THERMAL INERTIA FOR SMALL SCALE RESIDENTIAL BUILDING

STIJN VERBEKE

UNIVERSITYOF ANTWERP

UNIVERSITY COLLEGE

stijn.verbeke@ua.ac.be

BAUSIM 2010 CONFERENCE – Vienna University of Technology

Phd Student, University of Antwerp, Belgium

// PROBLEM DESCRIPTION //

1

Reduce summer overheating

++ Store heat gains

Fast reaction++ Benefits night setback

// PROBLEM DESCRIPTION //

2

What is the effect of building thermal inertia in houses in Belgian climatic conditions?

?

// METHODS // Whole Building Simulation //

3

Conduction finite difference

alghoritm

Annual simulation

Time step = 3 minutes

Weather data : IWEC Brussels

Energy Plus

// METHODS // Model Geometry //

4

// METHODS // Model Geometry //

5

Building thermal Mass

Orientation

Glazed surface

Level of thermal insulation: K70/K45/K35/K25

Design Variants:

// METHODS // Occupant behaviour //

6

deterministic

Unpredictable

behaviour

Various activities

User interference

// METHODS // Occupant behaviour //

6

stochastic

deterministic

// METHODS // Occupant behaviour //

7

Presence in the rooms

Artificial lighting

Electrical appliances

Heating Setpoint

Ventilation

Detailed stochastic occupancy model describing:

// METHODS // workflow //

8

°C / kWh

GEOMETRYMATERIALS

HVAC

PRESENCE INTERNAL HEAT GAIN THERMOSTAT WINDOW OPEN?

SCHEDULES

CLIMATE DATA

EVALUATION THERMAL COMFORT

MA

TLA

B

MATLAB

MATLAB SCRIPT ADJUSTS SCHEDULE FILE

// METHODS // discomfort indicator //

9

PPD/PMV (Fanger)

Adaptive comfort models?

Custom discomfort indicator =

Room thermostat: operative temperature control

+

// RESULTS //

10

K20

K35

K45

K70

// RESULTS //

11

Inertia has minor influence

Heating energy demand

HW LW Heating demand on average + 4.5%

Inertia has major influence

Thermal Discomfort

HW LW Discomfort on average + 20.4%

HW MW Heating demand on average + 1%

HW MW Discomfort on average + 2%

10

// RESULTS //DETAILED USER BEHAVIOUR

DETERMINISTIC USER BEHAVIOUR(no window opening)

10

// RESULTS //DETAILED USER BEHAVIOUR

DETAILED USER BEHAVIOUR

With sun shading

// RESULTS // Influence of occupancy model //

14

DETAILEDSTOCHASTIC

DETERMINISTIC CONSTANT

ENERGY +5% +1% +1%

DISCOMFORT +20% +43% +21%

HW LW HW MW

+1% +0% +1%

+2% +10% +19%

// CONCLUSIONS //

// CONCLUSIONS //

16

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

Impact of thermal inertia:

Heating demand: minor influenceThermal comfort: important influence

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

Preferably at least some thermal mass