Lecture Objectives:
- Discuss the final project presentations
- Energy simulation result evaluation
- Review the course topics
Oral presentation
• On Thursday class will start at 8:30 am– We will have some guests UTs
• PowerPoint (6-7 minutes presentation)– Upload the file before the class
• Approximately 6-7 slides (a minute per slide)– Problem introduction – Model development - specific problem– Results – Results – Discussion– Conclusions
Today Lab Demo Class
• 5:30 PM in ECJ 3.402
• Beopt Software – Energy Plus GUI
Presenter: Joshua Rhodes
How to evaluate the simulation tools
Two options:
1) Comparison with the experimental data - monitoring
- very expensive- feasible only for smaller buildings
2) Comparison with other energy simulation programs- for the same input data
- system of numerical experiments - BESTEST
BESTEST Building Energy Simulation TEST
• System of tests (~ 40 cases) - Each test emphasizes certain phenomena like
external (internal) convection, radiation, ground contact
- Simple geometry- Mountain climate
6 m
2.7 m
3 m
8 m
0.2 m
0.2 m
1 m
2 m
S
N
E
W
COMPARE THE RESULTS
Example of best test comparison
BESTEST test cases
0
2000
4000
6000
8000
10000
12000
195 200 220 230 240 270
Annual heating load [kWH]
new ES prog
ESP
BLAST
DOE2
SRES/SUN
SRES-BRE
S3PAS
TRYNSYS
TASE
BESTEST
http://www.nrel.gov/docs/legosti/old/6231.pdf
http://www.nrel.gov/analysis/
Advance Energy Modeling with coupled
energy and airflow Example: Night Cooling/Hybrid Ventilation
The IONICA Office Building, Cambridge, UK
Feasibility of natural ventilationFigure 1- Hourly internal temperature distribution according to strategy used
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
base-case external insulation mech. vent. 15ach/int.ins.
mv/ii/south shading mech. vent. 15ach/ext.ins.
mv 15ach/ei/southshading
ho
urs
18-21.1
21.1-23.9
23.9-26.7
26.7-29.4
above 29.4
oC
Coupling
EnergySimulationProgram
Air FlowProgram IAQData:
geometryweather
materials
Twall, CFM, Tsupply
Tnear surface, h surface
V,T,…
Energy cons.
Coupling
ESprogram
CFDprogram
(converged)(converged)
CFDprogram
(converged)
ESprogram
controlled parameters m su pp ly and T Tsup ply s ur fac eor
T surfaces
controlled parameters m su pp ly and T Tsu pp ly su rf aceor
T surfaces
satisfactorysmall error
Time s tep Time step
ha dj.c ell , Ta dj.c ell ha dj.c ell , Ta dj.c ell
ES CFD
Onion
ESprogram
CFDprogram
(converged)(converged)
CFDprogram
(converged)
ESprogram
controlled parameters m su pp ly and T Tsup ply s ur fac eor
T surfaces
controlled parameters m su pp ly and T Tsu pp ly su rf aceor
T surfaces
ha dj.c ell , Ta dj.c ell
Time step Time step
ES CFD
Ping-Pong
COUPLED PROGRAM Components and Data flow
GUIPREPROCESSOR
ESPROGRAM
CFDPROGRAM
CFDinputdata(txt)
Convectionb.c. for ES
(txt)TMY2wether
data (txt)
CFDG UI
postprocessor
ESG UI
p ostprocessor
Inputdata for
CFDandES(txt)
call
data flo w
call
ca
ll
ca
ll
call
data flowcall
data flow
ESoutputdata(txt)
CFDoutputdata(txt)
convergency control
Postprocessor Output
Preprocessor Solver
results
results
EnergyEnergy & Buildings
• Conduction (and accumulation) solution method – finite dif (explicit, implicit), response functions
• Time steps • Meteorological data• Radiation and convection models (extern. &
intern.) • Windows and shading• Infiltration models• Conduction to the ground• HVAC and control models
Accuracy of Your Energy Simulation
• Depends primarily on your input data!
• Geometry• Boundary condition• Selected models • Set points• Control• Internal loads and schedule
Building Modeling Software
Very powerful tool
Use it wisely!
Simulation SoftwareGarbage IN Garbage OUT
but
1. Identify basic building elements which affect building energy consumption and analyze the performance of these elements using energy conservation models.
2. Analyze the physics behind various numerical tools used for solving different heat transfer problems in building elements.
3. Use basic numerical methods for solving systems of linear and nonlinear equations.
4. Conduct building energy analysis using comprehensive computer simulation tools.
5. Evaluate the performance of building envelope and environmental systems considering energy consumption.
6. Perform parametric analysis to evaluate the effects of design choices and operational strategies of building systems on building energy use.
7. Use building simulations in life-cycle cost analyses for selection of energy-efficient building components.
Review Course Objectives