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Association "Green Leap", Novi Sad
Address: Mise Dimitrijevica 72/18
Tel. +381-60-0106083
E-Mail: zeleniskok@hotmail.com
Project: ENergy Efficiency and Renewables–SUPporting Policies in Local level for
EnergY (ENER-SUPPLY)
Work Package 4
Energy Audit
Date: 14.03.2012.
Country: SERBIA
Partner: University of Novi Sad (UNS)
Building: Elementary school ''Djura Jaksic''
Trg Slobode 4, Curug
2
Contents
1 BACKGROUND AND OBJECTIVE OF THE STUDY ............................................................... 3
2 BUILDING FEATURES ........................................................................................................... 4
Location ...................................................................................................................................... 4
The external appearance of buildings .......................................................................................... 4
Basic Data ................................................................................................................................... 5
Envelope of the building ........................................................................................................... 6
HVAC .......................................................................................................................................... 6
Power system and electromechanical equipment .......................................................................... 7
Domestic Cold and Hot Water (DHW) ......................................................................................... 7
Lighting system ............................................................................................................................ 7
3 Energy and Fuel Consumption .................................................................................................. 8
3.1 Actual Consumption of Energy and Fuels ............................................................................... 8
Unit prices of fuel and energy ................................................................................................... 8
3.2 Theoretical Energy Needs ...................................................................................................... 9
3.3 Comparison of Real and Theoretical energy consumption .................................................... 11
4. ENERGY EFFICIENCY MEASURES PROPOSAL .................................................................... 14
4.1 Reconstruction of object envelope ........................................................................................ 14
Costs and prices of thermal energy supply .............................................................................. 14
Sealing of windows and doors ................................................................................................. 14
Replacement of metal windows, doors and panels ................................................................... 14
Implementation of external walls thermal insulation ............................................................... 15
Implementation of a thermal insulation in the roof .................................................................. 16
Implementation of a thermal insulation of the ground floor..................................................... 17
4.2 Building energy infrastructure improvement ........................................................................ 18
Installation of balancing valves .............................................................................................. 18
Installation of thermoregulation valves ................................................................................... 18
Piping insulation .................................................................................................................... 18
4.3 Improvement of hot water boiler operation - switching fuel type .......................................... 19
4.4 Lighting ............................................................................................................................... 20
4.5 Introduction the energy management procedures ................................................................. 20
5. CONCLUSION .......................................................................................................................... 22
3
1 BACKGROUND AND OBJECTIVE OF THE STUDY
The ENER SUPPLY project intends to help the local authorities to realize energy management
implementation, planning of investment in RES and promotion of investments in RES. The ENER
SUPPLY project, financed by the South East Europe Transnational Cooperation Programme, is the
result of a common effort of 13 partners from 11 South-East Europe countries, whose Lead Partner
is the Municipality of Potenza, Italy.
The Studies is related to public buildings in education and administration sectors in order to
introduce various economically efficient and environmentally safe technical energy saving
measures in the buildings.
The objective of the this Study is to improve energy efficiency in heating buildings in order to make
heating more affordable and as well as improve the functional and health environment of the users.
An important associated objective is to reduce the local and global environmental impact of the use
of dirty fuels for heating buildings. Study considers energy efficiency improvements in selected
building. For buildings is performed energy audit in order to define investment packages proposals
with budget estimate for each building.
4
2 BUILDING FEATURES
Location
Elementary school ''Djura Jaksic'' is located at Trg Slobode, number 4, in Curug. Building of
Elementary school is educational type with teaching facilities and with separate physical culture
hall. Ownership of the School is public. Micro location of object is presented in Fig.1.
Figure 1: Micro location of building
The external appearance of buildings
School building consists of three objects: old (built in 1851.), new (built in 1969.) and gym (Fig 2, 3
and 4). All three objects are free standing buildings with all exposed facades. Old building and gym
have ground level and the new one is with ground floor and one storey.
5
Fig. 2 Old part of Elementary school "Djura Jaksic"
Fig 3 New part of Elementary school "Djura Jaksic"
Fig 4 Entrance to the school (left is gym, right is new object and right in the back is old object)
Basic Data
Overview of characteristics of school is presented in Tables 1 and 2.
6
Table 1: Occupational characteristics of school
Number of employees 75
Number of pupils 921
Number of shift per day 2
Number of simultaneous users 498
Other (temporary) users of building facilities 50
Operation days per year 270
Operation hours per day 14
Table 2: Basic characteristics of building
Heated floor area 2,699 m2
Unheated floor area 71 m2
Total floor area 2,770 m2
Total volume 9,782 m3
Heated volume 9,534 m3
Gross surface of the building (envelope) - wall area 1,978 m2
Total surface of the window, door and skylight/ panels 616 m2
NET surface of the walls 1,361 m2
Envelope of the building
Energy characteristics of building envelope are presented in Tables 3, 4 and 5.
Table 3: Energy characteristics of roof
Type of roof Average heat tranfer cofficient
W/m2 о
C τ -
New object, 908 m2 1.52 0.82
Gym, 404 m2 3.42 1
Old object, 621 m2 0.6 0.91
Table 4: Energy characteristics of walls
Type of walls Average heat tranfer cofficient
W/m2 о
C
Brick, layer of plaster. Without heat insulation. Wall thickness: 62 cm 0.94
Brick, layer of plaster. Without heat insulation. Wall thickness: 32 cm. 1.6
Table 5: Energy characteristics of the building envelop - glass surface
Type of glass surface W/m2 o
C
Metal windows, one frame with single pane: W/m2°C: 5.80
Wooden doors 3.5
Wooden windows 3.5
PVC windows 1.5
PVC doors 1.5
HVAC
7
Heating
Heating is provided by local heating system - 2 conventional gas boilers (2x600 W=1,200 W). School’s boiler house completely covers heat demand of the building. In the boiler room there are two hot-
water boilers that provide heat to radiator heating. The supply and return temperature are 90/70 oC. Heat
distribution is via radiators. System includes two pipes system with distribution from the bottom
with cast iron radiators without temperature regulation equipment.
Ventilation and air conditioning
School is without central cooling system. School facility is not air conditioned during summer
period. There are few split cooling system in some offices and meeting room.
Power system and electromechanical equipment
Electricity is supplied by local distribution company, with wide consumption tariff system. The
school receives power at voltage 0.4 kV.
In school facilities, there is no technological process, powered electric equipment etc., for which it
is necessary to provide electrical installation, as a "strong" power. All electrical sets appear as an
individual or as part of some technological entities, such as for example small capacities air
conditioning devices, small kitchen equipments, etc.
Electric installations are mono phased conductors.
Domestic Cold and Hot Water (DHW)
Object is supplied with cold water by local water supply system. Consumption of water is not
measured. The system for production and distribution of domestic (sanitary) hot water is
independent from system for production of thermal energy for heating and consists of an electric
boilers located in the kitchen and toilets. Total installed power of electric boilers is 11 kW.
Oldfashioned technical solutions for water and urinal flush, without photo sensors and stop
functions, as well as a numerous malfuncitoning devices, certainly produce higher consumption of
water than needed.
Lighting system
Lighting system includes: incandescent, fluorescent and mercury lamps. Photometric characteristics
are not satisfactory.
In Table 6 is given number of lamps and average consumed power per each type of lamps.
Recommendation: Option for replacing 47 incandescent lamps by fluorescent ones is not
appropriate because these locations are not proper for fluorescent type of lamps (toilets, pantries,
accessory spaces, auxiliary stairways, loft, etc).
Table 6: Types of lamps with structures and related install capacities
Types of lamps Number of devices Capacity [kW]/unit Total [kW]
Incandescent lamps 31 0.06 1.86
Fluorescent lamps 123 0.018 2.214
Fluorescent lamps 272 0.036 9.79
Mercury lamps 3 1.5 4.5
8
3. Energy and Fuel Consumption
3.1 Actual Consumption of Energy and Fuels
Unit prices of fuel and energy
The school is getting natural gas from gas distributor "Srbija gas". The school buys electricity from
national distributive network.
Unit prices of energy and fuels in 2010 are:
Unit price of natural gas: 3.68 RSD/kWh (0.034 €/kWh)
unit price of electricity: 6.75 RSD/kWh (0.063 €/kWh)
In Tab. 7 is presented monthly consumption of electricity and in Tab. 8 monthly consumption of
natural gas.
Tab. 7 Monthly consumption of electricity
Month Cumulative - monthly consumption of electricity Average unit price of
electricity
[kWh] [RSD/month] [kWh] [RSD/month] [kWh]
Jan. 5,986.00 360,802.54 340.76 6.15 0.057
Feb. 6,054.00 37,433.61 346.61 6.18 0.057
Mar. 6,476.00 44,667.40 413.59 6.90 0.064
Apr. 4,630.00 32,044.85 296.71 6.92 0.064
May 3,448.00 24,060.66 222.78 6.98 0.065
Jun 1,641.00 11,409.68 105.65 6.95 0.064
Jul. 801.00 5,468.63 50.64 6.83 0.063
Aug. 990.00 6,749.63 62.50 6.82 0.063
Sep. 3,553.00 24,256.33 224.60 6.83 0.063
Oct. 6,236.00 42,514.59 393.65 6.82 0.063
Nov. 6,298.00 42,965.98 397.83 6.82 0.063
Dec. 7,031.00 47,872.02 443.26 6.81 0.063
Total 53,144.00 356,245.92 3,298.57 6.75 0.063
9
Tab. 8 Monthly consumption of natural gas in 2010
Month Cumulative - monthly consumption of natural gas Average unit price of
natural gas
[m3]
[kWh] [RSD/month] [€/month]
[RSD/kWh
] [€/ kWh]
Jan. 8,603.00 79,663.78 450,95.00 4170.32 5.65 0.052
Feb. 10,162.00 94,100.12 337,398.00 3124.06 3.59 0.033
Mar. 8,612.00 79,747.12 259,815.00 2405.69 3.26 0.030
Apr. 747 6,917.22 0 0.00 0.00 0.000
May 0 0 0 0.00 0.00 0.000
Jun 0 0 0 0.00 0.00 0.000
Jul. 0 0 0 0.00 0.00 0.000
Aug. 0 0 0 0.00 0.00 0.000
Sep. 0 0 0 0.00 0.00 0.000
Oct. 1,574.00 14,575.24 145,499.00 1,347.21 9.98 0.092
Nov. 5,749.00 53,235.74 79,667.00 737.66 1.50 0.014
Dec. 6,058.00 56,097.08 140,138.00 1,297.57 2.50 0.023
Total 41,505.00 384,336.30 1,412,912.00 13,082.52 3.68 0.034
The review of basic indicators for 2010/11 is presented in Tab. 9.
Tab. 9 Energy Indicators for year 2010/11 (Note: The data source is the accounting of the
Institution)
Electricity consumption 53.144 kWh/a
Consumption of natural gas 41.505 m3/a (heating season 2010/11)
Consumption of sanitary water - m3/a
The total cost for electricity 356,245 RSD/a (approximately 3,298 €/a)
The total cost for natural gas 1,412,912 RSD/a (approximately 13,082 €/a)
The total cost for sanitary water - RSD/a (approximately - €/a)
The unit price of electricity (yearly
average) 6.75 RSD/kWh or 0.063 €/kWh.
The unit price of heavy fuel oil (yearly
average) 3.68 RSD/kg (approximately 0.034 €/kg)
The unit price of sanitary water (yearly
average) - RSD/ m
3 (approximately - €/ m
3)
3.2 Theoretical Energy Needs
In Tab. 10 are presented general data necessary for further calculation of heat losses.
10
Tab. 10 General data needed for heat losses calculation
Heated floor area 2,699 m2
Object envelope surface 5,442 m2
Heated volume 9,783 m3
Designed outdoor temperature -18 °С
Designed indoor temperature 20 °С
Heating hours per year 2,353 h
Number of simultaneous users 498 -
number of degree days 2,824 К⋅day
In Tab.11 are presented theoretical heat losses (due to transmission and infiltration) in W/K.
Tab. 11 Total losses of object due to transmission and infiltration
Area
Tau
coefficient k
Transmission
losses
Infiltration
losses
[m2] [-] [W/K⋅m2
] [W/K] [W/K]
Roof 1 908 0.82 1.52 1,137 -
Roof 2 621 0.91 0.6 341 -
Roof of gym 404 1 3.42 1,381
ground floor area 1,530 1 1.95 2,982 -
Wall 1 840 1 1.6 1,347 -
Wall 2 521 1 0.94 490 -
Metal windows 100 1 5.8 578 √
PVC windows 42 1 1.5 63 √
Wooden windows 363 1 3.5 1,271 √
Metal doors 100 1 5.8 585 √
Wooden doors 11 1 3.5 38 √
Total 5,441 10,213 6,880
In Tab. 12 are given data presenting theoretical energy needs.
Tab. 12 Theoretical energy needs
Annual infiltration losses 466,300 kWh/a
Percentage ratio of infiltration losses 40 %
Air volume exchange 14,940 m3/h
Building characteristics 0.56 -
Percentage ratio of windows in total surface area of facade 31 %
Annual transmission losses 692,152 kWh/a
Percentage rate of transmission losses 60 %
Transmission and infiltration heat losses through glass surfaces
per heated area 236 kWh/a m
2
Average transmission coefficient 1.88 W/Km2
11
Total need of heating energy 1,158,452 kWh/a
Total specific transmission and infiltration losses 17,094 W/K
Total loss coefficient (transmission and infiltration) 2.52 W/Km2
Specific heating energy consumption per object surface area 241 W/m2
Specific heating energy consumption per object volume 68.1 W/m3
Specific heating energy consumption per object heated surface
area
429 kWh/a m
2
Specific heating energy consumption per object user 2,326 kWh/a USER
Recommended specific heating energy consumption per heated
surface area
95 kWh/a m
2
Total specific transmission losses 10,213 W/K
Real specific transmission losses per heated surface area 3.78 W/Km2
Recommended specific transmission losses 1.4 W/Km2
In Tab. 13 is presented primary energy consumption.
Table 13 Primary energy consumption
Boiler efficiency rate 0.87 -
Efficiency rate of system for regulation 0.9 -
Efficiency rate of pipeline 0.92 -
Total efficiency rate of heating system 72 %
Primary energy consumption 1,608,157 kWh/a
Specific consumption of primary energy 595.8 kWh/a.m2
Final energy consumption per degree day 570 kWh/DGD
Specific consumption per degree day 0.21 kWh/DGD m2
3.3 Comparison of Real and Theoretical energy consumption
In Tab. 14 is presented monthly heat load calculated according to degree day and school
accounting.
Table 14 Monthly heat load according to degree day and school accounting
Month Temperature Temperature
difference
Number
of days
with
heating
Degree days
Object heat
load
according to
degree day
Object heat
load
according to
degree day
12
°С °С number
of days
°С×number of
days kW МWh
Jan. 0.1 19.9 31 616.9 273.15 110.08
Feb. 2 18 28 504 247.07 89.94
Mar. 5.4 14.6 31 452.6 199.03 80.21
Apr. 11.7 8.3 15 124.5 113.93 22.22
May 0 0 0.00
Jun 0 0 0.00
Jul. 0 0 0.00
Aug. 0 0 0.00
Sep. 0 0 0.00
Oct. 12 8 15 120 109.81 21.41
Nov. 5.9 14.1 30 423 193.54 75.48
Dec. 1.1 18.9 31 585.9 259.43 104.55
Yearly 181 2,826.9 1,395.97 503.89
In Fig. 3 is presented theoretical heat load of object calculated according to degree day. It is noted
that maximal needed power (275 kW) is far below installed power (1200 kW).
In Fig. 4 are presented both theoretical heating energy consumption calculated according to degree
day and monthly consumption of heating energy calculated according to school accounting.
13
0
50
100
150
200
250
300[k
W]
Theoretical heating load calculated according to degree days
Fig. 3 Object heating load calculated according to degeree day
0
20
40
60
80
100
120
MW
h
Theoretical consumption of heat energy calculated according to degree days
Consumption of heat energy according to monthly bill
Fig. 4 Theoretical and accounted consumption of heating energy calculated according to degree day
14
4. ENERGY EFFICIENCY MEASURES PROPOSAL
4.1 Reconstruction of object envelope
Costs and prices of thermal energy supply
End price of heating is formed according to equivalent price of some fuels and efficiency rates of
heating systems which depend on efficiency rate of boiler, pipeline and regualtion system. In Tab.
15 are presented prices of different fuels.
Tab. 15 Prices of final energy
Soy beans
straw
Natural gas /
condensation
boiler
Equivalent
price
RSD/kWh 1.16 4.00
€/kWh 0.011 0.038
Total
efficiency
rate of
heating
system
(%) 71 85
Final price of
heating
RSD/kWh 1.63 4.72
€/kWh 0.016 0.044
Annual price
of heating
RSD/a 1,955,364 5,474,403
€/a 18,105 50,689
Sealing of windows and doors
It has been noticed that windows are not sealed well, and that even such measure as sticking
insulation bands around windows would improve energy efficiency. The investment for such
measure is €3,131 and IRR is less than a year. Energy saving is 5%. In this way infiltration losses
would provide 15,125 m3/h of fresh air what is needed for normal functioning of object.
Replacement of metal windows, doors and panels
This measure includes building in new PVC windows and doors of surface area of 574.56 m2
instead of metal and wooden windows and doors. Calculated price is 150 €/m2, what includes
disassemble of windows and doors, purchase, transportation, installation of boards below the
window, internal protection (Venetian blinds and linen blinds) and other.
The value of coefficient of heat transfer for the proposed new PVC windows is adopted to be k =
1.7 W/m²K.
Infiltration losses include exchanges in the quantity of air that is less than required according to the
number of persons resident in the building. Hence, an additional ventilation air is going to be
15
needed. This requires additional heating energy of 138,244 kWh/a. Even though, this measure has
an effect. Simple payback period is 3.73 years and energy saving is 10.3 %.
In Table 16 are presented losses and energy savings.
Tab. 16 Energy savings due to windows and doors replacement
Losses before
measure
Losses after
measure Difference
Infiltration losses kWh 303,094 55,394 247,701
New total ventilation air
exchange
Нова укупна размена ваздуха
kWh 163,205 36,006 127,199
Transmission losses kWh 692,152 636,425 55,727
Total energy saving kWh 165,184
Total money saving RSD 909,833 = € 8,424.3
Investment: RSD 3,425,328 = € 31,716
Simple payback period: 3.73 years
Implementation of external walls thermal insulation
Entire building doesn't have thermal insulation. Considering that insulation of the walls is proposed
on entire building. Insulation characteristics: λ=0.041 W/m°C and thickness = 0.05 m. Unit price of
this measure is taken as 20 €/m². Surface area of 32 cm thick wall (Table 17) and 62 cm thick wall
(Tab. 18) is 1,362 m2.
Since walls of new building and gym are 32 cm thick with the transmission coefficient 1.6 W/Km2
and wall of old building is 62 cm thick and with heat transmission coefficient of 0.94 W/Km2, it is
justifiable to consider a measure which includes only insulation of walls of new object and gym. In
that case, investment is € 16,805, and simple payback period is 5.4 years and energy saving is
3.78%.
In the case of thermal insulation of all walls of all three objects (Tab. 19), simple payback period is
6.7 years and is not favorable due to current low price of final energy.
Table 17 Calculation of saving and payback period for the wall of the new object (thickness 32 cm)
Wall thickness 32 cm Losses before
measures
Losses after
measures Difference
Heat transfer coefficient W/°C.m² 1.6 0.53 1.07
Energy consumption kWh 91,281 30,464 60,817
Expenses € 4,693 1,566 3,127
Investment: RSD 1,814,940 = € 16,805
Simple payback period 5.4 years
Table 18 Calculation of saving and payback period for the wall of the old object (thickness 62 cm)
16
Wall thickness 62 cm Losses before
measures
Losses after
measures Difference
Heat transfer coefficient W/°C.m² 0.94 0.43 0.51
Energy consumption kWh 33,194 15,317 17,877
Expenses € 1,707 788 919
Investment: RSD 1,126,764 = € 10,433
Simple payback period 11.4 years
Table 19 Calculation of saving for proposed measure - walls thermal insulation (all three objects)
Total investment 27,237 €
Total saving 4,046 €
Simple payback 6.7 years
Implementation of a thermal insulation in the roof
Existing roof on gym and new building is covered with dilapidated asbestos cement panels. The
roof of old building is in pretty good condition, covered with tile and ceiling insulation is made of
reed. It is recomanded to put styrofoam, thicknes 10 cm, as insulation material on ceilings surface
area 1,530 m2. On the ceiling of old building it is necessary to put a hydroinsulation too, thickness 1
cm. On the ceiling od gym it is recomanded to put 10 cm styrofoam. Insulation characteristics are:
styrofoam λ=0.041 W/m°C and hydroinsulation λ=0.059 W/m°C. Tables 20 and 21 presents
calculation of energy saving for recomanded energy efficiency measures. In Table 20 is given total
expences and simple payback period of insulation of all roofs.
Since heat transfer coefficient of new roof is 1.52 W/Km2, and from old roof 0.6 W/Km
2 due to
reed layer, it is justifiable to insulate only new roof. Investment of such measure would be € 7,269
евра, simple payback period 1.9 year and energy saving 4.58%. Very payable measure is
implementation of thermal insulation on gym ceiling. It would cost € 8,080, and payback period is
1.9 years. Energy saving would be 4.5 %.
Unit price of the implementation of insulation on new roof is calculated as 8 €/m2, of old 12 €/m
2
and of gym 20 €/m2.
Table 20 Calculation of energy saving for proposed measure - New roof insulation
Roof of new object Losses before
measures
Losses after
measures Difference
Heat transfer coefficient W/°C.m² 1.52 0.32 1.2
Energy consumption kWh 93,503 19,692 73,811
Expenses € 4,807 1,012 3,795
Investment: RSD 785,052 = € 7,269
Simple payback period 1.9 years
Table 21 Calculation of energy saving for proposed measure - Old roof insulation
17
Roof of new object Losses before
measures
Losses after
measures Difference
Heat transfer coefficient W/°C.m² 0.6 0.24 0.36
Energy consumption kWh 25,395 10,057 15,337
Expenses € 1,306 517 789
Investment: RSD 804,816 = € 7,452
Simple payback period 9.5 years
Table 22 Calculation of energy saving for proposed measure - Gym roof insulation
Roof of gym Losses before
measures
Losses after
measures Difference
Heat transfer coefficient W/°C.m² 3.42 0.37 3.05
Energy consumption kWh 93,619 10,070 83,549
Expenses € 4,813 518 4,296
Investment: RSD 872,640 = € 8,080
Simple payback period 1.9 years
Table 23 Calculation of simple payback period of insulation of all three roofs
Total investment 22,801 €
Total saving 8,879 €
Simple payback period 2.57 years
Implementation of a thermal insulation of the ground floor
Existing ground floor is not insulated. Recommended measure of thermal insulation would be
applied on the whole ground floor surface, of all three objects, 1,529.60 m2, with a layer of
styrodur, thickness 10 cm, and cement layer, thickness 4 cm. Price of investment is €15,280, and
simple payback period is 1.8 years. This is very payable measure which brings 10.2 % energy
saving (Tab. 24).
Table 24 Calculation of energy saving for proposed measure - Ground floor insulation
Ground floor Losses before
measures
Losses after
measures Difference
Heat transfer coefficient W/°C.m² 1.95 0.37 1.58
Energy consumption kWh 202,116 38,176 163,939
Expenses € 10,392 1,963 8,429
Investment: RSD 1,651,968 = € 15,296
Simple payback period 1.8 years
18
4.2 Building energy infrastructure improvement
Installation of balancing valves
The existing heating network is not balanced. Each riser should be equipped with a balancing valve
for adjusting the flow in each riser. This will help in preventing overheating. The prices of
installation of balancing valves include purchase, transport and adoption of pipe connection. Table
25 presents calculation of energy savings for proposed measure.
Table 25: Installation of balancing valves and calculation of energy savings for proposed measure
Number of columns 46 -
Cost per column 50 €
Total investment 2,300 €
Estimated savings [%] 2 %
Estimated annual energy savings 32,163 kWh
Estimated annual cost savings 1,654 €
Simple pay back 1.4 years
Installation of thermoregulation valves (TRV)
Measure for implementation of thermostatic radiator valves is also proposed. We propose to install
200 pieces of TRVs. Price for installation of one TRV is around 20 €. Installation price for
thermoregulation valves include purchase, transport, discharge of installation, removal of existing
radiator valve and adoption of pipe connection. We have assumed the percentage of energy savings
of 10 % for this measure. Table 26 presents calculation of energy savings for proposed measure.
Investment of €1,840 has simple payback period less than heating season. Energy saving is
presumed as 10%. This is very payable and acceptable measure.
Table 26: Calculation of energy savings for proposed measure
Existing annual heating consumption 1,608,157 kWh
Estimated annual energy savings 160,816 kWh
Cost of heat 0.051 €/kWh
Estimated annual cost savings 8,268 €
Total investment 1,840 €
Payback 0.2 years
Piping insulation
The domestic hot water pipes and HVAC installation pipes located inside the building should be
insulated (60 m in total of not insulated pipeline). Tables 27 and 28 present calculation of energy
savings for proposed measure. By pipeline insulation could be achieved energy saving of 1,200
kWh, what is around 0.1 %.
Table 27: Piping insulation of heating system
Insulated U-
value, W/oC
linear meter
Insulated
U-value, W/oC
linear meter
Delta U-value,
W/°C linear
meter
Pipes located in unheated area 0.5 0.3 0.2
Temp.
Difference, oC
Savings kWh/lm-
year
Length
linear meters
Total saving
kWh/year
Pipes located in unheated area 46 40 60 2,400
Total: 2,400
19
The average diameter of pipes is typically 34 mm. The pipes located in unheated area have an
estimated average insulation of 2 cm, and the pipes located in the heated spaces (rooms and stair
cases) have no insulation. All pipes would be insulated with 2 x 13 mm POLYURETHANE
INSULATION. Price of installation of pipe insulation for linear meter is 10 €. This price includes
purchase, transport, removal of existing old insulation and setting the new insulation. We have
supposed that around 50% of energy losses are recovered.
Table 28: Calculation of energy savings for proposed measure
Total energy savings (supposing that only 50% of losses are recovered) 1,005 kWh
Total reduction of energy costs 30.14 €
Investment 500 €
Simple pay back 16.59 year
Table 28: Calculation of energy savings for proposed measure
Total energy savings (supposing that only 50% of losses are
recovered) 1,200 kWh/а
Total reduction of energy costs 61.70 €
Price per unit length 10 €/ml
Length of uninsulated pipeline 60 ml
Investment 600 €
Simple pay back period 9.72 years
4.3 Improvement of hot water boiler operation - switching fuel type
It is highly recommended to change type of fuel. Several options were considered, presented in
Table 29.
Table 29 Different types of biomass
Equivalen
t price
1 kWh
Total
efficiency
rate of
heating
system
Final price of energy Price of heating
RSD/kWh % RSD/kWh €/kWh RSD €
Soy bean straw 1.16 69 % 1.68 0.016 1,955,364 18,105
Natural gas 4.00 85 % 4.72 0.044 5,474,403 50,689
In Tab. 29 is made a comparison of two fuels: currently used - natural gas, but this time
combustioned in up to date condensation boiler and soy bean straw - representative of biomass with
the lowest price, and therefore the shortest payback period. Analyses showed that the most payable
case is combustion of natural gas in up to date condensation boiler with simple payback period of
1.77 years. Simple payback period of boiler on soy bean straw is 2.17 years.
After implementation of above mentioned measure of building in a condensation gas boiler, total
efficiency rate of heating system would rise from 72% to 85%. In Table 30 is given calculation of
simple payback period of investment.
20
Table 30 Calculation of simple payback period of investment: building in condensation gas boiler
Annual energy needs 1,158,452 kWh/a
Price for heating using natural gas 0.044 €/kWh
Annual costs for energy 50,689 €/a
Unite price of СО2 15 €/t
Annual consumption of natural gas 115,845 m3/a
Annual emission of СО2 from natural gas 232 tCO2/a
Market price of СО2 3,475 €/a
Investment in boiler 15,785 €
Saving 8,872 €/a
Simple payback period 1.8 years
It could be noted that this measure is very payable in a short time. The reason for that is high
efficiency rate of condensation boiler and relatively low price of natural gas.
4.4 Lighting
Existing lighting could be improved by switching from incandescent lamps to energy saving ones.
The price of energy saving bulb of 25 W is about 300 RSD. By switching 31 incandescent lamps
with energy saving ones, an energy saving of 1.86 kW is reached what represents 2% of total
electric energy. Total investment is € 60 and simple payback period is 1.3 year (Tab. 31).
Table 31 Switching of incandescent bulbs with energy saving ones
Current electrisity consumption 53,144 kWh
Anual saving in kWh 1,085 kWh
Electricity price 0.063 €/kWh
Anual saving in € 67.81 €
Total investment 86 €
Simple payback period 1.3 year
4.5 Introduction the energy management procedures
Energy management practice should be upgraded so that systematic monitoring and targeting
techniques are implemented. A closer cooperation between energy and end users departments will
be beneficiary for the overall school efficiency.
Introduction the energy management procedures understand follows:
• Monitoring & targeting activities
• Training and motivation of personnel
• Energy data collection, analysis and interpretation
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• Operational management improvement
• Maintenance service improvement
• Instrumentation and metering systems upgrading
Effect of implementation is difficult to determine precisely. Savings are from 3% to 5%, based on
school and education sector experiences and specialized literature. In case of school in Curug, we
could expect 3% approximately, because energy management already exist. Potential is recognized
by performance indicators created by available data (collected or experienced) and with a certain
degree of reliable, savings could be in scope from 1,500 EURO/a to 1,800 EURO/a.
If assume that sophisticated equipment, instruments, hardware and software etc. then training of the
staff, additional time etc. requires investment more than 5,000€ (mostly in first year), then simple
payback period is above 2 years.
22
5. CONCLUSION
In Tab. 32 are presented proposed measures for energy efficiency improvement. Here are calculated
simple paybacks periods with and without calculation СО2 emission. Although at this moment СО2
emission does not influence to energy price, it is only a matter of time.
Table 32 Proposed energy efficiency measures
Proposed EE
measures
Investment
(€)
Energy
saved
(kWh/a)
Annual
saving
(€/a)
Simple
payback
period
(a)
Energy
saving
(%)
Remaining
needed
energy
(%)
СО2
emission
reduction
(tCO2/a)
Saving by
СО2
emission
reduction
(€/a)
Simple
payback
period with
included
СО2 emission
reduction
(a)
1. Replaceme
nt of
windows
and doors
31,716 165,184.25 8,492.89 3.73 10.3 89.7 57.81 867.2 3.4
2. Walls insulation
27,237 78,693.93 4,046.02 6.73 4.9 95.1 27.54 413.1 6.1
3. Ground
floor insulation
15,296 163,939.47 8,428.89 1.81 10.2 89.8 57.38 860.7 1.6
4. Roof
insulation 22,801 89,147.97 8,879.13 2.57 5.5 94.5 31.20 468.0 2.4
5.
Temperatur
e control
1,840 160,815.71 8,268.28 0.22 10.0 90.0 56.29 844.3 0.2
6. Balancing
pipe
network
2,300 32,163.14 1,653.66 1.39 2.8 97.2 15.63 234.4 1.2
7. Building in gas
condensatio
n boiler
15,784.86 161,400.50 8,298.35 1.90 10.0 90.0 48.42 726.3 1.7
8. Pipeline
insulation 600 1,200.00 61.70 9.72 0.1 99.9 0.36 5.4 8.9
9.
Replacement of
incandesce
nt bulbs
86 1,085.00 67.81 1.27 2.0 98.0 11.49 172.4 0.4
10. EMS
procedures 5,000 48,244.71 2,480.48 2.02 3 96 16.89 253.3 1.8
23
11. Sealing of windows
and doors
3,131 76,554.46 3,936.02 0.80 5 95 26.79 401.9 0.7
12.
Building in
boiler on biomass
90,000 - 41,456.15 2.17 0 100 0.00 0.0 2.2
13. Insulation
of wall 1
16,805 60,816.67 3,126.87 5.37 5 95 29.55 443.2 4.7
14.
Insulation
of roof 1
7,269 73,810.85 3,794.96 1.92 6 94 35.86 537.9 1.7
According to data given in Table 32 it can be seen that the shortest payback period of investment
(up to 3 years) is gained with: temperature control, sealing of windows and doors, replacement of
incandescent bulbs, network balancing, ground floor insulation and roof 1 insulation (new
building). Particularly noteworthy is temperature control, i.e. building in thermo regulation valves
since it introduces 10% energy saving with short payback period.
Some of the measures bring high energy saving, like replacement of windows and doors (10.3 %),
replacement of conventional boiler with condensation one (10 %).
In Tab. 33 are proposed different investment packages.
Tab. 33 Proposed investment packages
Pac
kag
e
Measures from
Tab. 32 Investment Energy
saving
Expences
reduction
Simple
payback
period
Energy
saved
€ kWh/a €/a a %
1. Measures 1, 2, 3,
4 97,050 496,965 29,847 3.25 30.9
2. Measures 5, 6, 8,
10 9,740 242,423 12,464 0.78 16
3. Measures 1, 3, 5,
7 (max. energy
saving)
64,637 651,340 33,488 1.93 40.5
4. Measures 7 15,785 161,400 8,298 1.9 10
5. Measures 1, 2, 3,
4, 5, 6, 7, 8, 9, 10 122,661 901,874 50,677 2.42 58.8
COMMENT:
First package of measures includes building envelop reconstruction and has payback period of 3.25
years what is very favorable. Addition positive effect is energy saving of 30.9%. Emission of CO2
would be reduced for 173.9 t per year.
24
Second package includes measures applied on heat distribution equipment. Even though investment
is relatively small, € 9,740, in very short period of time (0.78 years) a significant energy saving can
be reach (16 %). This measure leads to reduction of СО2 emission of 89.1 t per year. This measure
should be priority one.
Third package of measures combines measures with the highest energy savings (replacement of
windows and doors, wall insulation, ground floor insulation and temperature control). Energy
saving would be 40.5 %, and simple payback period 1.93 years.
Forth measures predicts replacement of existing conventional gas boiler with condensation one.
Energy saving would be 10 %, and simple payback period 1.9 година. СО2 emission reduction
would be 48.4 t/a.
Fifth measure includes almost all measures of EE. Simple payback period would be 2.42 years,
what is economically feasible. This package gives 58.8 % energy saving and CО2 emission
reduction of 323 t/a.
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