting, reduced ventilation schemes, more changes in load on both sides of the equation. What climate are you concerned with? Rules of thumb I've seen (in books like Art Bell's) have a range with the upper boundaries 50% above the lower.

 

[cabalen]

Sometimes it depends on the location. You can try 15 sq.m. per ton.

 

[AbbyNormal]

the best rule of thumb is the one about how big a stick can be.

Rules of thumb are good for a preliminary ballpark estimate, or as a load check figure.

Take the "V" out of HVAC and you are left with a HAC(k) job.

 

[rossc]

Our local ASHRAE chapter a few years ago put out a rules of thumb guideline packet whihc was more up to date than the condensed ASHRAE Pocket handbook information.

From that guideline, a general office environment was listed as 300-400 sqft/ton but that number truly should only be as an estimate or as a check number to the load calc.

 

[zekeman]

You dont need rules of thumb.
Here's a freebe

http://www.mrhvac.com/loadcalcshortform.htm

 

[willard3]

If you design with rules of thumb, you will wind up with a thumb........

If rules of thumb would suffice, Engineers would not be required.

 

[cabalen]

try 30-40 BTUh/sq-ft.

 

[BronYrAur]

I also have a heating "cheat sheet". It says that office core areas are 32 BTUH/SQFT and perimeter 38 BTUH/SQFT. What I don't know, however, is if a ventilation laod was assumed and included in these numbers or if they are strictly envelope loads. Be careful.