TECHNICAL MEASURES TO DECREASE HEAT ENERGY CONSUMPTION OF FINAL CUSTOMER IN MULTI-APARTMENT BUILDINGS ACCORDING TO ENERGY EFFICIENCY DIRECTIVE

. Energy consumption in the world increases, so the measures in order to improve energy efficiency must be found. The aim of 2012/27/EU Energy Efficiency Directive targets is to decrease energy consumption for a final energy consumer by 1.5% every year, but there is no definition how these targets could be achieved by an individual member state. This article presents the analysis how these targets could be achieved by the means of individual heat metering by heat cost allocators for every flat thus decreasing an energy consumption for a final consumer. Statistical analysis of identical buildings with indivi dual metering by heat cost allocators and without them is presented. Heat cost allocators do not decrease energy consumption by themselves, so this article presents a technical solution and a set of additional equipment, i.e. thermostatic valves, balance valves, hot water meters and remote data collection system that must be installed. The final results show that the targets of 2012/27/EU Energy Efficiency Directive in Lithuania can be reached, because the buildings with individual heat cost allocators consume about 20–30% less of heat


Introduction. The role of final customer in energy efficiency process
World fuel prices have advanced and global warming still is increasing, so the attention is paid not to how to extract ever greater amounts of energy, but how to use extracted primary energy more efficiently. The European Union aims to deal with this problem, and to increase the efficiency of primary energy use, the European Parliament and of the Council on 25 October 2012 has approved the 2012/27/EU Energy Efficiency Directive which replaces Directives 2009/125/ EC and 2010/30/EU and repealing Directive 2004/8/EC and 2006/32/EC. It aims to oblige Member States to introduce the energy sector in order to improve energy efficiency measures to help ensure the most effective use of produced energy.
Taking a view on a local situation, energy efficiency problem is particularly acute in Lithuania. The evidence of this is that for a heat energy a statistical Lithuanian resident spends a considerably higher part of income than in other European countries, so it may be concluded that the group of heat energy consumers is financially the most sensitive group of all consumers. This group of users is divided into two large segments -those who live in private houses and those who live in multi-apartment buildings. As a private house has the possibility to select the free type of fuel and does not have a necessity to heat by expensive gas, can keep the desired temperature comfort level according to their income level, decrease temperature for the night, weekend or other desired time period of day, the multi-apartment buildings do not have such flexible options. In order to optimize the expenses for heat energy in residential buildings, in particular, reduction is possible in two main dimensions: the price of heat and amount of consumed heat. As practice shows, the heat price can be reduced by changing the structure of the balance of used fuel, i.e. reducing the use of expensive gas and increasing the use of local biofuel. In this case we have two main benefits: a) reduction of expenses for heating; b) instead of buying expensive imported fuel buying much cheaper local fuel, the expended money for these fuels remains within the country limits and do not crosses Lithuanian borders, that positively contributes to the economic welfare of the whole Lithuania. Municipalities which use the potential of local biofuel in the most intensive way, have a heat price range of 5-7 € cents/kWh and the municipalities for heating using natural gas has from 7 to 10 € cents/kWh ranging price. Comparing the lowest 5 € cents/kWh local biofuel and the highest 10 € cents/kWh natural gas price, the difference is almost double.
The reduction of consumed heat energy is much more complex task. This task is more complex not from the point of view of technical or engineering solutions, but taking a look from our country's legal framework, which precisely and unequivocally does not identify the entities responsible for the heat consumption in buildings. However, this legal framework was made by the European Parliament in the Efficiency Directive, which aims that energy distributors and retail energy sales companies would get for end-consumers annual new energy savings equivalent to 1.5%. That must be done from 1 January 2014 to 31 December 2020 (Directive 2012/27/EU: 2012. This article presents the analysis how 2012/27/EU Efficiency Directive targets can be achieved by the means of individual heat metering -by installing heat cost allocators for every final customer (flat) that decreases energy consumption for a final consumer. Heat cost allocators do not decrease energy consumption by itself -energy efficiency is obtained by the help of human factor and influence, so this article presents technical solutions that must be installed. This article presents a statistical analysis of identical buildings with individual metering by heat cost allocators and without them shows that the targets of 2012/27/EU Energy Efficiency Directive in Lithuania can be reached as the buildings with individual heat cost allocators consumes about 20-30% less of heat energy The main targets of energy efficiency directive 2012/27/EU for a district heating sector The European Union is facing with increased volume of imported energy resources, climate change and the economic crisis. This leads to draw extra attention to energy efficiency, because the reduction of primary energy consumption directly reduces dependence on imported energy resources and increases energy security. Development of energy-efficient economics is conducive to innovative technological solutions and enhances the European Union's industrial competitiveness, promotes economic growth and creation of a skilled workforce.
So great attention is paid to improve energy efficiency in the public sector. Even higher targets and obligations are provided for in order to enable the end user itself regulate his energy consumption, as buildings are responsible for 40% of total EU final energy consumption (Directive 2012/27/EU: 2012).
Energy efficiency directive 2012/27/EU section 7 of states that until 31 December 2020 must be reached a final energy consumption savings target to save annually 1.5% of end-user energy (Directive 2012/27/EU:2012). The aim is to ensure that all energy distributors and/or retail energy sales companies, as designated by obligated parties, from 1 January of 2014 until 31 December 2020 each year must save the new amount of energy equivalent to 1.5% of end user energy (Directive 2012/27/EU: 2012).
Energy efficiency directive 2012/27/EU section 9 states that in multi-apartment and multi-purpose buildings supplied from a district heating network individual consumption meters should be installed by 31 December 2016 to measure the consumption of heat or hot water for each unit where it is technically feasible and cost-efficient (Directive 2012/27/EU: 2012).Where the use of individual meters is not technically feasible or not cost-efficient, to measure heating, individual heat, cost allocators shall be used for measuring heat consumption at each radiator.
Energy efficiency directive 2012/27/EU Section 10 obligates that invoicing should be based on actual consumption. The final customer must be able to make a comparison of energy consumption during the current period and the same period of the last year. It should be done in graphic form. For a final customer provided information must be accurate and based on actual consumption. This obligation can be met by regular self-reading system that allows communicate readings from consumer meter to the energy supplier. Final customer must be able to obtain additional information on the previous consumption easily, which would allow the same end-user to make a detailed self-control.
The information on historical consumption must include cumulative data for at least the three previous years. The data shall include detailed data according to the time of use for any day, week, month and year and shall be made available to the final customer via Internet or the meter interface for the period of at least the previous 24 months. For a final customer must be offered the option of electronic billing information, a clear and understandable explanation of how their bill was derived.
At present moment main EU countries do not have a strong experience and confirmed technical means to reach Energy efficiency directive 2012/27/EU targets. Denmark applies energy efficiency measures in a wide way, but the technical solutions to obtain energy efficiency targets may have local significances so can't be applied for all countries in a blind way. Lithuania still does not have a confirmed solutions to increase energy efficiency for a final customer.

Actual energy consumption evaluation methodology
To assess not theoretical but actual energy consumption of each building for space heating, hot water preparation and hot water circulation, by R. Savickas defined actual energy consumption class (AECC) was used. AECC is used to evaluate real/actual supplied energy for premises heating. According to the energy consumption for space heating buildings are divided into 15 energy classes: the smallest and energetically most effective class is 1, the largest and energetically least effective buildings have 15 class. Numeric value of an AECC is the energy consumption amount for premises heating, from which by calculation procedure are eliminated various influencing factors -eliminated the factor of different heating season duration, the influence of different heating season outside air temperature and the influence of different buildings heated area. Results let to compare the energy consumption of the same or different types of buildings during different heating seasons. AECC lets to compare energy for premises heating of the same building during different time periods -years, months, etc. Also can be compared several buildings of different heating areas and so on. For AECC calculation energy balance of total consumed energy Q∑, MWh in building is used: where: ∑Q -total heat consumption in building, MWh; Q h -heat energy for space heating, MWh; Q hwp -heat energy for hot water preparation, MWh; Q hwc -heat energy for hot water circulation, MWh. For AECC calculation is eliminated actual hot water amount (not according to defined norms for all buildings): Heat energy for hot water Q hwp , MWh preparation is evaluated according to: where: G -hot water consumption before hot water exchanger (this consumption is not the sum of declared hot water amount of all final customers/flats in building), m 3 ; 0.051heat energy to rise hot water temperature by 44 ºC, kWh.
If an actual raised temperature is known, it should be used instead of 44 °C. After elimination of outside air temperature, heating season duration and heated area, the factor q m , Wh/DD/m 2 is obtained: where: q m -heat amount to rise 1 m 2 of premises heated area by 1 ºC during 1 day (24 h), Wh/DD/m 2 ; DD -Degree days (base temperature is 18 °C), DD; S -heated area of premises, m 2 . Evaluated heat amount q m is individual for every building. According to q m , the AECC is prescribed in Table 1.

Outcomes and results on implementation of energy efficiency means
Targets of 2012/27/EU directive on the energy efficiency in district heating sector can be implemented by application of technical energy efficiency means. Complete combination package allows to access it in the most energy efficient way. It is important to distinguish the minimal measures that enable to achieve energy efficiency at the minimum level. Performed analysis shows that the reconstruction of internal heating and hot water systems in multi-apartments buildings under 1992 and installing individual heat and hot water consumption meters for each final customer has a potential to decrease energy consumption for a final customer by about 25% (Fig. 1), (Savickas, Paulauskas 2014).
Mentioned potential savings for minimal energy efficiency can be achieved by in the Table 2 specified minimal technical means. Measures for larger energy efficiency can be described also, but they have a potential only of small saving percentage.
Minimal investment level to install minimal technical means (Fig. 2) for such individual heat metering is about 15 EUR/m 2 or about 900 EUR for a typical apartment of 60 m 2 . The reconstruction of one pipe heating system, installation of thermostatic valves and heat cost allocators for separate individual apartment can be performed in 1 day. The total reconstruction to have a potential of 25% energy savings also includes installation of automated balancing valves for heat and hot water systems, smart intelligent wireless monitoring and data collection system, hot water metering for each final customer.
Mentioned technical measures are applied and a potential of about 25% of energy savings is for buildings with independent heat substations with separate heat exchangers for heating and hot water. If the building does not have an independent type heat substation, the reconstruction of heat substation and installation of individual heat metering for every final customer in addition, gives savings much higher than 25%.
Heating system reconstruction does not preclude further renovation of the building envelope, as after additional building thermal insulation would be applied, the internal heating and domestic hot water systems still need to be reconstructed according to a new heat demand. Once this is done before building envelope renovation, the savings due to heating system reconstruction can be obtained and get already before partitions insulation.

The optimal scenarios for the implementation of 2012/27/EU energy efficiency directive
For the implementation of the 2012/27/EU energy efficiency directive for centralized heat supply sector with the lowest costs, the potential to achieve the targets by different implementation scenarios must be evaluated for the Member State.
Obligations for Lithuanian electricity, heat and gas sectors are provided in the Table 3. Lithuania during 2012 has consumed 646.8 ktne of final energy. The total final energy consumption goal of all the electricity, heat and gas sectors by 2020 is 2639 GWh. Heat sector provides 33% or 870 GWh of final energy consumption. The annual savings during 2014-2020 years is 145 GWh.
Investments and cumulated savings for implementation of 2012/27/ES Energy efficiency directive are presented in Figure 3. Independent heat substation for heat and hot water preparation (the analysed buildings almost have reconstructed heat substations, so if heat substation is not reconstructed, the potential energy savings will be much more higher) + +
Hot water system balancing + +

4.
Thermostatic valves on the building heating system heating appliances + +

5.
Individual heat metering for each final customer of the building (heat meters or heat cost allocators) + +

6.
Hot water metering for each final customer of the building + +

7.
Smart intelligent wireless monitoring and data collection system + +
Replacement of heating appliances with more efficient -+ 10.
Reflecting screens under heating devices -+  Table 4 shows implementation of technical means for 100% of the buildings with urgent investments on the year 2015, Table 5 shows implementation of technical means for 50% of the buildings with urgent investments on the year 2015, Table 6 shows implementation of technical means for 50% of the buildings when investments are set during the first three years (2015)(2016)(2017). Table 4 shows that implementation of technical means for 100% of the buildings then investments are instant on 2015 would lead to 4292 GWh savings then the obligation in heat sector is only 870 GWh. The obligation for all heat, gas and electricity sectors is just 2639 GWh, so the total savings for all sectors can be get only by heat sector. As it is difficult to implement all technical means during one year, the third scenarios (Table 6) is practicable and the savings of 1717 GWh is possible.