desogus, mura, pisano & ricciu - input2012
DESCRIPTION
Giuseppe Desogus, Salvatore Mura, Gian Luca Pisano and Roberto Ricciu on "Planning energy saving measures for existing buildings through linear problems solving "TRANSCRIPT
Tools and methods for sustainability in planningprocesses
Planning energy saving measures for existing
buildings through linear problems solving
Giuseppe Desogus, Salvatore Mura, Gian Luca Pisano, Roberto Ricciu
Department of Civil and Environmental Engineering and Architecture,
University of Cagliari
Tools and methods for sustainability in planningprocesses
Research’s aim:
The application of a linear problem solving technique on existing dwellings energy
savings planning .
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Tools and methods for sustainability in planningprocesses
1.000.000
2.000.000
3.000.000
4.000.000
5.000.000
10.000.000
15.000.000
Houses by geographical area
Regional
National
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
1951 1961 1971 1981 1991 2001
0 0
NW Italy NE Italy Middle Italy South Italy Insular Italy Italy
years
Data from 14th Population and House Census, National Institute of Statistics (ISTAT)
Tools and methods for sustainability in planningprocesses
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Data from Energy and Environment Reports, ENEA
Tools and methods for sustainability in planningprocesses
At the moment the most widespread solutions to improve existing buildings
energy performance in Italy are:
•Partial or complete renovation of HVAC system;
•Horizontal structures (roofs included) insulation;•Horizontal structures (roofs included) insulation;
•External wall insulation;
•External windows or doors replacement;
•Thermal or PV solar panels installation.
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Tools and methods for sustainability in planningprocesses
The choice of which energy saving measures best fit to an existing building
depends at least by three main factors:
•Building features (age, dimensions, construction technologies, HVAC systems
and use);
•Local climatic conditions;
•Market costs of energy saving measures.
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Tools and methods for sustainability in planningprocesses
Planning the best mix of energy saving works for a known context always requires
a building type classification.
Dwellings should be grouped by:
•Age;
•Dimensions;
•construction technologies;
•HVAC systems.
For a small-scale context, local climate classification can be neglected.
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Tools and methods for sustainability in planningprocesses
N = building types identified
M = energy saving works
The problem is finding the number of each work for each type of building that
gives the best results in terms of energy saving and invested capital.
xi,j unknown quantities are N·M
Mathematical expressions of energy savings and costs are linear equations, thus,
if appropriate constraints are identified, linear programming techniques can be
used.
Among them the Simplex Algorithm is adopted in this study.
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Tools and methods for sustainability in planningprocesses
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Tools and methods for sustainability in planningprocesses
A case study: optimizing national policy of energy saving subsidies (the so-called
“55% tax-reduction” )
Decision model inputs:
•number of submitted applications by geographical area;
•annual average energy saving by geographical area;•annual average energy saving by geographical area;
•average cost for works by geographical area;
•annual cost per MWh saved
All data extracted from ENEA “55%” Reports.
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Tools and methods for sustainability in planningprocesses
A case study: optimizing national policy of energy saving subsidies (the so-called
“55% tax-reduction” )
25 (5x5)decision variables:
•Number of wall energy efficiency works;
•Number of energy efficiency works for horizontal element;•Number of energy efficiency works for horizontal element;
•Number of windows energy efficiency works;
•Number of plant system replacing works;
•Number of solar panels installations.
Related to geographical areas:
•North-West Italy;
•North-East Italy;
•Middle Italy;
•Southern Italy;
•Insular Italy.
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Tools and methods for sustainability in planningprocesses
Macro area No. Works Cost € Energy saving GWh
NW Italy
Horizontal element inprovement works 204 146 3 882 657 878 3 774
Wall improvement works 1 844 099 17 729 628 811 36 702
Window improvement works 4 014 705 15 566 265 880 11 899
NE Italy
Horizontal element inprovement works 4 976 359 66 446 335 912 91 999
Wall improvement works 4 976 359 42 627 926 625 99 042
Best scenario for
energy efficiency
measure subsides by
category and
geographical area.
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Heating system replacing 2 322 649 13 316 791 909 22 797
Middle Italy
Horizontal element inprovement works 2 773 439 38 476 681 943 51 273
Wall improvement works 1 145 004 9 101 278 982 22 788
Window improvement works 3 955 181 14 809 977 495 11 723
Solar panels installations 4 728 293 12 977 036 553 36 442
Heating system replacing 4 954 312 21 185 257 401 48 627
South Italy
Heating system replacing 690 658 1 975 523 610 6 779
Insular Italy
Solar panels installations 3 214 236 6 220 993 066 24 773
Total 39 799 440 264 316 356 066 468 617
Tools and methods for sustainability in planningprocesses
50%
60%
70%
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90%
100%
Economic performance
% energ
y efficiency
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
Costs reduction - Proposed decision model trend compared to the present one.
10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%
0%
10%
20%
30%
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Present trend Proposed model trend
% works
% energ
y efficiency
Tools and methods for sustainability in planningprocesses
50%
60%
70%
80%
90%
100%
Energy performance
% energy efficiency
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving
10% 15% 20% 25% 30% 35% 40% 45% 50% 55% 60% 65% 70% 75% 80% 85% 90% 95% 100%
0%
10%
20%
30%
40%
50%
Present trend Proposed model trend
% works
% energy efficiency
Energy use reduction - Proposed decision model trend compared to the present one.
Tools and methods for sustainability in planningprocesses
Conclusions:
•Energy retrofit works on existing buildings can be very expensive and invasive. In
most case only few solutions can be adopted. Among them the most profitable
should be identified;
•The actual energy efficiency policies are only private initiative based;
•Using suitable decision instruments in planning can lead to consistent energy
and public capital savings.
Desogus G. Mura S. Pisano G.L. Ricciu R. - Planning energy saving measures for existing buildings through linear problems solving