ᐅ New single-family house construction, gas heating or heat pump, target KfW55 energy efficiency standard
Created on: 15 Aug 2013 20:51
E
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
E
Elektrofuzzi17 Aug 2013 15:37merlin667 schrieb:
Who put together your system from Ochsner? Do you have a buffer tank included?
I have an offer for the GMLW9 and the outdoor evaporator, 1x domestic hot water buffer tank, and 1x separating tank (necessary for the outdoor unit regeneration) for almost exactly €20,000. The heat recovery ventilator is additional in my case.The offer was prepared by my installer who is a friend and sells not only Stiebel Eltron but also Ochsner.
The package includes:
Split evaporator MSV14 Millennium
GMWL9 plus air-to-water heat pump for heating
Ochsner O-Tronic Easy PLUS OTE
Flow sensor
Display with control panel
Remote room control for heating and cooling
Heating and cooling module
Separating tank PU300NOROF
3.75 kW (12,700 BTU) electric heating element
323DK air-to-water domestic hot water heat pump
Installation and commissioning
E
Elektrofuzzi17 Aug 2013 16:22Calculation basis of the energy consultant:
Calculation software: Energieberater 18599 7.4.2 Hottengroth Software
The following standards and regulations were taken into account in the calculation:
DIN EN 832:2003-6
DIN V 4108-6:2003-6
DIN V4701-10/A1:2006-12
Regarding the first DIN standard:
Thermal performance of buildings – Calculation of heating energy demand – Residential buildings
Does the installer not have all the data needed for the design from this?
Calculation software: Energieberater 18599 7.4.2 Hottengroth Software
The following standards and regulations were taken into account in the calculation:
DIN EN 832:2003-6
DIN V 4108-6:2003-6
DIN V4701-10/A1:2006-12
Regarding the first DIN standard:
Thermal performance of buildings – Calculation of heating energy demand – Residential buildings
Does the installer not have all the data needed for the design from this?
Hello,
Qp ≤ 46.04 kWh/(m2a)
H'T ≤ 0.26 W/(m2K)
provided the calculation for the reference building is correct ;-)
Strictly speaking, both requirement values are missed here. H'T only just. There might be potential for optimizing the building envelope’s thermal performance.
Regarding Qp, clarification is needed. The reference building assumes a solar thermal system for hot water with theoretical coverage rates that are practically never reached with the standard off-the-shelf systems typically offered by general contractors. An absolute sham! This particularly penalizes builders who invest significant additional effort in building insulation!
In this case, however, it should be examined overall whether it actually makes economic sense. Subsidies (KfW) are not freebies, as often assumed, but are more accurately just a “band-aid” for the increased investment costs involved.
There are cases where it is economically worthwhile to achieve a subsidized status. In other cases, it can become a money pit. The latter especially applies when significant discrepancies arise during practical implementation (planning, construction) compared to the mostly optimistic calculations on paper. There are plenty of examples for this ;-)
Best regards
Elektriker schrieb:To achieve KFW 55 standard, the building must meet:
Here are the details from the KFW application....
Qp ≤ 46.04 kWh/(m2a)
H'T ≤ 0.26 W/(m2K)
provided the calculation for the reference building is correct ;-)
Strictly speaking, both requirement values are missed here. H'T only just. There might be potential for optimizing the building envelope’s thermal performance.
Regarding Qp, clarification is needed. The reference building assumes a solar thermal system for hot water with theoretical coverage rates that are practically never reached with the standard off-the-shelf systems typically offered by general contractors. An absolute sham! This particularly penalizes builders who invest significant additional effort in building insulation!
In this case, however, it should be examined overall whether it actually makes economic sense. Subsidies (KfW) are not freebies, as often assumed, but are more accurately just a “band-aid” for the increased investment costs involved.
There are cases where it is economically worthwhile to achieve a subsidized status. In other cases, it can become a money pit. The latter especially applies when significant discrepancies arise during practical implementation (planning, construction) compared to the mostly optimistic calculations on paper. There are plenty of examples for this ;-)
Elektriker schrieb:Probably yes, but that doesn’t help much if H'T is not met!
....Would it be possible to reach KFW 55 with a heat pump and photovoltaic system?
Elektriker schrieb:What is good or bad? By what standard? Without knowing the actual demand (performance, energy) for a defined building structure and user behavior, this question cannot be reliably answered.
...Are these generally good values or rather mediocre to poor?
Best regards
M
merlin66718 Aug 2013 09:38The configuration for me was done directly by the Ochsner field technician, and the only difference from your offer is that I have a second buffer tank instead of your wwwp. Check if you have the weather protection grille and refrigerant lines included.
Since I’m Austrian, I’m not very familiar with the conditions in Germany; from what I quickly saw, I would be in Germany at KfW 40-55.
He should have it, but ask him about your monovalence point and where it lies. If he doesn’t have that, then he just put something together without properly checking.
According to EN12831 (simplified), I have a heating capacity of 5.76 kW under my local conditions (standard outdoor temperature -12.3°C (9°F)). When I look at the control curve, at a 35°C (95°F) supply temperature and 6 kW output, I reach about -12°C (10°F) with a COP just under 3.
It’s basic physics that an air-source heat pump performs better at higher temperatures than others, but it must work efficiently at these cold points, not just at 0°C (32°F). Otherwise, it becomes a power guzzler. Of course, if you’re not really knowledgeable, you have to rely on the planner.
In my opinion, you shouldn’t try to reach some efficiency class on paper at all costs, but rather have everything properly assembled. What good is achieving KfW 55 if you have to use the backup electric heater below about -4°C (25°F) due to an incorrectly sized heat pump?
Since I’m Austrian, I’m not very familiar with the conditions in Germany; from what I quickly saw, I would be in Germany at KfW 40-55.
He should have it, but ask him about your monovalence point and where it lies. If he doesn’t have that, then he just put something together without properly checking.
According to EN12831 (simplified), I have a heating capacity of 5.76 kW under my local conditions (standard outdoor temperature -12.3°C (9°F)). When I look at the control curve, at a 35°C (95°F) supply temperature and 6 kW output, I reach about -12°C (10°F) with a COP just under 3.
It’s basic physics that an air-source heat pump performs better at higher temperatures than others, but it must work efficiently at these cold points, not just at 0°C (32°F). Otherwise, it becomes a power guzzler. Of course, if you’re not really knowledgeable, you have to rely on the planner.
In my opinion, you shouldn’t try to reach some efficiency class on paper at all costs, but rather have everything properly assembled. What good is achieving KfW 55 if you have to use the backup electric heater below about -4°C (25°F) due to an incorrectly sized heat pump?
E
Elektrofuzzi19 Aug 2013 11:18Good morning,
The price includes the complete installation, so the wiring and the weather protection grille are also included.
I just spoke with my heating technician:
He will start working on it and, together with Ochsner, will carry out a heat load calculation. This will be based on the calculation done by the energy consultant who submitted the KfW application.
The technician has already installed several systems like this and has gained good experience so far.
In his opinion, it is rather inefficient from an energy perspective to use a single heat pump for both heating and domestic hot water.
The reason for this is the conflicting temperature requirements.
The pump heats to 35°C (95°F) for the flow temperature, then up to 55°C (131°F) for domestic hot water, and then back down again. This can result in 55°C (131°F) entering the heating circuit at times, causing fluctuations in the heating curve.
I performed a preliminary heat load calculation using an online tool.
At -12°C (10°F), the heating load is 4700 W.
According to the data sheet, the pump delivers 6 kW at -10°C (14°F).
Could this be cutting it too close?
Best regards
The price includes the complete installation, so the wiring and the weather protection grille are also included.
I just spoke with my heating technician:
He will start working on it and, together with Ochsner, will carry out a heat load calculation. This will be based on the calculation done by the energy consultant who submitted the KfW application.
The technician has already installed several systems like this and has gained good experience so far.
In his opinion, it is rather inefficient from an energy perspective to use a single heat pump for both heating and domestic hot water.
The reason for this is the conflicting temperature requirements.
The pump heats to 35°C (95°F) for the flow temperature, then up to 55°C (131°F) for domestic hot water, and then back down again. This can result in 55°C (131°F) entering the heating circuit at times, causing fluctuations in the heating curve.
I performed a preliminary heat load calculation using an online tool.
At -12°C (10°F), the heating load is 4700 W.
According to the data sheet, the pump delivers 6 kW at -10°C (14°F).
Could this be cutting it too close?
Best regards
E
Elektrofuzzi19 Aug 2013 11:19And to return to the original question:
Assuming a heating load of 5-6 kW,
would a heat pump or a gas condensing boiler be more advisable?
Assuming a heating load of 5-6 kW,
would a heat pump or a gas condensing boiler be more advisable?
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