High Efficiency Hybrid Radiant and Heat Pump Heating Plants for Industrial Buildings: An Energy Analysis

High Efficiency Hybrid Radiant and Heat Pump Heating Plants for Industrial Buildings: An Energy Analysis

Marco Noro* Simone Mancin Francesco Cerboni

Department of Management and Engineering, University of Padova, 36100 Vicenza, Italy

Officine Termotecniche Fraccaro s.r.l., 31033 Castelfranco Veneto, Italy

Corresponding Author Email: 
marco.noro@unipd.it
Page: 
863-870
|
DOI: 
https://doi.org/10.18280/ijht.400401
Received: 
10 July 2022
|
Accepted: 
3 August 2022
|
Published: 
31 August 2022
| Citation

(This article is part of the Special Issue 7th int. Conf. AIGE-IIETA and 16th Conf. AIGE)

OPEN ACCESS

Special Issue
Abstract: 

A hybrid condensing radiant tubes system coupled to a heat pump to heat a typical industrial building was modeled in three climatic zones of Italy using dynamic simulation software. The heating system was set up by radiant tubes and an air heating system with terminals placed in the building supplied by hot water produced by the condensation of the exhausted of the radiant tubes and by a heat pump with external air heat source. An optimization of the main parameters (nominal power of the heat pump, bivalent temperature in alternative bivalent operation, and peak power of the photovoltaic system) was carried out on the basis of energy performance of the hybrid heating system. The optimal configuration of the hybrid heating system that minimizes the annual amount of total non-renewable primary energy and maximizes the non-renewable primary energy ratio was compared with traditional heating systems for industrial buildings. The energy savings of this innovative solution vary in the range of 40%-80% depending on the climate and the configuration of the system.

Keywords: 

heat pump, heating, hybrid heating system, industrial heating, industry, radiant tube

1. Introduction

Traditional climatization plants are not common in industrial buildings due to the particular characteristics of the latter: some equipment could be present on the ceiling or walls (pipes and tubes, bridge cranes, etc.), heights are typically higher (could be more than 8 m), floor areas are very large with different types of occupation by workers, doors can be large and can be often opened, comfort conditions requested are typically different, and thermal insulation of the walls and ceiling is usually scarce [1].

For example, in recent decades, evaporative cooling systems have been used in industrial buildings in northwest area of China, in particular semi-central systems that face the disadvantage of a large duct and difficult control of the temperature in different rooms [2]. More recently, De Angelis et al. [3] simulated different study cases by TRNSYS [4] varying the cooling system in the same reference industrial building, comparing the results in terms of energy savings and thermal comfort. A comprehensive evaluation of different heating, ventilation, and air conditioning (HVAC) systems for an industrial building was provided using the hybrid multicriteria decision making method [5]. Malyavina et al. [6] studied the influence of standard thermal protection of industrial buildings on heating load and seasonal heat consumption for heating in various climatic conditions of the Russian Federation.

Industrial facilities were studied in the case of energy retrofit [7], focusing both on the thermal envelope [8] and on technical building services such as the heating [9] or ventilation [10] plant. Gourlis and Kovacic presented a novel approach to evaluate the potential improvement in energy consumption and indoor climate of historical industrial buildings by dynamic thermal simulation modelling [11], also with regard to passive measures to prevent summer overheating [12]. The same authors also concentrated on developing a decision support tool to analyze the life cycle of facade systems for energy-efficient industrial facilities [13]. Smolek et al. [14] proposed a different modeling approach using cubes to decompose a manufacturing facility into modules such as the building, the energy system, production and logistics. Finally, the use of building information modeling and building energy modelling was explored for the analysis and optimization of two industrial buildings, to highlight the potentials and drawbacks of these methods [15].

In an analysis of the heating plant of an industrial building, traditional systems are not as common. Instead, high temperature radiant heating systems and air heater systems can be used because they are quite easy to install and with relatively low installation costs. Different air systems are available on the market: ground or wall air heaters fueled by natural gas or supplied by hot water and mechanical ventilation plants [16]. More recently, high-temperature radiant systems have been proposed: radiant tubes equipped with small gas burners, or the more traditional types of panels heated by pressurized water or steam, or electrical radiant panels [17, 18]. Such systems feature some positive characteristics: the heat flux can be directed towards the zone of interest, so comfort conditions can be reached with a lower air temperature [19, 20]. In the last decade, low temperature radiant heating floor systems have been installed in new industrial buildings with a higher level of thermal insulation, also due to the large diffusion of condensing boilers [21].

The indoor comfort conditions and energy performance of an innovative condensing radiant tube plant have been studied by the authors [22]. The system has been dynamically simulated by coupling a heat exchanger to condense the exhausted from the tubes. The hot water produced alimented wall-mounted air heaters, which improved the thermal efficiency of the system. The primary energy saving was 7% with respect to a radiant floor coupled to a condensing boiler and could reach 30% compared to a traditional air-heating system. As an additional advantage, better thermal comfort conditions could be allowed in the morning operation of the plant.

In the present study, a further development of the system presented by Noro and Lazzarin [22] is analyzed, that is, a hybrid heating system set up by an air-water heat pump coupled to the condensing radiant tubes plant (condensing radiant tubes + heat pump system, CRT+HP). Heating is provided by the radiant tubes and by the wall-mounted air heaters fed by hot water (40℃) produced by the condensation of the exhausted and by the heat pump. The scope of the study, based on TRNSYS rel. 17 software, is to optimize the hybrid configuration of the system, that is, to determine the values of external air bivalent temperature, heat pump nominal thermal power, and peak power of the photovoltaic plant (if installed on the roof) in order to:

  • minimize the PEnren,tot (annual total non-renewable primary energy consumed by the hybrid plant);

  • maximize the PESnren,tot (annual total saving of non-renewable primary energy compared to traditional heating systems);

  • satisfy the minimum value of the renewable quota (QR) according to Italian Legislative Decree 199/2021 (implementation of the Renewable Energy Source II Directive), i.e., at least 60% referring to the considered services (in this work only heating). QR is defined as the ratio between annual quantities of the renewable primary energy used (delivered or produced on site, calculated using the conversion factors (fp,ren) for natural gas, electricity from the grid, electricity from the photovoltaic system, thermal energy from the external environment as heat source of the heat pump) and of the total primary energy used (renewable + non-renewable), calculated using the conversion factors (fp,tot = fp,ren + fp,nren) for each energy carrier delivered or produced on site.

The best solution is then compared to benchmark heating systems:

  • only condensing radiant tubes (CRT));

  • air heater based system (Air);

  • radiant floor coupled to condensing boiler (condensing radiant floor, CRF).

For all benchmark systems, energy performances are compared with the innovative hybrid CRT+HP plant. To consider the variety of real situations, both modern and old plants are considered for both Air and CRF by varying the thermal efficiency of the generators in suitable ranges.

The paper is organized as follows: in Section n. 2, the different steps of the modelling and simulations of the building, the hybrid CRT+HP plant, and the benchmark systems are described. In Section n. 3, the results of the simulations are reported first for the cases with the presence of the PV plant and then in the absence of the PV plant. Some remarks on annual energy comparison between the systems are reported as well. Finally, some final conclusions are reported.

2. Methods

The study is conceived by three main steps:

  • calculation of the heating load in three different climates by modeling a typical industrial building (based on a real case) [22];

  • determination of the best set of bivalent temperature in alternative bivalent operation (the system gives priority to the heat pump, which switches off when the outside air temperature drops below the bivalent temperature and the radiant tubes turn on), HP thermal power and PV peak power installed on the building roof by modelling the hybrid condensing radiant tubes + heat pump system and analyzing the energy performance for each climate;

  • modelling of the three benchmark heating systems and comparison of the energy performance with the CRT+HP hybrid system.

2.1 Industrial building modelling

The climate conditions of the simulated industrial building are reported in Table 1 for the three climatic zones D, E, and F defined by the Italian Legislative Decree 412/1993on the basis of the heating degree days (zone D: 1401-2100; zone E: 2101-3000; zone F: >3000). The size and characteristics of the opaque and transparent structures are reported in Table 2 and Table 3. Other hypotheses consider an operation heating plant scheduling from 6.00 am to 6.00 pm, a presence of people and lighting scheduling (heating gain fixed at 5 W m-2) from 8.00 am to 6.00 pm, and a presence of people and degree of activity and clothing of 40 persons in zone 1, 8 persons in zone 2, 2 met, 1 clo. Air infiltration was supposed to be 0.5 vol h-1.

Table 1. General climatic data for the heating

Type of building use (DPR 412/93)

E.8 Building for industrial activity

Climatic zone

D

E

F

Resort (Province – State)

Roma (Roma – Italy)

Manta (Cuneo – Italy)

Agordo (Belluno – Italy)

Altitude a.s.l.

20

400

610

Latitude North

41° 54’

44° 36’

46° 17’

Longitude East

12° 29’

7° 29’

12° 00’

Degree Days

1415

2814

3376

Outdoor design air temperature

0℃

-9.3℃

-12℃

Table 2. Thermal transmittance of opaque and transparent structures of thermal zones of the building

Parameter (unit)

Value

Thermal transmittance (W m-2 K-1)

 

External wall

0.389

Door

3.50

Main door

3.50

Wall facing offices

2.954

Base facing wall

3.220

Floor facing ground

0.128

Ceiling

4.086

Ceiling shed

0.208

Window

5.0

Thermal bridge wall – floor facing ground (W m-2 K-1)

0.353

Thermal bridge wall – ceiling (W m-2 K-1)

0.262

Table 3. Main characteristics of the two thermal zones of the building for TRNSYS simulation

 

Thermal zone 1

Thermal zone 2

Floor area (m2)

7119

716.5

Net height (m)

8.24

8.22

Indoor air temp. (℃)

18

18

Net volume (m3)

58669

5886.2

The dynamic simulation of the building with a 0.25 h time step allows to calculate the heating loads (thermal power) and the heating needs (monthly energy, Figure 1). The thermal power of the heating generators is limited to 1200 kW, 1500 kW and 1500 kW for climatic zone D, E and F respectively, to be consistent with the installed power in the real building by the condensing radiant tubes’ manufacturer.

Figure 1. Monthly heating needs for the industrial building in three thermal zones

2.2 CRT+HP, CRT, Air, and CRF systems modelling

In the hybrid configuration (CRT+HP), an air-water heat pump is coupled to condensing radiant tubes to increase the utilization of renewable energy. A suitable thermal energy storage (1000 L) decouples wall-mounted air heaters from the hot water produced at 40℃ by the condensing heat exchanger and the heat pump (Figure 2a).

The combustion air flow rate is controlled by an exhausted tab that recirculates part of the exhausted to keep the excess air at the minimum value at part load operation (that is, when natural gas fuel is regulated by a proportional valve).

The dynamic operation of the system is simulated in TRNSYS by coupling types 607 and 659. The former has been modified in order to simulate the behavior of the high temperature radiant tube system. At the start of operation, the CRT burner is turned on at maximum power to obtain the maximum exhausted temperature. When the temperature of the indoor air increases near the set point, the thermal power of the CRT burner is modulated by controlling the proportional valve of natural gas to have the fuel mass flow rate that is necessary to produce the heating load requested at that time step. Fuel modulation decreases the exhausted temperature and the exhausted tab is regulated to have the correct minimum air excess in the burner (Figure 2b) [22].

The heat pump, whose nominal data are reported in Table 4, is simulated by means of type 941.

The heat pump has priority operation, providing the thermal power to face the heating load according to the external air temperature Text. It operates in an alternative bivalent mode, i.e. its shutdown is when Text < Tbiv, where the bivalent temperature Tbiv has to be optimized. In each time step, the radiant tubes cover the heating load that is not satisfied by the heat pump. A minimum load factor of 30% for the radiant tubes is considered. Thermal storage can compensate for an eventual surplus or deficit in thermal energy. Finally, the photovoltaic field, if present, can cover (partially or in excess, depending on the peak power installed) the electric consumption of the heat pump. The values of some parameters used in the energy analysis are reported in Table 5.

(a)

(b)

Figure 2. (a) Schematic of the CRT+HP plant; (b) Control logic of the proportional valve of natural gas (blue) and the exhausted tab (red). Gric (recirculated exhausted mass flow rate) is expressed in terms of the fraction of the return flow of the radiant tubes. Thermal efficiency (on HHV) versus modulation is also reported (green). In the simulations, the hypotheses are Tmin=17℃, Tavg=17.5℃, Tmax=18℃

Table 4. Nominal data of the air-water heat pump (mod. Clivet Spinchiller WSAN-XSC3 90.4) (D.B.=dry bulb temperature; W.B.=wet bulb temperature)

Text ()

Tout,cond ()

D.B.

W.B.

35

40

 

 

kWth

kWel

COP

kWth

kWel

COP

-7

-8

205.0

60.8

3.37

203.0

67.8

2.99

-5

-6

216.0

61.2

3.53

214.0

68.0

3.15

0

-1

245.0

62.4

3.93

243.0

68.9

3.53

2

1

260.0

62.8

4.14

256.0

69.4

3.69

7

6

297.0

64.1

4.63

290.0

70.7

4.10

12

11

344.0

65.7

5.24

336.0

72.1

4.66

Table 5. Main parameters for energy and economic analysis (following the Italian Legislative Decree 199/2021)

Symbol

Meaning

Value

fp,nren,NG

Non-renewable primary energy conversion factor for natural gas

1.05

fp,nren,el

Non-renewable primary energy conversion factor for electricity from the grid

1.95

fp,ren,el

Renewable primary energy conversion factor for electricity from the grid

0.47

fp,ren,PV

Renewable primary energy conversion factor for electricity from the PV field

1

fp,ren,heat_source_HP

Renewable primary energy conversion factor for external air thermal energy

1

QR

Minimum renewable ratio for new buildings

60%

PV (kWp)

(Reference) peak power of the PV field

200

PV (hnom)

(Reference) peak efficiency of the PV field

16.0%

PV (m2 kWp-1)

(Reference) specific area of the PV field

6.3

3. Results and Discussion

The results of the simulations refer to the annual energy performance of the CRT+HP system in the three climatic zones (D, E, F) in terms of sensitivity analysis: it is presented how the values of the main indices (PEnren,tot, PER, CO2 specific emission, QR) vary with the nominal power of the heat pump, with the peak power of the photovoltaic system (if present) and with the bivalent external air temperature. The main scope is to choose the best values of these three variables with respect to the reference values shown in Table 4 and Table 5. On the basis of such results, energy performances of the optimal configuration of the CRT+HP system are compared with the three benchmark heating systems (CRT, CRF, Air) in terms of non-renewable primary energy saving (PESnren,tot).

3.1 Energy analysis with PV

Figure 3 reveals that in climatic zone D the most advantageous configuration is set up by Tbiv = 0℃; nominal output of the heat pump (Pth_HP) = 493 kWth (170% of the nominal output of Table 4, equal to approximately 41% of the nominal power of the radiant tubes, which is 1200 kW in climatic zone D); peak power of the photovoltaic system (PPV) = 340 kWp (170% of the nominal peak power of Table 5). This is the configuration that simultaneously minimizes the consumption of non-renewable primary energy PEnren,tot and allows for a high renewable ratio QR.

In both climatic zones E and F, the most advantageous configuration is set up by: Tbiv = 0℃; Pth_HP = 392 kWth (135% of the nominal output of Table 4, equal to approximately 25% of the installed nominal power of the radiant tubes (1500 kWth)); PPV = 270 kWp (135% of the nominal peak power of Table 5).

Table 6 shows the annual values of energy performance indices of the CRT+HP system in the optimal configuration. PER decreases in colder climates mainly due to the greater use of radiant tubes (i.e., natural gas) and to a lower use of renewable energy by the heat pump. In fact, there is a lower use of both thermal energy (as a heat source at the evaporator due to lower COP) and electrical energy powering the compressor (due to lower production of the photovoltaic field). For the same reasons, the QR renewable ratio decreases in colder climates. Note that the 60% value required by Legislative Decree 199/2021 is exceeded only in climatic zone D.

The self-consumed (by heat pump) electricity quota of photovoltaic production is higher in colder climates (15% in zone D, 24% in zone F). Table 6 reports the annual value of the PER, which is quite high in general, and extremely high in milder climates.

Figure 4 reports the comparison in terms of annual non-renewable primary energy between the hybrid CRT+HP system and the benchmark plants. The hybrid system allows extremely high non-renewable primary energy savings (PESnren,tot) compared to the other solutions, especially in milder climates (zone D). In this case, there is a greater contribution from renewable sources in input to the heat pump, both the aeraulic one to the evaporator (higher COP due to higher external temperatures) and the electric one from photovoltaics.

As a final remark, note that, even with respect to the efficient condensing radiant tubes plant (CRT), the hybrid configuration allows for very high PESnren,tot ranging from 40% to 82%.

Figure 3. Annual values of PEnren,tot and QR of the hybrid CRT+HP system varying the multiplication factor of the nominal output of the heat pump (Pth_HP) and the peak power of the photovoltaic system (PPV) (lower abscissa, left ordinate) and varying the bivalent temperature (upper abscissa, right ordinate) (with PV, bivalent alternative operation)

Table 6. Annual values of the energy performance indices of the CRT+HP system in the optimal configuration for the three climatic zones (PE=primary energy) (with photovoltaic)

Symbol

Description

Unit

Zone D

Zone E

Zone F

PEren,el

Renewable quota of electricity from the grid

kWh

3,272

4,545

8,840

PEnren,el

Non-renewable quota of electricity from the grid

kWh

13,575

18,857

36,675

PEren,PV

Renewable quota of electricity from the PV self-consumed

kWh

77,435

99,845

89,512

PEren,PV,exp

Renewable quota of electricity from the PV exported to the grid

kWh

431,252

367,027

284,480

PEren,heat_source_HP

Thermal energy as heat source of the HP

kWh

246,289

287,078

281,042

PEren,tot

Total renewable

kWh

326,996

391,468

379,393

PEnren,NG

Non-renewable as natural gas

kWh

57,464

454,312

608,957

PEnren,tot

Total no-renewable

kWh

71,039

473,168

645,632

PER

Primary energy ratio

 

5.35

1.69

1.44

QR

Renewable ratio

 

82.2%

45.3%

37.0%

PEnren,tot

Specific total non-renewable

kWh

m-2 y-1

9.1

60.4

82.4

CO2

 

kgCO2 m-2

1.8

11.5

15.8

(a) Zone D

(b) Zone E

(c) Zone F

Figure 4. Total annual non-renewable primary energy consumption (PEn,ren,tot) and savings of the same energy (PESnren,tot) of the hybrid CRT+HP system in the optimal configuration (with photovoltaic)

3.2 Energy analysis without photovoltaics

In case of no economic investment in the photovoltaic plant, the optimal size of the heat pump (Pth_HP) with alternative operation decreases from climatic zone D to F: it is 200% of the value in Table 4 in zones D and E (i.e. 580 kWth, 48% and 39% of the nominal installed power of the radiant tubes, respectively), while it decreases to 170% in zone F (i.e. 493 kWth, 33% of the nominal installed power of the radiant tubes) (Figure 5) (with Tbiv = 5℃). In addition to the fact that the PES is lower than in the case with a PV plant, primary energy savings are still very interesting, especially in milder climates (from 30% with respect to CRT to 47% with respect to Air_old system in zone D) due to the high contribution of renewables in the HP evaporator (i.e. higher COP).

(a) Zone D

(b) Zone E

(c) Zone F

Figure 5. PEn,ren,tot, PER, QR, and specific CO2 emission varying the Pth_HP multiplying factor (without PV)

Based on previous results, the PER of the hybrid system is very high, especially in milder climates (in zone D it exceeds the value of 5 with the presence of the PV field). It decreases in colder climates mainly due to more extended use of radiant tubes (and therefore of natural gas) and to lower use of renewable energy by the heat pump (Table 7). Without the PV plant the PER cannot reach such values, even if very interesting in any case. Consequently, both the non-renewable specific primary energy consumption and the CO2 specific emissions with the PV plant are definitely higher than in the case of absence.

The QR renewable ratio decreases substantially in colder climates for the same reasons as above. The value of 60% is exceeded only in the presence of the photovoltaic system (Table 7).

Table 7. Energy performance of the CRT+HP system in optimal configuration

 

 

 

Zone D

Zone E

Zone F

WITH PV –

BIVALENT ALTERNATIVE

PER

 

5.35

1.69

1.44

QR

 

82.2%

45.3%

37.0%

PEnren,tot

kWh m-2

9.1

60.4

82.4

CO2

kgCO2 m-2

1.8

11.5

15.8

WITHOUT PV –

BIVALENT ALTERNATIVE

PER

 

1.73

1.33

1.21

QR

 

56.5%

43.2%

37.1%

PEnren,tot

kWh m-2

28.1

76.9

98.5

CO2

kgCO2 m-2

5.7

15.2

19.3

4. Conclusions

From the energy point of view, in the presence of the photovoltaic system it is not advantageous to size the heat pump of the CRT+HP system more than 40% of the installed power of the radiant tubes in climatic zone D, and 25% in zones E and F.

The most suitable values of bivalent temperature in alternative operation are equal, respectively, to 0℃ in zone D, 0℃ in zone E, 0℃ in zone F. Concerning the optimal peak PV power to be installed, it is between 5.5 and 7.5 m2 kWp-1 depending on the nominal peak efficiency of the panels (in the range of 14%-19%).

In the optimized configuration, the hybrid CRT+HP heating system allows very high PER especially in milder climates: in zone D it exceeds the value of 5 in the presence of the photovoltaic system, and it decreases in the colder zones E and F. The value of 60% for QR is exceeded only in the presence of the photovoltaic system.

The energy performance of the hybrid system allows for very high primary energy savings with respect to the benchmark plants: in the presence of the photovoltaic system, the PES varies from 40% (climatic zone F) to values greater than 80% (climatic zone D). In case of no investment in PV, the values are lower, but still interesting.

As a further development of this work, the effects on the energy performance of a different control logic of the hybrid configuration (such as the bivalent parallel one) could be analyzed. Furthermore, an economic analysis could be implemented to assess the economic viability of the hybrid system in comparison to the benchmark heating plants. The economic analysis could also be useful to highlight that installation of the PV field could make the hybrid solution less sensitive to the increase of the cost of electricity from the grid, which otherwise would heavily affect the actual economic viability of the investment.

Acknowledgment

The authors thank Officine Termotecniche Fraccaro s.r.l. for the data provided concerning the heating performance of the condensing radiant tubes.

Nomenclature

Acronym

Air

Air heating system

CRF

Condensing Radiant Floor

CRT

Condensing Radiant Tube

HHV

High Heating Value, MJ Sm-3

HP

Heat Pump

HVAC

Heating, Ventilation, Air Conditioning

NG

Natural Gas

PV

PhotoVoltaic

Symbol

COP

Coefficient Of Performance

fp

Primary energy factor

P

Power, kW

PE

Primary Energy, kWh

PER

Primary Energy Ratio

PES

Primary Energy Saving

QR

Renewable Ratio

h

Efficiency

Subscripts

biv

Bivalent

cond

Condenser

el

Electricity from the grid

exp

Electricity exported to the grid

ext

External

fuel

Fuel

heat_source

Heat source of the heat pump (at the evaporator)

nren

Non-renewable

out

Outlet

ren

Renewable

th

Thermal

tot

Total

  References

[1] Pu, J., Yuan, Y., Jiang, F., Zheng, K., Zhao, K. (2022). Buoyancy-driven natural ventilation characteristics of thermal corridors in industrial buildings. Journal of Building Engineering, 50: 104107. https://doi.org/10.1016/j.jobe.2022.104107

[2] Qiang, T.W., Shen, H.G., Huang, X., Qu, Y. (2005). Semi-central evaporative cooling air conditioning system. International Journal of Heat and Technology, 23(1): 109-113. https://doi.org/10.18280/ijht.230115

[3] De Angelis, A., Medici, M., Saro, O., Lorenzini, G. (2015). Evaluation of evaporative cooling systems in industrial buildings. International Journal of Heat and Technology, 33(3): 1-10. https://doi.org/10.18280/ijht.330301

[4] Solar Energy Laboratory. (2012). TRNSYS 17. TRaNsient SYstem Simulation Program; University of Wisconsin-Madison and Thermal Energy System Specialists: Madison, WI, USA.

[5] Bac, U., Alaloosi, K.A.M.S., Turhan, C. (2021). A comprehensive evaluation of the most suitable HVAC system for an industrial building by using a hybrid building energy simulation and multi criteria decision making framework. Journal of Building Engineering, 37: 102153. https://doi.org/10.1016/j.jobe.2021.102153

[6] Malyavina, E., Zdoronok, A., Ozerchuk, D. (2021). Comparison of heating loads in residential, public and industrial buildings. E3S Web of Conferences, 244: 050282, 2nd International Scientific Conference on Energy Management of Municipal Facilities and Sustainable Energy Technologies, EMMFT Voronezh. https://doi.org/10.1051/e3sconf/202124405028

[7] Trianni, A., Cagno, E., De Donatis, A. (2014). A framework to characterize energy efficiency measures. Appl Energy, 118: 207-220. https://doi.org/10.1016/j.apenergy.2013.12.042

[8] Katunska, J., Oberleova, J., Rusnak, A., Toth, S. (2014). Diagnosis of elected industrial hall object and idea for its reconstruction. Advanced Materials Research, 1057: 19-26. https://doi.org/10.4028/www.scientific.net/AMR.1057.19

[9] Chinese, D., Nardin, G., Saro, O. (2011). Multi-criteria analysis for the selection of space heating systems in an industrial building. Energy, 36(1): 556-565. https://doi.org/10.1016/j.energy.2010.10.005

[10] Caputo, A.C., Pelagagge, P.M. (2009). Upgrading mixed ventilation systems in industrial conditioning. Applied Thermal Engineering, 29(14-15): 3204-3211. https://doi.org/10.1016/j.energy.2010.10.005

[11] Gourlis, G., Kovacic, I. (2016). A study on building performance analysis for energy retrofit of existing industrial facilities. Applied Energy, 184: 1389-1399. https://doi.org/10.1016/j.apenergy.2016.03.104

[12] Gourlis, G., Kovacic, I. (2017). Passive measures for preventing summer overheating in industrial buildings under consideration of varying manufacturing process loads. Energy, 137: 1175-1185. https://doi.org/10.1016/j.energy.2017.05.134

[13] Kovacic, I., Waltenbereger, L., Gourlis, G. (2016). Tool for life cycle analysis of facade-systems for industrial buildings. Journal of Cleaner Production, 130: 260-272. https://doi.org/10.1016/j.jclepro.2015.10.063

[14] Smolek, P., Leobner, I., Gourlis, G., Mörzinger, B., Heinzl, B., Ponweiser, K. (2018). Hybrid building performance simulation models for industrial energy efficiency applications. Journal of Sustainable Development of Energy, Water and Environment Systems, 6(2): 381-393. https://doi.org/10.13044/j.sdewes.d6.0194

[15] Gourlis, G., Kovacic, I. (2017). Building Information Modelling for analysis of energy efficient industrial buildings – A case study. Renewable and Sustainable Energy Reviews, 68: 953-963. https://doi.org/10.1016/j.rser.2016.02.009

[16] Lazzarin, R. (2002). Intervista sul riscaldamento degli ambienti nell’industria. SGE, Padova.

[17] Negoitescu, A., Tokar, A. (2010). Efficiency and economy solutions regarding the industrial buildings heating. WSEAS Transactions on Environment and Development, 6(4): 288-297.

[18] Wang, W., Chapman, K.S., Keshavarz, A. (2005). Incorporate radiant heaters over 300°F into thermal comfort calculations using BCAP. ASHRAE Transactions, 111(1): 346-354.

[19] Brunello, P., De Carli, M., Polito, A., Zecchin, R. (2002). Comfort criteria and design aspects in high temperature radiant heating. Proc. Indoor Air 2002, Monterey, California.

[20] Kim, K.W., Olesen, B.W. (2015). Radiant heating and cooling systems. ASHRAE Journal, 57(2): 28-37.

[21] Lazzarin, R. (1986). Le caldaie a condensazione. Editrice PEG, Milano.

[22] Noro, M., Lazzarin, R. (2019). Energy analysis of industrial climatization by an innovative radiant condensing system. AIP Conference Proceedings, 2191: 020121. https://doi.org/10.1063/1.5138854