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.
S
Sebastian7910 Jul 2015 09:38And why should the gloss be gone? What makes you think that? I know plenty of houses with 20-year-old windows that still look very good both on the outside and inside...
The materials are also becoming more UV-resistant (at least that’s what is advertised), so it is expected that they will become even more durable.
The materials are also becoming more UV-resistant (at least that’s what is advertised), so it is expected that they will become even more durable.
Regarding Insulation
In the 1970s, more than 80 mm (3 inches) of glass wool insulation was already not worthwhile.
Combined with a high-temperature boiler, these still remain particularly valuable buildings today.
Preferences and possibilities are very individual.
I believe that features like insulation should take priority over items like a kitchen, which can be modified later.
Olli
In the 1970s, more than 80 mm (3 inches) of glass wool insulation was already not worthwhile.
Combined with a high-temperature boiler, these still remain particularly valuable buildings today.
Preferences and possibilities are very individual.
I believe that features like insulation should take priority over items like a kitchen, which can be modified later.
Olli
It’s not only about when windows should be replaced, but also about the type of windows, the manufacturer, and so on. However, I agree with the previous comments that you should save the least amount of money on insulation during installation. With really good windows, the price difference can easily be several hundred dollars, especially when it comes to installing roof windows, which can vary significantly depending on the type (pivot, casement, etc.). If the overall costs are manageable for you, I would always recommend maximizing insulation in a new build… it can only be beneficial, at least when it comes to insulation. Depending on the location (aircraft noise, etc.), it also matters whether you use double- or triple-glazing.
I would place a lot of importance on floor insulation, masonry, and the roof. I’m planning to build before I turn 30 and want to be able to live there until I’m 70 or 80, as long as possible. Triple glazing might not provide perfect insulation in 30 years, but no one can take away the quality of the masonry. If the house’s structure is already solid without external thermal insulation composite systems (ETICS) or exterior insulation, there is still room for improvement. You never know what the long-term future will bring. I would feel more comfortable initially investing in an affordable gas condensing boiler and using the remaining budget for other needs.
S
Sebastian7931 Jul 2015 11:12What is the long-term goal? Insulation values do not change – what keeps a house adequately warm today will still keep it warm in 30 years.
Similarly, the insulation curve doesn’t change – no matter how much more you add, the effect becomes minimal beyond a certain point.
But somehow, some people just don’t want to understand that...
Similarly, the insulation curve doesn’t change – no matter how much more you add, the effect becomes minimal beyond a certain point.
But somehow, some people just don’t want to understand that...
He probably meant the, in my opinion, unfounded fear that the kilowatt-hour might cost around 2.00 EUR (about 2.00 USD) in 30 years or something like that. I am more inclined to believe that energy prices will decrease again in the long term. In the past, no one would have thought that electricity from photovoltaics could be produced for 10 cents and from wind for 5 cents. I predict a "Peak Energy Price" – something new alongside Peak Oil.
If energy really became extremely expensive, then every house would probably HAVE to be upgraded to passive house standards.
On the other hand, friends of ours recently renovated an old building and certainly don’t have the money to invest in further optimization over the next 30 years (Note: Renovating an old building is more expensive than new construction). According to their energy performance certificate, they use about 100 kWh per square meter per year. When you look at this and then at truly old buildings that will still stand for many years, there should be no cause for concern regarding a new house built to current energy-saving regulation standards.
By the way, 80 percent of households here in Germany heat with gas. This is not likely to change quickly; in the future, at best, the share of wind gas and biogas will increase. In my view, there is nothing wrong with a gas boiler, and if it turns out to be the wrong choice, it would be a 1,500 EUR (about 1,500 USD) sunk cost. Depreciate it and move on (provided a floor heating system suitable for a heat pump was installed).
If energy really became extremely expensive, then every house would probably HAVE to be upgraded to passive house standards.
On the other hand, friends of ours recently renovated an old building and certainly don’t have the money to invest in further optimization over the next 30 years (Note: Renovating an old building is more expensive than new construction). According to their energy performance certificate, they use about 100 kWh per square meter per year. When you look at this and then at truly old buildings that will still stand for many years, there should be no cause for concern regarding a new house built to current energy-saving regulation standards.
By the way, 80 percent of households here in Germany heat with gas. This is not likely to change quickly; in the future, at best, the share of wind gas and biogas will increase. In my view, there is nothing wrong with a gas boiler, and if it turns out to be the wrong choice, it would be a 1,500 EUR (about 1,500 USD) sunk cost. Depreciate it and move on (provided a floor heating system suitable for a heat pump was installed).
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