I Congreso Internacional sobre investigación en Construcción y Tecnología Arquitectónicas 1st International Congress on research in Construction and Architectural Technologies Universidad Politécnica de Madrid. ETSAM. Madrid, 11-13 Junio de 2014
COMPARATIVE ENERGY MODELS FOR INDUSTRIAL BUILIDNGS THERMAL PERFORMANCES Authors: Giuseppe Losco (1), Eduardo Barbera (2), Angelo Figliola (2), Matteo Iommi (2), Nazzareno Viviani (2) (1) University of Camerino. School of Architecture of Ascoli Piceno.
[email protected] (2) University of Camerino. School of Architecture of Ascoli Piceno.
[email protected] (2) University of Camerino. School of Architecture of Ascoli Piceno.
[email protected] (2) University of Camerino. School of Architecture of Ascoli Piceno.
[email protected] (2) University of Camerino. School of Architecture of Ascoli Piceno.
[email protected] ABSTRACT An experimental study is presented concerning development of energy saving potential in prefabricated industrial buildings, through comparative energy simulation models. According latest European policy and programs focus the research field is into retrofit and refurbishment of existing building. The building stock in industrial sector in Italy is rather obsolete, with low comfort conditions and high energy consumption. In Italy, only few studies deal with this topic to support assessments about average actual or potential energy saving quality of industrial buildings. This study, based on selected case-studies, aimed to establish general background and effective criteria for refurbishment actions. One “key factor” for energy saving in prefabricated industrial building is the thermal performance of the envelope (walls, roofs and windows), where reduction of energy consumption, for full air conditioning, is directly related to envelope thermal performance. Energy building design tools have been used, such as Ecotect Analysis, Heat 2.0 and Wufi Pro, to investigate how different envelope assemblages affect the energy consumptions in industrial buildings with different size starting on common scenarios. Proceeding from statistic data of existing common buildings in Italy, and most diffused building elements, like concrete prefabricated wall panels etc, some general case studies are defined and used to run energy simulations. The results give back a range of average energy analysis to compare and evaluate mean efficiency factor of real buildings and show potential energy benefits obtainable with various single or multiple refurbishment options. Therefore, having control over the dominant factors in the building envelope is indeed an important step in the path to achieving energy savings and carbon reduction in industrial buildings. Keywords: prefabricated building envelope; energy simulation tools; industrial building; refurbishment and retrofitting
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INTRODUCTION
The energy requirement of the Italian industry is around 40/41 MTep/year and represents the 30% of the total energy consumption for the final uses 1. However, if considers energy consumption by industry, both for production processes and services, the proportion attributable to the industry move to 45%. The industrial sector, thus, is assessable as very intensive energy user, and therefore any possibility to reduce the consumption is allow. Providing operative actions and strategies to improve energy efficiency and reduce energy uses in Italian industry sector is fundamental, also in reference to Italy has an high level of energetic vulnerability caused by an high dependence for energy on foreign countries, and is possible to estimate that energy bill for Italian industry will increase in the coming years if not it will reduce the energy demand. Into an European view, the industry is put as strategic sector not only for improve energy efficiency and sustainability but also for improve economy, jobs and competitiveness 2. The European core message about industry is to overcame national approaches, looking at a synergic and integrated strategies and
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programs. Before to start with strategies and policies linked to European vision, is necessary to know the current scenarios. To give back a study about current energy efficiency, is recovered a knowledge about industrial buildings, mostly made up small and medium industries (about 200.000 industrial companies), about the typologies and dimensions of these existing buildings, about the age, about the solutions used for envelopes. In this sense, the research focus on the thermal performances of the industrial buildings envelopes, without consider other improvable aspects like as heating and cooling equipments, ect. The research target is to recover, about building performances, the current energy levels and define where and how industrial building perform in worse way, with the impact to encourage future operative studies and actions. 2
METHODS
To define the most probable energy performances of existing industrial buildings and produce analysis about the potential benefits from executive actions, aimed at reducing energy consumption, has been performed an investigation and analysis path that identified and classified the macro-variables that determine the energy behavior of the building envelopes of these buildings. These macro-variables such as the prevailing size, typology, climate conditions, thermal performances of the most common building elements, that represent a fundamental feedback, are been used a statistical approach, recovering and integrating existing data and statistics with specific case studies. It’s important to note that the research aims to identify limits and ranges of the most probable energy performance of these buildings, while the reliability of the results, if compared to singles cases, may not be so effective, though the results are never inconsistent. The main typological features and dimensions of industrial buildings have been carried out through the investigation of existing statistic data by CNR 3 and twenty five real buildings. From the obtained information, is possible to outline some typical conditions such as, the height (from 6m to 14m), covered areas, volumes, relationship between envelope surface and transparent surfaces, etc. By these information, has been defined four scenarios with which is possible to enclose most of industrial buildings, excluding buildings near and over one milion of sqm because represent a very particular and small part of industry sector. TYPE SMALL MEDIUM LARGE EXTRA-LARGE
Volume 24.900 m 3 121.800 m 3 338.500 m 3 645.000 m 3
Covered Surface 3.950 m 2 14.400 m 2 34.700 m 2 49.000 m 2
S/V 0,39 0,28 0,24 0,22
Windows/Envelopes 4% 6% 8% 11 %
Table 1. Main typological features and dimensions of industrial buildings
For a constructive characterization of the most widely used building elements and relative thermal performances, is done a selection through existing documents and previous researches. Buildings for small and medium sized industrial enterprises have different characteristics compared to others buildings in term of costs, useful life, functional requirements, ect. The industry makes extensive use of prefabrication systems, but the Italian overall scenario of industrial buildings from 60’ to 2010 shows also traditional construction systems. To analyze the most influence systems on the energy performance, have been recovered and identified the most widely used building elements, starting from data and documents by public and private institutions 4 about building materials productions and industrial building constructions and some real case studies site in Regione Marche. The technological solutions analyzed do not constitute an exhaustive overview but the most probable and diffuse solutions. Building elements which realize the envelope are subdivide in functional parts: roofs, opaque surfaces, transparent surfaces and floors. To determine thermal performances are used two different energy tools: ANIT-PAN 4.0 and Wufi, to run dynamic and stationary simulations. By these tools, are calculated the following coefficients:
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U value, Yie value, Thermal Lag, Thermal decrement. More detailed values and simulations could be calculated but, about the target of this study, has not been done. Results from simulations have been processed into overall diagrams and charts to give ranges, trends and frequencies about thermal performances of parts of industrial building envelopes.
Figure 1. Values and percentages of U and Yie of all roofs solutions analyzed. (part of the analysis)
Showing intermediate results is possible to recognize how perform each part of the current envelopes and use these data to simulate heat gains and losses through the entire envelopes of typological models of industrial buildings, previously identified.
Floors Vertical opaque surface Roofs Vertical transparent surface
U values (W/sq m K) 0,10 – 0,50 0,51 – 1,00 1,01 – 1,50 3% 7% 25% 5% 8% 33% 3% 8% 12% 1,00 – 2,00 2,10 – 3,00 3,10 – 4,00 2% 35% 35%
1,51 – 2,00 45% 40% 55% 4,10 – 5,00 15%
+ 2,00 20% 12% 20% + 5,00 13%
Table 2. Percentage distribution of U values performnaces by building elements. (Part of the analysis)
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RESULTS
Starting from all data obtained, simulations and analysis have been done, to identify the most probable thermal requirements. For energy simulations is used Ecotect Analysis, with which is been possible to model, quickly, different configurations with combinations of different building elements, in different weather conditions. For the climatic aspect, in order to evaluate the energy behaviors in realistic different climatic zones, were used climate data related to five locations, one for each climate zone in which the Italian territory is divided by the national legislation. In reference to the software’s functions, to identify a common and useful index, was run thermal analysis and compare the heating thermal loads. From these simulations, were returned the average performances and the minimum and maximum reliable performances. It was also possible to evaluate the contributions in terms of heat loss, for each elements (floors, walls, windows and roofs) defining which elements have the greatest “weight” in the building energy demands. From these results, additional simulations were carried out, introducing predetermined high performance elements, obtaining potential improvements by single or multiple retrofitting solutions.
Floors Walls Roofs Windows
SMALL 9,1 % 31 % 51,1 % 8,8 %
MEDIUM 11,2 % 24,5 % 57,4 % 6,9 %
LARGE 10,6 % 24,4 % 58,2 % 6,8 %
EXTRA-LARGE 14,8 % 21,1 % 58,7 % 5,9 %
Table 3. Percentage of thermal losses trough the envelope by typology in climatic zone E
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Figure 3. Diagram of potential energy requirement reduction by retrofitting single enevelope’s element. Medium typology. Climatic zone E
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DISCUSSION
The results show the roofs of these buildings represent the most critical surfaces allowing the larger benefits to obtain better energy balance. The “energy weight” of the roofs appears to increase in relation to the size of the buildings, larger buildings have covering surfaces that affect most of the energy requirements. Moreover, we can assume that, even if the simulations have assessed only heating thermal loads, with reference to the Italian climaticradiation conditions, the “energy weight” of the roofs would be greater if evaluate cooling thermal loads. However, to suggest effective and secure solutions for retrofitting, these aspects are not alone, other aspects such as affordability, feasibility, flexibility of modifications and influence on structural systems must be consider. In this sense, is possible to highlight that the walls, which are the second element of greater importance and, for small buildings, energy influence by walls is similar to the roofs, may be the most appropriate surfaces for a refurbishment or retrofitting. It should finally be noted that the results of the simulations are partially produced on personal decisions and on some restrictions, about climatic conditions, energy units, and pre-assigned thermal coefficients for the potential energy benefits results. 5
ACKNOWLEDGEMENT AND CONCLUSIONS
In conclusion, the results can not represent absolute and certain values, but certainly can represent trends and valid energy relationships. In Italy there are few studies about energy efficiency of industrial buildings and all of these are refer to local conditions (regions or districts). This research try to extend the industrial energy performance issue above specific situations, in order to define an overall panorama to start and reconnect more specific studies. Starting from the results of this research, a series of future developments has been planned, to continue the studies in this technological sector, especially on the design of building systems and pre-assembled building components, like as double vertical façade and double ceiling cover with the target in improvement of the energy performance related to internal consumption facilities for climate control. This research has been carried out, starting from a previous experimental work made with Energy Resource and ETA. REFERENCES 1
ENEA, Rapporto Energia Ambiente. Scenari e Strategie 2013, Roma, 2013
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European Commision, An Integrated Industrial Policy for the Globalisation Era Putting Competitiveness and Sustainability at Centre Stage, Brussel, 2010
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CNR-PFE, Sottoprogetto Usi finali civili industriali, energia e territorio – RF-21 “Studio e valutazione sperimentale dei flussi di energia in stabilimenti industriali”, Roma, 1985
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Environment Park, Osservatorio Bioedilizia, Qualità edilizia, energetica ed ambientale degli edifici industriali, Dossier n.16, Torino, 2007
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