1. Reduced-Order Models for Building Interzonal Transport EPA04 T3.2
Jensen Zhang, John Grunewald, Andreas Nicolai, Hui Li,
H. Ezzat Khalifa, Basman Elhadidi, and John Dannenhoffer, III
Syracuse University

2. Envisioned i-BES Occupant Satisfaction: ~100% >90% >80%
Envelope system
Material selection
HVAC system
Room air cleaner
Room ventilation
Personal ventilation
Smart furniture
Wearable air purifier
Occupant
Satisfaction:
~100%
>90%
>80%
80% (ASHRAE Standards)
Occupant
Personal
Env.
Zone/
Room
Multizone
Building
Outdoor
Airshed
Multi-level
Controls: 3 2 1
IEQ
Building Security
Energy Efficiency
Goals:

3. The Problem and Research Needs
i-BES control requires real/near real time prediction of pollutant transport
Reduced-order models
Efficient coupling of different component models
Need-based multi-level/scale modeling
Integrated BES design and optimization
IEQ
Energy
Cost-effectiveness
Exposure/performance prediction at different stages of building system design
Single zone
2-5 zones
Detailed multizone analysis
Spatial distribution analysis (CFD)

4. Interactions between CHAMPS Component Models
CHAMPS-BES/simplified
& EnergyPlus
POD/CFD
EnergyPlus/simplified
CHAMPS-Multizone
(CONTAM +)
Heating, cooling &
pollutant loads
Envelope
Model
HVAC
Model
Rates of H. A. M. P.
through structures
via the source terms
Q, T, and RH
of supply air
Interior
pressure
Multi-
zone
Model
B.C.’s on
Room surfaces
Q, T, and RH
of supply air
Mixing level
and
zone dynamics
Room
Model
*Databases: Material Properties; Pollutant Properties; Sources & Sinks; Weather

5. Research Objectives The Ultimate Goal:
Develop reduced-order models that can be used for BES analysis, optimization and control (T5).
Specific Objectives for EPA04 Project (3 years):
CHAMPS-Multizone (EPA04)
Pollutant and thermally-induced airflows
Multizone and envelope model coupling
Multizone and room model coupling
Reduced-order room model
Model validation: a case study

6. Development and applications of CHAMPS
Roadmap
EPA03
EPA04
2004
2005
2006
2007
2008
Development and applications of CHAMPS
New emphases:
Pollutant flows
Simpler models
Coupling
CHAMPS-BES 1.0
Material & VOC database procedure
Delphin
(7+ years)
Material & VOC database
CHAMPS-Multizone
CHAMPS/e+ coupling
CHAMPS/POD coupling
Case study

7. In response to the SAC06 review
SAC comments
CHAMPS model is too complex and overkill
How different is this effort from the others?
Actions
Build upon well-known existing models
Focus on knowledge gaps
Effects on pollutant flows
Reduced-order/simpler models
Efficient coupling between models
Enhance networking with other key players
CHAMPS workshop in June 2006
E+ developers, educator’s workshop, July 2007
CHAMPS forum in BS07, Beijing, China, September 2007 …

8. Presentations in this Review
Overview (5 minutes)
CHAMPS Multizone Development Roadmap and Preliminary Results (10 minutes)
Application of Proper Orthogonal Decomposition to Indoor Airflows (5 minutes)
Posters:
CHAMPS-Multizone model development and applications (by J. Grunewald, A. Nicolai and J. Zhang)
POD model development and applications (by E. Khalifa, B. Elhadidi and J. Dannenhoffer)

9. CHAMPS Multizone Development Roadmap and Preliminary Results
John Grunewald, Andreas Nicolai, Jensen Zhang,
H. Ezzat Khalifa, Basman Elhadidi and John Dannenhoffer, III
Syracuse University

10. Definition of the Challenge
Air Spaces
VOC emissions from interior sources (furniture, equipment,…)
Air change rate (indoor-outdoor) in zones
Pollution of outdoor air
Interzonal air flows
Zonal air flow (forced convection, buoyancy)
VOC emissions from Building Envelope Systems (BES)
Heat and moisture transmission through BES
Air flows through BES (leakage, flux in small air spaces)
BES
Challenge: Coupling of heat and mass transport in Air Spaces and in Building Envelope Systems (porous materials)

11. About Air Flows How do different programs handle air flow calculation?
Air flux input
Pressure field calculation
Air flow implementation types
How do different programs handle air flow calculation?
(EnergyPlus,
CHAMPS)
air change rate,
air tightness of BES
Interzonal
airflow, non-
geometric models
(CONTAM)
Zonal airflow,
geometric models,
buoyancy
(CFD)
Airflow in BES,
simplified
Navier-Stokes,
buoyancy
(CHAMPS)

12. Model Features Comparison
Indoor air quality = f(VOC, RH and T conditions in zones …)
EnergyPlus CONTAM CHAMPS
Balances
T in zones x - -
RH in zones x x x
VOC in zones - x x
Result: No model can handle all processes!
Conclusions: Need to bridge the gaps between the models!
1. EnergyPlus is the model to start with.
2. CONTAM + CHAMPS features need to be combined.

13. Model Features Comparison
EnergyPlus CONTAM CHAMPS
Emissions
Internal VOC sources - x x
(multilayer) x
VOC emission from BES x
(influence of T, RH) x
Pollution from outdoor - x x
VOC database - x ?
Research needed
VOC database with sorption/emission characteristics

14. Model Features Comparison
EnergyPlus CONTAM CHAMPS
Airflows
Air change rate x x x
Air tightness of BES x x x
Interzonal air flow x x x
Interzonal pollutant flow - x ?
Airflow in BES x
Airflow in large spaces ?
Research needed
VOC database with sorption/emission characteristics
Couple multizone interzonal airflow with BES
Air flows in large spaces
Research needed
VOC database with sorption/emission characteristics

15. CHAMPS Development Milestones
BES
CHAMPS
Coupled Heat, Air, Moisture, and Pollutant Simulation
2004
2005
Heat and moisture basis module
2D Air leakage and VOC extension modules
EPA03
Multizone
CHAMPS
Coupled Heat, Air, Moisture, and Pollutant Simulation
2006
EPA04
Heat, moisture and VOC in well mixed zones
Coupling to CHAMPS-BES constructions
2007
Zone - outdoor connections (Air flows + T, RH and VOC)
Interzonal connections (Air flows + T, RH and VOC)
Interface to EnergyPlus / DesignBuilder
2008
Zone discretisation (no well-mixed assumption)

16. CHAMPS-BES Application Example
Example construction to study air flow & VOC effects
upward infiltration airflow
Release of
VOC (Toluene)
Infiltration Airflow
OSB Board (20 mm)
OSB Board (20 mm)
© Reprinted with permission from

17. CHAMPS-BES Application Example
CHAMPS run with full BES models
VOC-field in log10(mg/m3)
BES
Air + VOC
convection
Air + VOC
diffusion
Air flow
Zone

18. CHAMPS-Multizone Application Example
Dual chamber moisture & VOC diffusion (experiment & modeling)
Injection air flow
(high RH, VOC)
Clean air flow
(low RH, no VOC)
Chamber A B
T const
Calcium silicate
Moisture and
VOC diffusion

19. Overview
Need for an efficient means to couple the multizone and CFD calculations.
Objective:
To model, in near-real-time, contaminant distribution in a building consisting of a large number of interconnected zones:
Small, well-mixed spaces (offices)
Non-uniform open spaces (NOS).
Challenge:
Network Flow Zonal (NFZ) models (e.g., CONTAMW), are very fast (seconds), but assume that each zone is well-mixed (lumped parameter).
Reasonable for small well-mixed rooms; not realistic for large non-uniform spaces.
CFD is time consuming (hours to days) and requires considerable computing resources.
Provides spatial resolution, but unsuitable for optimization or real-time control.
It is not feasible to run both simultaneously in near-real-time for control purposes, or for the large number of iterations needed for design optimization of a complex system.

20. Approach
See: Elhadidi & Khalifa, ASHRAE Trans. 111(1), 2005; and Khalifa & Elhadidi, ASHRAE Trans. 113(2), 2007; and the poster later today.
Run the CFD simulations offline before-hand over the expected parameter space (generate snapshots).
Use Proper Orthogonal Decomposition (POD) to generate a fast-executing, reduced-order representation of the CFD snapshot results:
Extract eigen-modes from CFD snapshots;
Reconstruct high-fidelity representations of the flow, temperature and concentration fields from these eigen-modes (in seconds).
Develop a method for coupling the POD modes with the NFZ model in near-real-time dynamic simulations, or in system design optimization.

21. Original and Reconstructed Concentration Field

22. Results and Conclusions
POD can be used to reconstruct CFD or experimental spatial and temporal results quickly and accurately.
The POD-reconstructed CFD results can be efficiently integrated with multi-zone, network-flow models.
The integrated POD/CFD and NFZ approach allows efficient optimization and near-real-time control of more complex indoor environments.
Ongoing work is addressing transient contaminant dispersion and coupling of temperature fields.
At 1.5 m height