Hello,
I am currently wondering how it would be practically possible to follow the ideal sequence for building a house in order to maintain the most accurate cost-effectiveness for the various components within the agreed budget.
Many homeowners always ask themselves, "Is this worth it?" But unfortunately, the answer usually comes much later, after the damage has already been done.
For me, the heating load calculation (HLB) provides a key answer regarding the cost-effectiveness of a house or its components. However, this calculation is usually only done once all components are already decided or even built. For prefab home suppliers/general contractors, it is probably even more expensive to maintain this kind of flexibility.
We have about €10,000 (around $11,000) left that we want to invest wisely. The first idea was to improve the masonry from T9 (unfilled) to T7 (filled). This should save real money later on. Assuming we have a quote from the mason with a €4,000 (about $4,400) surcharge compared to the T9. Basically, only the HLB can tell me approximately how many years it will take for the saved heating costs to offset this extra cost. I am aware that this also depends on how efficiently my heating system converts electricity into heat, how cold it will be in the coming years, and so on. But you can still get a rough estimate. Not to forget that the investment will also incur interest costs, which will have a compounding effect over the years of repayment. But all of this can theoretically be calculated.
So, would it be helpful to have the HLB done in advance and analyze different values along with the corresponding costs? Which, incidentally, is not cheap to commission itself... and I believe that is the main reason why this is not usually done in practice, right?
I am currently wondering how it would be practically possible to follow the ideal sequence for building a house in order to maintain the most accurate cost-effectiveness for the various components within the agreed budget.
Many homeowners always ask themselves, "Is this worth it?" But unfortunately, the answer usually comes much later, after the damage has already been done.
For me, the heating load calculation (HLB) provides a key answer regarding the cost-effectiveness of a house or its components. However, this calculation is usually only done once all components are already decided or even built. For prefab home suppliers/general contractors, it is probably even more expensive to maintain this kind of flexibility.
We have about €10,000 (around $11,000) left that we want to invest wisely. The first idea was to improve the masonry from T9 (unfilled) to T7 (filled). This should save real money later on. Assuming we have a quote from the mason with a €4,000 (about $4,400) surcharge compared to the T9. Basically, only the HLB can tell me approximately how many years it will take for the saved heating costs to offset this extra cost. I am aware that this also depends on how efficiently my heating system converts electricity into heat, how cold it will be in the coming years, and so on. But you can still get a rough estimate. Not to forget that the investment will also incur interest costs, which will have a compounding effect over the years of repayment. But all of this can theoretically be calculated.
So, would it be helpful to have the HLB done in advance and analyze different values along with the corresponding costs? Which, incidentally, is not cheap to commission itself... and I believe that is the main reason why this is not usually done in practice, right?
How much contingency do you have overall? 10,000 euros is not much when it comes to the exterior landscaping. We roughly estimated having about 20,000 euros left and are now glad we can afford to do quite a few more things outside. Economically, you won’t be able to recover your 10,000 euros through any energy efficiency investment, at least not with a building constructed to the current EnEV standards!
Ben1000 schrieb:
How much buffer do you have in total? 10,000 euros is not much when it comes to landscaping. We roughly estimated having about 20,000 euros left and are now happy to be able to have a few more outdoor things done. Economically, you won’t be able to recover your 10,000 euros with any energy efficiency investment, at least not with construction according to current EnEV standards!Approximately an additional 20,000 euros. For the landscaping, we will initially only have lawn (around 150m² (1600 sq ft)). The garden is already prepared (topsoil leveled).
I am not talking about investing the entire 10,000 euros right away. For now, it’s about the masonry work, which should cost a few thousand euros.
How do you come to the conclusion that “economically, you won’t be able to recover your 10,000 euros with any energy efficiency investment, at least not with construction according to current energy standards”?
We have about 240m² (2600 sq ft) of exterior wall. Upgrading from T9 to T7 would be an improvement of 0.05 W/m²K. Assuming an average indoor temperature of 22°C (72°F) and an average outdoor temperature of 9°C (48°F) during the heating season (outdoor temperature below 16°C (61°F)),
I get: 270m² (2900 sq ft) * 13K * 0.05 W/m²K = 175.5W
With about 2000 operating hours of the heat pump, that results in 351 kWh/year heating energy savings.
At an average annual performance factor of 2.5, that corresponds to 140 kWh electricity consumption per year. At €0.27 (27 cents) per kWh, this is almost €40 savings per year.
Where is the calculation mistake?
N
nordanney22 Dec 2015 09:38Tichu78 schrieb:
With an average annual performance factor of 2.5, that results in 140 kWh electricity consumption per year. At €0.27 per kWh, that’s just under €40 savings per year.
Where is the calculation error?... no calculation error. After 100 years, you will have recouped your additional costs for the masonry (assuming you actually save that much);)
nordanney schrieb:
... no calculation error. After 100 years, you will have recovered your additional costs for the masonry (assuming you actually save that much);)If you also take into account the interest on the capital, it will take even longer. 😀
Musketier schrieb:
If you also calculate the interest on the capital, it takes even longer. 😀 If the interest rate is more than 1%, it takes an infinite amount of time.
S
Steffen8022 Dec 2015 10:19Exactly... all quite silly 🙂 That’s why we’re building with 36.5 cm (14.4 inches) masonry plus gas heating... done. No underfloor heating, heat pumps nonsense, or other eco gimmicks. And I hope our neighbors spare us from annoying outdoor units as well. Those things are like the plague... I already know of 4 cases where homeowners ended up in disputes because of the noise at night!!!
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