How to model ASHRAE Std 62.1 in eQUEST part 1
This video has been moved to eQUEST 420 -How to eQUEST training videos
Energy Modeling Blog
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...
Filed under: TRACE 700Unmet hours
Design Days are here!
Maybe you already know about Design Days, but did you know that Energy Modeling was basically invented to determine the design day, and the design hour?
What is a Cooling Design Day and why is it important?
The Cooling Design Day is effectively the "worst case" day for your air conditioning loads. The "worst case" hour of this day determines equipment capacity, fan sizes, and subsequently duct sizes. This largely impacts first cost. The Design Hour also impacts peak KW demand which often has a huge impact on the utility bill.
When is the Design hour?
A common rule of thumb is that the design hour occurs during July at 15:00...
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...
Filed under: calibrationfacilities management
DIVA is a daylighting visualization and analysis plug-in for Rhinoceros. DIVA for Rhino can be used to perform iterative daylight and glare analysis to optimize design during conceptual design phase as well as detailed daylight analysis for IEQc8.1 for LEED v4. These concepts will be discussed in detail in the video tutorials. The following post explains the step-by-step instructions to download a free trial and educational version of DIVA 3.0 on your computer.
Step 1: Search for ‘download diva for rhino’ plug-in on your web browser and click on the link from ‘Solemma’. This would usually be the first link on the search results page.
Step 2: The link...
Filed under: DaylightDIVAInstallationPlug-inRhinoSimulation
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...
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The increasing popularity of building energy modeling (BEM) yields growing awareness of BEM to a variety of professionals. With exposure to larger audiences of various technical nature, energy modeling remains under increasing scrutiny. This scrutiny extends to all energy models, including yours.
Critics, all too often, cite discrepancies between a given BEM's projected energy cost and the reported cost of the existing building.Thus, the perceived validity of the energy-model is tied to its accuracy relative to actual utility bill data. This accuracy is most easily determined in existing building energy retrofits, where one can easily cross-reference existing utility bills with the energy...
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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.
What is a User Expression in eQUEST?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...
Filed under: eQUESTeQUEST Technical
Unmet Load Hours (aka “The Bane of the Completed Simulation”)
What is an unmet load hour?
Oddly, the definition of an unmet load hour is partially dependent on the software you are using, which may or may not allow you to define the throttling range (the acceptable +/- degrees where a space is deemed to be within its target setpoint).
An unmet load hour occurs when the HVAC system lacks the capacity to keep the design setpoint within the throttling range for the duration of an hour. The other caveats are that the space must be conditioned, and in operating mode (occupied).
Why do unmet load hours affect you?
Unmet hours will...
Filed under: tipsunmet load hours
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...
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