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...

If you are reading this, it is likely you clicked a link from our email series explaining energy modeling and it's benefits. Specifically, the email "How does Energy modeling save energy?"

In this case, R-50 insulation used more energy than R-25 in a building in Denver, Colorado.

The main issue was that the R-25 building did not need heating or cooling for most hours when the outdoor air temperature was between 50 and 67 degrees. The building with the extra insulation, on the other hand, did not need heating or cooling between 50 and 58 degrees (the sweet spot was half the size when adding the extra insulation).

In this example, R-50 used MORE energy than R-25. Here's why:

The extra insulation did save...