basics:affordability:investing_in_energy_efficiency:are_passive_houses_cost-effective
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basics:affordability:investing_in_energy_efficiency:are_passive_houses_cost-effective [2015/01/17 19:28] – [An analysis using the example of a single-family house] wolfgangfeist@googlemail.com | basics: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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+ | ====== Are Passive Houses cost-effective? | ||
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+ | Varying opinions about the Passive House abound, not only on the internet. It is still claimed by some that Passive Houses are not affordable. And others claim that a profit of over " | ||
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+ | Anticipating the results of a serious analysis, it suffices to say that none of these statements are correct. Under the present conditions in Germany and Austria, the construction of Passive Houses is profitable if they are built and designed competently. But quick profits should not be expected. The Passive House is more stable, more secure and more worthwhile than the alternative. Whoever wants “easy money” should try something else (...of course, the risk of losing a lot of money will also be greater).\\ | ||
+ | \\ | ||
+ | ===== An analysis using the example of a single-family house ===== | ||
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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 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}// | ||
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+ | * 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/ | ||
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+ | * 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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+ | |{{ : | ||
+ | |// | ||
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+ | |{{ : | ||
+ | |//**__Fig. 2:__ The most important step from the " | ||
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+ | The existing house was also a mostly **thermal bridge free construction**; | ||
+ | * this will have a considerably smaller build-up height and is even cheaper; | ||
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+ | * 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. | ||
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+ | * 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, | ||
+ | \\ )). | ||
+ | The savings due to the simpler ceiling construction will not be taken into account either.\\ | ||
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+ | |{{ : | ||
+ | |//**__Fig. 3:__ Floor plan of the single family Passive House (ground\\ floor). Due to intelligent planning the ventilation ducts are\\ very short.**// | ||
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+ | |{{ : | ||
+ | |//**__Fig. 4:__ Floor plan of the upper floor of the Passive House.**// | ||
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+ | All external walls are evenly plastered, the roof structures contain airtight membranes, which are plastered up in the knee wall area. Based on existing experience, **airtightness corresponding to n< | ||
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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 }// . | ||
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+ | * 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**__).\\ | ||
+ | \\ | ||
+ | |{{ : | ||
+ | |//**__Fig. 5:__ Passive House suitable windows. Highly insulating windows\\ are indispensable in a Passive House. Besides saving energy, such\\ windows have many additional advantages, see this page:\\ [[Planning: | ||
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+ | With the improvement of the details as described above, the Passive House Standard has already been achieved. **The existing heating** (boiler in storage room) can be retained. Nevertheless, | ||
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+ | ===== What will all this cost? ===== | ||
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+ | The improved thermal insulation necessitates more insulation materials and its application, | ||
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+ | * Additional costs for thermal insulation in wall, roof and floor slab: € 4800 //{ in the 2015 case reduced by 500 € }// | ||
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+ | * 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 }// | ||
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+ | * 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 // | ||
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+ | * 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)\\ | ||
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+ | => **Sum of additional capital outlay: € 14000**\\ | ||
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+ | in 2015, it's reduced already to € 9500 and still getting less expensive\\ | ||
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+ | 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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+ | ===== Financing the house ===== | ||
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+ | We will assume that there is no more capital available and the additional investment must be financed through a **higher mortgage loan**. At an interest rate of 4.7% and 1.6% repayment rate, this means an additional annual interest repayment of **€ 945**. | ||
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+ | However, for the construction of a Passive House, the house builder can apply for the** KfW’s (Development Loan Corporation) " | ||
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+ | It gets even better: instead of using about 13300 kWh fuel oil or natural gas, the Passive House only requires approximately 2290 kWh fuel for heating and 350 kWh electricity for the ventilation system. **This saves € 715 per year** - at 2009 fuel costs (which was 65 Cent per litre of heating oil; 2011 the savings are already € 825), while electricity for the ventilation system costs about **€ 65 per year**.\\ | ||
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+ | | **Investments and savings for a Passive House (149 m²)\\ - __Comparison for the first few years__ -**\\ \\ Additional investment* compared with a standard house: //**€ 15 000**//\\ \\ additional repayment in the first year (bank): //**+ € 945/ | ||
+ | \\ | ||
+ | |{{ : | ||
+ | |//**__Fig. 6:__ Temporal course of the cost burden of a normal house\\ (red) and a Passive House (green). From the outset, the annual\\ cost burden is lower for the energy-efficient house. And after\\ 30 years, there will be the “golden end“: the building loan will\\ have been paid off by then and the family will profit from the\\ extremely low energy consumption alone.**// | ||
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+ | ===== Is it worthwhile? ===== | ||
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+ | In contrast with a “normal house“, the cost burden is considerably less for the construction of a Passive House, even if energy costs do not increase in the future. The Passive House Standard is therefore economically attractive – even though the profits are not as enormously high as sometimes promised. But the house builder does benefit from a few more things.\\ | ||
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+ | ===== Enjoyment of life! ===== | ||
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+ | Energy consumption is so low in the Passive House that the occupants **no longer have to worry about increasing energy prices**. The house is practically independent of imported energy sources - it can even be **supplied with renewable energy alone** if a compact heat pump unit is installed and a green electricity provider is chosen (or if shares in a wind-energy generator are bought or wood pellet heating is used or ...). | ||
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+ | But there are even more benefits: there are **no mildewed walls, no cold draughts, no cold feet** in the Passive House. Instead, there is always **fresh air and less indoor air pollution in the house**.\\ | ||
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+ | As Robert Hastings stated at the 8th International Passive House Conference: // | ||
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+ | The occupants can also profit from the **reduced environmental impact**: the consequences of climate change affect everyone; in Passive Houses, climate-damaging emissions are reduced by a factor of 4 when compared with “normal” new buildings. The more people decide in favour of energy-efficient construction of new buildings or renovation of existing buildings, the more effective the contribution to environmental protection will be. | ||
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+ | These are the individual advantages to be gained – but doesn’t the Passive House builder also benefit if services are provided regionally, and not through energy commodities imported from unstable parts of the world? If a Passive House, like the one shown previously, currently costs € 14000 “more” than an ordinary new building, then 75 % of this € 14000 is rendered as **trades services**. The remaining 25 % stems mainly from European value creation. This preserves and creates **employment** and can even be “profitable”. We need not discuss the costs that can be saved if we don’t have to deal with international tensions, there is enough of that in the newspapers every day. This too contributes to the enjoyment of life, because **" | ||
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+ | ===== Saving costs with energy efficiency – in the long term ===== | ||
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+ | Saving energy is what mainly contributes to relieving the burden in the long term – fortunately, | ||
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+ | The following table and **__Fig. 6__** show the average result of the financial mathematical calculation over a period of 30 years. There is another benefit, as Fig. 6 shows:\\ | ||
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+ | **Even after 30 years one can continue to profit from reduced energy costs, because the inactive components of the Passive House continue to function as long as the house stands.**\\ | ||
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+ | Table showing the annual average costs over a period of 30 years based on the financial mathematical calculation method:\\ | ||
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+ | | **Investment and savings for a Passive House (149 m²)\\ - __ financial mathematical calculation over a period of 30 years nominally__ -**\\ \\ Additional investment *) compared with a standard house //**€ 15000**//\\ \\ Average additional repayment to the bank): //**+ € 945/ | ||
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+ | ==== Boundary conditions: ==== | ||
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+ | KfW credit incentive ESH40/ | ||
+ | Interest (nominal) 2.1 % p.a. 100% payment, 30 year duration, here: | ||
+ | * without repayment period. First few years. Cost-based usage duration: 30 years, | ||
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+ | * interest rate for calculation 4.7 % p.a. (mortgage loans, nominal, effective) | ||
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+ | * fuel price: 6.5 cents/ | ||
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+ | * electricity 18 cents/kWh (actual 2006), | ||
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+ | * energy price increase equal to inflation rate of 1.6% p.a. (nominal).\\ | ||
+ | \\ | ||
+ | **Remark, update 2015**: | ||
+ | Fuel prices have been up (more than 9 cents/kWh) and down (now again in the same range as 2006). These hefty short term changes are consistent with our evaluation in [[basics: | ||
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+ | Capital costs have been falling all the time - interest rates are really low (2015), in the range of 2%/yr for a mortage loan (nominal). The internal interest rates used in the analysis here are higher - thus overestimating the capital costs of the energy saving measures. Also, the investment costs of these measures have been reduced with better and less expensive solutions getting available. | ||
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+ | Conclusion: The economic conditions for improvement of insulation and other energy conservation measures are even better now than these have been in 2006. The analysis documented here is on the save side. | ||
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+ | **Method**: The actual cash values of all cash flows are determined nominally and converted into constant annuity values over 30 years. The components used have an expected usage duration of much more than 30 years (apart from worn out parts which are easily replaceable and also exist in conventional buildings). Maintenance costs remain unchanged.\\ | ||
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+ | ==== Remark about possible changes in the boundary conditions: ==== | ||
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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 (" | ||
+ | * 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). | ||
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+ | * "Much can happen" | ||
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+ | * Regarding the conditions for funding by the KfW, according to the Development Corporation, | ||
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+ | * The (nominal) market interest rate in turn is strongly influenced by the inflation rate. Due to this fact, the core statement of the " | ||
+ | \\ | ||
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+ | ==== Remark about the boundary conditions in 2015: ==== | ||
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+ | [{{: | ||
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+ | All of the above is still true - although boundary conditions have changed. And these conditions changed in the direction of: | ||
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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. | ||
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+ | * 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. | ||
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+ | 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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+ | ===== See also ===== | ||
+ | [[basics: | ||
+ | [[basics: | ||
+ | [[basics: |