ENER-SUPPLY
ENergy Efficiency and Renewables–SUPporting Policies in
Local level for EnergY
Energy audit of Vitez municipal administration building
REGIONAL EDUCATION AND INFORMATION CENTRE
FOR SUSTAINABLE DEVELOPMENT IN SOUTH-EAST EUROPE
REGIONALNI CENTAR ZA OBRAZOVANJE I INFORMISANJE
IZ ODRŽIVOG RAZVOJA ZA JUGOISTOČNU EVROPU
Partner: REIC, Bosnia and Herzegovina
RE
IC
Energy audit of Vitez municipal administration building
1. Introduction
Energy audit for the building of Vitez municipality was conducted within the scope of the
project ENER-SUPPLY - ENergy Efficiency and Renewables - SUPporting Policies in Local
level for EnergY. The Project is implemented in the countries of Adriatic-Ionic region within
the development programme for South-Eastern Europe. The project is implemented by the
consortium consisting of 14 regional companies. The leader of the consortium is the
Potenza municipality, Italy, and Regional Education and Information Centre for SouthEastern Europe (REIC) participates in the Project on behalf of Bosnia and Herzegovina
(BiH). REIC has identified the Central Bosnia Canton as the territory in BiH where the
project should be implemented. The implementation period is from November 2009 to
November 2012.
The main objective of the project is to provide assistance to local authorities in the area of
using potentials of renewables and improvement of energy efficiency when it comes to
energy utilisation for the purpose of sustainable development of the Canton. The Project is
especially focused on removing barriers against using renewables and improvement of
energy efficiency at local level.
In January and February 2011, a five-day training course was conducted for the employees
of municipalities and government authorities of the Central Bosnia Canton concerning
energy management. The training covered the following topics:
- analysis of energy supply (6 hours),
- development of energy balance (16 hours) and
- conducting of energy audit (16 hours).
There were on average 19 trainees for each of the topics. REIC provided local and
international trainers and training material. All trainees received training certificates. The
training was aimed at increasing energy efficiency of the municipalities and Canton. In that
context, trainees were trained on methodology of conducting energy audit for the purpose of
identifying measures for increasing energy efficiency. In the practical part of the training, the
trainees participated in the conducting of energy audit for the building of Vitez municipality.
The audit for the building was conducted following the proposal of the representatives of the
Municipality involved in the ENER SUPPLY Project.
In addition to energy management course within the scope of ENER SUPPLY, in the period
from September – October 2010, a 40-hour training course was conducted concerning
renewables. The focus of the course was the utilisation of biomass, construction of small
hydro power plants and wind plants, utilisation of geothermal energy and financial evaluation
of projects based on utilisation of renewables. Potentials of surveyed renewable energy
sources in BiH and Central Bosnia and Canton were presented, as well as barriers against
utilization of the potentials.
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Energy audit of Vitez municipal administration building
2. Methodology of conducting energy audit
There are two major types of energy audit (energy survey):
- preliminary walk-through audit
- detailed audit.
Phases of the walk-through audit are the following:

preparatory phase – collection of data concerning properties of the facility, major
energy systems and energy costs,

interviewing the responsible person in the facility,

site visit – visual examination of the energy status of the building envelope and all
technical systems, identifying basic characteristics of energy consumption and
places of major energy losses,

analysis of data collected and final report – survey of major problems in energy
consumption with recommendations to improve energy efficiency and identify need
to implement the detailed energy audit.
A walk-through energy audit does not include calculations, measuring or modelling of
energy consumption. A main purpose of the walk-through audit is to identify the potential for
energy consumption and make decision concerning conducting of a detailed energy audit.
The detailed energy audit includes a detailed energy analysis of al construction and
technical systems within the facility. For the existing facilities, depending on their purpose,
energy costs are analyzed during 36 months on average for the purpose of modeling of
energy consumption and assessing energy needs within the facility. If needed, the analysis
is complemented with the measuring of consumption of electricity consumption, heating
losses, and ventilation losses in the facility, etc. which is important for the establishment of
energy losses in certain systems. Collected data are processed and energy properties of the
analyzed facility are calculated.
Phases of the detailed energy audit are the following:

meeting and interviewing key personnel in the facility – manager and users/owners,

examination of the existing design documentation,
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Energy audit of Vitez municipal administration building

examination and analysis of bills concerning heating and electrical energy
consumption, as well as water for optimum 36 months (compulsory only for public
facilities),

visiting and scrutinizing the facility and undertaking consumption measuring,
following the identifying of key gaps,

interviewing key personnel in the facility again,

analyzing and processing of collected data,

identifying measures for improvement of energy properties of the facility and
improvement of energy efficiency,

energy related, economic and environmental evaluation of the recommended
measures and

preparation of the report with conclusions and recommendations and presenting
them to key people.
Within the energy audit of the building of the Vitez municipality, two energy systems within
the building were analyzed (i) space heating system i (ii) system using electricity. Energy
audit was conducted using the following methodology:
-
users of the building fill in the questionnaire
REIC received the questionnaire from the ENER SUPPLY project partner responsible for the
energy management project package and it is the Greek public institute for energy efficiency
and renewables (CRES). REIC provided translation of the questionnaire into local language
and delivered it to the Municipality.
-
Visiting the building in order to collect inputs
This phase includes the measuring of the level of heating losses by means of the infrared
camera and the measuring of the composition of flue gases from the boiler in order to
determine the level of efficiency of the boiler and meeting the requirements of limit values of
emission. All measuring devices used in this phase is regularly calibrated.
-
Analysis of data collected
Based on the analysis, measures for improvement of energy efficiency and decrease of
energy consumption costs are recommended in this phase. Preliminary analysis results
were presented at energy management workshop (practical part of energy management
training course) in the Municipality on 10 February 2011.
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Energy audit of Vitez municipal administration building
Although the energy audit of the building of the Vitez municipality included certain
measuring, the conducted audit was still a walk-through audit.
3. Description of the present use of energy in the building of Vitez Municipality
The building of Vitez Municipality was built in 1960. The total area of the building is 1,023
m2. The building consists of the ground floor and other two floors. The total area of the main
premises (office premises) is 730 m2, and the remaining area is about 293 m2 which
consists of corridors and toilets.
The facade of the building lacks heating insulation. The roof also lacks insulation. In the
beginning of 2010, new windows and entrance door were installed. These are PVC
products.
The building is used 8 hours a day every working day. There are 70 staff members (users of
the building) and about 400 visitors per day.
3.1.
Description of the existing heating system of the building of Vitez
municipality
The heating in the building of Vitez municipality is provided by the boiler fuelled on heating
oil, power 300 kW, by hot water through the radiators installed in the rooms. The same
boiler is used for heating the next-door police building. The boiler is about five years old and
is in quite good condition. There is a regular maintenance provided. The measuring of
composition of flue gases and loss of energy in flue gases has been conducted. The police
building, the heating of which is provided through this boiler, is of total area of 781 m2.
Therefore, the total area the heating of which is provided through the boiler of power of 300
kW is 1,804 m2, which means that the installed power is about 165 W/m2. This is much
more than it is now usually installed (80 – 100 W/m2). The consequence of this is that the
boiler during most of the season works at very low load (below 50%), which causes lower
efficiency than envisaged.
The heating system is designed for inlet water temperature of 90°C and outlet of 70°C. The
radiators have simple regulation valves (without thermostatic heads). Average working time
of the heating system during the season is 10 hours a day.
There is no system of separate measuring of energy consumption for the Municipality and
police building. Total annual consumption of heating oil for heating of both buildings is about
21 tons.
According to users of the building, the above described heating system does not provide
comfotable temperature, therefore the space is additionally heated with electrical heaters.
3.2.
Utilisation of electrical energy in the building of Vitez municipality
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Energy audit of Vitez municipal administration building
Electrical energy is used for:
-
lighting,
-
office equipment,
-
heating of sanitary water, and
-
additional heating of space by means of electrical heaters.
Taking into account that the time of using of the building is 8 hours a day every working day,
and estimated using of lighting 4 hours a day, electricity used for lighting is low. The total
installed capacity of lighting is 9,68 kW. Of that 2,34 kW is for bulbs with hot wire and 7,34
kW neon bulbs. Neon bulbs are used in offices and bulbs with hot wire in corridors and
toilets.
Electrical boilers of total power of 5 kW are used for heating of sanitary water. Estimated
time of operation of the electrical boilers is 4 hours a day every working day.
Electrical heaters are used to additionally heat the space cince, according to users of the
building, radiators do not heat the space sufficiently. There is no date on total power of
electrical heaters. Using electricity for heating significantly increases costs for energy in two
aspects (i) increased consumption of active energy and (ii) increased costs of calculated
peak power.
4. Measuring of composition of flue gases, losses of energy in flue gases of
boiler and thermographic screening of facade of the building of Vitez
municipality
Measuring of concentration of polluting substances in flue gases has been conducted by
means of a device MRU VARIO PLUS INDUSTRIAL (Figure 1). The measuring was
conducted on 10 February 2011.
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Energy audit of Vitez municipal administration building
Figure 1 Device MRU VARIO PLUS INDUSTRIAL
Measuring characteristics of the measuring device are provided in Table 1.
Table 1. Measuring characteristics of the g device MRU VARIO PLUS INDUSTRIAL
O2
0 – 21 %.
CO (H2)
0 – 10,000 ppm
COlow (H2)
0 – 500 ppm
NO
0 –5,000 ppm (0.1 ppm resolution)
NO2
0 – 1,000 ppm (0.1 ppm resolution)
SO2
0 – 5,000 ppm
CO2
(NDIR) 0 – 30 Vol. %
Measuring of composition of flue gases was conducted in the pipe which connects the boiler
and chimney. The measuring took about 15 minutes. The measuring of the concentration of
the following substances was conducted on four occasions:
- nitrate oxides presented as NO2
- sulphur dioxide SO2
- carbon oxide CO
- carbon dioxide CO2
- oxygen O2.
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Energy audit of Vitez municipal administration building
In addition to measuring of these parameters, measuring was conducted of temperature of
flue gases based on which the device calculated boiler losses in flue gases. On the basis of
the losses, the estimate of the level of efficiency of the boiler was provided.
The Table 2 provides the results of the measuring of composition of flue gases from the
boiler used for heating of the building of the municipality assemby.
Table 2 Results of the measuring of composition of flue gases (calculated for referent
oxygen concentration of3% and dry flue gases)
Parameter
Unit
Value
CO
mg/m3
31.00
SO2
mg/m3
164.25
NOx
mg/m3
67.25
O2
%
9.38
CO2
%
8.33
Losses of energy in flue gases
%
5.45
The concentration of polluting substances in flue gases of the examined boiler is below limit
value of emissions in FBiH. The surplus of air is slightly higher than usual value, and the
temperature of flue gases is quite low. Both phenomena are likely to be the consequence of
the low level of the boiler load during the time of measuring. Losses in flue gases are
relatively small (consequence of low temperature of flue gases). In addition to losses in flue
gases, there are losses caused by emission of heat and incomplete combustion (CO in flue
gases). Taking into account usual correlations between all losses of energy in the boiler, the
boiler level of efficiency has been estimated to be 88%.
On 28 January 2011, thermal imaging of the facade of the building of the municipal
administration was conducted in order to identify spots where significant losses of the
heating energy occur. External temperature during thermal imaging was -5°C. Specific
images are provided in Figures 2, 3, 4, 5 and 6.
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Energy audit of Vitez municipal administration building
Visible Light Image
IR000197.IS2
1/28/2011 12:38:52 PM
Image 2 Thermal image of windows on the building of the Vitez municipal administration
(South)
Visible Light Image
IR000200.IS2
1/28/2011 12:39:24 PM
Figure 3 Thermal image of windows on the building of the Vitez municipal administration
(South)
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Energy audit of Vitez municipal administration building
Visible Light Image
IR000228.IS2
1/28/2011 12:54:00 PM
Figure 4 Thermal image of windows on the building of the Vitez municipal administration
(North)
Visible Light Image
IR000231.IS2
1/28/2011 12:56:29 PM
Figure 5 Thermal image of facade on the building of the Vitez municipal administration
(North)
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Energy audit of Vitez municipal administration building
Visible Light Image
IR000230.IS2
1/28/2011 12:55:00 PM
Figure 6 Thermal image of roof on the building of the Vitez municipal administration
(North)
There are the following conclusions based on thermal images:
-
Windows on the Vitez municipal administration building have a relatively low
coefficient of heat transfer, however their ventilation losses are slightly increased,
leading to a conclusion that windows were not properly installed.
-
The facade is partly damaged and wet, which causes heat losses (Figure 5),
-
The roof of the building lacks insulation, therefore heat losses through the roof are
enormous,
-
Radiators are not visible on the thermal image (rather because of low temperature of
water in radiators than because of good facade).
Given the fact that the next-door police building uses the same heat source, thermal
imaging of that building was also conducted. This building is in worse condition concerning
the heat insulation mainly because the quality of windows is bad. The imaging helped to
determine the exact consumption of energy of the municipal building and police building
respectfully.
If there is no boiler regulation, the problem of heating of buildings of significantly different
energy characteristics like municipal assembly and police building, is that one keeps trying
to heat the building with weaker heat insulation. At the same time, the building with better
insulation is usually overheated and the users usually open the windows in order to cool
space. In this specific case, such thing does not happen since the heat insulation of both
buildings (especially the police building) is too bad and the existing boiler cannot adequately
heat the municipal assembly building alone.
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Energy audit of Vitez municipal administration building
5. Proposal for reducing of heating costs for Vitez municipal assembly building
5.1.
Replacement of the boiler fuelled by heating fuel by boiler fuelled by pellet
As described in section 3.1., the building of the municipal assembly is heated by the boiler
fuelled by heating oil. Table 3 provides comparison of prices of energy from various energy
sources with the prices at the beginning of 2011 in BiH.
Table 3 Prices of energy from various energy sources (prices at the beginning of 2011 in
Bosnia and Herzegovina)
energy
prices in
heat
value
fuel
coal
fire wood
l
heating
oil
KM/t
KM/t
KM/t
gas
KM/1000m3
wood chips
sbriquet
pellet
electrical energy
KM/t
KM/t
KM/t
KM/MW
120,00
100,00
1904,76
6
15,00 GJ/
10,28 GJ/
42,00 GJ/
boiler
efficiency
r level
fuel
KM/G
%
8,00
7
9,73
7
45,35
8
820,00
10,00 MWh/1000m3
22,78
9
90,00
140,00
280,00
150,00
10,28
15,00
17,00
1,00
8,75
9,33
16,47
41,67
8
8
9
10
GJ/
GJ/
GJ/
MWh
price
of usable
feeding
heat
energy
KM/G
10,67 manual
12,97 manual
51,54 automatic
24,76 automatic
10,30
10,98
17,90
41,67
automatic
manual
automatic
automatic
Note: Consumption of peak load in electricity consumption was not taken into account
Table 3 shows that heating oil energy is the most expensive. Taking into account that the
total cost of consumption of an energy source includes the cost of labour force (and some
other costs), it makes sense to compare different prices of energy of the system with
automatic feeding. In other words, it is not possible to compare prices of energy sources for
the systems with manual and automatic feeding and make conclusions on the basis of that.
Taking this into account, it makes sense to compare the price of energy from heating oil with
prices of energy from natural gas, wood chips, pellet and electricity. The price of energy
from fuel is about twice as expensive as that from natural gas and about three times as
expensive as that from pellet. If electricity peak load costs are somehow taken into account,
the price would exceed heating oil energy price. The price of energy from wood chips is
about five times cheaper than the price of energy from fuel. However, the market of wood
chips in BiH has not been much developed; therefore, the possibility of using wood chips
instead of heating fuel has not been considered.
In order to assess the cost-effectiveness of using pellet instead of fuel, the following was
taken into account:
-
investment in two boilers powered by pellet each of 200 kW,
-
prices of fuel and pellet at the beginning of 2011,
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Energy audit of Vitez municipal administration building
-
level of efficiency of boilers powered by pellet 92%1,
-
two boilers powered by pellet of total power 400 kW would be sufficient for adequate
heating of both buildings, therefore electrical heaters would not be necessary. Thus,
electricity costs would be reduced.
-
twice higher costs of maintenance of boilers powered by pellet than of the existing
boiler powered by heating oil and
-
Non-depreciated value of boiler fuelled by heating oil was not taken into account.
In order to assess the reduction of electricity costs following the installation of two boilers
powered by pellet, monthly electricity bills were examined for the building of the municipal
assembly for 2009. The analysis showed that electricity consumption was higher during the
season of heating (especially in months when temperature is quite low) and that calculated
power was significantly higher during the heating season. Saving of electricity in case of
using pellet is estimated along with the following preconditions:
- consumption of electricity in months of heating season will be on average the same like in
months beyond the heating season and
- amount of calculated power in months during the heating season will be on average the
same like in months beyond the heating season.
Table 4 provides the overview of consumption and costs for electricity in the building of Vitez
municipal assembly building in months of 2009.
Table 4 Consumption and costs for electricity in the Vitez municipal assembly building in
2009
Month
January
February
March
April
May
June
July
August
September
October
November
December
higher tariff
kWh
4411
4662
3851
3292
3015
2765
2331
2344
3052
4328
3825
5220
lower tariff
kWh
2372
2630
2480
1994
1669
1740
1511
1680
1672
2288
2466
2801
total
kWh
6783
7292
6331
5286
4684
4505
3842
4024
4724
6616
6291
8021
higher tariff
KM/kWh
0.2031
0.2031
0.1562
0.1562
0.1562
0.1562
0.1562
0.149
0.149
0.149
0.1937
0.1937
lower tariff
KM/kWh
0.1015
0.1015
0.0781
0.0781
0.0781
0.0781
0.0781
0.0745
0.0745
0.0745
0.0969
0.0969
costs
KM
895.87
946.85
601.53
514.21
470.94
431.89
364.10
349.26
454.75
644.87
740.90
1011.11
KM
240.76
266.95
193.69
155.73
130.35
135.89
118.01
125.16
124.56
170.46
238.96
271.42
1
88% was taken as average level of efficiency of the existing boiler, although the real efficiency is
slightly lower since the boiler operates on low level of load. Two boilers would solve the problem of
operation on low level of load and enhance the supply safety.
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KM
1136.63
1213.80
795.21
669.94
601.29
567.79
482.11
474.42
579.31
815.33
979.86
1282.53
Energy audit of Vitez municipal administration building
TOTAL
Winter
average
Summer
average
43096
25303
68399
4383
2506
6889
2800
1711
4511
7426.29
2171.93
Consumption of electricity in winter months2 is by about 50% higher than in summer months,
while the costs in winter months are by 70-80% higher as the price of electricity is in addition
higher in winter months. Under assumption that electricity is not used for heating,
consumption in winter months would be at summer average level. Based on that, an
estimate of additional heating by electricity was provided (due to increase in active energy)
amounting to 2,200.00 KM/a.
In electricity bills for Vitez municipal assembly building, peak power during winter months is
significantly higher, which is the consequence of using electrical heaters for additional
heating. Figure 7 presents calculated power for 2009.
Diagram of peak load
60
50
40
k
30
20
10
0
1
2
3
4
5
6
7
month
8
9
10
11
12
Figure 7 Peak power in the Vitez municipal assembly building
Peak power is the highest entirety of powers of electrical devices turned on for at least 15
minutes in a month. Bearing in mind the activities carried out in the building, all devices,
except electrical heater, are obviously used both in summer and winter. It can be expected
that the intensity of using electrical boilers for the preparation of warm water for
consumption is slightly higher in winter. However, that cannot significantly affect the
calculated power. Table 5 provides overview of costs for calculated power in 2009.
Table 5 Real and projected costs for calculated power of the Vitez municipal assembly
building
2
Winter months are January, February, March, October, November, December.
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9598.22
Energy audit of Vitez municipal administration building
January
February
March
April
May
June
July
August
September
October
November
December
TOTAL
calculated
power
kW
44
47
33
26
36
26
18
17
42
46
36
49
420
price
KM/kW
20.92
20.92
16.09
16.09
16.09
16.09
16.09
15.95
15.95
15.95
20.74
20.74
costs
KM
920.48
983.24
530.97
418.34
579.24
418.34
289.62
271.15
669.9
733.7
746.64
1016.26
7577.88
projected
calculated
power
kW
25
25
25
25
25
25
25
25
25
25
25
25
300
price
KM/kW
20.92
20.92
16.09
16.09
16.09
16.09
16.09
15.95
15.95
15.95
20.74
20.74
costs
KM
523.00
523.00
402.25
402.25
402.25
402.25
402.25
398.75
398.75
398.75
518.50
518.50
5,290.50
It is assumed that following the installation of boilers powered by pellet, calculated power in
winter months will be at the level of summer average. Assumed costs of calculated power
following the adoption of pellet are also taken into account here. Difference between real
and assumed costs for calculated power is 2,290.00 KM/a. Therefore, total saving of
electricity following the adoption of pellet is about 4,500.00 KM/a.
Following the installation of boilers powered by pellet, additional heating of space by
electricity will not be necessary because:
- power of boilers fuelled by pellets will be sufficient for adequate heating of both municipal
and police building and
- automatic control of inside temperature will enable thermal comfort at any time3.
Table 6 presents an analysis of energy saving due to use of pellet instead of heating oil for
heating of municipal building. Present consumption of fuel of about 22 tons per year can be
replaced by 49 tons of pellet. It can be expected that prices of both energy sources will go
up in future, and that prices of heating oil will go up even faster. Table 3 presents prices at
the beginning of 2011. It is assumed that costs of maintenance of boilers powered by pellet
are by 1000 KM/a higher than maintenance of the existing boiler powered by heating oil.
Since both systems (boilers) have automatic fuel feeding, they have the same labour force
costs. Price of electricity is expected to grow; thus, saving is expected to be higher.
Table 6 Analysis of saving due to use of pellet instead of fuel for heating in municipal
building
3According
to building users, in morning hours, electrical heaters are used for additional heating since
the temperature is slightly lower than the projected one, and because of inadequate air streaming
which causes the feeling of coldness at certain body parts (e.g. at ankles).
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Energy audit of Vitez municipal administration building
Description
Value
Note
present heating
fuel costs (heating oil)
fuel unit price
fuel unit price
average consumption in period 2007 - 2009
fuel supply costs
heating value of heating oil
Energy in consumed heating oil
boiler efficiency level
energy for heating
heating energy price
1,60
1,90
22,00
41,905
42
924
0.88
813
51,54
KM/l
KM/kg
t/a
KM/a
GJ/t
GJ/a
GJ/a
KM/GJ
calculation
18,00
0,92
813
49.10
300
14,730
GJ/a
tables
GJ/a
t/a
KM/t
KM/a
calculation
27,174.3
4,494.1
31,668.4
KM/a
KM/a
KM/a
calculation
In 2010
input - template
input - template
tables
calculation
assumptions based on measuring
calculation
pellet supply costs
pellet heating value
boiler efficiency level
amount of energy needed
amount of pellet needed
pellet prices
pellet costs
saving of fuel costs
potential electricity saving
total saving
assumption (based on literature)
calculation
upper market price
calculation
calculation
calculation
According to prices of energy sources at the beginning of 2011, saving of energy is about
31,500.00 KM/a. Investment related to replacement of the existing boiler powered heating oil
in the municipal building with two boilers powered by pellet was estimated to be 40,000.00
KM (VAT not included). This price covers boilers, equipment, silo for pellet from which pellet
is feeded and the system of remote control of boilers adjusted to internal temperature in the
building. It should be borne in mind that in this way about 25% more power is gained. The
existing boiler station meets basic requirements concerning accommodation and work of
boilers powered by pellet. Replacement of boilers themselves does not require additional
work out of the boiler station. A part of the basement of the municipal building to the boiler
station (separated by door from the boiler station itself) can be used as storage room for
pellet. Taking into account amount needed and vicinity of the pellet producer, not more than
10 tons of pellets should be kept in storage.
Period of repayment of investment concerning replacement of boiler fuelled by heating oil
with boiler powered by pellet is 1.3 years, which is short. Therefore, the project is
economical.
Table 7 Analysis of cost-effectiveness of heating by pellets instead heating oil
electricity
consumption
heating oil
consumption
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pellet
consumption
peak load
maintenance
cost
total cost
16
Energy audit of Vitez municipal administration building
Present status –
heating oil
Expected status pellet
saving
unit price
measuring cost
kWh/a
t/a
t/a
kW
KM/a
KM/a
68,399
22
0
420.00
500
59,581
54,131
0
49
300.00
1,500
28,912
14,268
22
1,904.76 KM
-49
300.00 KM
120.00
-1,000.00
30,668
KM
included in
equipment
40,000
included in
equipment
included in
equipment
design
equipment
installation
test work
total cost of boiler
replacement
period of investment
repayment
5.2.
note
40,000
1.30
year
Insulation of roof of municipal administration building in Vitez
The roof on the municipal building is slanted. The area of the ceiling is about 340 m2.
Neither roof nor ceiling has heat insulation. Heat losses through the ceiling (roof) are:
Ekrov  k krov  Akrov  T  t (1)
Where:
Ekrov - roof heat losses (J)
k krov  coefficient of heat transfer through the ceiling (W/m2K)
Akrov - roof area (m2)
T - average difference between internal and external temperature during heating time (K)
t – duration of the heating season (s/a)
The existing ceiling has the heat transfer coefficient of about 1 W/m2K. Average external
temperature in the heating season is about 4°C, and the duration of the heating season is
4,320 hours per year. By calculation (1) of the above values, losses of energy of roof are
calculated to be about 23,500 kWh/a. Heat losses in the municipal building through the roof
are about 18% of total heat losses.
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Energy audit of Vitez municipal administration building
Since the ceiling is not used actively, heat insulation is recommended for the ceiling as
presented on Figure 8. Two 10 cm thick layers of slag wool (or equivalent insulation
material) is recommended (total thickness 20 cm).
Figure 8 Proposal of heating insulation of the building of the Vitez municipal assembly
building
Following the installation of 20cm-thick slag wool on the ceiling, the coefficient of heat
transfer will be about 0.2 W/m2K. By calculating this value in (1) heat losses through the roof
are calculated to be 4,700 kWh/a. Therefore, the difference in heat losses before and after
the insulation of roof is 18,800 kWh/a. An equivalent to this energy is 4.1 tons of pellet4 or
1.835 tons of heating oil.
Taking into account that the area of the ceiling is 340 m2, and that an investment (including
assembly) in insulation of the roof includes 15 KM/m2 for the municipal building, an estimate
of the entire investment is 5,100 KM. Bearing in mind the price of pellet of 300 KM/t, the
period of investment repayment is about 4.15 years. If heating oil continues to be used for
heating, the period of investment repayment for thermal insulation of roof is 1.46 years.
5.3.
Insulation of heat pipelines from the boiler station to the police building
The police building is connected with the boiler in the boiler station of the municipal
assembly building through the underground insulated heat pipeline. According to its users,
the heat pipeline was not originally intended for heat supply to both police and municipal
building. The capacity of the heat pipeline exceeds needs, which is why the speed of water
in the pipe is lower than needed. The consequence of this is higher losses of heat in the
pipeline. In addition, the heat pipeline is longer than needed, thus more heat losses occur.
The length of the heat pipelines causes additional resistance, thus electricity consumption is
increased at circulation pumps. Heat pipeline cross section, length and insulation status are
not known, which hampers the estimation of heat losses.
4
5
Izračunato za toplotnu vrijednost peleta od 18 GJ/t i stepen iskorištenja kotla od 92%.
Izračunato za toplotnu vrijednost lož ulje od 42 GJ/t i stepen iskorištenja kotla od 88%.
Regional Education and Information Centre – REIC Sarajevo
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Energy audit of Vitez municipal administration building
6. CONCLUSION
Based on collected data concerning energy consumption in the Vitez municipal assembly
building, measuring carried out, site visit and analyses carried out, the following was
concluded:
-
It is the building with the most expensive fuel (heating oil) annually consuming about
22 tons (where the amount is also used for heating the police building) which makes
about 42,000.00 KM/a,
-
Condition and efficiency of the boiler powered by heating oil is quite good (efficiency
estimated to be 88%),
-
Municipal assembly building has good windows (concerning heat insulation), by
thermo-graphic screening it as detected that some of the windows were not properly
installed (no proper airtight), police building windows bad,
-
Heat losses through the roof are quite significant (no heat insulation on the ceiling),
-
Facade of the municipal assembly building has no heat insulation,
-
The existing boiler is not sufficient for proper heating which is why electricity is used
for additional heating, thus causing higher costs of about 4,500.00 KM/a,
-
Electricity consumption for other purposes is quite low.
Bearing all this in mind, the following recommendations for improvement of energy
efficiency and reduction of energy costs are provided:
1. Replacement of boiler fuelled by heating oil with boilers powered by pellet (two
boilers each 200 kW). Therefore, energy costs would be reduced by about 31,500.00
KM/a. Estimated investment for this measure is 40,000.00 KM, and the repayment
period is 1.3 years. The investment includes procurement and installation of boilers
and all other necessary equipment. No works are required concerning inside heating
installation. Suppliers of boilers powered by pellet provide five-year guarantee
period. Cost-effectiveness of the investment does not depend on pellet price. Pellet
price is expected to rise in future; however, the price of heating oil is expected to rise
even more. By the implementation of this measure, the emission of CO2 would be
reduced by about 70 tons per year.
2. Thermal insulation of the roof - It is recommended to install 20 cm-thick layer of rock
wool for the ceiling of the municipal assembly building. Thus, consumption of heating
oil would be reduced to 1.83 tons per year or 4.1 tons of pellet per year. Heat energy
cost saving would be about 3,500.00 KM/a for heating oil or about 1,200.00 KM/a for
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Energy audit of Vitez municipal administration building
pellet as fuel. Estimated investment amounts to 5,100.00 KM, which means that the
repayment period is 1.46 years for heating oil, and 4.15 years for pellet.
3. Reconstruction of the heat pipeline from the boiler station to the police building. The
police building is connected with the boiler in the boiler station of the municipal
building through the underground insulated heat pipeline. The capacity of the heat
pipeline is larger than needed, which is why the speed of water in the pipe is lower
than needed. This causes higher losses of heat in the pipeline. No data are available
for financial evaluation of this measure.
Thermal insulation of the facade of the municipal building would significantly reduce heating
needs of the building and improve comfort. However, the relation between invested
resources and expected saving is such that the repayment period is longer than
recommended. Thus, this measure is recommended only in case of using partly nonrepayable/grant funds.
No significant consumers of electricity exist in the municipal assembly building. The power
of boilers for the preparation of warm consumption water is 5 kW. Installation of the
combined boiler sis recommended (or installation of heat exchanger in the existing boilers)
for the preparation of warm consumption water (powered by electricity and by heat energy
from the heating system). Thus, energy consumption would be reduced, and saving of costs
of calculated power would be significant. Saving for calculated power during winter months
would be higher than 100 KM.
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