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basics:affordability:investing_in_energy_efficiency:are_passive_houses_cost-effective [2018/04/18 10:20] – [Remark about the boundary conditions in 2015:] kdreimanebasics:affordability:investing_in_energy_efficiency:are_passive_houses_cost-effective [2022/04/04 16:24] (current) – [Remark about the boundary conditions in 2015:] wfeist
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 The house in **__Fig. 1__** is a conventional detached house with a floor space of 149 m². It's not a Passive House – but it would be quite easy to build it as a Passive House. For that, the following details would have to be improved: The house in **__Fig. 1__** is a conventional detached house with a floor space of 149 m². It's not a Passive House – but it would be quite easy to build it as a Passive House. For that, the following details would have to be improved:
   * The external wall insulation should be increased to 300 mm and the brickwork should be reduced to 115 mm lime sandstone; this way the external wall will only be slightly thicker than it was before (about 25 mm) (see __**Fig. 2**__).//{ Remark from 2015: Because of the improvements in Passive House windows, a new built passive house now would only need some 200 mm of insulation (0.032 W/(mK)); the external wall will therefor be only 370 mm thick and thus thinner than the original one}//    * The external wall insulation should be increased to 300 mm and the brickwork should be reduced to 115 mm lime sandstone; this way the external wall will only be slightly thicker than it was before (about 25 mm) (see __**Fig. 2**__).//{ Remark from 2015: Because of the improvements in Passive House windows, a new built passive house now would only need some 200 mm of insulation (0.032 W/(mK)); the external wall will therefor be only 370 mm thick and thus thinner than the original one}// 
 +
   * In the roof, the insulation under the rafters and on the top ceiling should be increased from 100 to 225 mm each; between the rafters and in the ceiling it should remain 140 mm as before, with a thermal conductivity of 0.035 W/(mK).//{Remark 2015: The roof will have to met some 0.12 W/(m²K), which can be achieved in a lot of different ways and what will not add costs if done in a propper way}//    * In the roof, the insulation under the rafters and on the top ceiling should be increased from 100 to 225 mm each; between the rafters and in the ceiling it should remain 140 mm as before, with a thermal conductivity of 0.035 W/(mK).//{Remark 2015: The roof will have to met some 0.12 W/(m²K), which can be achieved in a lot of different ways and what will not add costs if done in a propper way}// 
 +
   * On the floor slab a total of 250 mm instead of 150 mm of PS insulation boards with a heat conductivity 0.035 W/(mK) should be used.//{ Now, 2015, the 150 mm of the original Low-Energy-Home solution will be sufficient; no extra costs}// \\   * On the floor slab a total of 250 mm instead of 150 mm of PS insulation boards with a heat conductivity 0.035 W/(mK) should be used.//{ Now, 2015, the 150 mm of the original Low-Energy-Home solution will be sufficient; no extra costs}// \\
 \\ \\
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 The existing house was also a mostly **thermal bridge free construction**; except for the increase in insulation thicknesses and the installation of the windows outside in front of the brickwork, no changes are required. In place of the wooden beam ceiling on the ground floor used in the original construction, it is supposed that a **concrete ceiling** is used for the Passive House variation; The existing house was also a mostly **thermal bridge free construction**; except for the increase in insulation thicknesses and the installation of the windows outside in front of the brickwork, no changes are required. In place of the wooden beam ceiling on the ground floor used in the original construction, it is supposed that a **concrete ceiling** is used for the Passive House variation;
   * this will have a considerably smaller build-up height and is even cheaper;   * this will have a considerably smaller build-up height and is even cheaper;
 +
   * this way it will be possible to gain more room height in the upper floor in spite of the slightly thicker insulation in the roof while the external height of the house remains the same.   * this way it will be possible to gain more room height in the upper floor in spite of the slightly thicker insulation in the roof while the external height of the house remains the same.
 +
   * the living area may slightly increase due to this, but we will not include the increased living space (a marginal 1 m²) in the calculation, so that the comparison does not become even more complicated due to a change in the reference areas.((**Note**: A “trick” that is often used in cost-effectiveness calculations is to alter the plans in such a way that different living or floor areas result. Since the value of such areas can be set to be high or low and this has very little to do with the construction costs, the calculation becomes confusing.\\ \\ **It is better to keep the reference areas the same.** Here, we have actually increased the area a little, but without taking it into account.\\   * the living area may slightly increase due to this, but we will not include the increased living space (a marginal 1 m²) in the calculation, so that the comparison does not become even more complicated due to a change in the reference areas.((**Note**: A “trick” that is often used in cost-effectiveness calculations is to alter the plans in such a way that different living or floor areas result. Since the value of such areas can be set to be high or low and this has very little to do with the construction costs, the calculation becomes confusing.\\ \\ **It is better to keep the reference areas the same.** Here, we have actually increased the area a little, but without taking it into account.\\
 \\ )). \\ )).
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   * Low-e triple-glazing in Passive House suitable frames should be installed in place of the original double-glazed windows (__**Fig.5**__). The** window U-value will be reduced to 0.75 W/(m²K) on average**, including the installation thermal bridge. The average g-value of the glazing is 0.54. //{ Remark from 2011: This year, new products with even better windows come to the market. The U-values can be reduced down to 0,65 W/(m²K), the g-values increased to 0,65. Even more important: The new windows have much smaller frame areas, thus increasing the light and the solar energy gains. All this together makes it much easier to achieve the Passive House Standard and allows a reduction of the thickness, as mentioned discussing the exterior walls }// .   * Low-e triple-glazing in Passive House suitable frames should be installed in place of the original double-glazed windows (__**Fig.5**__). The** window U-value will be reduced to 0.75 W/(m²K) on average**, including the installation thermal bridge. The average g-value of the glazing is 0.54. //{ Remark from 2011: This year, new products with even better windows come to the market. The U-values can be reduced down to 0,65 W/(m²K), the g-values increased to 0,65. Even more important: The new windows have much smaller frame areas, thus increasing the light and the solar energy gains. All this together makes it much easier to achieve the Passive House Standard and allows a reduction of the thickness, as mentioned discussing the exterior walls }// .
 +
   * A modern Passive House suitable **ventilation system with an effective heat recovery of 92%** should be installed. The concept for air distribution has been redesigned (see __**Fig. 3 and 4**__).\\   * A modern Passive House suitable **ventilation system with an effective heat recovery of 92%** should be installed. The concept for air distribution has been redesigned (see __**Fig. 3 and 4**__).\\
 \\ \\
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   * Additional costs for thermal insulation in wall, roof and floor slab: € 4800 //{ in the 2015 case reduced by 500 € }//    * Additional costs for thermal insulation in wall, roof and floor slab: € 4800 //{ in the 2015 case reduced by 500 € }//
 +
   * Additional investment for Passive House windows: € 5400 //{ That was until 2010; but now, windows with even better performance are available on the market - and these cost less, some 1600 € will be covering all difference costs to conventional windows }//    * Additional investment for Passive House windows: € 5400 //{ That was until 2010; but now, windows with even better performance are available on the market - and these cost less, some 1600 € will be covering all difference costs to conventional windows }// 
-  * Additional costs for ventilation with heat recovery: € 5200 //{ So far, even in 2015, this did not change much. But: now developments are in the pipe to reduce these costs significantly }//+ 
 +  * Additional costs for ventilation with heat recovery: € 5200 // So far, even in 2015, this did not change much. But: now developments are in the pipe to reduce these costs significantly // 
   * Less costs for smaller oil tank, boiler; radiators and distribution pipes are no longer required, post-heater coils instead: - € 1400 (the additional useable area is not taken into account)\\   * Less costs for smaller oil tank, boiler; radiators and distribution pipes are no longer required, post-heater coils instead: - € 1400 (the additional useable area is not taken into account)\\
 +
 => **Sum of additional capital outlay: € 14000**\\ => **Sum of additional capital outlay: € 14000**\\
 \\ \\
-{ in 2015, it's reduced already to € 9500 and still getting less expensive}\\+in 2015, it's reduced already to € 9500 and still getting less expensive\\
 \\ \\
 To be on the safe side, we will assume that an additional total investment of **€ 15000 ** was necessary in 2010, and in 2015 this is already reduced to less than 10000 €. This was about **8%** of the total average construction costs for such a house in Germany - and it's less than 5% alreday in 2015 with still existing potentials to lower the extra investment even more.\\ To be on the safe side, we will assume that an additional total investment of **€ 15000 ** was necessary in 2010, and in 2015 this is already reduced to less than 10000 €. This was about **8%** of the total average construction costs for such a house in Germany - and it's less than 5% alreday in 2015 with still existing potentials to lower the extra investment even more.\\
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 Interest (nominal) 2.1 % p.a. 100% payment, 30 year duration, here: Interest (nominal) 2.1 % p.a. 100% payment, 30 year duration, here:
   * without repayment period. First few years. Cost-based usage duration: 30 years,   * without repayment period. First few years. Cost-based usage duration: 30 years,
 +
   * interest rate for calculation 4.7 % p.a. (mortgage loans, nominal, effective)   * interest rate for calculation 4.7 % p.a. (mortgage loans, nominal, effective)
 +
   * fuel price: 6.5 cents/kWh(actual 2006),   * fuel price: 6.5 cents/kWh(actual 2006),
 +
   * electricity 18 cents/kWh (actual 2006),   * electricity 18 cents/kWh (actual 2006),
 +
   * energy price increase equal to inflation rate of 1.6% p.a. (nominal).\\   * energy price increase equal to inflation rate of 1.6% p.a. (nominal).\\
 \\ \\
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 This page was last updated at the end of April 2006. Prices for energy, interest rates and the requirements for incentives may change very quickly. However, such changes only have a small influence on the core statement ("yellow table") Why? This page was last updated at the end of April 2006. Prices for energy, interest rates and the requirements for incentives may change very quickly. However, such changes only have a small influence on the core statement ("yellow table") Why?
-  * The economic viability of building measures that are taken is determined not so much by the current market as it is by the average economical constraints for the duration of usage of a building, (which is more than 30 years).+  * The economic viability of building measures that are taken is determined not so much by the current market as it is by the average economical constraints for the duration of usage of a building (which is more than 30 years). 
   * "Much can happen" during this period. But: Today it is possible for the building constructor to have the interest rate conditions fixed at a comparatively low level for the next twenty or thirty years. It is rather unlikely that energy will become cheaper on average in the next few decades than it is now. The most important parameters are relatively certain, even if current fluctuations occur from time to time which give a different impression.   * "Much can happen" during this period. But: Today it is possible for the building constructor to have the interest rate conditions fixed at a comparatively low level for the next twenty or thirty years. It is rather unlikely that energy will become cheaper on average in the next few decades than it is now. The most important parameters are relatively certain, even if current fluctuations occur from time to time which give a different impression.
 +
   * Regarding the conditions for funding by the KfW, according to the Development Corporation, it intends to keep the equivalent value of the funding conditions at the same level (difference to the market rate). This means that this boundary condition will also remain constant.   * Regarding the conditions for funding by the KfW, according to the Development Corporation, it intends to keep the equivalent value of the funding conditions at the same level (difference to the market rate). This means that this boundary condition will also remain constant.
 +
   * The (nominal) market interest rate in turn is strongly influenced by the inflation rate. Due to this fact, the core statement of the "yellow table" remains applicable, even if the values change nominally. All values cannot be predicted to "exactly within a few Euros". However, the risk is highest for owners who build houses with high energy consumption.\\   * The (nominal) market interest rate in turn is strongly influenced by the inflation rate. Due to this fact, the core statement of the "yellow table" remains applicable, even if the values change nominally. All values cannot be predicted to "exactly within a few Euros". However, the risk is highest for owners who build houses with high energy consumption.\\
 \\ \\
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   * Even higher energy prices; future prices of energy are agreed now to be in the range of 8 Cent/kWh (end use heating energy), which is more than the price we used for the comparison above.   * Even higher energy prices; future prices of energy are agreed now to be in the range of 8 Cent/kWh (end use heating energy), which is more than the price we used for the comparison above.
 +
   * Even lower real interest rates. That is an effect of a lot of capital being available on the market - and the frustration resulting from the bubbles in the past. This is not going to change soon: so 2% real interest rate is more probable to be the future boundary condition.   * Even lower real interest rates. That is an effect of a lot of capital being available on the market - and the frustration resulting from the bubbles in the past. This is not going to change soon: so 2% real interest rate is more probable to be the future boundary condition.
  
-But, what changed much more, are the extra investment costs of building a passive house now, in 2015: Triple pane glazings do now have already more than 70% market penetration and have dropped in price significantly. Also the Passive house windows are much less expensive since 2014 - and the same will become true for the ventilation systems. So, it's no longer 14000 €, it's less than 9500 € you need in addition to build a well working passive house (140 m²). And that difference changes the picture in a dramatic way (see figure ): In 2015 building a new residential building, and not building a passive house - that is just foolish from an economic point of view. +But, what changed much more, are the extra investment costs of building a passive house now, in 2015: Triple pane glazings do now have already more than 70% market penetration and have dropped in price significantly. Also the Passive house windows are much less expensive since 2014 - and the same will become true for the ventilation systems. So, it's no longer 14000 €, it's less than 9500 € you need in addition to build a well working passive house (140 m²). And that difference changes the picture in a dramatic way (see figure 7): In 2015 building a new residential building, and not building a passive house - that is just foolish from an economic point of view. 
  
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 [[basics:affordability:investing_in_energy_efficiency:superior_thermal_protection_is_affordable|]]\\ [[basics:affordability:investing_in_energy_efficiency:superior_thermal_protection_is_affordable|]]\\
-[[basics:affordability:investing_in_energy_efficiency:economic_feasibility_of_passive_house_retrofits|]]+[[basics:affordability:investing_in_energy_efficiency:economic_feasibility_of_passive_house_retrofits|]]  {{:picopen:members_only.png?25}}
basics/affordability/investing_in_energy_efficiency/are_passive_houses_cost-effective.1524039603.txt.gz · Last modified: 2018/04/18 10:20 by kdreimane