1. Thermal Characteristics of High Thermal Mass Passive Solar Houses
Kumar Mithraratne and Brenda Vale
School of Architecture
The University of Auckland
Auckland, New Zealand.
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ICSES - July, 2004

2. Passive Solar House Direct Gain Trombe Wall Convection Convection + +
Radiation
Trombe Wall
Convection +
Radiation
Source : Szokolay 1995
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3. Active Solar House
Solar Panel
Fan Coil Unit
Hot Water
CoP= Useful Solar Energy Delivered / Parasitic Energy Use
CoP > 50 Passive System
50 > CoP > 20 Hybrid System
CoP < 20 Active System
Source : Szokolay 1995
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ICSES - July, 2004

4. Thermal Mass and Insulation
Effect of Mass
Effect of Resistance
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5. Non-massive Passive Solar Zone
Zone air temperature
in winter
Zone air temperature
in summer
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6. Simulation Programmes Used in the Study
Energy Plus (v – 2003)
Jointly developed by
University of Illinois and Berkeley National Laboratory
SUNREL(v )
National Renewable Energy Laboratory (NREL)
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7. Comparison Between EnergyPlus and SUNREL
EnergyPlus SUNREL
Conduction Time Series Finite Difference
Solver Method Method
Sky Diffuse Anisotropic Model Isotropic Model
Radiation (Perez et. al)
Zone Solar EPlus Model ‘area’ / User-defined
Distribution
Inter-zone EPlus Model User-defined
Transfer
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ICSES - July, 2004

8. High Thermal Mass Insulated House
(Hockerton – U.K)
CONSERVATORY
ROOMS
Double Glazing
Triple Glazing
400 mm Soil
300 mm Concrete
300 mm Insulation
150 mm Insulation
Insulated wall
Typical Cross Section
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ICSES - July, 2004

9. High Thermal Mass Insulated House
(Hockerton – U.K)
BED ROOM 1
BED ROOM 2
BED ROOM 3
SITTING ROOM
KITCHEN
HALL
CONSERVATORY
PORCH
BATH ROOM
STUDY AREA
UTILITY
Floor Plan
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10. Thermal Zoning 28/11/2018 ICSES - July, 2004 S E N W ROOM CONSERVATORY
PORCH S E N W
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11. Thermal Massiveness and Accuracy
t = Roverall  Coverall
t = Building Time Constant [s]
Roverall = Envelope Resistance excluding floor [K / W]
Coverall = Thermal Capacitance of walls [J / K]
Hockerton House
Roverall = K / W : Coverall = kJ / K
t = h
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12. Annual Simulations with EnergyPlus
Hockerton House
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13. Effect of Time Constant (Massiveness)
Building 1 (Hockerton House) Building 2 (Half-Hockerton House)
R = K / W : C = kJ / K R = K / W : C = kJ / K
t = 634 hrs : 3 t = 79 days t = 278 hrs : 3 t = 35 days
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14. Thermal Response of Mass
Temp.
To – outside Ti - inside To Ti C R
95 % of To
Time
3 t
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15. Inter-Zone Solar Transfer
EnergyPlus
 Treats as DIFFUSE radiation – Uses diffuse-transmittance
 Depends on optical properties of transparent surfaces
SUNREL
 User defined – Constant value or as a Schedule
 Does not depend on optical properties of transparent
surfaces
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16. EnergyPlus Simulation Results
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17. Room Solar Gains Solar altitude at noon on January 1st = 140
Solar altitude at noon on July 1st = 600
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18. SUNREL Simulation Results
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Solar
Transfer
Fraction
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19. EnergyPlus – SUNREL – Measured Data
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20. Conclusions
 Use of building thermal simulation programs for predicting thermal characteristics of a massive, zero-heating, passive solar house was investigated – (EnergyPlus and SUNREL)
 Same annual weather data have to be repeatedly simulate a period longer than a year to account for initial thermal accumulation – Initial error is a function of massiveness
 Accuracy of the predicted results significantly depends on the Solar transfer to the interior zones through interior transparent surfaces – Direct or Beam and Diffuse radiation must treated separately.
28/11/2018
ICSES - July, 2004