Nearly every energy modeler on the planet will ask at some point, “How do I solve unmet hours?”

Well, the rookie question would be “Which setting do I change to get rid of unmet hours?” or even better “Which button do I press to fix unmet hours?”

Sometimes a little naiveté is a good thing, but not when solving unmet hours. Experience matters and so does diligence. Being neurotic helps too. That’s where I come in.

In the past decade, I personally have taken unmet hours questions on over 1,000 files. There were only two times that I could not solve an unmet hours problem without “cheating” (such as tip #5...

You can design a ultra energy-efficient system. Maybe you designed an ultra energy-efficient building - a hard earned victory based on your knowledge of the first law of thermodynamics. Your energy model shows awesome results.

Now, the building is built and a fight against the Second law of thermodynamics begins. In case you forgot, the 2nd law basically states that “Everything tends to disorder”. Your ultra efficient building will not remain efficient without some help. And of course, the energy model is wrong.

Your building will trend towards inefficiency, and much faster than scheduled. This rapid decline isn’t the fault of your equipment selection, nor the fault of your control scheme, nor is it the...

What is the best energy modeling software?

If you are asking this question, you are probably either really new to energy modeling or really experienced.

Unfortunately, nobody really has the answer to this flawed question. The problem is that best can mean a number of things. Some might think that it means, "The most powerful, flexible, modern software package". But if it takes 5 years to learn how to use it, would it still be the best?

Many would argue that EnergyPlus is the best energy modeling software package. I will say with certainty that, on it's own, EnergyPlus is not the best software package.

Why isn't EnergyPlus the best software package?

EnergyPlus is not a...

We are going to delve into “User Expressions”. This is a topic that scares many an eQUEST user, so let me be clear, you can very easily complete an eQUEST model without “User Expressions”. They are optional, but they can be very helpful.

A User Expression, also called a User Input Expression, is an input that is dependent on another input. This is very powerful because it allows interdependence of inputs, and allows dynamic modeling. To really explain a user expression, let’s start out with a simple example.

Example 1:

Let’s say we wish to place one window on each wall in our simulation. It’s common that a band of glass...