FIU Solar House’s Potential Performance: A Study of Natural Ventilation StrategiesCheng-Xian Lin and Long Phan

Florida International UniversityMiami, FL 33174

FIU AT U.S. SOLAR DECATHLON 2005

1

10 Contests• Architecture• Dwelling• Documentation• Communications• Comfort Zone• Appliances• Hot Water• Lighting• Energy Balance1

• Getting Around Modular construction

The house exhibition FIU Solar House’s demonstration

An overview of the house

All credits to DOE Solar Decathlon (www.solardecathlon.gov) & FIU solardecathlon (http://gsl.eng.fiu.edu/webs/SOLAR2004/)

At a glance• Name: Engawa• Constructed by modules• 1/3 glass• PV-integrated windows

(projection surface)• Overall standing 13/18

FIU AT U.S. SOLAR DECATHLON 2011

10 Contests• Architecture• Market Appeal• Engineering• Communications• Affordability• Comfort Zone• Hot Water• Appliances• Entertainment• Energy Balance1 Overview of the house model

All credits to DOE Solar Decathlon (www.solardecathlon.gov) & FIU solardecathlon (www.solardecathlon.fiu.edu)

Visitors at the exhibition in Washington D.C.

Rooftop solar panels

Aerial view

Top view of the house model

Exterior & interior

2

At a glance• Name: perFORM[D]ance• Modular design• Open pavillion• Operable louvers/shade• Overall standing: 11/22

FIU AT SOLAR DECATHLON CHINA 2013

All credits to Solar Decathlon China (http://www.sdchina.org/) & FIU-Tsinghua team(http://www.thfisdc.com/)

Interior 3

Overview of the house model

Rooftop solar panels3

10 Contests• Architecture• Market Appeal• Engineering• Communications• Solar Application3

• Comfort Zone1

• Hot Water1

• Appliances• Entertainment• Energy Balance1

At a glance• Name: O-house• Modular house• PV louvers• Traditional courtyard• Overall standing: 5/22

CURRENT ACTIVITIES IN SOLAR HOUSE 2005 Public Exhibition and Educational Activities

Outreach: Annual Engineering Expo, Engineers on Wheel Visiting by students: undergraduate and K-12 Lab tours

Student Projects Senior design projects Course projects Exchange student studies

Elise Belleil, EI. CESI, France, Summer 2013 Francisco Zevallos, Loughborough/Northumbria University, UK, Fall 2013

Research Projects Real time temperature and humidity monitoring PV/T technology demonstration Building energy simulation model validation

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THE STUDY OF THE 2005 SOLAR HOUSE MODEL

Students: Elise Belleil and Long PhanThe Solar House Model 34’4” x 25’4” x 15’4” 7 typical residential

spaces Total conditioned

area 721.15 ft2

Window-to-wall ratio is 45.8 %

Rooftop PV panels with tilted angle of 75o

5Floor plan of the house

MOTIVATIONS The benefits of natural ventilation strategies The limitations and remedies of energy utilization in hot and humid climates

The aid of building energy simulation program providing insights for different strategies

Comparisons of a few natural ventilation strategies to seek the most possible solution in terms of thermal comfort and energy reduction

OBJECTIVES

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PHYSICAL MODEL  Total North East South West

Gross Wall Area (ft2) 1682 500.41 449.18 283.09 449.18Window Opening

Area (ft2) 764.99 360.59 202.25 0 202.25Gross Window-Wall

Ratio (%) 45.48 72.06 45.03 0.00 45.03

Room Type Area (ft2) Volume (ft3) Conditioned (Y/N)

Electrical Load (W)

Lighting Load (W/ft2)

Dining room 120.56 1,297.11 Y 0 1.8Living room 135.63 1,869.21 Y 1,050 1.8

Bedroom 135.63 1,869.21 Y 840 1.8Bathroom 78.79 718.30 Y 5,340 1.8

Study room 88.48 986.34 Y 60 1.8Kitchen 162.43 1,655.90 Y 8,964 1.8Battery room 19.48

407.53N - -

Mechanical room 30.10 N - -

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Typical rooms of the solar houseThe 2005 solar house model

Wall and window areas in different surfaces

BUILDING ENERGY SIMULATION MODEL

𝐶 𝑧𝑑𝑇 𝑧

𝑑𝑡 =∑𝑖=1

𝑁𝑠𝑙

�̇�𝑖+ ∑𝑖=1

𝑁 𝑠𝑢𝑟𝑓𝑎𝑐𝑒𝑠

h𝑖 𝐴𝑖 (𝑇 𝑠𝑖−𝑇 𝑧 )+ ∑𝑖=1

𝑁 𝑧𝑜𝑛𝑒𝑠

�̇�𝑖𝐶𝑝 (𝑇 𝑧𝑖−𝑇 𝑧 )+�̇�𝑖𝑛𝑓 𝐶𝑝 (𝑇∞−𝑇 𝑧)+�̇�𝑠𝑦𝑠

�̇�𝑙𝑜𝑎𝑑=∑𝑖=1

𝑁 𝑠𝑙

�̇� 𝑖+ ∑𝑖=1

𝑁𝑠𝑢𝑟𝑓𝑎𝑐𝑒𝑠

h 𝑖𝐴𝑖 (𝑇 𝑠𝑖−𝑇 𝑧 )+ ∑𝑖=1

𝑁𝑧𝑜𝑛𝑒𝑠

�̇�𝑖𝐶𝑝 (𝑇 𝑧𝑖−𝑇 𝑧 )+�̇�𝑖𝑛𝑓 𝐶𝑝 (𝑇 ∞−𝑇 𝑧 )

�̇�𝑠𝑦𝑠=�̇�𝑠𝑦𝑠𝐶𝑝𝜂 (𝑇 𝑠𝑢𝑝−𝑇 𝑧 ,𝑑𝑒𝑠𝑖𝑟𝑒𝑑)

Energy Balance Equation for a room model

Net Zone Load

System Load Equation

9Simulation Code: EnergyPlus

BOUNDARY CONDITIONS & MATERIALS

  Int. Door

Ext. Door

Ext. Windows

Roof Floor Ext. Wall Int. Wall

Layer 1

Wood 

Metal surface

Clear glass 

Plywood 

Metal surface Cellular Polyisocyanurate - Gas permeable

facers

Gypsum board

Layer 2

  Insulation

board

Air resistance 

Polystyrene(Extruded)

Polystyrene(Extruded)

Steel frame Steel frame

Layer 3

    Clear glass 

Steel frame Polystyrene(Molded beads)

Polystyrene(Molded beads)

Polystyrene(Molded beads)

Layer 4

      Polystyrene (Molded beads)

Steel frame Gypsum board Gypsum board

Layer 5

      Gypsum board Plywood    

Miami, FL climate graph

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NATURAL VENTILATION METHODS

(a) (b)

(c)

Natural ventilation methods

(a) Thermal chimney (TC)(b) Earth tube (ET)(c) Cool tower (CT)(d) Opening

11(d)

SINGLE METHOD RESULTS

(a) Annual energy consumption (b) Total uncomfortable days

Comparison among various natural ventilation systems

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HYBRID METHOD RESULTS

Comparison among various hybrid cooling systems

(a) Annual energy consumption (b) Total uncomfortable days

Hybrid system schedule

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SYSTEMS COMPARISON

Comparison among all cooling systems14

THERMAL ZONES COMPARISON

15Temperature profile of 7 thermal zones at different cooling strategies

CONCLUSION Various natural ventilation strategies including earth tube, thermal

chimney, wind tower, and opening, as well as hybrid strategies are investigated.

Relying on only natural ventilation could cause a dramatic impact to the human thermal comfort.

Hybrid systems have revealed the significant reduction in cooling energy consumption while complying with the minimum requirements for thermal comfort recommended by ASHRAE standards.

Combined thermal chimney and mechanical system (HVAC) method shows relatively better potentials for hot and humid climate such as Miami.

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THANK YOU !