Nathan Kegel of IES presents Modeling, It's not Just for Calendars and Energy at the 2012 Chicago Energy Modeling Conference.

1. Modeling
It’s not Just for Calendars and Energy
Nathan Kegel
ASHRAE Member, LEED AP BD+C
Project Manager
Business Development Manager
Nathan.kegel@iesve.com
www.iesve.com

2. Learning Objectives:
• Understand What a Model Is
• Understand Different Types of Models for
Buildings
• Understand the difference between BIM and
BAM and how to use them in practice
• Understand traditional, current, and potential
future best practices for building modeling
• Understand the value of a model for new and
existing buildings
• Introduce alternatives to ASHRAE 90.1

3. What’s a Model?

4. A MODEL is a device or structure that helps us:
• Understand the world around us
• Understand a piece of the world around us
• A simplified representation of our surroundings
in order that we may pursue understanding

5. Modeling Mindset
“… we must pursue understanding.
Not answers but understanding.”
Bellinger G. (2004) “Simulation is not the Answer”

6. Modeling Mindset
“Everything should be made as simple
as possible, but not simpler.”

7. Modeling Mindset
“Obstacles are those frightening things you
see when you take your eyes off goals.”
“Whether you think you can or think you
can’t, you’re right.”

9. Building Modeling: BIM and BAM
BIM: Building Information Model
• Building Information
• Uses include construction documents, clash detection &
constructability, cost estimating, scheduling, etc.
BAM: Building Analytical Model
• Building Analysis
• Uses include climate modeling, thermal loads modeling,
structural loads modeling, daylight modeling, thermal
comfort modeling, airflow modeling, temperature
modeling, energy modeling, solar modeling, performance
optimization, life cycle cost assesment, etc.

10. Building Analytical Modeling – Beyond Energy
Daylight Model
Airflow (CFD) Model Thermal Loads Model

11. BAM: Some more examples
Solar penetration Daylight levels Natural Ventilation
Results color coded on model Daylight Metrics Climate Understanding
J F M A M J J A S O N D
Cop yright © 2008 Integrated Environmental So lutions Limited. All rights reserved
Monthly Energy Output* Daylight contours Annual Energy Output*

12. Models for Buildings – Traditional Practice
Multiple Models for Multiple Purposes
CAD/BIM for construction; HVAC loads, energy,
daylight, solar, rendering, airflow, etc.
Thermal Loads Solar Airflow (CFD) Energy Ventilation
Daylight Rendering Artificial Light LEED Code Compliance

13. Traditional Practice - Benefits
1. It’s “familiar”
• Meaning Comfortable
• “What we’ve always done”
Traditional Practice - Drawbacks
1. It’s “familiar”
• Meaning Limited & Inefficient
2. Lots (and lots) of repeated work
• AKA - Inefficient
3. Lots (and lots) of loopbacks
4. Lack of Data Integrity
• Accuracy and QA can easily suffer leading to
higher chance for GIGO or incomparable
results

14. Models for Buildings
Possible in Today’s Practice:
Fewer Models serving Multiple Purposes:
CAD/BIM for construction plus an Analytical
Model studying thermal, energy, daylight, solar,
airflow, comfort, etc.
Building Analytical Model

15. Today’s Best Practice - Benefits
1. It’s not familiar
• Meaning innovative
2. Less data entry
• More time finding best solutions
3. Fewer loopbacks
• More efficient
4. Lower chance for GIGO
• Fewer datasets to manage and QC
Today’s Best Practice - Drawbacks
1. It’s not familiar
• Meaning there is a learning curve
• Innovation might be frightening to some
• Initial investment period before efficiency is
realized

16. Today’s Best Practice – Truly Informed Design
Analysis Informs Design

17. Models for Buildings
Ideal Practice?: 1 Building, 1 Model

18. Ideal Practice? - Benefits
1. Minimal re-work
• Best efficiency
2. Potential for minimal GIGO
• More time finding best solutions
3. Fewer loopbacks
• More efficient
4. Parametric
• When one thing changes, other related items
automatically update
Ideal Practice? - Drawbacks
1. Karoshi
2. Who manages what?
• For example, is the architect now responsible for the
quality of the thermal model?
• GIGO potentially bigger problem if not caught early
on and managed properly
3. Too much detail – leads to instability and uncertainty in
analysis
4. Parametric – Is it now just a “black box”?

19. Measures of Quantity – BIM

20. Measures of Quantity – Project Delivery

21. Measures of Quality – Daylight Analysis

22. Understanding Visual Quality - Glazing Options
Daylighting Quality Exterior Tint
SC = 0.6
VLT = 75%
SC = 0.2
VLT = 35%

23. Understanding Quality - Glare & Solar Shades
• Will glare be problematic late in
the day?
Lighting & Daylighting
No Solar Shading
• How Effective is the External (or
Internal) Shade at reducing Glare?
With Solar Shading

24. Understanding Solar Analysis
Building self-shading Building self-shading through brise soleil
Summer sun Winter
sun
Unexpected mid-evening peak
Shading from adjacent buildings
cooling load on east façade?

25. Understanding Quality of Envelope - Dynamic Infiltration
Heating Load (Btu/h)
Fabric Loss
Infiltration Loss
0 2000 4000 6000 8000 10000 12000 14000
Infiltration heat loss can account for
up to 40-50% of a building’s Heating
Load....
...Building Pressure Tests

26. Understanding Quality - Airflow (CFD)

27. Understanding Quality - Building Performance

28. Compliance With Codes & Rating Systems

29. BAM: Value to Existing Buildings
• Predict energy use, costs during operation
• Calibrate energy model per
utility bills or building performance
• Sensitivity Factors
• Calibration methods, tools
• Data collection
• Utility rates

30. The Future: Smart Buildings
• Continuous Calibration to
Optimize Performance
• Anticipate problems on the
fly using trended data
• Reduce Total Cost of
Energy and Improve
Occupant Comfort
• Detailed Analysis Models
will be the heart
– Note: +/- 10% is NOT good
enough
– Note: “Fudging factors” will
not work for Smart Buildings

31. Current Challenges
• Cost of calibrated models
• Construction QA practices lacking
• Cheap Energy & Current Financial Metrics
• Lack of accurate data
• Lack of enough detailed data
• “Fudge Factors” are still common practice
• ASHRAE 90.1 Mindset

32. ASHRAE 90.1 – 2010
• Prescriptive Path
– Prescriptive Path encourages building the worst possible “legal” building; it
does not encourage building the best possible building
– There are no requirements for testing or QA during construction and
occupancy
• Performance Path (Appendix G “Baseline”)
– There is no actual baseline in Appendix G
– Appendix G does not allow for certain measures to be included
• For example, reduction in OA by using a system type which delivers OA more efficiently
– There are no requirements for testing or QA during construction and
occupancy
• Benchmark versus Goal
– Benchmarks measure against current state; not against desired state
– Goals identify desired state; current state is less important
• Incredibly Complex
– Creates confusion in the marketplace
– Practitioners often spend more time on the baseline than on improving the
proposed building
• “Fudge Factors” are allowed – some even specified in Appendix G

33. ASHRAE 90.1 – 2010
New Appendix G requirements
• Accounting for Site Conditions
– Theory: Buildings aren’t built in a vacuum and site conditions do matter
– Practice: Poor implementation of this theory leads to more confusion & inaccuracies
• 90.1-2010 allows for site impacts that are physically impossible
• 90.1-2010 has exceptions which allow some software modeling tools to easily fake results
• Minimum requirements for HVAC efficiencies improved
– Baselines are (theoretically) more efficient
– Proposed case does not require modeling tools to accurately model actual HVAC
systems
• Convoluted (and frequently inaccurate) workarounds are still permitted
• Envelope requirements require more insulation for certain climate zones
– Meaning theoretical worst possible building is theoretically slightly better
– Mass factors still allowed – meaning detailed accounting of thermal mass impacts is
NOT REQUIRED
• Incredibly Complex
– 2010 version got more complex, not less
– Practitioners often spend more time on the baseline than on improving the proposed
building – this will probably get worse instead of better
• “Fudge Factors” are allowed – some even specified in Appendix G

34. ASHRAE 90.1 – 2010
Detailed Solar for the Appendix G Baseline & Proposed Cases
• Some obvious questions here:
– If the simulation program cannot simulate shading by adjacent structures,
how can it tell you which surfaces are shaded “most of the time”? Hence,
how can you determine which surfaces should be modeled as north-
facing?
– What about urban areas? Rotation of baseline and proposed with site will
cause physical impossibilities.

35. Self Shading Still not Required in 90.1
Building self-shading

36. Problems with Building Only Rotation

37. ASHRAE 90.1 – 2010
0-degree Solar for the Appendix G Baseline & Proposed Cases

38. ASHRAE 90.1 – 2010
180-degree Solar for the Appendix G Baseline & Proposed Cases

39. Alternatives: Moving Beyond Benchmarks
• A new paradigm:
– Require design and construction teams build and design the best
possible building
– What is the best possible building?
• Net Zero Energy
• Wisconsin
• New York
• Hawaii

40. Net Zero Energy is the Index
• Projects already constructed which achieve this standard
• Penalizes waste and encourages best possible building
• Simplifies the modeling process
• Encourages teams to seek best possible solutions, not just minimums
• More time available to explore best alternatives rather than spending
excessive amounts of time struggling with theoretical baselines
• Promotes understanding
• Promotes changes to occupant behavior
• Changes the financial model for implementing renewables
• Grows several segments in the economy
– Energy Modeling
– Renewable Energy
– Construction (renovation and new)
– Generates a revenue source for new research
• Funded by the biggest energy users
• More efficient use of resources
– Human
– Renewable
– Non-renewable