Good day!
I am the type of person who likes to address and solve things before they become a problem. Therefore, I am considering whether there is a sensible way to move away from heating oil without switching to natural gas. Based on some basic data, can you roughly estimate what might be possible?
The total usable area of the house is 300 square meters, of which 178 square meters (about 1917 square feet) is living space. The difference mainly consists of basement rooms, which I partly use for my freelance work. Two adults and one child live in the house; both adults also work from home. We use about 3,000 liters (approximately 792 gallons) of heating oil per year (around 10 liters (2.6 gallons) per square meter including hot water) and consume about 8,000 kWh of electricity, as we also charge two electric cars.
The house is built with 24 cm (9.4 inches) thick solid Liapor elements, which provide excellent thermal buffering: in summer it remains cool for a long time, and in autumn it stays warm for a long time. Outside, there is 6 cm (2.4 inches) of mineral insulation, followed by a 4 cm (1.6 inches) air gap, and then a brick cladding. The wooden windows are double-glazed. The house has a carpentry-style roof structure with 20 cm (7.9 inches) of mineral insulation, and during the interior work we paid close attention to precise airtightness.
The oil-fired central heating system is now 22 years old but still runs very well. We do not have underfloor heating but radiators in every room. The flow temperature is about 40°C (104°F), and we operate a heating curve roughly as flat as that used for underfloor heating. Our roof shape (half-hipped roof with four gable dormers) is not suitable for photovoltaic panels; however, the garage roof (gable roof with about 30° pitch, ridge orientation north-south) offers space for about 70 square meters (around 753 square feet) of photovoltaic panels, half facing east and half west, with no shading from trees. Between the garage and the house, I have already installed a 5x16 square NyY cable (50 meters long (164 feet)) because that is where the cars are charged. So, if photovoltaic panels are installed on the garage roof, the inverter and control system could be housed in the garage, and there is also space beside the garage for battery storage. There is sufficient garden space for ground collectors as well.
Now I am wondering: is there a reasonable overall concept involving photovoltaics, battery storage, heat pump, and flat plate collectors? I would like to remove the oil tank but do not want a gas connection. Under these conditions, is it possible to achieve a relatively high degree of self-sufficiency for much of the year, so that only a small amount of electricity needs to be purchased, while avoiding the risk of running out of heat in cold periods?
Ideally, I would like to commission an independent energy consultant for such a concept, but I have no idea how to find someone who approaches this in a technology-neutral way while keeping an eye on political decisions that, of course, cannot be predicted now regarding how they will develop over the coming years. If you act too early, you might regret it later when stronger subsidies become available; but if you wait too long, you might have to endure rising oil and electricity prices for a longer period. Besides, I simply no longer find it acceptable to burn oil or gas.
Matthias
I am the type of person who likes to address and solve things before they become a problem. Therefore, I am considering whether there is a sensible way to move away from heating oil without switching to natural gas. Based on some basic data, can you roughly estimate what might be possible?
The total usable area of the house is 300 square meters, of which 178 square meters (about 1917 square feet) is living space. The difference mainly consists of basement rooms, which I partly use for my freelance work. Two adults and one child live in the house; both adults also work from home. We use about 3,000 liters (approximately 792 gallons) of heating oil per year (around 10 liters (2.6 gallons) per square meter including hot water) and consume about 8,000 kWh of electricity, as we also charge two electric cars.
The house is built with 24 cm (9.4 inches) thick solid Liapor elements, which provide excellent thermal buffering: in summer it remains cool for a long time, and in autumn it stays warm for a long time. Outside, there is 6 cm (2.4 inches) of mineral insulation, followed by a 4 cm (1.6 inches) air gap, and then a brick cladding. The wooden windows are double-glazed. The house has a carpentry-style roof structure with 20 cm (7.9 inches) of mineral insulation, and during the interior work we paid close attention to precise airtightness.
The oil-fired central heating system is now 22 years old but still runs very well. We do not have underfloor heating but radiators in every room. The flow temperature is about 40°C (104°F), and we operate a heating curve roughly as flat as that used for underfloor heating. Our roof shape (half-hipped roof with four gable dormers) is not suitable for photovoltaic panels; however, the garage roof (gable roof with about 30° pitch, ridge orientation north-south) offers space for about 70 square meters (around 753 square feet) of photovoltaic panels, half facing east and half west, with no shading from trees. Between the garage and the house, I have already installed a 5x16 square NyY cable (50 meters long (164 feet)) because that is where the cars are charged. So, if photovoltaic panels are installed on the garage roof, the inverter and control system could be housed in the garage, and there is also space beside the garage for battery storage. There is sufficient garden space for ground collectors as well.
Now I am wondering: is there a reasonable overall concept involving photovoltaics, battery storage, heat pump, and flat plate collectors? I would like to remove the oil tank but do not want a gas connection. Under these conditions, is it possible to achieve a relatively high degree of self-sufficiency for much of the year, so that only a small amount of electricity needs to be purchased, while avoiding the risk of running out of heat in cold periods?
Ideally, I would like to commission an independent energy consultant for such a concept, but I have no idea how to find someone who approaches this in a technology-neutral way while keeping an eye on political decisions that, of course, cannot be predicted now regarding how they will develop over the coming years. If you act too early, you might regret it later when stronger subsidies become available; but if you wait too long, you might have to endure rising oil and electricity prices for a longer period. Besides, I simply no longer find it acceptable to burn oil or gas.
Matthias
taschenonkel schrieb:
I’m really curious how the electricity bill has changed. On paper, it’s actually quite unfavorable for a heat pump (no insulation, old windows, and you don’t mention underfloor heating). No, they have regular radiators.
I think she mentioned something about a €120 (about $130) monthly heat pump electricity advance payment, if I remember correctly. So that’s just for heating, excluding household electricity.
It’s a duplex with four people living across three floors. Downstairs, in the basement apartment, the mother still lives there; part of it is built into the earth (the house is built into a slope). I believe that uses a lot of energy and is planned to be insulated next year.
It’s really hard to compare with before since they previously had an oil heating system, and oil isn’t exactly cheap right now. They also have solar panels on the roof, but I think that will play a minor role regarding the heat pump’s electricity. During the coldest months, the solar output is quite limited.
D
Deliverer29 Dec 2021 13:47kati1337 schrieb:
... the mother still lives in there, and part of it is also below ground level ...Then it probably won’t cost much anymore. ;-)And adding insulation afterwards is obviously inconvenient. Either they have significantly undersized the heat pump now and are supplementing with space heaters, or they will carry an oversized heat pump around for 15 years...
Deliverer schrieb:
Then it won’t cost much anymore. ;-)
Retrofitting insulation is obviously inconvenient. Either they have now severely undersized the heat pump and are supplementing with electric heaters, or they’re carrying an oversized heat pump for 15 years... Most likely the latter, though I’m not sure. Maybe a compromise until the insulation is done. An energy consultant was involved, so they must have planned something. This year, the house was also a bit cooler than usual (but not drastically – it could also be because we normally keep our home quite warm at around 24°C (75°F)), perhaps they accepted one winter like that until the insulation is installed next year. It wasn’t an easy fix on short notice since you have to dig quite deep around the house.
What supply temperatures are typically required for this kind of system? Do you need a special high-temperature heat pump for that? (I once read that such models exist, or for example with ground-source heat pumps, sometimes two heating circuits are used.) Or is it just a standard heat pump that runs somewhat less efficiently? My parents are currently considering their options as their existing oil boiler is aging. So far, they have mostly ruled out a heat pump because there are no large-area heating systems (only regular radiators), but they haven’t had a full consultation yet.
D
Deliverer29 Dec 2021 17:16The best way to test this is with the old heating system. There are plenty of instructions available. Anything up to 50°C (122°F), at most 55°C (131°F) flow temperature with natural circulation is still acceptable. Often, simply replacing individual radiators is sufficient.
taschenonkel schrieb:
I’m really curious about how your electricity bill has changed. On paper, it seems quite unfavorable for a heat pump (no insulation, old windows, and you don’t mention any underfloor heating).You can estimate it roughly. 1000 liters (264 gallons) of oil per year equal about 10,000 kWh. A heat pump with radiators has a COP between 2.5 and 3, or even worse, so that means 3,300 to 4,000 kWh per year. At $0.30 per kWh, that’s around $1,000 per year. The COP depends on the flow temperature, and from a COP of 3 upwards, it becomes cost-effective.Similar topics