ᐅ Is it worth investing in insulation beyond the standard requirements for new construction?
Created on: 8 Jul 2015 19:25
G
Grym
Concepts like these from the prefab house provider Kampa initially sound quite good, and there are many people in forums who believe that nowadays you shouldn’t build a house with a U-value above 0.15.
On the other hand, when you calculate the raw numbers, I struggle to understand how insulation beyond what is necessary can actually be cost-effective.
Let’s take a 140-150 sqm (1500-1600 sq ft) house with 1.5 stories as an example. This would have an exterior wall surface area of about 170 sqm (1830 sq ft) (excluding roof, top floor ceiling, foundation slab, and windows, with a relatively high knee wall as we plan).
The local provider, in a standard case, offers a U-value of 0.21, while Kampa advertises 0.11. According to a U-value calculator, the local provider’s wall consumes 16 kWh/m² per year, and the 0.11 U-value leads to 7 kWh/m² per year. Calculated over the surface area, that’s 2,720 kWh versus 1,190 kWh. With an air-to-water heat pump with an annual performance factor of 4.1 (yes, these are available for about 4,000 EUR – greetings to the purple forum), this equates to 663 kWh_el versus 290 kWh_el. So, you save about 373 kWh just from the exterior wall construction. Variant A: standard solid construction and Variant B: passive house wall. In strict monetary terms, that’s about 93.25 EUR per year or 7.77 EUR monthly installments.
Over 20 years, the difference adds up to 1,865 EUR. In 20 years!!!
Of course, additional savings come from insulating the foundation slab, roof, and better windows in a passive house, but those also require separate higher investments.
On the other hand, a photovoltaic self-consumption system can save a lot, especially during transitional seasons (self-generated electricity costs less than half compared to grid electricity). This is particularly true for an energy-saving standard house, which benefits significantly from PV power during these periods, unlike a KFW40-level house where heating is mostly needed only in the coldest winter months.
The question in the end is: is it even worth it, or is the current energy-saving regulation standard already so strict that the economic feasibility has long been exceeded?
There’s also a bit of a question between timber frame prefab houses versus solid construction. Only with a timber frame prefab house can you achieve a high insulation value for the exterior facade with a reasonably manageable wall thickness (in cm). In my opinion, this is the only advantage of a timber frame prefab house compared to solid construction.
On the other hand, when you calculate the raw numbers, I struggle to understand how insulation beyond what is necessary can actually be cost-effective.
Let’s take a 140-150 sqm (1500-1600 sq ft) house with 1.5 stories as an example. This would have an exterior wall surface area of about 170 sqm (1830 sq ft) (excluding roof, top floor ceiling, foundation slab, and windows, with a relatively high knee wall as we plan).
The local provider, in a standard case, offers a U-value of 0.21, while Kampa advertises 0.11. According to a U-value calculator, the local provider’s wall consumes 16 kWh/m² per year, and the 0.11 U-value leads to 7 kWh/m² per year. Calculated over the surface area, that’s 2,720 kWh versus 1,190 kWh. With an air-to-water heat pump with an annual performance factor of 4.1 (yes, these are available for about 4,000 EUR – greetings to the purple forum), this equates to 663 kWh_el versus 290 kWh_el. So, you save about 373 kWh just from the exterior wall construction. Variant A: standard solid construction and Variant B: passive house wall. In strict monetary terms, that’s about 93.25 EUR per year or 7.77 EUR monthly installments.
Over 20 years, the difference adds up to 1,865 EUR. In 20 years!!!
Of course, additional savings come from insulating the foundation slab, roof, and better windows in a passive house, but those also require separate higher investments.
On the other hand, a photovoltaic self-consumption system can save a lot, especially during transitional seasons (self-generated electricity costs less than half compared to grid electricity). This is particularly true for an energy-saving standard house, which benefits significantly from PV power during these periods, unlike a KFW40-level house where heating is mostly needed only in the coldest winter months.
The question in the end is: is it even worth it, or is the current energy-saving regulation standard already so strict that the economic feasibility has long been exceeded?
There’s also a bit of a question between timber frame prefab houses versus solid construction. Only with a timber frame prefab house can you achieve a high insulation value for the exterior facade with a reasonably manageable wall thickness (in cm). In my opinion, this is the only advantage of a timber frame prefab house compared to solid construction.
Interesting topic. However, there are some terms I didn’t quite understand:
The share of wind gas
and biogas.
I am particularly interested in how wind gas is produced and how it can be utilized by homeowners or small-scale builders. I’m not very familiar with this and have never really read much about it.
Regarding biogas, I am quite sure that—besides a huge amount of substrate residues—it is mainly used on-site in plants to generate electricity via generators, which is then sold to local energy utilities under fixed purchase agreements. Possibly, there is no gas available from this process for homeowners.
But I could be wrong and am happy to learn more.
The share of wind gas
and biogas.
I am particularly interested in how wind gas is produced and how it can be utilized by homeowners or small-scale builders. I’m not very familiar with this and have never really read much about it.
Regarding biogas, I am quite sure that—besides a huge amount of substrate residues—it is mainly used on-site in plants to generate electricity via generators, which is then sold to local energy utilities under fixed purchase agreements. Possibly, there is no gas available from this process for homeowners.
But I could be wrong and am happy to learn more.
I have heard of "mini biogas systems" for "household use" and that biogas can power combined heat and power (CHP) units. In practice, however, I believe this is not very common.
Wind gas, on the other hand, is completely unfamiliar to me—even the term itself—and is my primary interest. It brought a very broad smile to my face early on and was therefore valuable. That’s a great way to start the day.
Wind gas, on the other hand, is completely unfamiliar to me—even the term itself—and is my primary interest. It brought a very broad smile to my face early on and was therefore valuable. That’s a great way to start the day.
I was not familiar with the term either, but Wikipedia knows everything:
Power-to-Gas (abbreviated PtG or P2G) refers to a chemical process in which a fuel gas is produced by water electrolysis, sometimes followed by methanation, using electricity from renewable energy sources (RES). This gas is also called renewable energy gas (RE gas). Depending on the type of renewable energy used, the gas may also be referred to as wind gas, solar gas, or similar. Depending on its chemical composition, the gas is alternatively called methane or hydrogen instead of “gas.” The produced fuel gas can either be fed into the public gas grid, stored seasonally in cavern storage facilities, or used in transportation. Additionally, there are concepts for integrated storage power plants based on reversible fuel cells, a technology now introduced to the market that promises higher efficiencies than the applications mentioned above.
Power-to-Gas (abbreviated PtG or P2G) refers to a chemical process in which a fuel gas is produced by water electrolysis, sometimes followed by methanation, using electricity from renewable energy sources (RES). This gas is also called renewable energy gas (RE gas). Depending on the type of renewable energy used, the gas may also be referred to as wind gas, solar gas, or similar. Depending on its chemical composition, the gas is alternatively called methane or hydrogen instead of “gas.” The produced fuel gas can either be fed into the public gas grid, stored seasonally in cavern storage facilities, or used in transportation. Additionally, there are concepts for integrated storage power plants based on reversible fuel cells, a technology now introduced to the market that promises higher efficiencies than the applications mentioned above.
D
DerBjoern11 Aug 2015 12:19Voki1 schrieb:
However, I am not familiar with wind gas at all – not even by name – and it is my primary interest. It gave me a very broad smile early on, so it was valuable to me. That’s definitely a nice way to start the day. Wind gas, as Musketier already mentioned, is more commonly known as "Power to Gas." For example, Audi has commissioned a first plant in Werlte.
In terms of price, the gas produced this way is not yet competitive, but it is a good method to temporarily store excess electricity from wind and solar systems in our gas network.
Just as a note – also off-topic:
Modern heat pumps are "smart grid ready," so with a reasonable expansion of infrastructure (Internet is available in almost every modern home), surplus energy can be stored in the hot water tank or, if applicable, a buffer tank. With a sufficiently large number of centrally controlled heat pumps, this allows for relief of the power grid and a higher share of renewable energy—without the need for additional energy-loss-prone conversion into hydrogen or "wind gas."
Furthermore, modern batteries are said to be able to return up to 90% of the energy used for charging—allegedly over many years. What efficiency does Power-to-Gas achieve? 30% or even less?
Modern heat pumps are "smart grid ready," so with a reasonable expansion of infrastructure (Internet is available in almost every modern home), surplus energy can be stored in the hot water tank or, if applicable, a buffer tank. With a sufficiently large number of centrally controlled heat pumps, this allows for relief of the power grid and a higher share of renewable energy—without the need for additional energy-loss-prone conversion into hydrogen or "wind gas."
Furthermore, modern batteries are said to be able to return up to 90% of the energy used for charging—allegedly over many years. What efficiency does Power-to-Gas achieve? 30% or even less?
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