ᐅ New single-family house construction, gas heating or heat pump, target KfW55 energy efficiency standard
Created on: 15 Aug 2013 20:51
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Elektrofuzzi
Hello Forum,
I have been reading here for some time and am very impressed by the quality of some of the answers, so I hope to get the right guidance for myself as well.
I am currently planning my single-family house with 171m2 (1840 sq ft) of living space to KfW 70 standard.
Through the developer, I would get a gas condensing boiler with solar hot water and a Zehnder ComfoAir residential ventilation system.
Through a heating installer friend, I could get an Ochsner air-to-water heat pump GMLW9 plus VX with split outdoor unit Millennium MSV 14 for heating,
and an Ochsner Europa 323DK air-to-water heat pump with integrated residential ventilation. This pump would be installed in the utility room and extract warm air from the hallway and bathroom; fresh air would be supplied back to the rooms via membrane flaps on the window.
I would get both options at the same price.
About the house:
Setback floor, 171m2 (1840 sq ft) living space
Underfloor heating with supply temperature approx. 35°C (95°F)
2-layer wall construction: 17.5cm (7 inches) Ytong, 14cm (5.5 inches) insulation, brick veneer
10cm (4 inches) perimeter insulation
Triple glazing, 6-chamber profile, Ug value 0.7
Results of the energy assessment according to DIN 4108-6 and DIN 4701-10
Annual primary energy demand 56.92 kWh/m2
Transmission heat loss 0.27 W/(m2K)
Building envelope area 534.65m2 (5752 sq ft)
Building volume 705.65m2 (7598 sq ft)
Heated air volume 536.29m2 (5772 sq ft)
Usable building area 225.81m2 (2430 sq ft)
A/V ratio 0.76 1/m
Window area 39.36m2 (424 sq ft)
Ground slab U-value 0.23 W/(m2K)
Exterior wall U-value 0.17 W/(m2K)
Wood beam ceiling U-value 0.19 W/(m2K)
Ceiling to outside air above U-value 0.23 W/(m2K)
Ceiling to outside air below U-value 0.22 W/(m2K)
Absolute heating demand 10,704 kWh/year
Absolute hot water demand 2,823 kWh/year
I hope this is enough for now.
My questions:
Which of the above heating systems makes more sense?
Are these values reasonable?
Would I possibly reach KfW 55 with the heat pump system combined with a 5 kWp photovoltaic system?
I look forward to your answers.
Thank you
Elektriker
I have been reading here for some time and am very impressed by the quality of some of the answers, so I hope to get the right guidance for myself as well.
I am currently planning my single-family house with 171m2 (1840 sq ft) of living space to KfW 70 standard.
Through the developer, I would get a gas condensing boiler with solar hot water and a Zehnder ComfoAir residential ventilation system.
Through a heating installer friend, I could get an Ochsner air-to-water heat pump GMLW9 plus VX with split outdoor unit Millennium MSV 14 for heating,
and an Ochsner Europa 323DK air-to-water heat pump with integrated residential ventilation. This pump would be installed in the utility room and extract warm air from the hallway and bathroom; fresh air would be supplied back to the rooms via membrane flaps on the window.
I would get both options at the same price.
About the house:
Setback floor, 171m2 (1840 sq ft) living space
Underfloor heating with supply temperature approx. 35°C (95°F)
2-layer wall construction: 17.5cm (7 inches) Ytong, 14cm (5.5 inches) insulation, brick veneer
10cm (4 inches) perimeter insulation
Triple glazing, 6-chamber profile, Ug value 0.7
Results of the energy assessment according to DIN 4108-6 and DIN 4701-10
Annual primary energy demand 56.92 kWh/m2
Transmission heat loss 0.27 W/(m2K)
Building envelope area 534.65m2 (5752 sq ft)
Building volume 705.65m2 (7598 sq ft)
Heated air volume 536.29m2 (5772 sq ft)
Usable building area 225.81m2 (2430 sq ft)
A/V ratio 0.76 1/m
Window area 39.36m2 (424 sq ft)
Ground slab U-value 0.23 W/(m2K)
Exterior wall U-value 0.17 W/(m2K)
Wood beam ceiling U-value 0.19 W/(m2K)
Ceiling to outside air above U-value 0.23 W/(m2K)
Ceiling to outside air below U-value 0.22 W/(m2K)
Absolute heating demand 10,704 kWh/year
Absolute hot water demand 2,823 kWh/year
I hope this is enough for now.
My questions:
Which of the above heating systems makes more sense?
Are these values reasonable?
Would I possibly reach KfW 55 with the heat pump system combined with a 5 kWp photovoltaic system?
I look forward to your answers.
Thank you
Elektriker
M
merlin66719 Aug 2013 13:01Hmm, if you have a gas connection nearby and don’t need a tank, it’s always worth considering. Of course, the running costs are still cheaper with an air source heat pump, but a gas condensing boiler is significantly cheaper to purchase, and you can pay the higher running costs for a long time.
Especially with lower power outputs, in my opinion, you should never decide without considering another option, because the basic components of a heat pump are more or less always the same. A somewhat larger compressor, evaporator, heat exchanger, etc., doesn’t cost that much more.
I don’t have a gas connection within about 10 meters (30 feet), so I would have to pay extra for a tank, delivery costs, and so on, which doesn’t make sense.
I agree with you about the 55/35°C (131/95°F) system, BUT: you have a separate buffer tank in the heating circuit, so the heat pump output doesn’t go directly into the heating system, and there shouldn’t really be any overshooting.
Can’t you find any information or do you have no experience of how cold it really gets in winter at your location? The standard outdoor temperature is one thing, but temperatures of −20°C (−4°F) are not uncommon where I am, and that is exactly where the heat pump is really challenged. Just wait and see what actual heating output you get. Then you can still evaluate further.
You do have an electric heat exchanger, if I remember correctly. In about 97% of cases, a preheater is installed to prevent the heat exchanger from freezing in winter. That, of course, adds to the total power required for heating.
Especially with lower power outputs, in my opinion, you should never decide without considering another option, because the basic components of a heat pump are more or less always the same. A somewhat larger compressor, evaporator, heat exchanger, etc., doesn’t cost that much more.
I don’t have a gas connection within about 10 meters (30 feet), so I would have to pay extra for a tank, delivery costs, and so on, which doesn’t make sense.
I agree with you about the 55/35°C (131/95°F) system, BUT: you have a separate buffer tank in the heating circuit, so the heat pump output doesn’t go directly into the heating system, and there shouldn’t really be any overshooting.
Can’t you find any information or do you have no experience of how cold it really gets in winter at your location? The standard outdoor temperature is one thing, but temperatures of −20°C (−4°F) are not uncommon where I am, and that is exactly where the heat pump is really challenged. Just wait and see what actual heating output you get. Then you can still evaluate further.
You do have an electric heat exchanger, if I remember correctly. In about 97% of cases, a preheater is installed to prevent the heat exchanger from freezing in winter. That, of course, adds to the total power required for heating.
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Elektrofuzzi19 Aug 2013 13:20I am from the Bremen area, in northern Germany.
Temperatures around -15°C (5°F) are rather rare here, but that is just my personal impression.
The gas connection is available on the property.
Ventilation is planned to be handled by the air-to-water heat pump (323DK),
and this is also the major cost factor.
With the heat pump option, ventilation is basically included, whereas with the gas condensing boiler option, I would need to purchase it separately for €8,000 (approximately $8,800) or €10,000 (approximately $11,000) if including the cooling function, specifically a mechanical ventilation system with heat recovery.
A building permit / planning permission is clearly planned.
Temperatures around -15°C (5°F) are rather rare here, but that is just my personal impression.
The gas connection is available on the property.
Ventilation is planned to be handled by the air-to-water heat pump (323DK),
and this is also the major cost factor.
With the heat pump option, ventilation is basically included, whereas with the gas condensing boiler option, I would need to purchase it separately for €8,000 (approximately $8,800) or €10,000 (approximately $11,000) if including the cooling function, specifically a mechanical ventilation system with heat recovery.
A building permit / planning permission is clearly planned.
Elektriker schrieb:
....I used an online calculator to perform the heat load calculation in advance... My condolences ;-)Best regards
M
merlin66719 Aug 2013 13:47My climate data is included at the end of the private message. Although I am located much farther south than you, it is unfortunately extremely cold here in winter (well, on the plus side, I am only 15 minutes away from the nearest ski resort), and pleasantly warm in summer (we regularly reached 39°C (102°F) this year 🙂 ).
If we haven’t had at least one week in winter with temperatures of -15°C (5°F) or lower, it wouldn’t even be considered a proper winter here.
An additional cost of €8,000 for a proper mechanical ventilation system with heat recovery is definitely significant. Fortunately, I don’t have to pay that much since I work with a manufacturer, so it’s “a bit” less for me.
If we haven’t had at least one week in winter with temperatures of -15°C (5°F) or lower, it wouldn’t even be considered a proper winter here.
An additional cost of €8,000 for a proper mechanical ventilation system with heat recovery is definitely significant. Fortunately, I don’t have to pay that much since I work with a manufacturer, so it’s “a bit” less for me.
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Elektrofuzzi19 Aug 2013 14:10My sincere condolences ;-)
Well, at least it provides a starting point in the right direction.
I’m aware that this calculation does not replace professional advice. 🙄
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Elektrofuzzi19 Aug 2013 14:11Can someone tell me how I can edit a post after it has been published?
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