SETTLEMENTS OF INDIVIDUAL HEATING COSTS IN MULTIFAMILY BUILDINGS – POLISH EXPERIENCE

S t r e s z c z e n i e Dyrektywa dotycząca efektywności energetycznej nakłada obowiązek rozliczania odbiorców energii według faktycznego zużycia. Stosowanie właściwie działających i akceptowalnych społecznie systemów rozliczeń indywidualnych kosztów ogrzewania przyczynia się do oszczędności energii w sektorze mieszkaniowym. W artykule przedstawiono krajowe wymagania prawne w tym zakresie oraz możliwości stosowania różnych systemów rozliczeń kosztów ogrzewania. Wyszczególniono i opisano najważniejsze przyczyny występowania nieprawidłowości w rozliczeniach indywidualnych kosztów ogrzewania przy zastosowaniu podzielników kosztów w budownictwie mieszkaniowym w Polsce. Podano również propozycje usunięcia występujących nieprawidłowości, w celu uzyskania odpowiedniej jakości podziału kosztów ogrzewania budynku na lokale mieszkalne. K e y w o r d s : Energy efficiency; Energy saving; Heating; Heat cost allocators; Heating costs. 3/2017 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 143 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T The Si les ian Univers i ty of Technology No. 3/2017 A . S p e c j a ł , H . C i u m a n 144 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 3/2017 of tenants and respectively to reduced energy consumption. Nowadays, this matter is of particular importance due to the requirements of the Directive on energy efficiency [1]. This is connected with obligation of metering the energy use in premises and apartments in multi-purpose and multifamily buildings. Devices enabling the settlement of individual heating costs according to the actual consumption and ensuring the proper billing accuracy should be installed in such buildings. 2. LEGAL REQUIREMENTS CONCERNING THE NEED FOR SETTLEMENTS OF INDIVIDUAL HEATING COSTS General rules of settlements of heat costs between administrators or owners of buildings and energy companies, as well as between an owner or an administrator of multifamily building and its occupants are set out in regulations like: Energy Law Act [2] and Regulation on technical conditions for buildings [3] (which is the executive act to Building Law Act [4]). According to the above regulations, in multi-family buildings supplied with heat from a district heating network or using their own boiler is necessary to apply energy consumption measurement in whole building and in every dwelling as well. According to the Energy Law [2] the basis for settlements of individual heating costs in multifamily building should be: a) for residential and commercial premises: – indications of heat meters – indications of devices enabling settlements of individual costs, which are not measuring devices in the meaning of metrological rules, – the surface area or the volume of these premises, b) for common parts of multifamily building – the area or the volume of these parts accordingly in proportion to the surface area or the volume of occupied dwellings. According to the Regulation [3] devices enabling settlement of individual heating costs should be used in a building with more than one dwelling or a commercial premise. The Regulation does not define a type of device and it is not required that it should be a measuring equipment. The Act [2] requires an owner or an administrator of the building to use such a method of settlement of individual heating costs that meets the following requirements: a) ensures the correct operating conditions of the building, b) takes into account handicap factors resulting from the location of premises within the building, c) stimulates energy-efficient behavior of users, d) provides fees for heat corresponding to its consumption, e) takes into account the amount of heat delivered to the premises by heating risers, f) takes into account the amount of heat connected with heat transfer through partitions between premises. There have not been developed yet detailed guidelines on the method in order to ensure transparency and accuracy of settlement of individual costs of heat consumption in the premises. 3. CONNECTION BETWEEN THE METHOD OF SETTLEMENT OF HEATING COSTS AND TYPE OF CENTRAL HEATING SYSTEM Settlements of individual heating costs in multifamily building are carried out by dividing the total cost of heating the building into the costs of heating Ki individual units of account (premises). The total cost of heating the building is the sum of the fixed cost Ksb (independent of heat consumption) and the variable cost Kzb (cost of heat used for heating the building). The cost of heating a single apartment Ki also includes two parts: the fixed cost Ksi as a part of the cost Ksb proportional to the surface area (or volume) of a premise and the variable cost Kzi as part of the cost Kzb proportional to the amount of heat used for heating an apartment. In order to determine the cost Kzi of a single apartment it should be extracted the amount of heat for heating this apartment from the summary heat consumption, measured for the entire building. The choice of the method of individual heating costs settlements for residential premises in multifamily building depends on the solution of central heating system. Settlement systems based on indications of heat meters can be used for “the horizontal installation system”, with horizontal distribution network in apartments, in which all radiators within a single S E T T L E M E N T S O F I N D I V I D U A L H E A T I N G C O S T S I N M U L T I F A M I L Y B U I L D I N G S – P O L I S H E X P E R I E N C E E N V I R O N M E N T e 3/2017 A R C H I T E C T U R E C I V I L E N G I N E E R I N G E N V I R O N M E N T 145 premise are supplied from one riser (Fig. 1). Settlement systems of individual heating costs based on indications of heat cost allocators are used for “the vertical installation system”, with several risers in each apartment, in which different radiators within a single premise are supplied from different risers (Fig. 2). Such a system is dominant in existing multifamily buildings in Poland. 3.1. Division of heating costs according to indications of heat meters in premises Direct measurement of heat consumption using heat meters is possible in new buildings or thoroughly modernized ones equipped with central heating system supplied from one riser in each apartment. It is noteworthy that in such buildings heat consumption of individual premises is so small that volume flows of the heating medium during the average operating conditions of installation are very small. The correct measurement of very small flow rates is not possible if it is within inaccuracy or even deadband range. This causes problems in settlement of heating costs. In fact, these heat meters play a role similar to heat cost allocators. 3.2. Division of heating costs based on heat cost allocators The method of division of heating costs using heat cost allocators is currently the most widespread in Poland, due to the dominant structure of central heating systems with radiators in each dwelling supplied from many risers. This method involves estimating the amount of energy supplied to the premises by individual heating surfaces. Auxiliary devices called heating heat cost allocators are used for this purpose. They are mounted on heating surfaces (on radiators) in the manner specified in the standards [6, 7]. The method assumes that an indication of a heat cost allocator in the billing period is proportional to amount of energy transmitted by a radiator to a room during the heating season. Two types of heat cost allocators are used in heating costs settlement systems in Poland: • without electrical energy supply, based on the evaporation principle – called evaporative heat cost allocators (only single-sensor allocators), • with electrical energy supply, devices for the registration of the temperature integral with respect to time – called electronic heat cost allocators (singleor two-sensor allocators). Single-sensor allocators register the temperature of the room heating surface or heating medium (assuming a constant air temperature in the room). In twosensor allocators one sensor registers the temperature of the room heating surface or heating medium, the second sensor registers the room temperature or a temperature in a defined relation to it [8]. In settlement algorithms using heat cost allocators, it is assumed that the energy Q transmitted by the radiator in the accounting period is determined by the equation: where: C – constant for the radiator, n – exponent of the characteristic equation of the radiator, Figure 1. Scheme of double-pipe central heating installation with horizontal distribution in apartments [5] Figure 2. Scheme of double-pipe central heating installation with several risers in each apartment [5]