TOWARDS NEARLY-ZERO ENERGY RETROFITTED BUILDINGS. Milan, March 19 th 2014

Transcription

1 TOWARDS NEARLY-ZERO ENERGY RETROFITTED BUILDINGS Milan, March 19 th 2014

2 THE ROLE OF ENERGY SIMULATION TOWARDS nzeb: CASE STUDIES Enrico Fabrizio University of Torino

3 WHY DYNAMIC ENERGY SIMULATION FOR nzeb? The design of New (N) and Existing (E) nzebs is a complex task for many conflicting requirements There is usually a trade-off between heating, cooling and electricity needs, financial and energy objectives, etc. A compromise between the requirements must be found It is necessary to build models that consider the mutual relationship between the various inputs Renewable sources are highly time variable Use of dynamic building simulation in association with parametric and optimization studies Use of new approaches that compare and contrast at the same time both energy demand side options and energy supply side options for the energy retrofitting/savings. 3

4 DYNAMIC SIMULATION IN ASSOCIATION WITH PARAMETRIC AND OPTIMIZATION STUDIES Building simulation Energy needs and energy consumptions Global cost Parameters selection/optimization optimization Computation of the objective function Output TRNSYS Building Simulation Program Input Input GenOpt Optimization Program Output TECHNICAL OPTIMUM COST OPTIMUM 4

5 CONTRASTING ENERGY DEMAND AND SUPPLY SIDE OPTIONS FOR RETROFITTING Standard approach (sequential) - Energy demand reduction - Energy supply optimization (system effiency and renewable sources) 5

6 CONTRASTING ENERGY DEMAND AND SUPPLY SIDE OPTIONS FOR RETROFITTING New approach (integrated) 6

7 CASE STUDIES Two case studies of single-family houses: SFH1 and SFH2 Two locations: Ambérieu (Lyon) for SFH1 and Torino for SFH2 Two software tools: TRNSYS + GenOpt for SFH1 and EnergyPlus for SFH2 Method: cost optimal analysis (2010/31/EU) 7

8 CASE STUDY 1 SFH 1 8

9 BUILDING ENVELOPE OPTIMIZATION Need of parametric studies in order to model and optimize the thermal behaviour of the building envelope Type and number of parameters to be selected SFH 1 9

10 BUILDING ENVELOPE OPTIMIZATION Need of parametric studies in order to model and optimize the thermal behaviour of the building envelope Type and number of parameters to be selected Building structure (massive, light wooden, etc. N) Thermal insulation (thickness and layers order, N&E) SFH 1 10

11 BUILDING ENVELOPE OPTIMIZATION Need of parametric studies in order to model and optimize the thermal behaviour of the building envelope Type and number of parameters to be selected Window types (N&E) and dimensions (N) SFH 1 11

12 BUILDING ENVELOPE OPTIMIZATION Need of parametric studies in order to model and optimize the thermal behaviour of the building envelope Type and number of parameters to be selected Shadings (fixed roof overhang, movable N&E) SFH 1 12

13 Decrease in energy needs Increase in energy needs BUILDING ENVELOPE OPTIMIZATION Example of results for insulation thickness SFH 1 O : outwall R : roof S : slab Better performance Worse performance Each curve intersects the x axis for the initial value of the insulation. Trend of the cooling needs is inverse with respect to heating neds. However, influence of the cooling is negligible on the total need 13

14 BUILDING ENVELOPE OPTIMIZATION Example of results for insulation thickness SFH 1 Impact variation of the thermal resistance of insulation for each construction element. Increase of the roof insulation is positive for both heating and cooling 14

15 BUILDING ENVELOPE OPTIMIZATION Example of results for window dimensions SFH 1 Low impact for vertical windows dimensions Interesting the case of the roof window Optimal value 15

16 BUILDING ENVELOPE OPTIMIZATION The influence of the initial scenario (low/medium/ref/high insulation) on the results SFH 1 Pag. 117! 16

17 BUILDING GLOBAL OPTIMIZATION What happens if we change the construction technology (massive, wood, )? What happens when we take into account the system (four types of different primary systems)? How the results change in terms of global cost? SFH 1 3 construction technologies: 1. Initial, 2. Massive, 3. Wood 4 systems: 1. HP-VMC, 2. All electric, 3. Boiler, 4. Biomass 17

18 System # 4 Wood boiler Wood boiler SFH 1

19 CASE STUDY 2 SFH 2 19

20 Types of EEM Energy Efficiency Measures (EEM) SFH 2 Packages of measures ZEB

21 [kw] BUILDING LOADS SIMULATION Example of results: thermal and electricity loads profles RB ZEB3 SFH 2 Annual profiles of thermal loads [kw] RB ZEB3 Annual profiles of electricity loads

22 [kwh/m 2 a] Energy needs heating cooling lighting plug loads DHW RB ZEB3 Comparison between RB and ZEB3 Reduction of 79% on the heating need Reduction of 39% on the cooling need [kwh/m 2 y]

23 [kwh/m 2 a] Energy needs heating cooling lighting plug loads DHW [kwh/m 2 a] Energy needs Net primary reported energy into primary balance energy

24 Packages of measures: [ /m 2 ] Gobal cost zeb1 zeb2 1 zeb3 2 3 Cost optimal level 4 Net primary energy [kwh/m 2 a] 5 6 RB RB RB (FV3,2) RB (FV6,3) (FV3,2) 4 (FV6,3) (ACS50%) 19 (FV3,2) 19 (FV6,3) (ACS50%) 22 (FV3,2) 22 (FV6,3) zeb1 zeb2 zeb3 Energy efficiency measures: Envelope insulation level Isol.0 Isol.1 Isol.2 Isol.3 Movable shading system Internal Venetian blind Venetian blind betw. Shade between External Venetian blind External shade System Gas boiler Hybrid boiler-hp system All electric HP (ground-water) All electric HP (air-water)

25 Packages of measures: [ /m 2 ] Gobal cost zeb1 zeb2 zeb3 116 [ /m 2 ] 118 [kwh/m 2 a] [kwh/m 2 a] Net primary energy [kwh/m 2 a] RB 28 [ /m 2 ] RB RB (FV3,2) RB (FV6,3) (FV3,2) 4 (FV6,3) (ACS50%) 19 (FV3,2) 19 (FV6,3) (ACS50%) 22 (FV3,2) 22 (FV6,3) zeb1 zeb2 zeb3 The cost optimal solution is 10 The nzeb solution that has the lower global cost is ZEB3

26 COST OPTIMAL VS. ZEB Energy efficiency measures Envelope insulation Movable shading system System Solar thermal RB 10 ZEB3 Level 0 Cog. L.R.13/07 Internal blind Gas boiler Split system DHW (5,9 [m 2 ]) Level 1 (incentive) Level 3 (superinsulation) External blind All electric HP system (air-water) DHW (5,9 [m 2 ]) SFH 2 Photovoltaic (1,6 [kwp]) Space heating (9,1 [m 2 ]) (6,3 [kwp])

27 CONCLUSIONS ZEB is still far from being cost optimal! Where is nzeb? Technologies for nzeb target exist but the main problem is the pay back period. Given the low energy requirements of a nzeb, a sequential simulation and optimization approach (energy demand energy supply energy from renewables) is not sufficient. It is necessary to compare at the same time energy efficiency measures of the building envelope, systems and renewables. To reach the nzeb target the system plays a crucial role (small room for efficiency improvement in the envelope optimization). In particular, systems with medium-low installation and running costs are preferable (e.g. air-water HP with integrated MV instead of ground-water HP with MV). 27

28 REFERENCES M. Bayraktar, E. Fabrizio, M. Perino, The extended building energy hub : A new method for the simultaneous optimization of energy demand and energy supply in buildings, HVAC&R Research, 18(2012):1-2, Maria Ferrara Modelling Zero Energy Buildings: technical and economical optimization, Master Degree under the supervision of M. Filippi, E. Fabrizio, J. Virgone, F. Causone, Politecnico di Torino, 2013 Paolo Dabbene Livelli di prestazione energetica ottimali in funzione dei costi, Master Degree under the supervision of M. Filippi, E. Fabrizio, C. Becchio, V. Monetti, Politecnico di Torino, 2013 M. Ferrara, J. Virgone, E. Fabrizio, F. Kuznik, M. Filippi, Modelling of Zero-Energy Buildings: technical and economical optimization, Climamed 2013 Conference, Istanbul (Turkey) M. Ferrara, J. Virgone, E. Fabrizio, F. Kuznik, M. Filippi, Modelisation des batiments Zero Energie: optimisation technico-économique, submitted to Conférence francophone IBPSA France 2014, Arras (France). M. Ferrara, J. Virgone, E. Fabrizio, F. Kuznik, M. Filippi, Modelling of Zero-energy Buildings: parametric study for the technical optimization, submitted to Sustainability and Energy in Buildings SEB-14 Conference, Cardiff (UK). 28

29 Thankyoufor yourattention 29