Decision-Making with Sefaira

Sefaira quickly delivers robust performance data in support of performance-based design. But what if you don’t understand the data? You might not get very far! This session of our bi-weekly Master Class Series focuses on what Sefaira measures, why it matters, and what you can do with it to achieve high-performing buildings.

Current customers can watch a recording of the webinar by signing into the Knowledge Base and following this link: Building Science 101 You can also learn about building science at learn.sefaira.com.

What Sefaira Measures & Why It Matters

The Real-Time Analysis plugin for SketchUp and Revit delivers data on Energy Use, Energy Distribution, Daylighting, and Heat Transfer (heating and cooling losses and gains).

Energy Use – EUI

EUI stands for Energy Use Intensity, and expresses annual site energy use per square foot of the building. (Site Energy is energy consumed at the building site, as opposed to Source Energy use which is energy consumed at the power plant.) The EUI measure is used as a contextual benchmark: it can be compared across buildings of similar use and location, or industry benchmarks like the 2030 challenge. (Sefaira’s 2030 Challenge EUI number is derived from CBECS and your project’s Climate Zone.)

Sefaira's Energy Use Intensity

 

EUI matters because designing a “better” building demands a comparison:

  • A comparison provides a reference point against which to set goals, and
  • Without a framework for assessing great performance, you’ll never get there.

The EUI metric not only supports comparisons, but it is also a key metric associated with The 2030 Challenge.

The 2030 Challenge is just that — a challenge — issued to the global architecture and building community, that all new buildings and major renovations be carbon neutral by the year 2030. The 2030 Challenge has been adopted by professional organizations like the AIA and USGBC, as well as all levels of government throughout the US.

Participants of the challenge adopt the following target: energy consumption performance of 60% below the regional (or country) average/median for that building type. The 60% number increases to 70% in 2015.

Energy Distribution – Energy Segments

This measure tells you how your energy is being used. Understanding this helps you focus your design strategies where they will have the greatest impact.

Sefaira Energy Segments

Daylighting – sDA & ASE

Sefaira analyses the daylighting performance of your design and expresses it in terms of the same metrics used by LEEDv4: Spatial Daylight Autonomy (sDA) and Annual Sunlight Exposure (ASE).

Real Time Analysis Daylighting

Sefaira’s “Well Lit” value aligns with sDA, and shows the percentage of floor area that receives an illuminance of 300 lux for over 50% of the annual occupied hours. The “Glare” value aligns with ASE and shows the percentage of floor area that receives an illuminance of at least 1000 lux for 250 or more annual occupied hours.

This information is important, as sDA has been shown to be a good predictor of actual as-built daylight performance, and ASE is an early indicator (though not a direct measurement) of glare and thermal comfort issues.

Heat Losses & Gains

Given the performance feedback, you’ll want to improve your design, right? But what do you do?! Understanding heat losses and gains helps you conceptualize why your building may be using more or less energy.

Heat gains in your building will require you to increase the cooling capacity of your HVAC systems, and expend more energy to cool the interior of the building. These can result from the following factors:

Heat Gains Diagram

Heat losses in your building will also affect your building’s performance:

Heat Losses Diagram

Legend: 1. Solar gain 2. Conduction 3. Infiltration 4. Ventilation 5. Appliances 6. Lighting 7. People

 

So What Do I Do Now? D.I.D.A!

Sefaira gives you Data. Using your building science knowledge, you take that Data and turn it into Information:

  • Data: “Glazing and wall conduction is resulting in heat transfer.”
  • Information: “I may need to offset heat gains or losses with mechanical means, or change the building envelope to resist heat transfer.”
  • From there, you make a Decision to gain an Advantage:
  • Decision: At this stage, I’d rather focus on improving the envelope than assessing potential mechanical systems. What can I change? Wall R-value, Glazing U-value, or maybe change the glazing or wall area altogether.
  • Advantage: With these changes in place, the client may save capital costs–they no longer need as large an HVAC system. At the very least, we’re armed to make a comparison between options instead of just guessing.

Conclusion

Data is one thing; Advantage is another. In order to take Sefaira’s analyses from Data to Information to Decision and Advantage, you need to understand the basic building science behind your building’s performance. Once you do, you will be able to achieve high-performance consistently across your project portfolio.