planning:refurbishment_with_passive_house_components:economic_analysis_for_the_retrofit_of_a_detached_single_family_house_to_the_enerphit_standard

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planning:refurbishment_with_passive_house_components:economic_analysis_for_the_retrofit_of_a_detached_single_family_house_to_the_enerphit_standard [2019/01/30 13:11] cblagojevic |
planning:refurbishment_with_passive_house_components:economic_analysis_for_the_retrofit_of_a_detached_single_family_house_to_the_enerphit_standard [2019/02/28 09:41] (current) cblagojevic |
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We’ll assume the following financial hypothesis: | We’ll assume the following financial hypothesis: | ||

- | \\ -real interest rate 2%, | ||

- | \\ -financial assessment period = 30 years, | + | * real interest rate 2%, |

- | \\ -no Residual Value, | + | * financial assessment period = 30 years, |

- | \\ -heating and hot water price = €0.15/kWh | + | * no Residual Value, |

+ | | ||

+ | * heating and hot water price = €0.15/kWh | ||

The comparison between EnerPHit and low-energy variants, for Step 1 (walls, windows, ventilation, stove) gives a slightly lower total annual cost than the low-energy variant (see Figure 2) at €6500/a. The actualised payback period of the EnerPHit variant is 28 years. The saved kWh price is €0.14/kWh. | The comparison between EnerPHit and low-energy variants, for Step 1 (walls, windows, ventilation, stove) gives a slightly lower total annual cost than the low-energy variant (see Figure 2) at €6500/a. The actualised payback period of the EnerPHit variant is 28 years. The saved kWh price is €0.14/kWh. | ||

+ | |||

CO2 tax can be added to the operational cost. The price of CO2 is fixed according to a French law issued in 2015 [3]: stepwise increases from €22/tCO2 for 2016-2019 to €100/tCO2 after 2030. The declared CO2 content of the electricity mix is 88gCO2/kWh in France [4], against 532gCO2/kWh according to GEMIS [PHPP9]. Heating and hot water are fully electric. Figure 3 indicates that a CO2 tax is not a strong enough lever to shift towards efficiency if the energy source has a low carbon intensity (CO2 tax is only 3% of the total cost for existing French prices and CO2 electricity content). On the other hand, EnerPHit grants a “CO2 bonus” of 3% on the total investment with German carbon intensity and prices. | CO2 tax can be added to the operational cost. The price of CO2 is fixed according to a French law issued in 2015 [3]: stepwise increases from €22/tCO2 for 2016-2019 to €100/tCO2 after 2030. The declared CO2 content of the electricity mix is 88gCO2/kWh in France [4], against 532gCO2/kWh according to GEMIS [PHPP9]. Heating and hot water are fully electric. Figure 3 indicates that a CO2 tax is not a strong enough lever to shift towards efficiency if the energy source has a low carbon intensity (CO2 tax is only 3% of the total cost for existing French prices and CO2 electricity content). On the other hand, EnerPHit grants a “CO2 bonus” of 3% on the total investment with German carbon intensity and prices. | ||

[{{ :picopen:t_annual_cost_dbl_vs_trpl.png?500|Figure 4: Total annual cost compared: double glazing and triple glazing on a similar window type (left), supply only vs heat recovery ventilation (right)}}] | [{{ :picopen:t_annual_cost_dbl_vs_trpl.png?500|Figure 4: Total annual cost compared: double glazing and triple glazing on a similar window type (left), supply only vs heat recovery ventilation (right)}}] | ||

+ | |||

The Comparison worksheet allows us to assess the economic efficiency of a single component. Application of this feature on a window type (casement windows, inward opening – 12m² gross area, 30 year investment period, 30 year product lifetime) gives a similar annual cost for triple glazing than double glazing (Figure 4). The actualised payback period for choosing triple glazing is 20 years, the saved kWh price is €0.10/kWh. Similar analysis on mechanical ventilation with heat recovery versus supply only gives a clear advantage to mechanical ventilation with heat recovery (saved kWh price = €0.08/kWh). | The Comparison worksheet allows us to assess the economic efficiency of a single component. Application of this feature on a window type (casement windows, inward opening – 12m² gross area, 30 year investment period, 30 year product lifetime) gives a similar annual cost for triple glazing than double glazing (Figure 4). The actualised payback period for choosing triple glazing is 20 years, the saved kWh price is €0.10/kWh. Similar analysis on mechanical ventilation with heat recovery versus supply only gives a clear advantage to mechanical ventilation with heat recovery (saved kWh price = €0.08/kWh). | ||

The following factors can explain moderate total costs: | The following factors can explain moderate total costs: | ||

- | \\ -Reusing supply air ducts reduced the investment by €1830 (35m supply ducts at €36/ml: €1670, and 5 inlets €30/u = €150). | + | * Reusing supply air ducts reduced the investment by €1830 (35m supply ducts at €36/ml: €1670, and 5 inlets €30/u = €150). |

- | \\ -No specific treatment of existing render (good strength) prior to exterior insulation (€30/m² wall avoided for scraping and refill of existing render) | + | * No specific treatment of existing render (good strength) prior to exterior insulation (€30/m² wall avoided for scraping and refill of existing render) |

+ | | ||

+ | * Good airtightness of concrete walls, which spared specific airtightness treatment on regular wall surfaces. | ||

- | \\ -Good airtightness of concrete walls, which spared specific airtightness treatment on regular wall surfaces. | ||

A few measures could be further optimized: | A few measures could be further optimized: | ||

- | \\ -The position of the ventilation unit and layout of extract ducts | + | * The position of the ventilation unit and layout of extract ducts |

- | \\ -The Lambda value of wall insulation, avoid dowels to fix insulation | + | * The Lambda value of wall insulation, avoid dowels to fix insulation |

[{{ :picopen:total_present_value.png?300|Figure 5: Detailed total present value of retrofit variants, modelled with phEco.}}] | [{{ :picopen:total_present_value.png?300|Figure 5: Detailed total present value of retrofit variants, modelled with phEco.}}] | ||

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\\ Realistic price distributions are set up and the following parameters are fixed constant: | \\ Realistic price distributions are set up and the following parameters are fixed constant: | ||

- | \\ -Financial evaluation period = 30 years | + | * Financial evaluation period = 30 years |

- | \\ -Average residual value of components after financial evaluation period = 10 years. | + | * Average residual value of components after financial evaluation period = 10 years. |

- | \\ -Thermal performance of components | + | * Thermal performance of components |

Sensitivity assumptions: | Sensitivity assumptions: | ||

- | \\ -Log-Normal laws used for prices with observed stable minima: heat price (electric), wall insulation. | + | * Log-Normal laws used for prices with observed stable minima: heat price (electric), wall insulation. |

+ | | ||

+ | * Normal laws used for high added value components, for which prices have a higher reduction potential due to industrial scaling: windows and shutters, ventilation with heat recovery. | ||

- | \\ -Normal laws used for high added value components, for which prices have a higher reduction potential due to industrial scaling: windows and shutters, ventilation with heat recovery. | + | * Ventilation: standard deviation is chosen equal to the investment reduction reached by reusing the existing supply distribution system = €6/m²TFA. |

- | | + | |

- | \\ -Ventilation: standard deviation is chosen equal to the investment reduction reached by reusing the existing supply distribution system = €6/m²TFA. | + | |

[{{ :picopen:total_cost_enerphit_step_1.png?400|Figure 6: Cumulated probability of total cost for EnerPHit Step 1 (cost analysis by phEco, uncertainty propagation by Crystal Ball). Reference cost for low-energy variant in red (560 €/m²)}}] | [{{ :picopen:total_cost_enerphit_step_1.png?400|Figure 6: Cumulated probability of total cost for EnerPHit Step 1 (cost analysis by phEco, uncertainty propagation by Crystal Ball). Reference cost for low-energy variant in red (560 €/m²)}}] | ||

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Two decision variables are investigated: | Two decision variables are investigated: | ||

- | \\ - Lambda insulation for walls (0.022 to 0.038 W/m.K), linear cost dependency (+8% cost for lowest lambda). Thermal bridge coefficients are kept constant. | + | * Lambda insulation for walls (0.022 to 0.038 W/m.K), linear cost dependency (+8% cost for lowest lambda). Thermal bridge coefficients are kept constant. |

- | \\ - Ventilation heat recovery (79% to 95%), linear cost dependency (+20% cost for highest efficiency). | + | * Ventilation heat recovery (79% to 95%), linear cost dependency (+20% cost for highest efficiency). |

A stochastic simulation to find minimum total cost while respecting constraint on heating demand (<25 kWh/m².a) gives the following results: | A stochastic simulation to find minimum total cost while respecting constraint on heating demand (<25 kWh/m².a) gives the following results: |

planning/refurbishment_with_passive_house_components/economic_analysis_for_the_retrofit_of_a_detached_single_family_house_to_the_enerphit_standard.txt · Last modified: 2019/02/28 09:41 by cblagojevic