Thermal Characteristics of High Thermal Mass Passive Solar Houses Kumar Mithraratne and Brenda Vale School of Architecture The University of Auckland Auckland, New Zealand. 28/11/2018 ICSES - July, 2004

Passive Solar House Direct Gain Trombe Wall Convection Convection + + Radiation Trombe Wall Convection + Radiation Source : Szokolay 1995 28/11/2018 ICSES - July, 2004

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 28/11/2018 ICSES - July, 2004

Thermal Mass and Insulation Effect of Mass Effect of Resistance 28/11/2018 ICSES - July, 2004

Non-massive Passive Solar Zone Zone air temperature in winter Zone air temperature in summer 28/11/2018 ICSES - July, 2004

Simulation Programmes Used in the Study Energy Plus (v 1.1.0 – 2003) Jointly developed by University of Illinois and Berkeley National Laboratory SUNREL(v 1.53 - 2001) National Renewable Energy Laboratory (NREL) 28/11/2018 ICSES - July, 2004

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 28/11/2018 ICSES - July, 2004

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 28/11/2018 ICSES - July, 2004

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 28/11/2018 ICSES - July, 2004

Thermal Zoning 28/11/2018 ICSES - July, 2004 S E N W ROOM CONSERVATORY PORCH S E N W 28/11/2018 ICSES - July, 2004

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 = 0.0056 K / W : Coverall = 404932 kJ / K t = 633.8 h 28/11/2018 ICSES - July, 2004

Annual Simulations with EnergyPlus Hockerton House 28/11/2018 ICSES - July, 2004

Effect of Time Constant (Massiveness) Building 1 (Hockerton House) Building 2 (Half-Hockerton House) R = 0.0056 K / W : C = 405071 kJ / K R = 0.0049 K / W : C = 205512 kJ / K t = 634 hrs : 3 t = 79 days t = 278 hrs : 3 t = 35 days 28/11/2018 ICSES - July, 2004

Thermal Response of Mass Temp. To – outside Ti - inside To Ti C R 95 % of To Time 3 t 28/11/2018 ICSES - July, 2004

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 28/11/2018 ICSES - July, 2004

EnergyPlus Simulation Results 28/11/2018 ICSES - July, 2004

Room Solar Gains Solar altitude at noon on January 1st = 140 Solar altitude at noon on July 1st = 600 28/11/2018 ICSES - July, 2004

SUNREL Simulation Results Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Solar Transfer 0.353 0.239 0.115 0.003 0.003 0.0005 0.001 0.015 0.073 0.183 0.313 0.389 Fraction 28/11/2018 ICSES - July, 2004

EnergyPlus – SUNREL – Measured Data 28/11/2018 ICSES - July, 2004

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