ᐅ Experience with KfW55 solid construction + gas heating + 5 sqm solar panels
Created on: 1 May 2017 20:11
N
Nutshell
Hello everyone,
I wanted to share my experience with my Kfw55 new build from 2013/2014.
We live at just under 300 meters (985 feet) above sea level and built with solid construction.
The house has a rather simple shape.
A standard gable roof without dormers or skylights (upstairs there is one window per room on the gable side).
Styrofoam was not an option for various reasons, so we chose the rather expensive monolithic plan blocks with a lambda value of 0.08.
Size: 111 sqm (1195 sq ft) living space.
Exterior wall: 36.5 cm (14 inches) Ytong blocks // Lambda 0.2 W/m²K
Floor slab insulated with XPS // 0.21 W/m²K
Ceiling on the upper floor has a sloping roof with 24 cm (9.5 inches) // ceiling insulated with 34 cm (13.5 inches) mineral wool // 0.12 W/m²K
Doors and windows are triple-glazed and gas-filled // overall including frames 1.05 W/m²K
Heat generator:
Gas condensing boiler: Viessmann Vitodens 300
System control: Vitotronic 200
Solar thermal system 5 sqm (54 sq ft): Vitosol 200-F
Solar storage tank: Vitocell 100-W 300 liters (79 gallons)
The solar system is used only for domestic hot water (no heating support).
Our gas boiler is switched off from May to September for heating and still consumes about 100 kWh of gas over the summer.
In winter, the solar system barely manages to heat the hot water (2 people), so it usually runs on gas.
Ventilation is handled by decentralized Lunos e² units with 90% heat recovery.
Over 12 months, we had a gas consumption of 8000 kWh.
That currently corresponds to heating costs of about €28 for the house.
We have the temperature set to 23°C (73°F) throughout the house.
(Electricity costs are about €39.)
Overall, we are very satisfied. Of course, the energy certificate shows lower consumption than we actually have.
There is no night setback, and nothing ever switches off or regulates down.
Maybe someone has had similar experiences?
Personally, I’m relaxed about heating costs; even if energy prices rise, paying twice as much would still be less than I used to pay in my smaller 80 sqm (860 sq ft) apartment built in 1990.
I wanted to share my experience with my Kfw55 new build from 2013/2014.
We live at just under 300 meters (985 feet) above sea level and built with solid construction.
The house has a rather simple shape.
A standard gable roof without dormers or skylights (upstairs there is one window per room on the gable side).
Styrofoam was not an option for various reasons, so we chose the rather expensive monolithic plan blocks with a lambda value of 0.08.
Size: 111 sqm (1195 sq ft) living space.
Exterior wall: 36.5 cm (14 inches) Ytong blocks // Lambda 0.2 W/m²K
Floor slab insulated with XPS // 0.21 W/m²K
Ceiling on the upper floor has a sloping roof with 24 cm (9.5 inches) // ceiling insulated with 34 cm (13.5 inches) mineral wool // 0.12 W/m²K
Doors and windows are triple-glazed and gas-filled // overall including frames 1.05 W/m²K
Heat generator:
Gas condensing boiler: Viessmann Vitodens 300
System control: Vitotronic 200
Solar thermal system 5 sqm (54 sq ft): Vitosol 200-F
Solar storage tank: Vitocell 100-W 300 liters (79 gallons)
The solar system is used only for domestic hot water (no heating support).
Our gas boiler is switched off from May to September for heating and still consumes about 100 kWh of gas over the summer.
In winter, the solar system barely manages to heat the hot water (2 people), so it usually runs on gas.
Ventilation is handled by decentralized Lunos e² units with 90% heat recovery.
Over 12 months, we had a gas consumption of 8000 kWh.
That currently corresponds to heating costs of about €28 for the house.
We have the temperature set to 23°C (73°F) throughout the house.
(Electricity costs are about €39.)
Overall, we are very satisfied. Of course, the energy certificate shows lower consumption than we actually have.
There is no night setback, and nothing ever switches off or regulates down.
Maybe someone has had similar experiences?
Personally, I’m relaxed about heating costs; even if energy prices rise, paying twice as much would still be less than I used to pay in my smaller 80 sqm (860 sq ft) apartment built in 1990.
R
Radfahrer16 Aug 2023 19:28I have reviewed your numbers and have a few questions.
Where is the house located, or what is the standard outdoor temperature?
With gas, you are probably still paying a basic service charge.
For new contracts, I find around 220€ depending on the provider in tariff comparisons.
Do you have a heat pump tariff for electricity?
You have a controlled ventilation system with heat recovery.
What are the additional costs?
Maintenance, cleaning, filters, and electricity consumption?
Maintenance of the heat pump?
Maintenance of the heating system?
Chimney sweep costs?
Unfortunately, these costs are always added on regardless of consumption.
At around 28€ per month, we will not be able to get much lower without significant investments.
Where is the house located, or what is the standard outdoor temperature?
With gas, you are probably still paying a basic service charge.
For new contracts, I find around 220€ depending on the provider in tariff comparisons.
Do you have a heat pump tariff for electricity?
You have a controlled ventilation system with heat recovery.
What are the additional costs?
Maintenance, cleaning, filters, and electricity consumption?
Maintenance of the heat pump?
Maintenance of the heating system?
Chimney sweep costs?
Unfortunately, these costs are always added on regardless of consumption.
At around 28€ per month, we will not be able to get much lower without significant investments.
Radfahrer schrieb:
Where is the house located or what is the standard outdoor temperature? At about 300 meters (980 feet) above sea level, rather exposed to wind, not in an urban center, more on the outskirts near fields.
Radfahrer schrieb:
You probably still pay a basic fee for gas.
For new contracts, I found about 220€ depending on the provider in price comparisons.Gas:
| Assumed consumption | 4,000 kWh/year | |
| x | Gross (net) price per kWh | 9.70 (9.07) cents/kWh |
| =</TD] | Total consumption cost | 388.00 €/year</TD] |
| +</TD] | Basic fee gross (net)</TD] | 150.00 (140.19) €/year</TD] |
| =</TD] | Gross price without bonus in the first year</TD] | 538.00 €/year</TD] |
| </TD] | Average per month</TD] | 44.83 €/month</TD] |
| -</TD] | Immediate bonus</TD] | 10.00 €</TD] |
| -</TD] | New customer bonus</TD] | 40.00 €</TD] |
| =</TD] | Gross price including bonus in the first year</TD] | 488.00 €/year</TD] |
| </TD] | Average per month</TD] | 40.67 €/month</TD] |
Electricity:
| Assumed consumption</TD] | 3,950 kWh/year</TD] | </TD] |
| x</TD] | Gross (net) price per kWh</TD] | 26.60 (22.35) cents/kWh</TD] |
| =</TD] | Total consumption cost</TD] | 1,050.70 €/year</TD] |
| +</TD] | Basic fee gross (net)</TD] | 151.89 (127.64) €/year</TD] |
| =</TD] | Gross price without bonus in the first year</TD] | 1,202.59 €/year</TD] |
| </TD] | Average per month</TD] | 100.22 €/month</TD] |
| -</TD] | New customer bonus</TD] | 50.00 €</TD] |
| =</TD] | Gross price including bonus in the first year</TD] | 1,152.59 €/year</TD] |
| </TD] | Average per month</TD] | 96.05 €/month</TD] |
Radfahrer schrieb:
Do you have a heat pump electricity tariff? No
Radfahrer schrieb:
You have a controlled ventilation system with heat recovery.
What are the additional operating costs?
Maintenance, cleaning, filters, and electricity consumption? It is a decentralized ventilation system.
4 units with heat recovery.
3 units in wet rooms that only exhaust air outside.
Cleaning: just a cloth and soap, so nothing special.
Filters: 20€ every 5 years.
Electricity consumption: around 140 kWh, about 37€ per year.
Radfahrer schrieb:
Heat pump maintenance? First minor defect after one year: a condensate pump, covered by warranty, otherwise it would have cost 120€.
The refrigeration technician wants to come every 2 years after the heating season in spring. I estimate the cost at about 450€, but not certain yet.
A climate compressor in the outdoor unit lasts about 8 years, so in 2030, 1,250€ are planned.
That makes 3,050€ planned maintenance costs up to the 12th year.
Radfahrer schrieb:
Heating system maintenance? First maintenance after 9 years cost 1,151€, a few parts needed proactive replacement. This also included maintenance of the solar storage tank and a new sacrificial anode.
They would prefer to come annually, but I don’t see the need for that. I have now budgeted 400€ every 2 years. That should be sufficient.
Radfahrer schrieb:
Chimney sweep costs? Last time 89€, only needs to come for the gas system every three years.
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