1. OPTIMUM DESIGN OF A HOUSE AND ITS HVAC SYSTEMS USING SIMULATION
BASED OPTIMISATION
M.Hamdy
A.Hasan
K.Sirén
Aalto University

2. Introduction buildings a major sector of energy consumption
continuously stricter energy directives
demand for improved energy solutions in buildings
OPTIMISATION
of the building structures and HVAC systems

3. Case building two-floor semi-detached house total floor area 143 m2
room height 2.5 m
mechanical ventilation + heat recovery
air exchange rate 0.6 1/h
initial design according to Finnish building code

5. Ground floor
Upper floor

6. Design variables x1 insulation thickness, wall 40
x2 insulation thickness, roof 40
x3 insulation thickness, floor 40
x4 type of window 5
x5 building tightness 5
x6 type of heating (cooling) system 5
x7 type of heat recovery 3
x8 type of shading 2
Alternatives = 40x40x40x5x5x5x3x2 = 48 ∙106

7. Objective functions Problem definition F1 = Investment cost [€]
F2 = CO2 emissions of heating [kg/a]
Problem definition
Min [F1(x), F2(x)];
x = [x1, x2,…, x8]T;

8. New decision variables.
Start
Tools
Simulation: IDA-ICE
Optimisation: Genetic
Algorithm (MATLAB)
Simulation
IDA-ICE
New decision variables.
Energy
CO2
PPD
Optimisation
MATLAB
Investment
LCC
MinF(x)? no
yes
End

9. Investment cost € CO2 emissions (kg/a) 40000 35000 30000 25000 20000
15000
10000
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
CO2 emissions (kg/a)

10. Non-dominated solutions, no constraint41

11. Indoor air temperature, point 41

12. Indoor air temperature, point 41

13. DH24 CONSTRAINT DH24 = S (Ti - 24) dt Ti - 24 > 0
8760
DH24 = S (Ti - 24) dt
Ti - 24 > 0
Ti indoor air temperature during the hour i
dt time increment (3600 s)
i=1

14. Non-dominated solutions, DH24 constraint
Heat Pump + free cooling (sys 5) + Shading
Heat Pump +
free cooling (sys 5)
District heat (sys 3)
Heat Pump +
free cooling (sys 5)
Fuel boiler (sys 2)
Ele. Rad (sys 1)

15. Conclusions
the non-constrained optimisation finds 41 non- dominated solutions
the electric radiator system and the heat-pump system are the extremes of the selection
these solutions suffer from summer time overheating
adding a DH24 constraint shifts the pareto front towards more expensive solutions
setting DH24<1000 Chr selects heat-pump only