Why do electric ovens click

Advice: high heating costs with electric heating - what now?

Guide> Electric heating

Author: Dr. Rüdiger Paschotta

Anyone who suffers from high and still rising heating costs with an electric heater can find out here which options can be checked in order to escape this unpleasant situation. It is discussed how one could heat more economically, whether a modernized electric heating would help or what other possibilities could exist.

Many have the problem that their apartment or house is equipped with electric heating, which gives them very high and even higher heating costs. After there had been very cheap electricity tariffs for years, especially for electric storage heaters (with cheaper night-time electricity), with which one could obtain electricity much cheaper than normal small consumers, the situation has turned significantly - in large part because of the liberalization of the electricity market. There is real competition here today, and no supplier wants to offer electricity at conditions that are uneconomical for him, just to generate more sales. (In the past you could just let the other small consumers pay for it.)

Unfortunately, the running costs of the electric heater aren't even the only problem. From an ecological point of view, too, these heaters are unfortunately very bad: they contribute significantly to the situation Tightening theClimate hazards and to Deterioration in air quality at. With the average German electricity mix, you have to have 600 g CO2 calculate, and this is even unrealistically low for heating electricity, since this is generated for the greater part than the average with coal-fired power plants. For comparison, an efficient gas heating system is around 200 g / kWh, i.e. around three times better, and incidentally approx. 25% better than with heating oil. In principle, one could use green electricity for the electric heating and thus almost CO2-Heat free, but only a few do that because of the slightly higher operating costs.

What CO2 is expelled cannot be described as “peanuts”!

It must be emphasized that climate protection is really strongly affected here. If, for example, an unrenovated single-family house requires 50,000 kWh of heat per year and the electricity used with 600 g of CO2 per kWh is loaded, it is about emissions of 30 tons of CO2 per year - comparable to 150,000 km driving an SUV! However, climate protection requires that we only have one tonne of CO2 emit per person and year - mind you, not for the heating, but for everything together! Consoling oneself with the fact that the German electricity mix will at least become a bit “greener” over time is obviously a glossing over of the problem. In any case, this does not change the enormous electricity costs in the order of 10,000 € per year for 50,000 kWh.

So, of course, the question arises as to what can be done in this uncomfortable situation. Unfortunately, I cannot offer you a magic solution here, but at least a well-founded and understandable discussion of various supposed or real options. You can find comprehensive information here, especially through the many references (links) to lexicon articles, which provide even more details if required.

Before you either spend significant money or give up in resignation, have a competent energy advisor analyze your situation!

Of course, even the best article cannot perform well competentEnergy advisor replace on site. Depending on the situation, very different measures can be useful; that is why the situation must always be examined on the concrete object before doing anything - or giving up in resignation.

Reduction of heat consumption

As with any other heating system, you can of course always save primary energy if you can reduce the heating consumption. There are different possibilities for this.

The classic options are, of course, to set the required room temperature as low as possible using the heating thermostats and to ventilate the apartment in a sensible way, i. H. in the heating season only in the form of burst ventilation. Perhaps you would also like to generally heat certain rooms that are seldom used to a lesser extent; Unfortunately, this can increase the risk of mold formation - especially if the outer walls get relatively cold due to inadequate thermal insulation. With such methods you can save a few percent or even significantly more - depending on how economical you have already been. Many victims of electric heating, plagued by high heating costs, are already very economical, but perhaps you will discover certain savings opportunities after all.

An energetic renovation can be very effective - you can hardly achieve that much in any other way.

A much more effective method would be that energetic renovationof the building. In a typical house from the 1960s, a thorough renovation (with thermal insulation for the facade, roof and basement ceilings) can easily reduce the heat requirement by a factor of 3 or 4 (we did it ourselves!); this would of course also alleviate the problem of heating costs to a large extent, while at the same time improving comfort and reducing the risk of mold formation (expert implementation is required). In this context you are probably also interested in my article "Heating exchange before or after the building renovation?".

In the long term, heating costs make sense for landlords.

If you are a tenant, it will of course be difficult with an energetic renovation; You can't force anything there, of course - maybe at least a cheaper cold rent with the threat of looking for another apartment where you can live more cheaply overall. Of course, it is not wise of a landlord to see heating costs only as a problem for the tenant - every euro of additional heating costs means one euro less rent excluding heating in the long term, because you are in competition with other offers. In addition, the landlord can, on the one hand, obtain state subsidies for a renovation (e.g. through KfW) and, on the other hand, pass the remaining costs on to the tenants; in the long run, he achieves a free increase in the value of his property. Nevertheless, landlords (as well as self-users of their property) often do nothing for years, e.g. B. due to a lack of knowledge or because of the short time horizon for investments in old age.

Sometimes there is simply a lack of understanding that a building requires certain investments every few decades. Everything ages, and requirements change over time. You just have to consider whether you can see a future for the house of a few more decades. If so, it makes little sense to postpone a renovation as long as possible and to spend an enormous amount of money on energy until then.

In spite of everything, one may also look for ways to improve only the method of heat generation (or of course to do both in combination); We consider this in the following.

Modernization of the electric heating?

If someone changes from an old gas boiler to a modern condensing boiler, energy savings of 30% or even more are often possible. Can you do that with the modernization of the electric heating?

Unfortunately, that's pretty unrealistic. In principle, an old electric heating system also generates one kilowatt hour of heat from one kilowatt hour of electricity - bad business that cannot be improved this way. At most, you can have certain energy losses (heat losses) z. E.g. an old insufficiently thermally insulated electric storage heater in the basement should be greatly reduced, but this should not usually have a dramatic effect on heating costs - at least not so much that a substantial investment (e.g. for a new electric storage heater) would be worthwhile.

Modern infrared heaters are only more efficient when used in a spatially and temporally targeted manner - by no means for basic heating of an apartment!

Unfortunately, many believe it today modern types of electric heating that are far more energy efficient than the old ones. In particular, will be Infrared heaters often advertised accordingly by manufacturers (also as heat wave heating, natural stone heating, etc.), and misinformed journalists pass on such claims uncritically. It is true, however, that a spatially and temporally targeted heating z. B. a seat in the living room or office with an infrared heater can be more efficient than electric heating with conventional electric ovens. But if you use such heaters the Basic heating take over the apartment (i.e. not spatially and temporally specific, but nationwide and continuously), you consume about the same amount as with the old devices; You then do not take advantage of the targeted heating at all. In addition, you will then usually not be able to benefit from cheaper electricity tariffs as you would with an electric storage heater. It is therefore clear that you will certainly not solve your problem with it - it is therefore strongly advised not to switch the entire heating of the apartment or house to infrared heaters in order to have even higher heating costs afterwards. For more details, see the article on infrared heating.

What can be quite useful is that optimized setting of an electric heater. For example, you should avoid letting electric storage heaters (decentralized or centralized) heat up more than necessary. But of course no dramatic savings effects can be achieved here either.

Now you know that the only way to fundamentally solve the problem is by either the heating requirement is greatly reduced (most effectively through an energetic renovation) or else the heating does not exceedElectric heatgenerated. We consider possibilities for the latter approach below.

Heating with solar power?

The costs for photovoltaic systems have fallen so dramatically in recent years that they can be used to generate electricity in Germany for less than 10 ct / kWh. You could therefore think that you only have to operate the electric heating with electricity from a solar system, and the costs would be roughly halved, while the CO2Emissions would even be almost entirely eliminated.

Unfortunately, there is one major problem: photovoltaics preferably do not provide electricity when you would need it for electrical heating. Intermediate storage for the required amounts of heating current is by far not practicable; The central solar power storage units sold today can only store a few kilowatt hours at a cost of around € 10,000, while the electricity consumption of the electric heating in an unrenovated single-family house can easily amount to hundreds of kilowatt hours on a cold winter's day.

Feeding the photovoltaic electricity into the public grid in order to then obtain heating electricity at other times does not solve the cost problem either, because the feed-in tariff that you can receive is much lower than the electricity tariff that you pay for heating electricity at other times . Of course, if someone else were to operate a storage facility for you, it would also cost something ...

At most, you could benefit a little from the fact that a photovoltaic system of the usual size on your house roof (e.g. 4 kW maximum output for a single-family house) could work with a slightly larger proportion of self-consumption and thus even more economically thanks to the electric heating. This is on the condition that you can receive a corresponding statement. It is unclear whether that would work; the system would have to be built in such a way that the electric heating consumes all the solar power generated that is not needed for other purposes in the house. In any case, you could only cover a small part of your heating power consumption directly with the solar system.

Alternatives to electric heating

Which alternatives to electric heating would be practicable for you depends largely on whether you have central heating in the house or not.

Central heating solutions

Where there is already a central heating system, the best way to get the heat you need is in a more efficient and cost-effective way. However, it always depends on the specific case:

Heat pump heating would massively reduce the electricity demand. This works particularly well after an energetic renovation of the building; otherwise it can z. B. fail because of the high costs for several geothermal probes.
  • Switching to heat pump heating would be advantageous in several ways - in most cases with an electric heat pump. Then they will still need electricity for heating, but much less than before. For example, if your system achieves an annual performance factor of 4, you need around four times less kilowatt hours per year in the form of electrical energy than you have consumed with the electrical heating. Particularly high coefficients of work are possible with the combination of a geothermal probe (or almost equally well an earth register) with underfloor heating. However, this is unfortunately not always possible, e.g. B. because geothermal probes are not allowed everywhere. In addition, the installation costs are relatively high if several probes are required due to a high heat requirement (without renovating the building). With an air / water heat pump you don't need something like that anymore, but unfortunately you usually have a significantly lower annual coefficient of performance - especially if the heating system requires a relatively high flow temperature. (This problem would of course be resolved after an energetic refurbishment.) If you are ready to cover the remaining electricity consumption with real green electricity, you can even get close to CO2-heat free.
A modern gas heating system still needs a fossil fuel with CO2Emissions, but much less than electric heating.
  • In terms of investment, a condensing gas heating system would be more cost-effective, which could also massively reduce operating costs - roughly estimated at 6 ct / kWh (as of 2016) compared to around 20 ct / kWh for electric storage heating. Unfortunately, there is not a natural gas connection everywhere, and certain CO2-Emissions (around 200 g / kWh) also remain; in addition, gas prices can rise again. By the way, you also need an exhaust pipe - if there is no chimney through which it can be laid, such a pipe may have to be laid along the facade.
  • Where there is no natural gas connection, one could use liquid gas instead, which would have to be stored in a tank (usually set up outdoors). It's just as clean as natural gas, but a bit more expensive to run.
  • Almost CO2-neutral (at least CO2-arm) and you could heat relatively comfortably with a pellet heating system. Here, however, you need a chimney or, alternatively, a stainless steel exhaust pipe, which is laid on the facade. There is also a pellet store, which takes up a lot of space. The investment costs are usually significantly higher than for gas heating, the fuel costs tend to be somewhat lower, but the maintenance costs are in turn higher. A log boiler works with even lower fuel costs, but causes a lot more work. By the way, you should be very careful to get a model with very low particulate matter emissions.
  • Practical, often relatively inexpensive and environmentally friendly, would be the use of district heating or local heating z. B. from a block-type thermal power station; Unfortunately, in most places there is no connection option for this.
Combined heat and power plants can be a good solution for larger heat consumers.
  • In principle, you can also operate a block-type thermal power station (BHKW, e.g. with natural gas) yourself. For an apartment building, this can be a realistic option. (The investment and maintenance costs do not depend too much on the required output.) Then you need a lot more natural gas than with gas heating, but you generate valuable electrical energy that you can sell with a decent feed-in tariff, if it doesn't is used for personal consumption.
  • So-called micro-CHPs are also available for small-scale cogeneration. B. on the basis of a fuel cell with natural gas. Compared to gas heating, the investments are much higher here, but the effective operating costs (taking into account the generation of electricity) are cheaper.

This would at least cover the most common ways of generating heat for central heating. But you shouldn't forget the solar thermal system. It is true that a complete solar heating system can only be implemented with it in rare cases. However, it is usually necessary to cover a certain proportion of the annual heat requirement in a very environmentally friendly way - especially if heating support is possible.

One should also not forget the hot water preparation, which is usually done with an electric boiler in houses with electric heating.Of course you would like to replace this at the same time. This is easily possible with many central heating systems.

If you don't have central heating (yet)

Of course, you could also retrofit central heating - preferably not with conventional radiators, but z. B. with underfloor heating, wall heating or ceiling heating, d. H. any form of surface heating that can be used to implement low-temperature heating. This gives you all of the options discussed in the previous section. Of course, this means a larger investment, which is most likely to make sense in the course of a general renovation.

If it is only about a single apartment - such as a condominium - one can also think of a floor heating system. Such a thing is often operated with natural gas. Of course, radiators of some kind have to be installed here as well - just for the apartment alone and not for the entire building. The floor heating can work just as efficiently as central heating for the whole house.

If none of this is an option, there are still a few options:

Today you don't really want to work with wood stoves for the individual rooms - too much speaks against it.
  • Heating with single stoves z. B. for wood is possible in principle, but there are good reasons why: The installation costs are quite high (especially if a chimney would have to be installed), the operation is very labor-intensive and the outside air can be polluted with fine dust and other pollutants lie very high (far worse than with a good central wood boiler); you don't really want all of that.
  • Decentralized gas heaters are more likely to come into question (e.g. on outer walls with a core drill hole for the discharge of the exhaust gas); here the great workload of wood stoves as well as the strong formation of air pollutants are eliminated. Of course, gas pipes have to be laid for this; So you might ask yourself why you shouldn't lay cables for central heating or floor heating right away.
  • There are also mobile gas heaters with liquid gas and without a chimney connection. Since the gas cylinder has to be changed and refilled over and over again, this is hardly an option for long-term use. The exhaust gas entering the room is very clean, but contains CO2; you have to ventilate sufficiently, otherwise excessively high CO2-Concentrations make you tired and slack.
  • There are decentralized room air conditioning units (e.g. split air conditioning units) that can also be used for heating. They then work as an air / air heat pump - except when the emergency mode is switched to an electric immersion heater when the outside temperature is too low. Modern devices work for outside temperatures down to −15 ° C or even lower, and the achievable annual performance factors are well above 4 with good devices. This is impressive - also in comparison to central heat pump heating with an air / water heat pump. However, the installation costs add up considerably if a larger number of rooms have to be equipped with it; Such a solution is most likely to be of interest where e.g. B. a large living room together with a kitchen area can be heated with a single device. If necessary, you could then continue to heat the smaller rooms (with low heat requirements) electrically, but at least heat the large living area much more efficiently than before.

Of course, you can see that with a central heating system you have a much better choice of options. It is no coincidence that almost no houses are built without one - with the exception of passive houses, for which a kind of small emergency heating (e.g. connected to the ventilation system) is sufficient.

By the way, we also have useful advice articles on various other topics in the energy sector.

Questions and comments from readers

11.03.2019

The article is helpful because we are facing this problem right now:

  • House in BW, built in 1973. Living space 290 sqm. According to the energy pass: 141 kWh / sqm (class E).
  • Electric floor heating and large tiled stove on the ground floor (open rooms in the middle) and electric storage heaters in the basement. An additional 6 square meters of solar thermal energy for hot water
  • Electricity bill € 450 per month.
  • No central heating available.

What would you advise in this combination?

A 190 sqm PV would also fit on the roof (15 degrees, 180 sqm). If we reduce the electricity bill to € 180 per month. I find it acceptable, because amounts in this direction are also due for gas or pellets.

Answer from the author:

A “nice” example of horrific electricity costs thanks to an unfavorable approach that is difficult to correct afterwards. In such cases, you should ask an energy advisor who can thoroughly analyze the specific situation on site and work out suggestions.

I am afraid that a PV solution cannot solve the problem, since a large part of the solar power is generated at times when it is not needed for heating. A system that is not supposed to generate huge surpluses that cannot be used in the house in summer can unfortunately not contribute much to heating in winter.

In any case, I would check whether comprehensive thermal insulation is possible. If the heat demand can be reduced by a factor of three or four, which is quite conceivable in such houses, the problem has largely been mitigated. Unfortunately, in some houses, the options for doing this are difficult, for example due to insufficient roof overhang or complicated facade structures.

12.06.2019

Kudos for their site and articles.

I bought a house from 1994 in which a night storage underfloor heating is installed. With the corresponding night-time electricity tariff, the previous owner paid € 300 / a including other electricity consumption.

We decided to convert to pellet central heating. A cellar for the plant and warehouse was given. The conversion of the floors to a water-based FBH was less problematic than expected. All floor coverings were removed in-house, so that the bare screed was exposed again. Glued carpets were more difficult to remove than tiles. In any case, positions for a heating circuit distributor box were found on each floor and piped vertically. On a single day, the company JK milled slots in the screed and laid the pipes in it and connected them to the heating circuit distributors. The surfaces were sealed with leveling compound and covered with new floor coverings / tiles and vinyl floors (those without dense fibers). The system has been working without problems for two years.

The investment was 20 k € with some personal contribution. The consumption of pellets is astonishingly low at 3.5 t / year. Costs per ton approx. € 235 (2018), i.e. € 823 / a. In addition, there are costs for chimney sweeps and maintenance of the system about 340 € / a. The pellet heating also requires operating electricity, approx. 230 kWh / a. So we are now at around € 100 heating costs per month.

The conversion takes 14 years to reach the economic break-even point.

With what I know today, I would examine the option of a heat pump more closely, but so far I have been very satisfied with the decision.

Answer from the author:

It's nice that you seem to have found a good working solution.

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See also: electric heating, electric storage heating, infrared heating, electric heat pump, energy efficiency, climate hazards