Although we have Decree No. 269/2015 Coll., On the allocation of costs for heating and hot water preparation, which should be a guarantee that basic justice in this area will be a matter of course, a significant percentage of residents living in apartment buildings, but after the experience he sees completely differently on his own skin. While some cannot praise the results of the billing, others see red when paying the bills for the heat supplied, so it is definitely not possible to talk about agreement in assessing the benefits of the legislation. And an independent view? Unfortunately, any more detailed analysis confirms that reality is far from justice, precisely because of the aforementioned decree.
In general, it should be true that binding rules for the functioning of processes in society must be simple, unambiguous and respect the broader context of the issues addressed. Then it can be assumed that despite the fact that not everyone can be fully satisfied with the result, the environment will be fair and predictable enough for everyone to be able to move safely within the set boundaries. When I look at Decree No. 269/2015 Coll. In more detail, I must state that it does not meet practically any of these expectations.
Above all, it completely ignores the fact that all prefabricated blocks of flats, and thus the vast majority of domestic apartment buildings, were designed for a uniform internal temperature, so that they did not intentionally address the insulating capabilities of internal partitions, walls and ceilings. The heat passes through them with minimal resistance, and the whole house functions as one compact unit, not as a set of independent housing units that can compete with each other to save more heat, as some naively think.
Therefore, there is central heating in the apartment buildings, one system that ensures the supply of heat to the entire house, regardless of which housing unit the room belongs to. Switching off every single radiator has an impact on the whole house, because the current heat demand in the house always corresponds to the total output of the heating system. If you miss an article, the others must surprise you. In other words, an apartment with the radiators switched off will be heated by its neighbors by the passage of heat through the walls and ceilings, without the owners of the neighboring apartments having a chance to influence it in any way. It is a system based on the principle of cooperation, not competition.
Rules set by Decree No. 269/2015 Coll. they are not simple. In the past, the more the floor area, the larger the share of total heat consumption. A calculation that every homeowner could do on a calculator in a few minutes, and which none of the tenants at the time protested because it was logical and understandable to everyone.
Today, in order to meet the conditions set by the decree, the calculation must be repeated several times, because the binding algorithm sometimes produces such unrealistic results that they are completely unusable without further modifications. Although this is a clear signal that the input data is defective, the solution is not surprisingly a change in their acquisition, but a repetition of the calculation with the gradual exclusion of those input data that deviate from the expected variance. You can't really look for simplicity and justice in this.
Surveys on indicators are dimensionless numbers, in the final statement their unit is often given a "division". But what this "piece" says about the heat consumption in a given room and what is its physical relationship to the Joule heat unit you will not find anywhere, even though the answer is laconic: nothing and none. So whatever the indicators measure, their outputs cannot be used without correcting them according to the position of the room within the house.
Position coefficients are used for this correction, which ensure that heating costs in flats of comparable size with a comparable level of heating are also comparable. Thus, it might seem that, despite indicating God knows what, the end result will be valid due to the physically calculated coefficients. However, MMR admits something like free creation for positional coefficients. Therefore, deliberately ask where your coefficients came from. Were their values determined by physical calculation, or are they universal prefabricated coefficients determined by mere estimation, or the Bulgarian constant of the second type?
Officials have decided to reduce heat consumption in apartment buildings in a way that completely puts the principle on which houses with central heating work. They introduced the obligation to equip heating systems with ratio indicators in order to detect and punish users who consume more heat than the house average, regardless of whether it is just a result of poorly set position coefficients or involuntary heating of neighboring apartments. Although the results show that without an accurate calculation of the positional coefficients, the data from the indicators are useless and heating costs cannot be distributed fairly without them, officials seem to leave this key step in the whole billing process at the discretion of its processor. He determines the positional coefficients in the vast majority empirically, ie by estimation without any physical verification of their validity. The result is calculation errors in the order of tens of percent, for which part of the house's inhabitants pay extra and some of them benefit. So a huge amount of artificial injustice as a result of the irresistible urge of legislators to improve something that somehow worked after the introduction of combined power regulation.
Reason stands above all this. Fortunately, this problem also has a solution.
The location of the apartment within the house determines its energy intensity, which is expressed by the specific heat demand for heating relative to 1 m 2 of floor space. It is obvious that the resulting value will depend both on the construction system of the house and on the climatic conditions in the given locality, but also on the orientation of the house towards the world and on the surrounding buildings. If we want to objectively assess the energy intensity of individual apartments, and the mandatory installation of ratio indicators does not give us a choice, we must accept the fact that not only heat losses but also heat gains contribute to the overall energy balance, often to a surprisingly high degree.
A great advantage in evaluating energy efficiency and complexity is the fact that we perform this calculation only after the end of the billing period, so we can easily obtain relevant data for it. We know the length of the heating season and the average outdoor temperature during it, so we can calculate the heat loss rates of individual apartments much more accurately than if we were operating with normal values of temperature and length of the heating season, or even the calculated outdoor temperature. In addition, we know the time of sunshine for the site and the effect of shading by surrounding buildings or vegetation, so we can calculate with satisfactory accuracy the volume of solar heat gains entering the building through glazed areas, as well as the effect of radiation on increasing the average air layer. facades and roof of the building. This must be taken into account when calculating the real heat loss through.
Creating the right position coefficients requires projecting locally and temporally relevant meteorological data into the assessment of the energy performance of individual rooms. Although the blocks of flats look like each other, they often differ significantly from each other in the overall heat balance, which is the result of heat fluxes that occur in the building due to heat losses and gains. And that's why a universal set of position coefficients can't work at all.
The methodology for calculating heat losses is gradually being refined. However, it should be added that of the three parameters that enter into the calculation - the area of the structure, the heat transfer coefficient of the structures and the temperature difference before and after the structure - the refinement concerns only the second and is in the order of percentage units. On the other hand, the temperature difference remains completely unnoticed.
Heat from the heated rooms escapes not only outside the building, but also into the adjacent unheated spaces such as stairs or cellars, while the temperature in these rooms is determined by the standard. The deviation of the standard from the actual temperature difference can then be several degrees Celsius, which, with regard to the area of the dividing structures and their high permeability, generates significant calculation errors. Although the designers may have waved their hands over the sizing of the heating system, as there is a considerable power reserve due to heat gains, these errors have a completely different weight and impact on the correct calculation of position coefficients when assessing the complexity of individual flats. Temperatures in unheated rooms must be calculated, not estimated.
It is similar with the outdoor temperature. The average air temperature around the perimeter cladding varies depending on how much the area is exposed to sunlight and the color of the cladding. The black areas, the south and the roof have a significant advantage, but even on the bright northern façade we notice a slight increase in temperature compared to the temperature in the open space due to the diffuse component of solar radiation.
The importance of solar radiation in the heating season is underestimated. However, when we look at the total totals of global radiation in our conditions from October to April, we divide them by the total number of hours for this time period, we get an average of 25 to 95 W / m 2 , depending on the orientation of the facade. And because night hours are included, performance will be at least twice as high during the day. After all, almost everyone has experience with the contribution of the spring or autumn sun to the level of interior temperature.
However, few houses have the privilege of being exposed to sunlight from morning to evening. Almost every façade is sometimes shaded by the surrounding buildings, dense vegetation or terrain, so local values need to be further corrected. The sun exposure time must therefore be divided into the time when the global radiation acts and the time when only the diffuse component acts. And we must not forget the shadow from the lining or lintel, or the influence of curtains, blinds, etc. The calculation is quite complicated, but necessary.
The following video shows how the facades of the building and its glazed areas are exposed to solar radiation during one cloudless November day, and how the surrounding buildings are affected. The color scale for the glazing expresses the effective length of exposure during the entire heating season due to the variable path of the sun and the length of the cast shadows. Dark red areas gain the most energy, followed by blue areas, which are, however, minimally represented in this south-eastern view.
I assume that at this point everyone will wonder how it will be with other heat gains - metabolic heat or heat generated during the operation of household appliances. Unlike the previous one, the volume of this component can be attributed to the individual behavior of the users of a given apartment. If we compare two climatically identical days, and if the whole family is at home during the first one and leaves the next day, it will have no effect on solar heat gains, but there will be a fundamental difference in gains from people and appliances. Therefore, other heat gains are not calculated when assessing the energy performance of apartments.
At first glance, this may seem to be a disadvantage for the part of the party that generates more heat gains. But it is definitely not a mistake of this method of calculating positional coefficients. Thermostatic valves, a quantitative part of power regulation, reduce the output of the respective radiators with increased production of heat gains, and if the indicators really know what their manufacturers say about them (and for which I have not seen a single piece of evidence), then evaluate the volume of heat savings, which has occurred at a given moment, this shall be duly taken into account in the overall plan, and therefore in the annual accounts. If they can't, then the question is, what does everyone have to have on their radiators…
A corner apartment under a roof with walls facing south and west may have a lower specific heat demand than an apartment in a sheltered position, but with a north facade. The energy intensity of two flats of the same size, located in one house in a mirror image, the first at the southern gable and the second at the northern one, can differ by more than 10%. The apartment above the unheated cellar will be worse than the apartment under the roof.
That you have it differently in your house? Then I would like to know on the basis of which assessment your positional coefficients were created. On one smaller house of 11 flats, for which I recently calculated the positional coefficients, I made a comparison of the values of the coefficients calculated according to the overall balance and determined empirically. Differences in heat billing ranged from −30 to + 38%. For entire apartments, for individual rooms, the deviations were even more dramatic.
The calculation of positional coefficients according to the total balance is not simple, but in comparison with other possible alternatives it gives an objective picture of the actual energy intensity of each room in the house. And without it, justice in the area of heating cost allocation cannot be considered.
In the next article you will find a description, comparison and evaluation of three different methods used to create positional coefficients.
Decree No. 269/2015 Coll. I consider it one of the worst regulations I have ever encountered. I start from the experience of people who asked me for advice on what to do when they have winter at home and yet the highest share of heating costs in the whole house. At first I bet on the effect of heat parasitizing unoccupied neighboring apartments, but then I thought of looking at positional coefficients.
