By calculating the load and energy consumption in an accurate fashion, you can save tons of money (that’s a lame HVAC pun, if you get it, and if you don't, you will by the end of this email)

Consider the peak building cooling and heating loads. These are the hours where the building is either gaining the most heat or losing the most heat and thus needs to run cooling equipment or heating equipment. The peak hour for heating or cooling determines how big the equipment needs to be.

You might already know this, but such equipment can be expensive. Bigger equipment costs more money. Bigger equipment can also use more energy to do the same job.

That’s where right-sizing comes in....

You want to size your equipment correctly for a building. Instead of running an energy model, a lot of people use pen & paper and rules of thumb for sizing equipment (for example 1 ton of air conditioning for every 400 square feet of building space).

That’s a really archaic way of calculating things because we all know that every building is different, and that buildings nowadays are getting more and more diversified. Would the same rule of thumb apply to both an air-conditioned warehouse and a data center? Of course not!

When using a rule of thumb and other oversimplified methods, designers usually add a very large “safety factor”. This often results in oversizing (too big) of equipment. Oversizing results in buying much larger equipment than needed (plus larger ducts, diffusers, fans, and more). For cooling, the equipment is often labeled in the HVAC unit of tons (i.e. a 10 ton unit, a 50 ton unit, etc.). Given the same line of equipment: more tons = more money.

Oversizing by a little is not a bad thing and is a pretty standard design practice, but oversizing by a lot is VERY EXPENSIVE because you spend a lot more $$$ on equipment up front. You also will probably spend a lot more on energy cost over the life of the building.

On the opposite end, if the rule of thumb plus a safety factor yields undersized (too small) equipment, this means that your equipment may not be able to adequately heat or cool your building, resulting in a lot of complaining from the building occupants, or even damage to sensitive equipment.

Undersized equipment also has the tendency to burn out faster. (Think, would your car last as long if you “floor it” every time you take it out?)

THUS,  when you consider that heating and cooling equipment can cost thousands or even millions of dollars - rightsizing, which can be done by an energy model, WILL save you a lot of money.

The most comprehensive and versatile method available to properly size heating and cooling equipment is through energy modeling!

By the way, the technical jargon used for determining equipment size is often described as “Load design”.

If you are looking for the correct software that does this, one of the industry standards for load design is TRACE 700, which you can purchase from Trane (but if you want to get up to speed quickly we have an on-demand course on how to use TRACE 700).