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Modeling Details

Get informed on being informed with modeling. We know there's a lot to cover, but we've done our best to make the information simple for you. Please enjoy our most common modeling service FAQs.


Why Should I Get Modeling Done?

Energy modeling can quickly and easily inform design and construction ideas specific to your project. If you're talking about solar, it's simple - we can make sure you're getting the right array fit for your project's energy use. We all know how important that is and how much money it can save.

Because people are wanting more custom and less cookie-cutter designs, rules of thumb about insulation, ceiling heights, and solar, etc. are applying less and less, energy modeling can speak directly to your specific circumstance. Additionally, as energy codes become more and more stringent, energy modeling can help architects figure out how to design buildings that meet the energy code without having to follow the prescriptive path.

Do I Need Modeling? 

Modeling is suggested for those building projects that don’t align, or don’t allow for prescriptive building methods. Very generic structures might not need modeling, but for those designing custom projects, or for projects that might have multiple or different use patterns, modeling can inform how a building can perform if it is different, or to be used differently.

Additionally, if the goal is to make sure a design is meeting a certain energy efficiency criteria, or that a solar array really will make the building net-zero energy, modeling will provide a much more accurate evaluation than relying on generally accepted rules-of-thumb.


What will modeling tell me? 

Common topics we can address include:

  • Optimal levels of insulation for different walls/structures
  • Evaluating energy savings between window types
  • Evaluating impact of exterior and interior shading on energy consumption
  • Determining design and equipment choices necessary to meeting energy code with higher window areas than allowable under the prescriptive code pathway
  • Cost effectiveness of higher efficiency HVAC and water heating equipment
  • Calculating a more accurate annual energy consumption for net-zero solar array sizing
  • Evaluating envelope and equipment upgrades (in both new construction and retrofits) to maximize value under my electricity rate structure.

What softwares are you doing this modeling in? 

The basis of all of our energy modeling lies in the EnergyPlus simulation engine. EnergyPlus has been under constant development and refinement since 1997 and is the industry standard for building energy simulation. It has an open, modular approach which allows for it to be used for almost any situation.

We use two primary front-end software suites that interface with EnergyPlus: BEOpt and OpenStudio.  BEOpt is a streamlined software geared specifically toward quick, simplified modeling of residential houses using standardized equipment and envelope choices.  OpenStudio is a much more in-depth modeling tool, with the capability of fully customizing the geometry and building envelope parameters, as well as modeling a much wider range of HVAC systems, along with more sophisticated modeling of building thermal zones and Temperature/RH controls.  OpenStudio is geared more toward commercial buildings, but we have experience using it to create very detailed models of large and non-standard residential homes.


How Will Modeling Help My Project?

We have had energy modeling projects where we were able to show that the amount of solar specified for that particular project was too much, this allowed the installer to go with a lower-cost solar option (given the limited roof area) and over the development, saved tens of thousands of dollars. Energy modeling will give you more confidence in how your design will function and allow you to tell your clients with more certainty how different design iterations will solve their problems. 

Rather than upgrades or design changes being made on a hunch, or the value of such changes being nebulous, modeling provides a calculated and quantified value to inform decision making.


Why should I choose your modeling services over someone else's? 

In the energy modeling group at Positive Energy, we have run over a quarter million building energy models, including both residential and commercial. Many services use equipment-specific “energy models” such as Carrier’s HAP, or Trane Trace. These models are really for commercial properties only, and even then for more generic or typical building types.  We can model almost any aspect of a building, and are technology and vendor agnostic. 

We are certified for the Austin Energy’s Integrated Modeling Incentive Program, which is a rebate available from the city of Austin for implementing energy modeling early in the design process. We also specialize in modeling residential houses, and both have an academic background in residential home energy use research.  We are literally house energy doctors (PhDs). 


Do I need to have a BIM file for modeling? 

These files can be helpful, but we do not require them. Simple blueprints or CAD files can be enough to start with, provided they include dimensions for walls, windows, etc.. The earlier in the design phase that energy modeling starts, the more helpful it can be.

Do I need to have a BIM file for modeling? 

These files can be helpful, but we do not require them. Simple blueprints or CAD files can be enough to start with, provided they include dimensions for walls, windows, etc.. The earlier in the design phase that energy modeling starts, the more helpful it can be.


What does my modeling deliverable look like?

An extra layer of value that we add to the energy modeling is the clear explanation of results in a succinct report. We try to keep this very on point to the client’s specific questions and goals. We make sure that the data coming from the energy models is formatted very clearly in charts and graphs so that no one has to look at massive tables of data, unless they want to!