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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 [2016/03/31 14:51] – [See also] kdreimane
+++ 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
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 Fixed costs are known for each measure, for example wall insulation: scaffolding, exterior acrylic render, and displacement of drainpipes sums up to €36/m².
 [{{ :picopen:t._annual_costs_with_co2_tax.png?450|Figure 3: Total annual cost including CO2 tax with prices of electricity and CO2 in France (FR) and Germany (DE).}}]
-The Comparison worksheet in PHPP 9 enables us to compare two project variants, including maintenance costs like filter replacement. We’ll assume the following financial hypothesis:
+The Comparison worksheet in PHPP 9 enables us to compare two project variants, including maintenance costs like filter replacement.
+We’ll assume the following financial hypothesis:
 \\ -real interest rate 2%,
 \\ -financial assessment period = 30 years,
 \\ -no Residual Value,
 \\ -heating and hot water price = €0.15/kWh
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 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).
 \\ -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.
 A few measures could be further optimized:
 \\ -The position of the ventilation unit and layout of extract ducts
 \\ -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.}}]
 **4. Detailed cost analysis with phEco**
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 **5. Sensitivity analysis: is the economic performance robust?**
 \\ The energy efficiency market is subject to high price variability. We can use the phEco model to find out if investing in EnerPHit is robust, given uncertainty on energy tariffs and component prices (wall insulation, windows and ventilation). Investment robustness is defined here as the probability of a total cost lower than the low-energy alternative (€560/m²TFA present value). A sensitivity analysis is carried out with the Crystal Ball Excel Plug-In.
 \\ Realistic price distributions are set up and the following parameters are fixed constant:
 \\ -Financial evaluation period = 30 years
 \\ -Average residual value of components after financial evaluation period = 10 years.
 \\ -Thermal performance of components
 Sensitivity assumptions:
 \\ -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.
 [{{ :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:sensitivity_analysis.png?300|Figure 7: Sensitivity analysis for EnerPHit step 1 total cost, contribution to variance}}]
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 **6. Was there room for optimization: would higher efficiency pay off?**
-\\ The ventilation layout could be improved: extract ducts were placed in the ceiling insulation to maximize room height, the ventilation unit is placed in the building core and does not have the highest efficiency on the market. We estimate a maximum achievable heat recovery rate of 90% instead of the current 79%.
+\\ The ventilation layout could be improved: extract ducts were placed in the ceiling insulation to maximize room height, the ventilation unit is placed in the building core and does not have the highest efficiency on the market. We estimate a maximum achievable heat recovery rate of 95% instead of the current 79%.
 \\ The exterior insulation could have a lower lambda value for the same thickness, down to 0.021W/m.K. Windows could not be significantly improved under current market conditions.
 \\ The reference EnerPHit total cost with actual price is €535/m²TFA.
 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.
 \\ -	Ventilation heat recovery (79% to 95%), linear cost dependency (+20% cost for highest efficiency).