ea school curug - ener-supply.eu · elementary school ''djura jaksic'' is...

Association "Green Leap", Novi Sad

Address: Mise Dimitrijevica 72/18

Tel. +381-60-0106083

E-Mail: [email protected]

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

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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.

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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.

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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

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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

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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

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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.

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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

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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.

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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

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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



Expenses € 1,707 788 919

Investment: RSD 1,126,764 = € 10,433


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



Expenses € 4,807 1,012 3,795

Investment: RSD 785,052 = € 7,269


Table 21 Calculation of energy saving for proposed measure - Old roof insulation

17

Roof of new object Losses before

measures

Losses after

measures Difference



Expenses € 1,306 517 789

Investment: RSD 804,816 = € 7,452


Table 22 Calculation of energy saving for proposed measure - Gym roof insulation

Roof of gym Losses before

measures

Losses after

measures Difference



Expenses € 4,813 518 4,296

Investment: RSD 872,640 = € 8,080


Table 23 Calculation of simple payback period of insulation of all three roofs


Total saving 8,879 €


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



Expenses € 10,392 1,963 8,429

Investment: RSD 1,651,968 = € 15,296


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 €


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 €


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.


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


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


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.

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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


10 9,740 242,423 12,464 0.78 16


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


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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