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A simulation of the energy consumption monitoring in Mediterranean hotels
Energy and Buildings 39 (2007) 416–426 www.elsevier.com/locate/enbuild
A simulation of the energy consumption monitoring in Mediterranean hotels Application in Greece Michaelis Karagiorgas a, Theocharis Tsoutsos b,*, A. Moia´-Pol c a Mechanical Engineering Department, ASPETE Faculty of Pedagogical Engineers, 14121 N. Iraklio, Greece Environmental Engineering Department, Technical University of Crete, Kounoupidiana Campus, Chania, GR 73100, Greece c Department of Physics, Mechanical Engineering Area, University of Balearic Islands, Ctra. Valldemossa km. 7.5, 07122 Balearic Islands, Spain b
Received 10 October 2005; received in revised form 4 July 2006; accepted 17 July 2006
Abstract Due to the competitiveness the importance of reducing cost and the growing sensitivity to environmental factors in the hotel design, is leading to the introduction of environmental friendly elements; if will be added the considerable increase in the cost of fossil fuel, it is obvious that all these factors create conditions favorable to the optimization of energy resources. In this paper are presented the results of audits, in the form of specific energy indicators, in 10 hotels in Greece grouped to various star categories and hotel typologies (Mount, City and Coastal type). Furthermore, in this paper is applied a basic model of the energy flow through the hotel interface starting from the various fuel input, through eight cost centers and finally down to five end-use services. The basic model is based on the energy mix matrix, which relates the cost centers (facilities) to the final services. As an example of result, a specific energy consumption of 5.5 kWh/lunch is found in a deluxe Greek hotel. # 2006 Elsevier B.V. All rights reserved. Keywords: Energy indicators; Energy saving; Hotels; Monitoring; Energy consumption
1. The potential for energy saving applications in the hotel sector Nowadays the tourism policy in national, European and international level is aiming at the improvement of the existing infrastructure, the lengthening of the operating period, the encouragement of alternative forms of tourism (i.e. ecotourism, health tourism, etc.) but, always putting emphasis on environmental matters [1]. EU strongly encourages the environmental performance of services and products. Additionally the public awareness and the demand of the tourism product continuously require more environmental friendly services. The adoption of energy saving applications in current hotel units shall give them a comparative advantage of environmental performance. Considering any forthcoming EU eco-labeling scheme in the hotel sector, any energy saving application would be considered a surplus advantage for hoteliers to participate in. Even though renewable energy technology (RET) applications would not be involved in
* Corresponding author. Tel.: +30 28210 37825; fax: +30 28210 37847. E-mail address: [email protected] (T. Tsoutsos). 0378-7788/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.enbuild.2006.07.008
any mandatory approval criteria for an eco-management scheme; surely they would be accepted as the first step on a positive environmental image of the enterprises. For this purpose methodologies have been developed, such as the XENIOS [2] and researches for energy conservation and retrofitting potential [3]. The exiting experience shows, up today, that, in order to support energy saving to the tourism sector effectively isolated promotional activities are not sufficient [4]. A new methodology should be worked out in order to take the interested party by hand, through all the stages leading up to the implementation of the system in the sector. This is particularly relevant in the hotel sector where you meet poor technically oriented staff, and you have to drain out who can receive information on energy saving applications and then follow the subject of their installation themselves according to their technical knowledge [5]. The hotel sector in Greece is highly important comprising 8689 hotel units. This number comprises 339,540 rooms and to 644,898 beds Crete has the largest Greek tourist capacity of the year 2003. Energy consumption in hotels is among the highest in the non-residential building sector in absolute values (for example, 215 kWh/(m2 a) in Italy, 287 kWh/(m2 a) in Spain,
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280 kWh/(m2 a) in Greece and 420 kWh/(m2 a) in France [6]). In this paper are presented the results of the audits in 10 hotels in Greece grouped in various star categories and hotel typologies (Mount, City and Coastal type). Furthermore, in this paper is applied the basic model of the energy flow through the hotel interface, from the various fuel intake through eight cost centers and finally down to five enduse services. In the model, indicators calculated in kWh/ns (night spent) are proposed to simulate more reliable the energy use intensity (EUI) in the hotels than the ones proposed so far [6] or usually taken in benchmarking procedures [7], expressed then in kWh/ (m2 a) or MJ/(m2 a). Same units, kWh/ns appear for the benchmarking in the EUI in wider Mediterranean hotel sector, i.e. in the Balearic hotels [8]. For the simulation of the above energy flow, a number of considerations are taken, such as the energy mix coefficient from the cost center c down to the product p, mc,p. For instance (see Table 3), the energy mix coefficient, HVAC/stay room = 0.6 means that the energy consumed in the HVAC system, yearly based, is allocated by 60% to the stay room activity. The evaluation of the simulation model is then done by matching the yearly consumed-invoiced energy, for each type of fuel, with the simulated results, integrated on yearly basis. An application of the simulation is done for a case study, the hotel Montana, a mount full year operated luxury Greek hotel. The results of the application give the specific energy indicators for the hotel. For instance, for the above hotel, one specific indicator is equal to 5.5 kWh/lunch, if 2 lunches/ns are considered.
The auditing of the energy consumption concerns three types and three star categories of the Greek hotels and it is based on data collection and analysis of the invoiced fuel and electricity. It was also based on bookkeeping, particularly related to the parameter ‘‘ns’’ of the hotel throughout the year; the reference year was 2003. The monitoring comprised the following phases:
2. Methodology
2.2. Energy cost centers. Calculation of the specific energy indicator per energy cost center
2.1. Introduction With scope to study the energy consumption indicators in the hotels of the Greek territory, we have implemented a methodology, which followed three steps: (1) Simulation of the energy flow through a typical hotel unit suggesting eight energy cost-centers inside the hotel interface and five end-user services out coming from the unit, taking into consideration benchmarking principles. In the simulation, an allocation of the energy mix down to fixed and variable cost is also assessed with calculations. (2) Audit of the energy consumption in the Greek hotels of three geographical types (Mount, City, Coastal/resort) and three star categories, based on data collection and analysis of the invoiced fuel and electricity; extracting conclusions on indicators, mainly related to average yearly based values. (3) Extraction of results by applying the above simulation in the case study of one particular hotel unit (the Montana hotel, Greece, mount type ‘‘Deluxe category’’). The matching between these results and the audition data from the step 2 yields to the identification of the values of the parameters in the simulation model.
(1) Definition of the statistical sample of hotels. (2) Development of the template for each hotel to be assessed. (3) Data collection from hotels relevant to the invoices of 2003 and related to various fuels taken in the unit and to the electricity consumed as well as to the bookkeeping (related to the ns). (4) Collection of data, control and processing; filling in of the templates. (5) Statistical analysis and calculation of energy indicators at local level (in the hotel unit) as well as at sectoral level and/ or at national level. The consideration of the critical energy parameters is from the point-of-view of the user (hotel energy manager in our case), because the authors would like: (i) to present a user friendly methodological tool, (ii) to overcome the potential differences between climate zones, especially taking about Mediterranean, (iii) to overcome the missing, often, long-term weather data. As a next step a more detailed in situ analysis could prove the accuracy of the current method.
The energy cost centers are obtained based on the existing experience of the authors to monitor the Greek hotels. A single fuel per equipment is assumed, as shown in Fig. 1a. For the equipment i (consuming fuel j), the total amount of energy Ei is calculated based on time integration: Ei ¼
X Pi PLi ti y hi
(1)
where i is the unitary equipment used in the energy cost center c (usually 1 or 2 type of equipments operate in each cost center; the electric type and the fuel fired, often gas), c the energy cost center (usually eight cost centers are considered), Pi the capacity of the equipment i, PLi the partial load factor of the equipment i, ti the operation hours of the equipment i, while PLi occurs, y the period of integration (yearly), and hi is the energy conversion efficiency of the equipment i. For the energy cost center c, is calculated the total amount of energy consumed Ec: Ec ¼
X
E i i
8 i comprised in a given c
(2)
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Fig. 1. (a) Definition of equipment i and fuel consumed j in the cost centre c. (b) Allocation of fuels and equipment i to the final service (product) p, with a discrete or a sharing mode.
Moreover, the fuel j presents overall energy consumption Ej: X E 8 c using the fuel j (3) Ej ¼ i i= j where j is the (main) fuel used for the operation of the unitary equipment i. The total energy consumption E for all type of fuels is: X X X E¼ E ¼ E ¼ E (4) c c j j i i Three specific energy indicators (per fuel, per cost center, overall) are determined as follows: Ej ej ¼ ; ns
Ec ec ¼ ; ns
E e¼ ns
(5)
where ej is the energy indicator per ns of the energy consumed (after losses) for the fuel j, ec the energy indicator per ns of the energy consumed (after losses) for the center c, e the energy indicator per ns of the overall energy consumed (after losses), and ns is the nights spent in the hotel, yearly, this value being. As shown in Section 2.4, a matching can be done between the fuel energy consumptions Ej (for various fuels) against the invoiced energy intakes for the same fuels in a given hotel unit (before losses calculation). This matching may yield to the inverse control of some parameters, i.e. the PLi applied for each equipment, etc.
the real energy consumption in the unit mainly based in terms of ‘‘how much of the energy’’ type c and for which product p is consumed. The energy mix coefficient mc,p is determined with calculations following audits of the time based operations and programation of the various departments in the hotel under study. For instance, in Table 3, we have calculated and sometimes estimated the energy mix coefficients to final products, for a specific case study. For instance (in Table 3) the VAC cost centre (ventilation and air conditioning, since heating is a different cost center) is rated during the lunches at 10%, during the bar use at 10%, during the leisure (mainly playroom and lobby) at 20% and of course during the stay room at 60%, these values been calculated. Obviously, the heating cost centre has the same mix when it is allocated to the various products. In this particular hotel, the swimming pools (for leisure activities) are heated and consume the main amount of energy in a cost centre named DHW. In there, the mc,p becomes the most important consumption coefficient, these value been calculated on audited values such as the temperature and water mass consumptions in the spa center, in the rooms, in the lounge, etc.). The energy indicator necessary for the production of the service p is equal: X mc; p Ec ep ¼ (6) c ns where c is the energy cost center (usually eight cost centers are considered), p the product or end-use service (usually five services-products are depicted), mc,p the energy mix coefficient which shows the allocation of the energy consumed in the cost center c allocated down to the specific product p, Ec the energy consumed (after losses) in the cost center c, ns the number of nights spent over the year, and ep the indicator per ns of the energy consumed (after losses) for the product p. 2.3.1. Precise the energy mix coefficient mc,p As shown in Fig. 1b, for a given end use service or product ( p), the number of the equipment, from the cost centre c, used for the production of this specific product p is: ip < i It is obvious that: X i ¼i p p Therefore, the energy consumed in the cost centre c and supplied for the production of the specific service p is calculated with the formula: X Ei ; Ei calculated according to ð1Þ i p
2.3. End-use services. Calculation of the specific energy indicator per end-use service An energy mix between energy cost center and final product must be considered. This energy mix coefficient mc,p reflects
While the overall energy consumed by the cost centre c and supplied for the production of the whole services p is calculated with the integrated formula: X E ; identical to the ð2Þ i i
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In order to precise the energy mix coefficient mc,p we apply (7) either (8), whether exists discrete or shared use of equipment, respectively. P P The fraction of i Ei to give i p Ei , in the area of a specific cost center c, is then called energy mix coefficient mc,p: P i Ei mc; p ¼ P p (7) i Ei mc; p ¼ f ðX k Þ
(8)
where Xk is the number of audited parameters such as mass flows, time schedules, temperature menus and levels, in the energy assisted processes which for the production of the products that share the equipment under question and f is a stand alone calculation dedicated for the specific process. Fig. 1b clarifies the allocation, in a given c, of fuels and equipment to products. A specific fuel (i.e. j = 2) can be met several times in various equipment. A discrete use of equipment is the case of equipment 1, 2, 3 and i, while a shared use is the case of the equipment 4.
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lobby space heating, ns1 the number of nights spent in year 1, ns2 the number of nights spent in year 2, and v j is the variable amount of the energy consumed yearly per ns (for fuel j) for running ns. This is related to the running type of energy consumptions such as stay room of clients, baths and lunches, etc. In the above system of equation [2 2], we have two unknown parameters, f j and v j , while E1j, E2j, ns1 and ns2 can be picked up from the bookkeeping and from the energy consumptions of the hotel given in templates for years 1 and 2. The solution is: 1 E1 j 1 E2 j vj ¼ 1 ns1 1 ns2 E1 j E f j ¼ 2 j 1 1
ns1 ns2 ns1 ns2
2.4. Identification of parameters Vj For fuel j, we audit the amount consumed annually in the hotel unit. This amount Ea,j is then equal:
3. Results from auditing of the energy consumption in the Greeks hotels
Ea; j ¼ V j E j
As far as the definition of the statistical sample of hotels is concerned, the analysis has been focused on 10 hotel units, which are selected so that the number of units from each type or from each hotel category is at least three (see Table 1). Lack of some data occurs for A and B category in mount type hotels, which are excluded. As far as the design of the template for the data collection is concerned, we made conversion of the amount of fuels consumed in the hotel into primary energy (see Table 2 in kWh/ ns). The end-use energy is calculated after applying conversion coefficients related to each specific fuel (in this particular hotel it was considered cos w correction furnaces installed and therefore an electricity conversion of 96% has been considered). At last, the above consumptions were divided by the ns and were concluded the energy indicators related to fuel intakes, where losses also appear. Sectoral situations are given below in terms of average values of energy consumed after conversion and extraction of losses.
(9)
where Vj is a correction factor, which corrects in Eqs. (3) and (1) the value (PLi, ti), so that the audited values equals the simulated value. If the number of fuels used in the hotel (including electricity) is three, then the number of equations [(9)] is three same as the number of the correction factors Vj. The solution of equations [(9)] relies on the assumption that we supply a single fuel per equipment (Fig. 1a). 2.5. Fixed and variable energy cost. Calculation of the specific energy indicator We assume constant value f j in function of years 1 and 2 (in kWh/a) for the fixed energy consumption, for a given fuel j. Moreover, we assume also constant value v j in function of years 1 and 2 (in kWh/ns) for the variable energy consumption, for a given fuel j. The consumption for years 1 and 2 respectively and relevant to the fuel j is equal: E1 j ¼ f j þ ns1 v j
(10)
E2 j ¼ f j þ ns2 v j
(11)
where E1j is the energy consumed for year 1 (after losses) relevant to the fuel j, E2j the energy consumed for year 2 (after losses) relevant to the fuel j, f j the intercept value of Eqs. (10) and (11) thus the fixed amount of the energy consumed yearly (for fuel j) in the case ns = 0. This is related to the energy consumptions of sharing type such as external lighting, common space and swimming pool heating of water, common and
Table 1 The statistical sample of Greek hotels Geographical type of hotel
Hotel category
Mount
Montana
City Coastal and resorts
Deluxe
A
B
Royal Olympic
Electra
Candia Olympic
Candia Maris
To Pelagos Sani beach
Marathon beach Rethymno village
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Table 2 End-use energy calculated on data collected from the Montana Hotel for year 2003 Months
Days spent (ds)
Occupancy (%)
January February March April May June July August September October November December
3740 2283 3271 2847 1305 1561 2809 3465 1510 2029 1609 3457
33.05 22.34 28.91 26.00 11.53 14.26 24.83 30.62 13.79 17.93 14.69 30.55
Energy input Conversion coefficient End use energy Losses
DHW oil (kWh)
Space heating oil (kWh)
Electrical power (kW)
Electrical (kWh)
Energy LPG (kWh)
Energy natural gas (kWh)
Total energy (kWh)
23,472.50 21,594.70 23,472.50 51,733.39 28,167.00 521.09 18,778.00 28,167.00 18,778.00 0.00 28,167.00 18,778.00
138,957.2 206,558 201,863.5 138,957.2 0 0 0 0 28,167 0 46,945 73,234.2
186.6 135.1 174.7 145.4 170.8 139.1 184.6 232.1 183.7 141.1 154.7 121.8
89,600 85,600 73,600 61,600 72,000 62,000 76,000 100,800 80,400 58,800 65,200 54,600
28,828.71 45,044.86 32,031.90 71,404.44 25,024.92 0 34,701.22 48,047.85 100,099.68 76,743.09 100,767.01 274,273.12
0 0 0 0 0 0 0 0 0 0 0 0
280,858 358,798 330,968 323,695 125,192 62,521 129,479 177,015 227,445 135,543 241,079 420,885
261,629.18 0.85 222,384.8 39,244.38
834,682.1 0.85 709,479.79 125,202.32
880,200 0.96 844,992 35,208
836,966.78 0.88 736,530.77 100,436.01
0 0.95 0 0
DHW oil consumption Heating oil consumption Electricity consumption LPG consumption Natural gas consumption Losses
7.44 23.74 28.27 24.64 0 10.04
kWh/ns kWh/ns kWh/ns kWh/ns
Total consumption
94.14
kWh/ns
kWh/ns
3.1. Auditing of the energy consumption in the category ‘‘Deluxe’’ hotels
3.3. Monitoring of the energy consumption in the category ‘‘B’’ hotels
The average value of the energy consumed in the ‘‘Deluxe’’ category hotels monitored following the above procedure and its allocation down to the various fuels is shown in Fig. 2a. In the figure was observed a total energy consumption equal to 68.15 kWh/ns. This average is based on the following figures:
The average value of the energy consumed in the ‘‘B’’ category hotels monitored following the above procedure and its allocation down to the various fuels used is shown in Fig. 2c. In this figure, we observe a total energy consumption equal to 17.59 kWh/ns. This average is based on the following figures:
Hotel Montana Royal Olympic Candia Maris
Candia Olympic Marathon beach Rethymnon village
94.14 kWh/ns 59.72 kWh/ns 50.61 kWh/ns
The electricity remains the most important energy intake, because approximately it covered 45% of the overall yearly consumption.
19.01 kWh/ns 17.48 kWh/ns 26.17 kWh/ns 7.67 kWh/ns
Again the electricity remains the most important energy intake (almost 38% of the overall yearly consumption).
3.2. Auditing of the energy consumption in the category ‘‘A’’ hotels
4. Identification of the main parameters of the energy flow through a typical hotel unit
The average value of the energy consumed in the ‘‘A’’ category hotels monitored following the above procedure and its allocation down to the various fuels used is shown in Fig. 2b. In this figure, we observe a total energy consumption equal to 41.54 kWh/ns. This average is based on the following figures:
In recent benchmarking research work, regression models for commercial buildings, climate adjusted, are proposed [9]. In our paper, an occupancy adjusted (ns = night spent), simplified regression model is tested for the Greek hotels. In this first degree model (see Section 3), the intercept value is identified as the fixed component of the energy consumption.
Hotel Electra To Pelagos Sani beach
36.28 kWh/ns 64.81 kWh/ns 23.53 kWh/ns
The electricity remains, also, the most important energy source (over 60% of the overall yearly consumption).
4.1. The energy flow model—the specific energy indicators Fig. 3 has been elaborated in order to present the physical model of the simulation to be developed. The numbers, which appear in Fig. 3, refer to a specific hotel (the Hotel Montana,
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Fig. 2. Energy indicators in the Greek hotel sector for: (a) ‘‘DELUXE’’ hotels; (b) ‘‘A category’’ hotels; (c) ‘‘B category’’ hotels.
Evritania, Greece, mount type) with full year operation; therefore, these figures are effective. In the same figure, three allocations of the energy flow are considered: The energy intakes (fuel and electricity). The energy cost centers. The end-use services. Also, two modes of the energy consumption are important to provide accuracy: (1) The fixed component of the energy consumption, for ns = 0.
(2) The variable component of the energy consumption, for effective running ns value. The energy intake comprises both the fossil fuel and the electricity, shared down to the various fuels used for the operation of the unit, in terms of kWh/ns. Losses are also calculated. 4.2. The specific energy indicators related to energy cost center The energy enters the hotel interface, where exist eight energy cost centers determined as follows:
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Fig. 3. Energy flow in hotels to end-user services.
(1) the ventilation and air conditioning component of the HVAC (VAC/HVAC), (2) the space heating component of the HVAC (H/HVAC), (3) the domestic hot water (DHW), (4) the laundry facility, (5) the catering comprising the cooking and conservation of food, (6) the shared lighting including external lighting of building, (7) the electricity consumed while room staying, including the lighting for this stay, (8) the lift.
Losses, both electrical (based on factor cos w) and thermal, are excluded from the allocation down to energy cost centers. The losses relate to the conversion efficiency of fossil fuels entering in the hotel unit as well as to the electricity conversion factor. 4.3. The specific energy indicators related to end-user service Five end-user services (or products) are considered for the simulation, and their number per ns is considered as follows:
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Table 3 The energy mix coefficients to form final products, mc,p End use service ( p)
Energy cost centre (c) VAC/HVAC
H/HVAC
DHW
Laundry
Catering
Shared lighting
Two lunches Two baths Bar use Stay room Leisure
0.10
0.10
0.20
0.10 0.60 0.20
0.20 0.15 0.05 0.60
0.90
0.10 0.60 0.20
0.05 0.15 0.05
Total
1.00
1.00
1.00
1.00
(1) One stay-room, including sleep and any remaining activity in room, per ns. (2) One leisure, including facilities (swimming pools, lobby stay, etc.), per ns. (3) Two baths, per ns. (4) Two lunches (lunch and dinner), per ns. (5) One bar use, per ns. We have also considered same number of services per ns, for instance two baths per ns are taken, two lunches per ns, etc. all year around. For the calculation of the energy per end use service, a linear allocation of the consumption per cost center down to the end use services is taken into consideration based on a calculated or audited matrix displaying the sharing of this energy flown from the cost center down to the end-user service (see Table 3, these figures being effective on audits carried out in the Hotel Montana). 4.4. The specific energy indicators related to fixed and variable energy consumption Two modes of the energy consumption seem to be important for the energy benchmarking in hotels. As fixed energy consumption we consider the component of the energy consumed which does not depend on the ns and is (almost) constant on a monthly basis throughout the year. This value is equal to the total energy consumption if ns = 0. As variable energy consumption we consider the component of the energy consumed which does depend on the ns and varies on a monthly basis throughout the year. This value is equal to zero if ns = 0.
0.60
0.10
0.15 0.05 0.60
0.70
0.30
1.00
1.00
0.10 1.00
The total energy consumption (94.14 kWh/ns) in this particular hotel is the highest ever-observed in Greece since the hotel is of mount type and it is included in the deluxe-category. Losses are of low value (equal to 10.04 kWh/ns) since LPG (with a high conversion efficiency equal to 88%) and electricity (with a conversion factor 96%) are the major part of the used fuels against to the oil also which is used (with a lower conversion efficiency of 85%). 5.2. The allocation of the energy consumption down to the primary energy fuels The result of the allocation is given in Fig. 4. In this figure, 94.14 kWh/ns are allocated down to electricity B1 (28.27 kWh/ns), LPG (24.64 kWh/ns), ‘‘DHW’’ oil (7.44 kWh/ns), space heating oil (23.74 kWh/ns) and losses (10.04 kWh/ns). 5.3. The allocation of the energy consumption down to the energy cost center As calculated in the formula (1), we took into consideration the installed capacity of the equipment related to the eight cost
5. Results of the estimation of the energy flow in a specific Greek Hotel We have applied the presented simulation model for the Hotel Montana, Greece, that has technical characteristics, type of fuel used and yearly consumptions given in Table 2. The results obtained for this particular hotel are given in the following paragraphs. 5.1. Energy flow Observing Fig. 3, we conclude that electricity is the main energy source of the hotel energy intake (oil consumption is third, mainly for space heating purposes).
Lift
0.30
0.75 1.00
Electric room
Fig. 4. Energy indicators by fuel intake in the Montana hotel.
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Fig. 5. Energy indicators by cost centre in the Montana hotel.
centers, the partial load factor, as well the (estimated) operation hours of each equipment yearly. The results of calculation are matched to the amount of the invoiced energy (various fuels) shown in the template of the hotel (Table 2). Then the results of the allocation are given in Fig. 5. We observe that space heating is the most consuming energy center presenting more than 60% of the total year consumption; this seems obvious since the hotel is mount type/luxury and therefore the heating period is large enough. Moreover, the air conditioning needs are almost inexistent and limited to the operation of some conference rooms. 5.4. The allocation of the energy consumption down to the final product (end-use service)
Fig. 6. Energy indicators by final product in the Montana hotel.
5.5. The allocation of energy consumption down to fixed and variable component As calculated with the system (10–11), we take into consideration the energy consumption of the various fuels and the bookkeeping for 2 years: 2003 and 2004. The fixed energy consumption is the energy amount to be covered by the central management and not analogue to the parameter ns. It is the value of the overall year consumption for ns = 0 and it is allocated down to the four fuels used in the hotel, at the right side of Fig. 7 (in kWh/a).
In order to allocate energy to the five end-use services in this particular hotel, we took into consideration the energy mix coefficients depicted in Table 3. The data included have been calculated on audited values in this particular hotel. The useful energy internal to the unit, which is 83.75 kWh/ ns is allocated to the end user services of the hotel (per ns) and shown in Fig. 6. It is very interesting to observe the energy consumption by final product (end-use service): the ‘‘stay room’’ absorbs almost the 40% of the overall consumption, the leisure, an important energy consuming service of this hotel, including swimming pools, stay in lobby, playroom use etc, absorbs almost 30% of the overall consumption. Moreover, it is useful to observe that in mount luxury hotels one lunch needs 5.5 kWh, a bath absorbs 1.66 kWh.
Fig. 7. Fixed energy consumption, yearly based (right side) and indicators for variable energy consumption unitary based (left side) in the Montana hotel.
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The variable energy consumption (related to the number of the effective ns/a) is allocated to the four fuels used in the hotel, at the left side of Fig. 6 (in kWh/ns and kWh/a). The fixed energy cost is of important rate (representing the 45% of the total consumption). Moreover, we observe that the fixed cost for the space heating is 110% of the variable cost for the space heating (on a year basis), a number extremely large. Nevertheless, this figure is obvious since the hotel building annexes are multiple and extended; they comprise a lot of lobbies, swimming pool spaces, play rooms and other spaces that need space heating. LPG is used mainly for the DHW, including the swimming pool waters; this is why the fixed cost of LPG is also important (40% of the variable cost LPG-yearly based). Same image for the electricity consumption: the fixed cost is 80% of the variable cost. The main centre for the fixed cost of electricity is the external lighting of the building. 6. Conclusions We have established a simplified linear model for the simulation of the energy flow and the energy consumption in Greek hotels, which aids the energy management in the hotel sector, for policy planning using benchmarking procedure. The applied simplified simulation procedure requires a high quality audit of the hotel which must support the calculation of reliable coefficients of the energy mix parameters mc,p. Therefore the usefulness of this simplified simulation strongly depends on a good audit. Nevertheless, the procedure seems to be of high reliability when comparative studies are to be made for the same hotel unit, i.e. when comparing unit operations of 2 years, operation of the various cost centers in the unit, etc. For the specific hotel under study (hotel Montana) we conclude that: (1) Electricity is the main energy source for the hotel (LPG is second, used mainly for water heating purposes). The total energy consumption (94.14 kWh/ns) in this particular hotel is the highest ever observed in Greece: mount type deluxecategory. (2) Losses (10.39 kWh/ns) are of low rate when compared to other hotels. The reason for this is that the energy mix comprises fuels with high-energy conversion coefficients. (3) The space heating is the most important energy cost center, consuming more than 60% of the energy used. (4) The stay room is the most energy consuming end-use service (or product) with more than 40% of the energy used (leisure is second). (5) A lunch in a deluxe category hotel in Greece absorbs 5.5 kWh/lunch. (6) A bath in a deluxe category hotel in Greece absorbs 1.66 kWh/bath. Moreover, in these figures, the fixed energy cost is of important rate (representing the 45% of the total consumption). More specifically, for the space heating, we observe that the
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fixed annual cost is 110% of the variable annual cost, a number extremely large. A same image is observed for the electricity consumption: the fixed annual cost is 80% of the variable annual cost. The main cost centre for the fixed cost of electricity is the external lighting of the building. Following the above results, we observe that a lunch in a deluxe category hotel in Greece absorbs 5.5 kWh/lunch, in which 2.47 kWh/lunch come from overhead costs (fixed energy costs). As a next step for the above analysis could be: (1) the application of the above model for hotel categories and hotel geographical typologies other than deluxe-mountain which is delt within this paper; (2) the calculation of the energy mix in each final product (i.e. the quantity of fuels used for each lunch, etc.); (3) the further analysis of the energy mix coefficients mc,p between cost centers and final product which depend on the operation schedules of the various cost centers, on the type of facility in which the service is given, etc.; (4) the support to existing software tools for the energy consumption in hotels [2,10]; (5) the implementation in the sector of a synthetic approach by using also renewable energy applications, such as the solar cooling ones, which have been already adopted by several Mediterranean hotels [11]. References [1] M. Karagiorgas, T. Tsoutsos, R. Berkmann, A strategic market development of the solar thermal sector in Europe. Results from the PHILOSOL project, Energy Conversion and Management 44 (11) (2003) 1885– 1901. [2] E. Dascalaki, C. Balaras, XENIOS—a methodology for assessing refurbishment scenarios and the potential of application of RES and RUE in hotels, Energy and Buildings 36 (11) (2004) 1091–1105. [3] M. Santamouris, C.A. Balaras, E. Dascalaki, A. Argiriou, A. Gaglia, Energy conservation and retrofitting potential in Hellenic hotels, Energy and Buildings 24 (1996) 65–75. [4] M. Karagiorgas, V. Drosou, T. Tsoutsos, Solar Energy, RES for the Tourism Sector, International Conference on RES for Island: RES and RUE for Islands, Sustainable Energy Solutions, Larnaka (Cyprus), 30–31 August, 2004. [5] M. Karagiorgas, T. Tsoutsos, V. Drosou, S. Pouffary, T. Pagano, G. Lopez Lara, J. M. Melim Mendes, HOTRES: renewable energies in the hotels. An extensive technical support for the hotel industry, Renewable and Sustainable Energy Reviews, in press. [6] A.A. Argiriou, C.A. Balaras, E. Dascalaki, A. Gaglia, G. Gountelas, K. Moustris, M. Santamouris, M. Vallindras, Energy audits in public and commercial buildings in Greece, in: Proceedings of the third European symposium on soft’ energy action at the local level, Chios (Hellas), 11–14 September, 1991. [7] T. Sharp, Energy benchmarking in commercial-office buildings, in: Proceedings of the ACEEE 1996 summer study on energy efficiency in buildings, vol. 4, 1996, pp. 321–329. [8] A. Moia´-Pol, Michaelis Karagiorgas, D. Coll-Mayor, V. Martı´nez-Moll, Carles Riba-Romeva, Evaluation of the Energy Consumption in Mediterranean islands Hotels: Case study the Balearic Islands Hotels, ICREPQ 2005 Congress, Spain. [9] W. Chung, Y.V. Hui, Y. Miu Lam, Benchmarking the energy efficiency of commercial buildings, Applied Energy, in press.
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[10] F. Flourenztou, J.L. Genre, C.-A. Roulet, TOBUS software-an interactive decision aid tool for building retrofit studies, Energy and Buildings 34 (2002) 193–202. [11] T. Tsoutsos, J. Anagnostou, C. Pritchard, M. Karagiorgas, D. Agoris, Solar cooling technologies in Greece, Applied Thermal Engineering 23 (2003) 1427–1439.
Glossary and abbreviations B1: electrical energy tarification rate (s/kWh) DHW: domestic hot water ‘‘DHW’’ oil: the oil used to produce DHW has higher price than the one used SH EU: European union
EUI: energy use intensity G22: electrical energy tarification rate (s/kWh) H/HVAC: heating component of the HVAC HVAC: heating, ventilation and air conditioning LPG: liquefied natural gas ns: nights spent RET: renewable energy technology SH: space heating ‘‘space heating’’ oil: the oil used to produce SH with lower price than the one used for DHW stay room: the service of the hotel including sleep, staying in the room etc. VAC/HVAC: ventilation and air conditioning component of the HVAC
A simulation of the energy consumption monitoring in Mediterranean hotels Application in Greece Michaelis Karagiorgas a, Theocharis Tsoutsos b,*, A. Moia´-Pol c a Mechanical Engineering Department, ASPETE Faculty of Pedagogical Engineers, 14121 N. Iraklio, Greece Environmental Engineering Department, Technical University of Crete, Kounoupidiana Campus, Chania, GR 73100, Greece c Department of Physics, Mechanical Engineering Area, University of Balearic Islands, Ctra. Valldemossa km. 7.5, 07122 Balearic Islands, Spain b
Received 10 October 2005; received in revised form 4 July 2006; accepted 17 July 2006
Abstract Due to the competitiveness the importance of reducing cost and the growing sensitivity to environmental factors in the hotel design, is leading to the introduction of environmental friendly elements; if will be added the considerable increase in the cost of fossil fuel, it is obvious that all these factors create conditions favorable to the optimization of energy resources. In this paper are presented the results of audits, in the form of specific energy indicators, in 10 hotels in Greece grouped to various star categories and hotel typologies (Mount, City and Coastal type). Furthermore, in this paper is applied a basic model of the energy flow through the hotel interface starting from the various fuel input, through eight cost centers and finally down to five end-use services. The basic model is based on the energy mix matrix, which relates the cost centers (facilities) to the final services. As an example of result, a specific energy consumption of 5.5 kWh/lunch is found in a deluxe Greek hotel. # 2006 Elsevier B.V. All rights reserved. Keywords: Energy indicators; Energy saving; Hotels; Monitoring; Energy consumption
1. The potential for energy saving applications in the hotel sector Nowadays the tourism policy in national, European and international level is aiming at the improvement of the existing infrastructure, the lengthening of the operating period, the encouragement of alternative forms of tourism (i.e. ecotourism, health tourism, etc.) but, always putting emphasis on environmental matters [1]. EU strongly encourages the environmental performance of services and products. Additionally the public awareness and the demand of the tourism product continuously require more environmental friendly services. The adoption of energy saving applications in current hotel units shall give them a comparative advantage of environmental performance. Considering any forthcoming EU eco-labeling scheme in the hotel sector, any energy saving application would be considered a surplus advantage for hoteliers to participate in. Even though renewable energy technology (RET) applications would not be involved in
* Corresponding author. Tel.: +30 28210 37825; fax: +30 28210 37847. E-mail address: [email protected] (T. Tsoutsos). 0378-7788/$ – see front matter # 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.enbuild.2006.07.008
any mandatory approval criteria for an eco-management scheme; surely they would be accepted as the first step on a positive environmental image of the enterprises. For this purpose methodologies have been developed, such as the XENIOS [2] and researches for energy conservation and retrofitting potential [3]. The exiting experience shows, up today, that, in order to support energy saving to the tourism sector effectively isolated promotional activities are not sufficient [4]. A new methodology should be worked out in order to take the interested party by hand, through all the stages leading up to the implementation of the system in the sector. This is particularly relevant in the hotel sector where you meet poor technically oriented staff, and you have to drain out who can receive information on energy saving applications and then follow the subject of their installation themselves according to their technical knowledge [5]. The hotel sector in Greece is highly important comprising 8689 hotel units. This number comprises 339,540 rooms and to 644,898 beds Crete has the largest Greek tourist capacity of the year 2003. Energy consumption in hotels is among the highest in the non-residential building sector in absolute values (for example, 215 kWh/(m2 a) in Italy, 287 kWh/(m2 a) in Spain,
M. Karagiorgas et al. / Energy and Buildings 39 (2007) 416–426
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280 kWh/(m2 a) in Greece and 420 kWh/(m2 a) in France [6]). In this paper are presented the results of the audits in 10 hotels in Greece grouped in various star categories and hotel typologies (Mount, City and Coastal type). Furthermore, in this paper is applied the basic model of the energy flow through the hotel interface, from the various fuel intake through eight cost centers and finally down to five enduse services. In the model, indicators calculated in kWh/ns (night spent) are proposed to simulate more reliable the energy use intensity (EUI) in the hotels than the ones proposed so far [6] or usually taken in benchmarking procedures [7], expressed then in kWh/ (m2 a) or MJ/(m2 a). Same units, kWh/ns appear for the benchmarking in the EUI in wider Mediterranean hotel sector, i.e. in the Balearic hotels [8]. For the simulation of the above energy flow, a number of considerations are taken, such as the energy mix coefficient from the cost center c down to the product p, mc,p. For instance (see Table 3), the energy mix coefficient, HVAC/stay room = 0.6 means that the energy consumed in the HVAC system, yearly based, is allocated by 60% to the stay room activity. The evaluation of the simulation model is then done by matching the yearly consumed-invoiced energy, for each type of fuel, with the simulated results, integrated on yearly basis. An application of the simulation is done for a case study, the hotel Montana, a mount full year operated luxury Greek hotel. The results of the application give the specific energy indicators for the hotel. For instance, for the above hotel, one specific indicator is equal to 5.5 kWh/lunch, if 2 lunches/ns are considered.
The auditing of the energy consumption concerns three types and three star categories of the Greek hotels and it is based on data collection and analysis of the invoiced fuel and electricity. It was also based on bookkeeping, particularly related to the parameter ‘‘ns’’ of the hotel throughout the year; the reference year was 2003. The monitoring comprised the following phases:
2. Methodology
2.2. Energy cost centers. Calculation of the specific energy indicator per energy cost center
2.1. Introduction With scope to study the energy consumption indicators in the hotels of the Greek territory, we have implemented a methodology, which followed three steps: (1) Simulation of the energy flow through a typical hotel unit suggesting eight energy cost-centers inside the hotel interface and five end-user services out coming from the unit, taking into consideration benchmarking principles. In the simulation, an allocation of the energy mix down to fixed and variable cost is also assessed with calculations. (2) Audit of the energy consumption in the Greek hotels of three geographical types (Mount, City, Coastal/resort) and three star categories, based on data collection and analysis of the invoiced fuel and electricity; extracting conclusions on indicators, mainly related to average yearly based values. (3) Extraction of results by applying the above simulation in the case study of one particular hotel unit (the Montana hotel, Greece, mount type ‘‘Deluxe category’’). The matching between these results and the audition data from the step 2 yields to the identification of the values of the parameters in the simulation model.
(1) Definition of the statistical sample of hotels. (2) Development of the template for each hotel to be assessed. (3) Data collection from hotels relevant to the invoices of 2003 and related to various fuels taken in the unit and to the electricity consumed as well as to the bookkeeping (related to the ns). (4) Collection of data, control and processing; filling in of the templates. (5) Statistical analysis and calculation of energy indicators at local level (in the hotel unit) as well as at sectoral level and/ or at national level. The consideration of the critical energy parameters is from the point-of-view of the user (hotel energy manager in our case), because the authors would like: (i) to present a user friendly methodological tool, (ii) to overcome the potential differences between climate zones, especially taking about Mediterranean, (iii) to overcome the missing, often, long-term weather data. As a next step a more detailed in situ analysis could prove the accuracy of the current method.
The energy cost centers are obtained based on the existing experience of the authors to monitor the Greek hotels. A single fuel per equipment is assumed, as shown in Fig. 1a. For the equipment i (consuming fuel j), the total amount of energy Ei is calculated based on time integration: Ei ¼
X Pi PLi ti y hi
(1)
where i is the unitary equipment used in the energy cost center c (usually 1 or 2 type of equipments operate in each cost center; the electric type and the fuel fired, often gas), c the energy cost center (usually eight cost centers are considered), Pi the capacity of the equipment i, PLi the partial load factor of the equipment i, ti the operation hours of the equipment i, while PLi occurs, y the period of integration (yearly), and hi is the energy conversion efficiency of the equipment i. For the energy cost center c, is calculated the total amount of energy consumed Ec: Ec ¼
X
E i i
8 i comprised in a given c
(2)
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Fig. 1. (a) Definition of equipment i and fuel consumed j in the cost centre c. (b) Allocation of fuels and equipment i to the final service (product) p, with a discrete or a sharing mode.
Moreover, the fuel j presents overall energy consumption Ej: X E 8 c using the fuel j (3) Ej ¼ i i= j where j is the (main) fuel used for the operation of the unitary equipment i. The total energy consumption E for all type of fuels is: X X X E¼ E ¼ E ¼ E (4) c c j j i i Three specific energy indicators (per fuel, per cost center, overall) are determined as follows: Ej ej ¼ ; ns
Ec ec ¼ ; ns
E e¼ ns
(5)
where ej is the energy indicator per ns of the energy consumed (after losses) for the fuel j, ec the energy indicator per ns of the energy consumed (after losses) for the center c, e the energy indicator per ns of the overall energy consumed (after losses), and ns is the nights spent in the hotel, yearly, this value being. As shown in Section 2.4, a matching can be done between the fuel energy consumptions Ej (for various fuels) against the invoiced energy intakes for the same fuels in a given hotel unit (before losses calculation). This matching may yield to the inverse control of some parameters, i.e. the PLi applied for each equipment, etc.
the real energy consumption in the unit mainly based in terms of ‘‘how much of the energy’’ type c and for which product p is consumed. The energy mix coefficient mc,p is determined with calculations following audits of the time based operations and programation of the various departments in the hotel under study. For instance, in Table 3, we have calculated and sometimes estimated the energy mix coefficients to final products, for a specific case study. For instance (in Table 3) the VAC cost centre (ventilation and air conditioning, since heating is a different cost center) is rated during the lunches at 10%, during the bar use at 10%, during the leisure (mainly playroom and lobby) at 20% and of course during the stay room at 60%, these values been calculated. Obviously, the heating cost centre has the same mix when it is allocated to the various products. In this particular hotel, the swimming pools (for leisure activities) are heated and consume the main amount of energy in a cost centre named DHW. In there, the mc,p becomes the most important consumption coefficient, these value been calculated on audited values such as the temperature and water mass consumptions in the spa center, in the rooms, in the lounge, etc.). The energy indicator necessary for the production of the service p is equal: X mc; p Ec ep ¼ (6) c ns where c is the energy cost center (usually eight cost centers are considered), p the product or end-use service (usually five services-products are depicted), mc,p the energy mix coefficient which shows the allocation of the energy consumed in the cost center c allocated down to the specific product p, Ec the energy consumed (after losses) in the cost center c, ns the number of nights spent over the year, and ep the indicator per ns of the energy consumed (after losses) for the product p. 2.3.1. Precise the energy mix coefficient mc,p As shown in Fig. 1b, for a given end use service or product ( p), the number of the equipment, from the cost centre c, used for the production of this specific product p is: ip < i It is obvious that: X i ¼i p p Therefore, the energy consumed in the cost centre c and supplied for the production of the specific service p is calculated with the formula: X Ei ; Ei calculated according to ð1Þ i p
2.3. End-use services. Calculation of the specific energy indicator per end-use service An energy mix between energy cost center and final product must be considered. This energy mix coefficient mc,p reflects
While the overall energy consumed by the cost centre c and supplied for the production of the whole services p is calculated with the integrated formula: X E ; identical to the ð2Þ i i
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In order to precise the energy mix coefficient mc,p we apply (7) either (8), whether exists discrete or shared use of equipment, respectively. P P The fraction of i Ei to give i p Ei , in the area of a specific cost center c, is then called energy mix coefficient mc,p: P i Ei mc; p ¼ P p (7) i Ei mc; p ¼ f ðX k Þ
(8)
where Xk is the number of audited parameters such as mass flows, time schedules, temperature menus and levels, in the energy assisted processes which for the production of the products that share the equipment under question and f is a stand alone calculation dedicated for the specific process. Fig. 1b clarifies the allocation, in a given c, of fuels and equipment to products. A specific fuel (i.e. j = 2) can be met several times in various equipment. A discrete use of equipment is the case of equipment 1, 2, 3 and i, while a shared use is the case of the equipment 4.
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lobby space heating, ns1 the number of nights spent in year 1, ns2 the number of nights spent in year 2, and v j is the variable amount of the energy consumed yearly per ns (for fuel j) for running ns. This is related to the running type of energy consumptions such as stay room of clients, baths and lunches, etc. In the above system of equation [2 2], we have two unknown parameters, f j and v j , while E1j, E2j, ns1 and ns2 can be picked up from the bookkeeping and from the energy consumptions of the hotel given in templates for years 1 and 2. The solution is: 1 E1 j 1 E2 j vj ¼ 1 ns1 1 ns2 E1 j E f j ¼ 2 j 1 1
ns1 ns2 ns1 ns2
2.4. Identification of parameters Vj For fuel j, we audit the amount consumed annually in the hotel unit. This amount Ea,j is then equal:
3. Results from auditing of the energy consumption in the Greeks hotels
Ea; j ¼ V j E j
As far as the definition of the statistical sample of hotels is concerned, the analysis has been focused on 10 hotel units, which are selected so that the number of units from each type or from each hotel category is at least three (see Table 1). Lack of some data occurs for A and B category in mount type hotels, which are excluded. As far as the design of the template for the data collection is concerned, we made conversion of the amount of fuels consumed in the hotel into primary energy (see Table 2 in kWh/ ns). The end-use energy is calculated after applying conversion coefficients related to each specific fuel (in this particular hotel it was considered cos w correction furnaces installed and therefore an electricity conversion of 96% has been considered). At last, the above consumptions were divided by the ns and were concluded the energy indicators related to fuel intakes, where losses also appear. Sectoral situations are given below in terms of average values of energy consumed after conversion and extraction of losses.
(9)
where Vj is a correction factor, which corrects in Eqs. (3) and (1) the value (PLi, ti), so that the audited values equals the simulated value. If the number of fuels used in the hotel (including electricity) is three, then the number of equations [(9)] is three same as the number of the correction factors Vj. The solution of equations [(9)] relies on the assumption that we supply a single fuel per equipment (Fig. 1a). 2.5. Fixed and variable energy cost. Calculation of the specific energy indicator We assume constant value f j in function of years 1 and 2 (in kWh/a) for the fixed energy consumption, for a given fuel j. Moreover, we assume also constant value v j in function of years 1 and 2 (in kWh/ns) for the variable energy consumption, for a given fuel j. The consumption for years 1 and 2 respectively and relevant to the fuel j is equal: E1 j ¼ f j þ ns1 v j
(10)
E2 j ¼ f j þ ns2 v j
(11)
where E1j is the energy consumed for year 1 (after losses) relevant to the fuel j, E2j the energy consumed for year 2 (after losses) relevant to the fuel j, f j the intercept value of Eqs. (10) and (11) thus the fixed amount of the energy consumed yearly (for fuel j) in the case ns = 0. This is related to the energy consumptions of sharing type such as external lighting, common space and swimming pool heating of water, common and
Table 1 The statistical sample of Greek hotels Geographical type of hotel
Hotel category
Mount
Montana
City Coastal and resorts
Deluxe
A
B
Royal Olympic
Electra
Candia Olympic
Candia Maris
To Pelagos Sani beach
Marathon beach Rethymno village
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Table 2 End-use energy calculated on data collected from the Montana Hotel for year 2003 Months
Days spent (ds)
Occupancy (%)
January February March April May June July August September October November December
3740 2283 3271 2847 1305 1561 2809 3465 1510 2029 1609 3457
33.05 22.34 28.91 26.00 11.53 14.26 24.83 30.62 13.79 17.93 14.69 30.55
Energy input Conversion coefficient End use energy Losses
DHW oil (kWh)
Space heating oil (kWh)
Electrical power (kW)
Electrical (kWh)
Energy LPG (kWh)
Energy natural gas (kWh)
Total energy (kWh)
23,472.50 21,594.70 23,472.50 51,733.39 28,167.00 521.09 18,778.00 28,167.00 18,778.00 0.00 28,167.00 18,778.00
138,957.2 206,558 201,863.5 138,957.2 0 0 0 0 28,167 0 46,945 73,234.2
186.6 135.1 174.7 145.4 170.8 139.1 184.6 232.1 183.7 141.1 154.7 121.8
89,600 85,600 73,600 61,600 72,000 62,000 76,000 100,800 80,400 58,800 65,200 54,600
28,828.71 45,044.86 32,031.90 71,404.44 25,024.92 0 34,701.22 48,047.85 100,099.68 76,743.09 100,767.01 274,273.12
0 0 0 0 0 0 0 0 0 0 0 0
280,858 358,798 330,968 323,695 125,192 62,521 129,479 177,015 227,445 135,543 241,079 420,885
261,629.18 0.85 222,384.8 39,244.38
834,682.1 0.85 709,479.79 125,202.32
880,200 0.96 844,992 35,208
836,966.78 0.88 736,530.77 100,436.01
0 0.95 0 0
DHW oil consumption Heating oil consumption Electricity consumption LPG consumption Natural gas consumption Losses
7.44 23.74 28.27 24.64 0 10.04
kWh/ns kWh/ns kWh/ns kWh/ns
Total consumption
94.14
kWh/ns
kWh/ns
3.1. Auditing of the energy consumption in the category ‘‘Deluxe’’ hotels
3.3. Monitoring of the energy consumption in the category ‘‘B’’ hotels
The average value of the energy consumed in the ‘‘Deluxe’’ category hotels monitored following the above procedure and its allocation down to the various fuels is shown in Fig. 2a. In the figure was observed a total energy consumption equal to 68.15 kWh/ns. This average is based on the following figures:
The average value of the energy consumed in the ‘‘B’’ category hotels monitored following the above procedure and its allocation down to the various fuels used is shown in Fig. 2c. In this figure, we observe a total energy consumption equal to 17.59 kWh/ns. This average is based on the following figures:
Hotel Montana Royal Olympic Candia Maris
Candia Olympic Marathon beach Rethymnon village
94.14 kWh/ns 59.72 kWh/ns 50.61 kWh/ns
The electricity remains the most important energy intake, because approximately it covered 45% of the overall yearly consumption.
19.01 kWh/ns 17.48 kWh/ns 26.17 kWh/ns 7.67 kWh/ns
Again the electricity remains the most important energy intake (almost 38% of the overall yearly consumption).
3.2. Auditing of the energy consumption in the category ‘‘A’’ hotels
4. Identification of the main parameters of the energy flow through a typical hotel unit
The average value of the energy consumed in the ‘‘A’’ category hotels monitored following the above procedure and its allocation down to the various fuels used is shown in Fig. 2b. In this figure, we observe a total energy consumption equal to 41.54 kWh/ns. This average is based on the following figures:
In recent benchmarking research work, regression models for commercial buildings, climate adjusted, are proposed [9]. In our paper, an occupancy adjusted (ns = night spent), simplified regression model is tested for the Greek hotels. In this first degree model (see Section 3), the intercept value is identified as the fixed component of the energy consumption.
Hotel Electra To Pelagos Sani beach
36.28 kWh/ns 64.81 kWh/ns 23.53 kWh/ns
The electricity remains, also, the most important energy source (over 60% of the overall yearly consumption).
4.1. The energy flow model—the specific energy indicators Fig. 3 has been elaborated in order to present the physical model of the simulation to be developed. The numbers, which appear in Fig. 3, refer to a specific hotel (the Hotel Montana,
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Fig. 2. Energy indicators in the Greek hotel sector for: (a) ‘‘DELUXE’’ hotels; (b) ‘‘A category’’ hotels; (c) ‘‘B category’’ hotels.
Evritania, Greece, mount type) with full year operation; therefore, these figures are effective. In the same figure, three allocations of the energy flow are considered: The energy intakes (fuel and electricity). The energy cost centers. The end-use services. Also, two modes of the energy consumption are important to provide accuracy: (1) The fixed component of the energy consumption, for ns = 0.
(2) The variable component of the energy consumption, for effective running ns value. The energy intake comprises both the fossil fuel and the electricity, shared down to the various fuels used for the operation of the unit, in terms of kWh/ns. Losses are also calculated. 4.2. The specific energy indicators related to energy cost center The energy enters the hotel interface, where exist eight energy cost centers determined as follows:
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Fig. 3. Energy flow in hotels to end-user services.
(1) the ventilation and air conditioning component of the HVAC (VAC/HVAC), (2) the space heating component of the HVAC (H/HVAC), (3) the domestic hot water (DHW), (4) the laundry facility, (5) the catering comprising the cooking and conservation of food, (6) the shared lighting including external lighting of building, (7) the electricity consumed while room staying, including the lighting for this stay, (8) the lift.
Losses, both electrical (based on factor cos w) and thermal, are excluded from the allocation down to energy cost centers. The losses relate to the conversion efficiency of fossil fuels entering in the hotel unit as well as to the electricity conversion factor. 4.3. The specific energy indicators related to end-user service Five end-user services (or products) are considered for the simulation, and their number per ns is considered as follows:
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Table 3 The energy mix coefficients to form final products, mc,p End use service ( p)
Energy cost centre (c) VAC/HVAC
H/HVAC
DHW
Laundry
Catering
Shared lighting
Two lunches Two baths Bar use Stay room Leisure
0.10
0.10
0.20
0.10 0.60 0.20
0.20 0.15 0.05 0.60
0.90
0.10 0.60 0.20
0.05 0.15 0.05
Total
1.00
1.00
1.00
1.00
(1) One stay-room, including sleep and any remaining activity in room, per ns. (2) One leisure, including facilities (swimming pools, lobby stay, etc.), per ns. (3) Two baths, per ns. (4) Two lunches (lunch and dinner), per ns. (5) One bar use, per ns. We have also considered same number of services per ns, for instance two baths per ns are taken, two lunches per ns, etc. all year around. For the calculation of the energy per end use service, a linear allocation of the consumption per cost center down to the end use services is taken into consideration based on a calculated or audited matrix displaying the sharing of this energy flown from the cost center down to the end-user service (see Table 3, these figures being effective on audits carried out in the Hotel Montana). 4.4. The specific energy indicators related to fixed and variable energy consumption Two modes of the energy consumption seem to be important for the energy benchmarking in hotels. As fixed energy consumption we consider the component of the energy consumed which does not depend on the ns and is (almost) constant on a monthly basis throughout the year. This value is equal to the total energy consumption if ns = 0. As variable energy consumption we consider the component of the energy consumed which does depend on the ns and varies on a monthly basis throughout the year. This value is equal to zero if ns = 0.
0.60
0.10
0.15 0.05 0.60
0.70
0.30
1.00
1.00
0.10 1.00
The total energy consumption (94.14 kWh/ns) in this particular hotel is the highest ever-observed in Greece since the hotel is of mount type and it is included in the deluxe-category. Losses are of low value (equal to 10.04 kWh/ns) since LPG (with a high conversion efficiency equal to 88%) and electricity (with a conversion factor 96%) are the major part of the used fuels against to the oil also which is used (with a lower conversion efficiency of 85%). 5.2. The allocation of the energy consumption down to the primary energy fuels The result of the allocation is given in Fig. 4. In this figure, 94.14 kWh/ns are allocated down to electricity B1 (28.27 kWh/ns), LPG (24.64 kWh/ns), ‘‘DHW’’ oil (7.44 kWh/ns), space heating oil (23.74 kWh/ns) and losses (10.04 kWh/ns). 5.3. The allocation of the energy consumption down to the energy cost center As calculated in the formula (1), we took into consideration the installed capacity of the equipment related to the eight cost
5. Results of the estimation of the energy flow in a specific Greek Hotel We have applied the presented simulation model for the Hotel Montana, Greece, that has technical characteristics, type of fuel used and yearly consumptions given in Table 2. The results obtained for this particular hotel are given in the following paragraphs. 5.1. Energy flow Observing Fig. 3, we conclude that electricity is the main energy source of the hotel energy intake (oil consumption is third, mainly for space heating purposes).
Lift
0.30
0.75 1.00
Electric room
Fig. 4. Energy indicators by fuel intake in the Montana hotel.
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Fig. 5. Energy indicators by cost centre in the Montana hotel.
centers, the partial load factor, as well the (estimated) operation hours of each equipment yearly. The results of calculation are matched to the amount of the invoiced energy (various fuels) shown in the template of the hotel (Table 2). Then the results of the allocation are given in Fig. 5. We observe that space heating is the most consuming energy center presenting more than 60% of the total year consumption; this seems obvious since the hotel is mount type/luxury and therefore the heating period is large enough. Moreover, the air conditioning needs are almost inexistent and limited to the operation of some conference rooms. 5.4. The allocation of the energy consumption down to the final product (end-use service)
Fig. 6. Energy indicators by final product in the Montana hotel.
5.5. The allocation of energy consumption down to fixed and variable component As calculated with the system (10–11), we take into consideration the energy consumption of the various fuels and the bookkeeping for 2 years: 2003 and 2004. The fixed energy consumption is the energy amount to be covered by the central management and not analogue to the parameter ns. It is the value of the overall year consumption for ns = 0 and it is allocated down to the four fuels used in the hotel, at the right side of Fig. 7 (in kWh/a).
In order to allocate energy to the five end-use services in this particular hotel, we took into consideration the energy mix coefficients depicted in Table 3. The data included have been calculated on audited values in this particular hotel. The useful energy internal to the unit, which is 83.75 kWh/ ns is allocated to the end user services of the hotel (per ns) and shown in Fig. 6. It is very interesting to observe the energy consumption by final product (end-use service): the ‘‘stay room’’ absorbs almost the 40% of the overall consumption, the leisure, an important energy consuming service of this hotel, including swimming pools, stay in lobby, playroom use etc, absorbs almost 30% of the overall consumption. Moreover, it is useful to observe that in mount luxury hotels one lunch needs 5.5 kWh, a bath absorbs 1.66 kWh.
Fig. 7. Fixed energy consumption, yearly based (right side) and indicators for variable energy consumption unitary based (left side) in the Montana hotel.
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The variable energy consumption (related to the number of the effective ns/a) is allocated to the four fuels used in the hotel, at the left side of Fig. 6 (in kWh/ns and kWh/a). The fixed energy cost is of important rate (representing the 45% of the total consumption). Moreover, we observe that the fixed cost for the space heating is 110% of the variable cost for the space heating (on a year basis), a number extremely large. Nevertheless, this figure is obvious since the hotel building annexes are multiple and extended; they comprise a lot of lobbies, swimming pool spaces, play rooms and other spaces that need space heating. LPG is used mainly for the DHW, including the swimming pool waters; this is why the fixed cost of LPG is also important (40% of the variable cost LPG-yearly based). Same image for the electricity consumption: the fixed cost is 80% of the variable cost. The main centre for the fixed cost of electricity is the external lighting of the building. 6. Conclusions We have established a simplified linear model for the simulation of the energy flow and the energy consumption in Greek hotels, which aids the energy management in the hotel sector, for policy planning using benchmarking procedure. The applied simplified simulation procedure requires a high quality audit of the hotel which must support the calculation of reliable coefficients of the energy mix parameters mc,p. Therefore the usefulness of this simplified simulation strongly depends on a good audit. Nevertheless, the procedure seems to be of high reliability when comparative studies are to be made for the same hotel unit, i.e. when comparing unit operations of 2 years, operation of the various cost centers in the unit, etc. For the specific hotel under study (hotel Montana) we conclude that: (1) Electricity is the main energy source for the hotel (LPG is second, used mainly for water heating purposes). The total energy consumption (94.14 kWh/ns) in this particular hotel is the highest ever observed in Greece: mount type deluxecategory. (2) Losses (10.39 kWh/ns) are of low rate when compared to other hotels. The reason for this is that the energy mix comprises fuels with high-energy conversion coefficients. (3) The space heating is the most important energy cost center, consuming more than 60% of the energy used. (4) The stay room is the most energy consuming end-use service (or product) with more than 40% of the energy used (leisure is second). (5) A lunch in a deluxe category hotel in Greece absorbs 5.5 kWh/lunch. (6) A bath in a deluxe category hotel in Greece absorbs 1.66 kWh/bath. Moreover, in these figures, the fixed energy cost is of important rate (representing the 45% of the total consumption). More specifically, for the space heating, we observe that the
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fixed annual cost is 110% of the variable annual cost, a number extremely large. A same image is observed for the electricity consumption: the fixed annual cost is 80% of the variable annual cost. The main cost centre for the fixed cost of electricity is the external lighting of the building. Following the above results, we observe that a lunch in a deluxe category hotel in Greece absorbs 5.5 kWh/lunch, in which 2.47 kWh/lunch come from overhead costs (fixed energy costs). As a next step for the above analysis could be: (1) the application of the above model for hotel categories and hotel geographical typologies other than deluxe-mountain which is delt within this paper; (2) the calculation of the energy mix in each final product (i.e. the quantity of fuels used for each lunch, etc.); (3) the further analysis of the energy mix coefficients mc,p between cost centers and final product which depend on the operation schedules of the various cost centers, on the type of facility in which the service is given, etc.; (4) the support to existing software tools for the energy consumption in hotels [2,10]; (5) the implementation in the sector of a synthetic approach by using also renewable energy applications, such as the solar cooling ones, which have been already adopted by several Mediterranean hotels [11]. References [1] M. Karagiorgas, T. Tsoutsos, R. Berkmann, A strategic market development of the solar thermal sector in Europe. Results from the PHILOSOL project, Energy Conversion and Management 44 (11) (2003) 1885– 1901. [2] E. Dascalaki, C. Balaras, XENIOS—a methodology for assessing refurbishment scenarios and the potential of application of RES and RUE in hotels, Energy and Buildings 36 (11) (2004) 1091–1105. [3] M. Santamouris, C.A. Balaras, E. Dascalaki, A. Argiriou, A. Gaglia, Energy conservation and retrofitting potential in Hellenic hotels, Energy and Buildings 24 (1996) 65–75. [4] M. Karagiorgas, V. Drosou, T. Tsoutsos, Solar Energy, RES for the Tourism Sector, International Conference on RES for Island: RES and RUE for Islands, Sustainable Energy Solutions, Larnaka (Cyprus), 30–31 August, 2004. [5] M. Karagiorgas, T. Tsoutsos, V. Drosou, S. Pouffary, T. Pagano, G. Lopez Lara, J. M. Melim Mendes, HOTRES: renewable energies in the hotels. An extensive technical support for the hotel industry, Renewable and Sustainable Energy Reviews, in press. [6] A.A. Argiriou, C.A. Balaras, E. Dascalaki, A. Gaglia, G. Gountelas, K. Moustris, M. Santamouris, M. Vallindras, Energy audits in public and commercial buildings in Greece, in: Proceedings of the third European symposium on soft’ energy action at the local level, Chios (Hellas), 11–14 September, 1991. [7] T. Sharp, Energy benchmarking in commercial-office buildings, in: Proceedings of the ACEEE 1996 summer study on energy efficiency in buildings, vol. 4, 1996, pp. 321–329. [8] A. Moia´-Pol, Michaelis Karagiorgas, D. Coll-Mayor, V. Martı´nez-Moll, Carles Riba-Romeva, Evaluation of the Energy Consumption in Mediterranean islands Hotels: Case study the Balearic Islands Hotels, ICREPQ 2005 Congress, Spain. [9] W. Chung, Y.V. Hui, Y. Miu Lam, Benchmarking the energy efficiency of commercial buildings, Applied Energy, in press.
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[10] F. Flourenztou, J.L. Genre, C.-A. Roulet, TOBUS software-an interactive decision aid tool for building retrofit studies, Energy and Buildings 34 (2002) 193–202. [11] T. Tsoutsos, J. Anagnostou, C. Pritchard, M. Karagiorgas, D. Agoris, Solar cooling technologies in Greece, Applied Thermal Engineering 23 (2003) 1427–1439.
Glossary and abbreviations B1: electrical energy tarification rate (s/kWh) DHW: domestic hot water ‘‘DHW’’ oil: the oil used to produce DHW has higher price than the one used SH EU: European union
EUI: energy use intensity G22: electrical energy tarification rate (s/kWh) H/HVAC: heating component of the HVAC HVAC: heating, ventilation and air conditioning LPG: liquefied natural gas ns: nights spent RET: renewable energy technology SH: space heating ‘‘space heating’’ oil: the oil used to produce SH with lower price than the one used for DHW stay room: the service of the hotel including sleep, staying in the room etc. VAC/HVAC: ventilation and air conditioning component of the HVAC