5th INTERNATIONAL ACADEMIC CONFERENCE ON ...

5th INTERNATIONAL ACADEMIC CONFERENCE ON PLACES AND TECHNOLOGIES EDITORS

ALEKSANDRA KRSTIĆ-FURUNDŽIĆ MILENA VUKMIROVIĆ EVA VANIŠTA LAZAREVIĆ AND ALEKSANDRA ĐUKIĆ

PLACES AND TECHNOLOGIES 2018 THE 5TH INTERNATIONAL ACADEMIC CONFERENCE ON PLACES AND TECHNOLOGIES EDITORS: Aleksandra Krstić-Furundžić, Milena Vukmirović, Eva Vaništa Lazarević, Aleksandra Đukić FOR PUBLISHER: Vladan Đokić PUBLISHER: University of Belgrade - Faculty of Architecture DESIGN: Stanislav Mirković TECHNICAL SUPPORT: Jana Milovanović PLACE AND YEAR: Belgrade 2018 ISBN: 978-86-7924-199-3 PRINTED BY: University of Belgrade - Faculty of Architecture

TOWARDS DIMINUISHING DISADVANTAGES IN MIGRATION ISSUES IN SERBIA (FROM 2015) THROUGH PROPOSAL OF SOME MODELS 287 Eva Vaništa Lazarević Jelena Marić Dragan Komatina

ARCHITECTURAL DESIGN AND ENERGY PERFORMANCE OF BUILDINGS APPLICATION OF ENERGY SIMULATION OF AN ARCHITECTURAL HERITAGE BUILDING 303 Norbert Harmathy Zoltán Magyar

APPLICATION OF TRADITIONAL MATERIALS IN DESIGN OF ENERGY EFFICIENT INTERIORS 311 Vladana Petrović Nataša Petković Grozdanović Branislava Stoiljković Aleksandar Keković Goran Jovanović

DETERMINATION OF THE LIMIT VALUE OF PERMITTED ENERGY CLASS FOR THE KINDERGARTENS IN THE NORTH REGION OF BOSNIA AND HERZEGOVINA 318 Darija Gajić Biljana Antunović Aleksandar Janković

ARCHITECTURAL ASPECTS OF ENERGY AND ECOLOGICALLY RESPONSIBLE DESIGN OF STUDENT HOUSE BUILDINGS 326 Malina Čvoro Saša B. Čvoro Aleksandar Janković

ENERGY EFFICIENCY ANALYSES OF RESIDENTIAL BUILDINGS THROUGH TRANSIENT SIMULATION 332 Ayşe Fidan ALTUN Muhsin KILIC

INNOVATIVE TECHNOLOGIES FOR PLANNING AND DESIGN OF “ZERO-ENERGY BUILDINGS” 340 Kosa Golić Vesna Kosorić Suzana Koprivica

ENERGY REFURBISHMENT OF A PUBLIC BUILDING IN BELGRADE Mirjana Miletić Aleksandra Krstić-Furundzić

348

TYPOLOGY OF SCHOOL BUILDINGS IN SERBIA: A TOOL FOR SUSTAINABLE ENERGY REFURBISHMENT 357 Nataša Ćuković Ignjatović Dušan Ignjatović Ljiljana Đukanović

ARCHITECTURAL DESIGN AND NEW TECHNOLOGIES EVALUATION OF ADVANCED NATURAL VENTILATION POTENTIAL IN THE MEDITERRANEAN COASTAL REGION OF CATALONIA 367 Nikola Pesic Jaime Roset Calzada Adrian MurosAlcojor

TRENDS IN INTEGRATION OF PHOTOVOLTAIC FACILITIES INTO THE BUILT ENVIRONMENT 375 Aleksandra Krstić-Furundžić Alessandra Scognamiglio, Mirjana Devetaković, Francesco Frontini, Budimir Sudimac

5th INTERNATIONAL ACADEMIC CONFERENCE

DETERMINATION OF THE LIMIT VALUE OF PERMITTED ENERGY CLASS FOR THE KINDERGARTENS IN THE NORTH REGION OF BOSNIA AND HERZEGOVINA Darija Gajić 1 Assistant Professor, University of Banja Luka, Faculty of Architecture, Civil Engineering and Geodesy, Bulevar Petra Bojovića 1a, [email protected] Biljana Antunović Associate Professor, University of Banja Luka, Faculty of Architecture, Civil Engineering and Geodesy, Bulevar Petra Bojovića 1a, [email protected] Aleksandar Janković Senior Teaching Assistant, University of Banja Luka, Faculty of Architecture, Civil Engineering and Geodesy, Bulevar Petra Bojovića 1a, [email protected]

ABSTRACT According to the European Standard EN 15217 parameters affecting determination of the energy performance indicator (EP) for permitted energy class (energy performance requirement - EPr) are: climate, building type and function, energy carrier, shape factor of the building, ventilation - air change rate and illumination level. In the rulebooks related to the energy efficiency of buildings in Bosnia and Herzegovina as well as in the surrounding countries the energy performance indicator is defined by energy need for heating – QH,nd. Furthermore, in these rulebooks the residential buildings have the same upper limit values for permitted energy class as buildings for education and culture and kindergartens are not considered as buildings of a special type and function. However, taking into account widespread size of kindergartens with the ground floor only they cannot be treated neither as residential buildings nor as schools. Therefore, the main objective of this paper is to show parameters that directly affect required level of energy performance indicator for kindergartens. The research is based on the analysis performed on the sample of 11 detached kindergartens according to the architectural key design parameters primary based on the building function which are located in the north region of Bosnia and Herzegovina. As the result of presented research the permitted energy class for existing and new kindergartens will be defined on the basis of parameters related to the representative building shape factors, the air change rates and other relevant parameters important for the building energy efficiency and according to the rulebooks that are currently being used in Bosnia and Hercegovina. Keywords: energy performance indicator, shape factor of the building, energy need for heating, ventilation rate, kindergarten

Introduction The annual energy need for heating of the buildingis influenced by various parameters that have arisen from all phases which take part in the process of planning and designing of buildings (Hegger and others, 2008). For new buildings these parameters are directly taken from design documentation, whilefor existing buildings due to their durability, maintenance and many modifications through the lifecycle of the building, these parameters are obtained by an auditor’s assessment, on-site verification and standards specified in the national rulebooks. 1 corresponding author 318 |ARCHITECTURAL DESIGN AND ENERGY PERFORMANCE OF BUILDINGS|

PLACES AND TECHNOLOGIES 2018

The energy performance indicatorof buildings (Energy Certification Indicator) in Bosnia and Herzegovina and the Republic of Srpska as well is QH,nd - the annual energy need for heating. The rulebooks on energy efficiency of buildings in the Republic of Srpska (Rulebook on minimum requirements for building energy characteristics, Rulebook on calculation methodology of building energy characteristics andRulebook on energy survey and energy certification) define permitted energy classes according to the 8 building types: residential buildings (single-family houses, residential-commercial buildings and apartment blocks) and non-residential buildings (administrative andcommercial buildings, buildings for education and culture, health and social protection, tourism and catering, sport and recreation,trade and service activities). According to the European Standard EN 15217 parameters affecting determination of the energy performance indicator (EP) for a permitted energy class (energy performance requirement - EPr) are: climate, building type and function, energy carrier, shape factor of the building, ventilation - air change rate and illumination level. The same standard specifies the 9 buildings types.In neighboring Croatia and Serbia the additional building type has been identified as ‘other non-residential buildings’ and‘other building types which consumes energy including mixed-use buildings’. According to the current energy efficiency regulations in Bosnia and Hercegovina and the Republic of Srpska as well, kindergartens have not been treated as buildings of a special type and function and due to their spread basis with the ground floor only they cannot be treated neither as residential buildings nor as buildings for education and culture. This paper examines two out of six previously mentioned parameters, which directly affect the energy performance indicator: the representative building shape factors and the air change rates, separately for existing and new kindergartens. These parameters are directly influenced by architectural design of the building (architecture), position of the building in relation to the environment and microclimate (urbanism) and the period of construction (applied materials/ construction technology).

The energy performance indicator, the building shape factor and the air change rates For the purpose of energy certification of buildings,energy performance indicator (QH, nd – annual energy need for heating) requires that the minimum estimated energy characteristics of the building are taken from design documentation which also represents a simplified audit (Gajic and others, 2017). According to the calculation given in the standard EN 13790, the parameters for determination of the energy performance indicator are parameters that affect the building’s heat losses and the parameters affecting the building’s heat gains. The parameters required for calculation affecting heat losses (by transmission and ventilation) are:the heat zones of building, the compactness ratio or A/V ratio, the U-values of opaque envelope elements(gross dimensions), the U-values and the g-coefficients for the transparent envelope elements, the thermal bridges, the air changes per hours or ventilation rate and the thermal capacity of building. The parameters affecting the building’s heat gains (the internal gains due to occupancy, the lighting and the electrical appliances and the solar radiation gains through the transparent elements of the envelope) are: the metabolic heat, the occupancy, the contribution of lighting and various equipment devices (electricity) andthe sun radiation according to the orientation of the transparent elements of building and shading factor. In the rulebooks in Bosnia and Herzegovina and the neighboring countries, estimator of the building compactness is its shape factor. The smallersurface of the envelope required for a certain volumeindicatesmore compact surface and the lower energy requirementsfor heating. When it comes to the building shape factor researches are usually concerned with the build|ARCHITECTURAL DESIGN AND ENERGY PERFORMANCE OF BUILDINGS| 319


ing’s geometric shape (Gajic and others, 2017) without analyzing its interior, building conditioned zones and the existence of heated and unheated spaces. The most important parameter for calculating the ventilation heat losses in buildings with natural ventilation (the kindergartens in the city of Banja Luka also belong to this class) is the number of air changes per hour. According to the current regulation and the standard BAS EN ISO 13789, this parameter is estimated based on the exposure of a building to the wind, its tightness and the shielding class. For the purpose of the energy certification of buildings, the rulebooks in the Republic of Srpska require that the minimum estimated energy characteristics of the building are based on the design documentation of the building and do not take into account the actual energy consumption nor the measurements of the physical quantities which are used for determination of the building’s energy efficiency.According to the Rulebook on energy survey and energy certification the determination of the energy class of the building is carried out relative to the limit value of the permitted energy class C.The kindergartens are not considered as a special building type and energy auditors use the parameters for residential buildings and buildings for education and culture in their audit. Both building types have the same permitted energy class C (QH,nd ≤ 65 kWh / m2a). According to the standard EN 15217 Annex B, the EP value for the permitted energy class C is between the reference value QH,nd obtained on the basis of the lowest energy requirements defined by the energy performance regulations (Rr) and the average of the reference value Rr and the reference valueof considered building type (Rs) or Rr ≤ EP < 0,5 (Rr+Rs).

The selection of the representative samples of existing and new kindergartens The representative sample of the existing kindergartens was selected based on the analysis of ten detached kindergartens in the city of Banja Luka located in the Republic of Srpska (north part of Bosnia and Hercegovina)according to the architectural key design parameters. The primary and the original purpose of this kindergarten as defined by design documentation has been held to date. A special attention was given to the shape factor of the kindergarten and the average thermal transmittance of its envelope. A representative sample of new kindergartens is an energy efficient construction according to the current regulations that have been valid in the Republic of Srpska since 2016.

The building shape factor and the average U-value of the kindergarten envelope The kindergartens in Banja Luka are built with characteristic widespread size of ground floor and a ground floor only, whereas the constructions and materialization are carried out in three ways dependingon the historical and the social circumstances,as well as the industrial development of building technologyand according to the valid regulations and same conditions, principles and requirements as the residential buildings. These kindergartens do not have a compact formand theiraverage building shape factor is 0.95 (Figure 1). As the representative sample of existing kindergartensthe one with the building shape factor of 0.94 has been chosen. On the other hand, the representative sample of new kindergartens, although with the widespread size of ground floor, is the modern one which larger part of a ground floor with a gallery makes an increased volume of the kindergarten which building shape factor is 0.77. This indicates that it is possible to design and built new kindergartens which are more compact and have a lower shape factor than existing ones.

320 |ARCHITECTURAL DESIGN AND ENERGY PERFORMANCE OF BUILDINGS|


Figure 1: The average value of the building shape factor according to the period of construction The most ofkindergartens in Banja Lukaare built during the ten-year period, following the disastrous earthquake in Banja Luka in 1969 (Gajic and others, 2017). After the Second World War massive walls were built with solid brick and without reinforced concrete cuttings. After the catastrophic earthquake, various reinforcedconstructions were built: constructions with a vertical reinforced concrete beam, skeletal construction of reinforced concrete columns and beams with hollow bricks and clinker-concrete thermo-blocks without thermal insulation on exterior walls.From analyzed design documentationit can be seen that a light wooden construction - a wooden substructure filled with the thermal insulation (mineral wool), as the most commonly built construction in a five-year period after the earthquake has been used as well. The characteristic construction and materialization of the envelopes after 1974 with increase in the thickness ofthermal insulation has been used till this day. In kindergartens built as lightweight constructionswithdemountable wooden structures, thermal insulation (mineral wool) appears as a filler. The average U-value for the outer wall is 1.4 W/ m2K. The windows are usually with woodenframes-two wings andwith single glazing. Although it is evident from Figure 2 that the average U-value is around 3.5 W/m2K, apart from the type of frame and glazing, the U-valueis also influenced bydimension of the opening area anddivision of a casement (the length of the joints between glass and frame).

Figure 2: The average U-value of the exterior walls (left image) and windows (right image) according to period of the kindergarten construction The kindergartens built until 1970 are characterized by non-heated attic spaces without thermal insulation. After year 1970, the construction of thermally insulated flat roofs with 5 cm thickness, as well as the use of the gas concrete of 16 cm thickness in the role of thermal insulation has begun. The lowest U-value is observed in wooden structures. Furthermore, the average U-value for the roof is around 0.8 W/m2K. In ten existing detached kindergartens there are slab-on-ground floors. From Figure 3 it can be seen that some of existing kindergartens meet |ARCHITECTURAL DESIGN AND ENERGY PERFORMANCE OF BUILDINGS| 321


the criteria of current regulations (2016) in terms of maximum permitted U-value for the floor. The reason for this is the change in the calculation methods of the heat transfer via ground according to the standard EN 13370. The average U-value of the floor is around 0.9 W/m2K.

Figure 3: The average U-value of the roof (left image) and of the floor (right image) according to the period of kindergarten construction The representative sample of kindergarten from 1977 has characteristics of existing kindergartens with materialization according to the original design documentation. Analyzed kindergartens were built more than 35 years ago and they did not have envelope reconstruction so far. The U-values for around 90% of the envelope elements of the representative new kindergarten satisfy criteria defined by the Rulebook on minimum requirements of buildings energy characteristics. The parts of the envelope that do not satisfy criteria refer to the walls and ceilings adjacent to the unheated spaces.

The air changes per hour of the representative samples of kindergartens The parameters listed in Table 1 of Annex 6 of Rulebook on minimum requirements of building energy characteristics are used for determination of the air changes per hour for existing buildings as taken from the standard EN ISO 13789. According to this standard the air changes per hour are estimated based on the exposure of the facade to the wind, the position of the building relative to the built environment and its tightness.The average value of the air changes per hour of existing kindergartens in Banja Luka is estimated to be n = 0.7 h-1 (Figure 4). The estimation is based on the assumption given in the standard taking into account the average wind speed in the urban zone(Jankovic et al, 2016). Poor tightness of building occurs due to lack of maintenance and the lifecycle of the built-in products (windows and doors) in the openings of the envelope.

Figure 4: The average U-value of roof according to the period of construction of kindergarten Although the measured value of the air change per hour can be lower than n = 0.5 h-1, the table given in the rulebook indicates that for the existing buildings this minimum value must be estimated at n = 0.5 h-1. According to the Article 24 of this rulebook measured air changes per hour by in-situ measurements must be below n = 0.2 h-1for naturally ventilated new buildings. Also, the Article 22 requires that the enclosure tightness must be at least n = 0.2 h-1 when space is not 322 |ARCHITECTURAL DESIGN AND ENERGY PERFORMANCE OF BUILDINGS|


occupied or n = 0.5 h-1 when it is occupied. Although it is possible that the air change per hour in new buildings are lower than n = 0.5 h-1, for hygiene reasons it should be at least n = 0.5 h-1.

The comparative analysis of the energy performance parameters and indicators of the representative samples of kindergartens The kindergarten Neven with the design documentation dating from 1977 was considered as an example of existing detached kindergarten, while the kindergarten Kolibri with the design documentation from 2009 was considered as an example of the concept of energy efficient construction, which is required by the regulations-rulebooks in the Republic of Srpska since January 2016. In order to determine the energy need for heating for the permitted energy class C, both representative samples were analyzed. The analysis was done for the existing state and designed onewith the aim to fulfill the minimum energy characteristics of the envelope required by the current regulations. (Table 1). Table 1: The comparative review of the specific energy need for heating of representative samples of existing and new kindergartens in the city of Banja Luka

SAMPLE 1 “Neven”

SAMPLE 2 “Kolibri”

PERIOD

1955 - 1980 (1977)

2010 - 2020 (2009)

1014 m²

1110 m²

P

P+G

3044 m³

4157 m³

HEATED SPACE AREA No OF FLOORS

HEATED SPACE VOLUME heat capacity

Wh/m²a

72

46

metabolic heat

W/m²

7

7

existing

new

existing

new

U-value WALLS

W/m²K

1.47

0.30

0.41

0.30

U-value WINDOWS

W/m²K

3.55

1.60

1.51

1.50 (1.60)

U-value ROOF

W/m²K

0.77

0.20

0.20

0.20

U-value FLOOR

W/m²K

1.12

0.30

0.33

0.30

g-value

-

0.77

0.61

0.61

0.61

A/V ratio

-

0.94

0.94

0.77

0.77

Infiltration/air change

h-1

0.70

0.50

0.50

internal temperature

°C

DESIGN 20.0

0.50 DESIGN 20.0

internal heat gains ventilation

kWh/m²a

0.00

0.00

users

kWh/m²a

5.93

5.93

lighting and various equipment/electricity

kWh/m²a

5.80

5.80

ENERGY NEED

kWh/m²a

284.80

102.50

81.95

76.90 (78.50)

|ARCHITECTURAL DESIGN AND ENERGY PERFORMANCE OF BUILDINGS| 323


For the sample of existing kindergarten, the difference between the air changes per hour changing from 0.70 h-1 for the current state to 0.50 h-1for the new design tightening other requirements according to the new rulebooks affects the change of the energy need for heating lowering it from 284.80 kWh∙m-2a-1 to 102.50 kWh∙m-2a-1. The comparative analysis of the representative sample of existing and new kindergarten to which the minimum requirements for the envelope energy characteristics are applied (the U-values, the g-solar transmittance, the air changes per hour) has shownthat the compactness of the building (the difference between building shape factors from 0.94 m-1 to 0.77 m-1) influences the change of the energy need for heating lowering it from 102.50 kWh∙m-2a-1 to 78.50 kWh∙m-2a-1. Furthermore, the minimum energy performance requirements used for the representative kindergarten showsthat it is impossible to reach the energy need for heating for the reference class C (QH, nd ≤ 65 kWh∙m-2a-1) as defined for the buildings used for education and cultural buildings.

Conclusions In the rulebooks used in the Republic of Srpska the energy performance indicator for kindergartens is not defined as a special category/energy class of the building. According to the rules of the profession, energy performance indicator is considered as the parameter for residential buildings and buildings used for education and culture (project temperature, natural ventilation). However, the value of the permitted energy class C for kindergartens according to the standard EN 15217 Annex B and the analysis of representative samples of existing and new kindergartens,shown in this paper is proposed to be 80 kWh∙m-2a-1 ≤ EP