THERMAL INERTIA FOR SMALL SCALE RESIDENTIAL BUILDING

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THERMAL INERTIA FOR SMALL SCALE RESIDENTIAL
BUILDING
STIJN VERBEKE
stijn.verbeke_at_ua.ac.be
Phd Student, University of Antwerp, Belgium
BAUSIM 2010 CONFERENCE Vienna University of
Technology
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// PROBLEM DESCRIPTION //
Reduce summer overheating
Fast reaction
Store heat gains
Benefits night setback
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// PROBLEM DESCRIPTION //
?
What is the effect of building thermal inertia in
houses in Belgian climatic conditions?
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// METHODS // Whole Building Simulation //
Energy Plus

• Conduction finite difference alghoritm
• Annual simulation
• Time step 3 minutes
• Weather data IWEC Brussels

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// METHODS // Model Geometry //
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// METHODS // Model Geometry //
Design Variants

• Building thermal Mass
• Orientation
• Glazed surface
• Level of thermal insulation K70/K45/K35/K25

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// METHODS // Occupant behaviour //

• Unpredictable behaviour
• Various activities
• User interference

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// METHODS // Occupant behaviour //
stochastic
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// METHODS // Occupant behaviour //
Detailed stochastic occupancy model describing

• Presence in the rooms
• Artificial lighting
• Electrical appliances
• Heating Setpoint
• Ventilation

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// METHODS // workflow //
GEOMETRY MATERIALS HVAC
C / kWh
MATLAB
CLIMATE DATA
MATLAB
SCHEDULES

• PRESENCE
• INTERNAL HEAT GAIN
• THERMOSTAT
• WINDOW OPEN?

EVALUATION THERMAL COMFORT
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// METHODS // discomfort indicator //
PPD/PMV (Fanger)
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Adaptive comfort models
Custom discomfort indicator

Room thermostat operative temperature control
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// RESULTS //
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// RESULTS //
Heating energy demand

• Inertia has minor influence

• HW ? LW Heating demand on average 4.5

HW ? MW Heating demand on average 1
Thermal Discomfort

• Inertia has major influence

• HW ? LW Discomfort on average 20.4

HW ? MW Discomfort on average 2
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// RESULTS //
DETAILED USER BEHAVIOUR
DETERMINISTIC USER BEHAVIOUR
(no window opening)
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// RESULTS //
DETAILED USER BEHAVIOUR
DETAILED USER BEHAVIOUR
With sun shading
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// RESULTS // Influence of occupancy model //
DETAILED STOCHASTIC DETERMINISTIC CONSTANT
ENERGY 5 1 1

DISCOMFORT 20 43 21



1 0 1

2 10 19
HW ? LW
HW ? MW
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// CONCLUSIONS //
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// CONCLUSIONS //

• Impact of thermal inertia

Heating demand minor influence Thermal comfort
important influence
Preferably at least some thermal mass

• Insulations, glazed surface and orientation
  more important than building thermal mass

• More detailed model of occupant behaviour may
  leed to different design decisions

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