Frequently asked questions – ELECTRIC HEATING

Question: I would like to ask you for a design for the heating system of a family home. What information should I send you? Answer: For the creation of a price quotation, you will need: to decide on the heating system which you wish to use (Ecofloor,...

Question:
I would like to ask you for a design for the heating system of a family home. What information should I send you?

Answer:
For the creation of a price quotation, you will need:

to decide on the heating system which you wish to use (Ecofloor, Ecofilm, Ecosun, Ecoflex)
a properly dimensioned floor plan and cross-section of the building
the composition of floors (including floor coverings), walls and ceilings, given in cm, in the direction interior → exterior
the heat loss of the building (this is not necessary but it will speed up the creation of the price offer)

This information is essential for the design of a heating system; a price quotation cannot be created without it.

Question:
How is the wattage of the heating chosen?

Answer:
To obtain a correct heating system design, a calculation of the heat loss of the building according to the ČSN 06 0210 standard has to be ordered from a design office, preferably the one where you acquired the project documentation. You can also do the calculation yourself, using a simplified version, on the http://www.tzb-info.cz web pages. The heat loss equals the total heat flow which penetrates the individual walls (incl. the floor and ceiling) that delimit the heated room, and the heat loss through infiltration (leakage through windows, doors, etc.). For a basic calculation of heat loss we need to know:

the required temperature in the room and the lowest temperature beyond the wall (there is a map of the lowest outside temperatures for the given areas in an attachment to the standard – for use in the case that there is an outdoor area outside the wall) – the difference between the inside and outside temperature is called the temperature gradient (it ranges between 30 – 40 °C)
the surface area of the wall (windows and doors are excluded and calculated separately)
the heat transfer coefficient “U” (W/m²K) – manufacturers of building materials state this value, or it can be calculated according to the aforementioned standard

Question:
What will the electricity consumption be (kWh) and what are the costs of heating a building?

Answer:
The yearly consumption of electricity for the heating of a building depends on the heat losses of the building and the quality of the selected regulation system. The heat loss is the value of energy which you need to supply to the building in order to achieve the required ambient temperature. The total heating costs per year thus depend on the electricity consumption and the selected electricity tariff. Electric heating can be operated either via direct heating or through the use of storage heaters. The direct mode of heating is realised in such a way that the consumer has the option of using low tariff heating for 20 hours and has only 4 hours of high-tariff operation. The low tariff can also be used for other appliances in the building. The heating mode utilising storage heaters involves the “charging” of the heating medium (water, concrete, bricks) for a maximum of 8 hours during the low tariff period, and then using the accumulated energy for the heating of the building itself for the remaining 16 hours. For these 16 hours, any additional electricity is taken at the high tariff.

Question:
What are the main reasons for choosing electric heating?

Answer:
There are many reasons; we will name only the main ones:

Electric heating is the most perfectly controllable heating system with the lowest specific energy consumption. While the average energy consumption on heating is about 0.8 GJ/m² per year in the Czech Republic, for electric heating the value equals 0.3–0.4 GJ/m² per year.
Perfect and cheap temperature regulation systems enable users of electric heating to fully adapt their heating method to changing family and economic conditions.
The acquisition costs of electric heating systems are considerable lower (in tens of per cent) than in the case of other systems. This fact is very important particularly in new buildings with low heat loss and thus also low energy consumption on heating.
There are special tariffs for heating with electricity which enable the use of cheap so-called “low tariff” energy also for other household needs. This fact, with regard to the increasing amount of electric appliances in households, is again an important means of lowering the total cost of household operation.

Question:
What are the operating costs of electric heating? I know it is a comfortable and service-free type of heating but aren't the high operating costs an excessive tax for comfort?

Answer:
Users shouldn't just be interested in operating costs (even though they are certainly important) but also in the total cost of energy together with so-called amortization, i.e. with part of the acquisition cost. In this respect, electric heating is fully comparable with gas heating (see the section concerning references and news). It is hard to predict the long-term development of energy prices; however, it is a fact that gas is a non-renewable natural resource and its acquisition will get harder and harder. Also, the price of gas is fully dependent on the fluctuations of the world economy.

Question:
Friends are dissuading me from the acquisition of electric heating, stating high fixed payments for heating tariffs. They claim that these sums are supposed to put off those interested in electric heating – is it really true?

Answer:

The fixed payments are under no circumstances a prohibitive issue; they have two functions:

To pay the energy supplier’s costs related to the reservation of the required wattage in the nn network (depending on the value of the main circuit breaker).
To prevent speculative use of special low heating tariffs for standard use in households (small consumption).

Nowadays, there are devices which enable a significant reduction in the value of the main circuit breaker and thus also the height of the fixed payment. Such devices distribute the consumption of the household across a longer time period and prevent peaks in consumption (see the section on regulation – Regulators for decreasing the value of the main circuit breaker).

Question:
I’ve heard that the use of electric energy for heating isn't ecological and that advanced countries are moving away from it. Is this true?

Answer:
It is mainly the way electric energy is produced that decides whether electric heating is ecological or not. Generally speaking, electric heating is only a minority heating method, being used by about 10–15 % of all heated buildings in countries where electricity is produced mainly from solid fuels and gas. In countries where electricity is produced from nuclear energy or renewable resources, electric heating plays a very important role – in countries such as Sweden, Norway, Finland and France, electric heating has been the main source of heating, except in block-style buildings, for a long time, and 30 or more per cent of residential buildings are heated with it.
In the last four years, with regard to the liberalisation of the electricity market, there is a noticeable tendency towards strengthening the importance of electric heating also in other countries. At present, the Czech Republic gains a significant amount of energy from nuclear power and it can be assumed that it will rank among the countries from the second group mentioned above. Moreover, only 8.4 % of residential buildings are heated using electricity in the Czech Republic at present.

Question:
What kinds of electric heating can you recommend to me?

Answer:
Our company offers practically all kinds of electric heating, from storage systems, through mixed (semi-storage) installations all the way up to direct heating systems. The only product which is missing from our range of products is a line of electric boilers, due to the fact that this kind of heating is highly inefficient. We do not even recommend this product to our customers because of the high operating costs. In Europe, there is a tendency towards the installation of what are known as large-surface heating systems, whose use provides the highest comfort possible. These systems (installed in the floor or ceiling) warm up large heat-exchanging surfaces to temperatures which are only slightly higher than the temperature of their environment. The heat exchange takes place partially via micro convection. Micro convection takes place across the whole surface. A significant difference in contrast with so called spot sources of heat is the much more even distribution of temperatures in the room, the limitation of circulation and the drying out of the air (for other information see ECOFLOOR and ECOFILM products).

Question:
I'm interested in buying electric heating but my friends are raising concerns regarding problems which occur when heating is disconnected during high tariff periods, as well as its non-functionality during power cuts.

Answer:
At present, there is a set condition for switching off heating during the high tariff that makes it possible for heating in the so-called direct heating mode to be switched off for a maximum of 2 hours during the morning and 2 hours during the afternoon; the maximum period for which the heating can be continuously switched off at one time is 1 hour. During this time, the temperature in the rooms probably won’t drop by more than 1 °C. Buildings with bad heat insulation can be an exception; in such cases we recommend the installation in day rooms of WMX static storage heaters from our range of products. If there is a power cut, practically all modern ways of heating are put out of operation, as electrical devices governing the function of boilers will also go offline. Therefore, in this case, there is no difference between electric heating and e.g. gas heating.

Question:
How should the wattage of a heater be dimensioned for a specific room or building?

Answer:

To obtain a correct heating system design, a calculation of the heat loss of the building according to the ČSN 06 0210 standard has to be ordered from a design office, preferably the one where you acquired the project documentation. You can also do the calculation yourself, using a simplified version, on the http://www.tzb-info.cz web pages. The heat loss equals the total heat flow which penetrates the individual walls (incl. the floor and the ceiling) that delimit the heated room, and the heat loss through infiltration (leakage through windows, doors, etc.). For a basic calculation of heat loss we need to know:

The required temperature in the room and the lowest temperature beyond the wall (there is a map of the lowest outside temperatures for the given areas in an attachment to the standard – for use in the case that there is an outdoor area outside the wall) – the difference between the inside and outside temperature is called the temperature gradient (it ranges between 30 – 40 °C).
The surface area of the wall (windows and doors are excluded and calculated separately).
The heat transfer coefficient “U” (W/m²K) – manufacturers of building materials state this value, or it can be calculated according to the aforementioned standard.

Other “extras, coefficients, etc.” need to be taken into consideration for a more exact calculation. If you add a larger-than-necessary heater to a room and equip it with a suitable thermostat, it won't use more electricity (kWh) than a correctly sized heater and it will have the advantage of providing a much shorter reaction time to heat demands. However, there are disadvantages in the shape of higher acquisition costs and possibly a higher required value for the main circuit breaker, which means a higher fixed payment. This forms a significant part of the electricity bill. Note: Even this doesn't have to be a problem as the value of the main circuit breaker before the energy meter can be standardly lowered by up to two orders of magnitude than that which would correspond to the installed wattage, if the BMR HJ regulation system supplied by us is used.