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Simulation-Based Design Study:

Jason Brown, Huafen Hu, Sean Hay KimCollege of Architecture

Georgia Institute of Technology04-26-2007

Energy Cost in a Solar House

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Background and the Goal

• Solar Decathlon - Department of Energy and The National Renewable Energy Laboratory (NREL);

• Competition in 10 contests: Architecture, Engineering, Marketability, Communications, Comfort Zone, Appliances, Hot Water, Lighting, Energy Balance, and Getting Around;

• The Levelized Cost of Energy (LCoEwh) – economic measure expressing the affordability of the energy produced by a house’s photovoltaic (PV) system;

• Problem:

What design decision has the lowest LCoEwh ?

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Calculation of LCoEwh

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System of Interactions

NoPV YrEnConYrEnProd

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Lessons Learned - 1

Version Incompatibility

Old Version Modelica The latest Version of Modelica

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Lessons Learned - 2

Simulation time is expensive

Yearly Energy Simulation

1 year = 3.15×107 seconds

20 mins per one single Dymola run

More than 300 hours for a DOE with 9 design variables

“Yearly” Energy Simulation

1 “year” = 2.4×106 seconds

1.5 mins per one single Dymola run

Around one dayfor a DOE with 9 design variables

One typical week For each season

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Lessons Learned - 3

The objective not well defined

No room for utility theory

RoofSHGC

NoPV

NPVpv

NPVutil

ACH

RH

Module_costfactor

pvprod

galp

LCoEwh

Reduction in CO2 emissions: RCO2

U(LCoEwh)

U(RCO2)

Overall Utility

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Lessons Learned - 4

Integer design variable

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Interesting Results

DOE Optimizer

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Insights of Building Simulation in Modelica

• More simplified models – full weather;– sensitivity analysis;

• Decision making under uncertainties