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A global approach of indoor environment in an air-conditioned office room
ARTICLE IN PRESS
Building and Environment 40 (2005) 29–37 www.elsevier.com/locate/buildenv
A global approach of indoor environment in an air-conditioned office room Emmanuel Rutmana, Christian Inardb,, Andre´ Baillya, Francis Allardb a
CIAT Research and Development Center, Culoz, France LEPTAB, University of la Rochelle, La Rochelle, France
b
Received 6 January 2003; received in revised form 20 February 2004; accepted 20 May 2004
Abstract This study presents a multi-criteria method used for analysing the quality of an air-conditioned indoor environment. Indoor air flow induced by an actual Heating Ventilation and Air Conditioning system was experimentally studied under various conditions. The attention was focused on thermal comfort, acoustical comfort and indoor air distribution by considering spatial statistic studies of comfort indices. The compounded electric power of fan, compressor and pumps was measured in order to get information about energy consumption. A first analysis of these parameters showed that indoor comfort cannot be described by a general law. Thus, to reach the objective of a global approach of comfort by a spatial statistical study of the various discomforts, a multi-criteria analysis based on ELECTRE II method adapted to the comfort of air-conditioned indoor environment was applied. In this way the operating rules for coherent air conditioning systems can be defined, with a requirement for quality of indoor environment. r 2004 Elsevier Ltd. All rights reserved. Keywords: Thermal comfort; Acoustical comfort; Air-conditioned; Building; Multi-criteria analysis
1. Introduction Since 1973 and the first fuel shortage, the French government has conducted actions for a reduction of building energy consumption. First, building actors worked on insulation, then on equipment energy consumption reduction. In the last 10 years, the CIAT laboratory staff has been working on indoor environment quality in accordance with the European and international preoccupations. Fanger [1] showed that the occupants of offices are submitted to various local discomforts, due to temperature, draft and noise. In order to improve comfort, different types of HVAC systems can be applied. Rutman [2] carried out an experimental work to link the cold air jet characteristics and a global approach of comfort, which takes into account thermal and acoustical comforts. Furthermore, Corresponding author. Fax: +33-5-46-45-82-41.
E-mail address: [email protected] (C. Inard). 0360-1323/$ - see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2004.05.006
Rutman et al. [3] showed that the comfort criteria such as the PPD, DR, NR and ADPI indices do not vary in the same way with Archimede’s number as reference. Thus, PPD index and ADPI index increase as NR level and DR index decrease. Lastly, they pointed out the difficulties of improving local comfort with occupants. In another way, many building designers use the multicriteria analysis in their results [4] and some authors [5,6] have started using these tools to improve the ventilation of buildings. That is why, a multi-criteria method has been used to analyse the experimental results in this study.
2. Methodology and test conditions The measurements [2] were carried out in the CIAT’s laboratory located in Culoz, France. The longitudinal section of the experimental test chamber is shown in Fig. 1. The volume was equal to 5:2 4:0 2:5 m3
ARTICLE IN PRESS E. Rutman et al. / Building and Environment 40 (2005) 29–37
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Nomenclature A0 ADPI aij Ar0 C AC1 C AC2 C AI C EC ck C max C min C moy C TH1 C TH2 C TH3 C TH4 C TH5
supply area, m2 Air Diffusion Performance Index actions with i ¼ unit 1 or unit 2 and j ¼ 1; 2; 3; 4; 5 or 6 inlet Archimede’s number acoustical criteria No. 1 acoustical criteria No. 2 air diffusion performance criteria economical criteria concordance indices (k ¼ 1; 2 or 3) maximum of concordance indices minimum of concordance indices average of concordance indices thermal criteria No. 1 for the DR thermal criteria No. 2 for the DR thermal criteria No. 3 for the DR thermal criteria No. 1 for the PPD thermal criteria No. 2 for the PPD
bounded on five sides by air volume controlled at a constant temperature level. The sixth side is submitted to the influence of a climatic housing, where external air temperature can be simulated. For the present experiments, the value of external temperature was set at þ30 C. Real internal heat loads were simulated with a computer and two dummies. These thermal heat loads were balanced by a fan-coil unit mounted on the ceiling. Two fan-coil units, unit 1 and unit 2, were tested as shown in Figs. 1 and 2. For each unit, six tests with various supply conditions were carried out including two mechanical configurations of the fan-coil unit. For unit 1, the air jet had one supply direction (mechanical parameter 1) or three directions for the airflow (mechanical parameter 2). For unit 2, the direction of the jet was toward the ceiling (mechanical parameter 1) then toward the floor (mechanical parameter 2). In all the tests, the cold water temperature level was constant ð6 C=12 CÞ and it was possible to select five air flow rates. In order to study the overall band of the air flow rate, the tests were carried out with three air flow rate values (low, medium and high) and the two mechanical parameters for each unit. For all the tests, the operative temperature in the occupied zone was equal to 24:5 1:5 C. Tables 1 and 2 give the parameters used for the experiments. The air velocity, the relative intensity of velocity turbulence, and temperature in the occupied zone of the room were measured with a thermoanemometric sensor (type DANTEC 54T21) placed at 76 different locations in the occupied zone. Vertical test points were located from the floor at 0.1 m for the feet, 0.6 m for the hips, 1.1 m for the head of an occupant in the sitting position and 1.7 m for the head of
dk DR I LT lo NR Pe PPD Q0 Re0 SO T0 DT 0 U0
discordance indices (k ¼ 1 or 2) draft rating incomparability thermal length, m low outclass noise rating electrical power, W predicted percentage of dissatisfied, % air flow rate, m3 h1 initial Reynolds number strong outclass inlet air temperature, C inlet excess temperature, C inlet air velocity, m s1
Greek letters m r
viscosity, kg m1 s1 density, kg m3
an occupant standing up [7]. This probe calibrated by DANTEC, is characterized by a precision of 0:02 m=s for the air velocity and 0:2 C for the air temperature. The inner wall surface temperatures were measured with thermocouples type K calibrated with a precision of 0:25 C at the CIAT laboratory. The acoustical level was measured with a microphone sensor with a precision of 3 dB type Bruel & Kjaer 4189 and a frequency analyser type Kontron FFT-AD3524. To calibrate the microphone, a pistonphone type Bruel & Kjaer 4231 was used. For the acoustical measurements, the probe was placed at 36 different locations in the occupied zone. 2 Archimede’s number, Ar0 ¼ gb DT 0 A0:5 0 =U 0 , Rey0:5 nolds number Re0 ¼ rU 0 A0 =m and thermal length LT ¼ ðA0 =Ar0 Þ0:5 [8] define the supply conditions. The square root of the supply area A0 was used because the ratio effective length ðl 0 Þ/effective width (h0 ) is equal to 13 for unit 1 and more than 4 for unit 2. So in accordance with Rajaratnam [9], these values are characteristic of a three-dimensional jet. The mean value of the inlet temperature T 0 was measured with a Newport Omega, 0.051 mm diameter, K-type thermocouple calibrated with a precision of 0:25 C at the CIAT laboratory. For the velocity U 0 , a Dantec laser doppler anemometer unidirectional system was used.
3. Experimental test results The main results presented here consist in the spatial statistical studies of comfort indices and energy consumption.
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Fan-coil unit1 Unit1 Climatic guard T = +25 ˚C Climatic Housing T =+ 30 ˚C
Dummies
Lights
One supply direction
2.5 m
Computer on table
Unit1
Climatic guard T =+ 25 ˚C Three supply directions
5.2 m
Fig. 1. Longitudinal section of the test cell and unit 1.
Fan-coil unit2 Climatic guard T = +25 ˚C Climatic Housing T =+ 30 ˚C
Unit2
Dummies
Lights
Toward the floor
2.5 m
Computer on table
Toward the ceiling
Climatic guard T =+ 25 ˚C 5.2 m
Fig. 2. Longitudinal section of the test cell and unit 2.
Table 1 Experimental conditions for unit 1 Test No.
Number of supply directions
Q0 ðm3 =hÞ
U0 (m/s)
T0 ð CÞ
1 2 3 4 5 6
1 1 1 3 3 3
732 537 366 722 532 366
5.5 4.5 3.0 5.6 4.2 2.9
14.1 11.0 12.5 11.8 12.1 11.5
DT 0 ð CÞ 9.1 12.5 12.1 11.8 12.7 13.5
Ar0 ð103 Þ
Re0
LT (m)
0.91 1.87 4.05 1.14 2.17 4.85
30517 24969 16646 31072 23304 16091
5.7 3.9 2.7 5.0 3.7 2.4
Table 2 Experimental conditions for unit 2 Test No.
Supply direction to
Q0 ðm3 =hÞ
U0 (m/s)
T0 ð CÞ
DT 0 ð CÞ
Ar0 ð103 Þ
Re0
LT (m)
7 8 9 10 11 12
Ceiling Ceiling Ceiling Floor Floor Floor
684 623 570 725 623 560
5.8 5.2 4.7 5.6 5.1 4.2
15.6 16.3 16.3 14.5 14.1 14.5
8.5 7.8 8.4 9.1 9.3 10.2
0.97 1.08 1.44 1.64 2.07 3.27
41050 37063 33240 58620 52887 44090
3.6 3.4 2.9 4.1 3.6 2.9
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3.1. Acoustical comfort The assessment of acoustical comfort was made using the Noise Rating (NR) index. This index came from the Beraneck [10] experimental studies. The author produced a network of curves called Noise Criteria (NC) which give the sensibility of the ear to the noise for various acoustical pressure levels and the sound frequencies audible by a human being. Based on this work, complementary studies allowed to obtain the NR curves which are used by the International Standard Organisation (ISO) [11]. The NR index is the value of the NR level for a sound frequency equal to 1000 Hz. Following the ISO recommendations, the maximum value of the NR index in an office has to be in the range [30,35]. Table 3 gives the percentage of locations in the occupied zone where the NR index value is lower than 30, between 30 and 35, and higher than 35 for the unit 1. From Table 3 it can be seen that the NR index is lower than 35 everywhere for tests No. 3 and No. 6. For tests No. 2 and No. 5, only 50% of the values are lower than 35 and any value is less than 30. All the values are higher than 35 for tests No. 1 and No. 4. The experiments carried out with the unit 2 result in a poor acoustical comfort since the index NR values are higher than 35 everywhere and for all the tests.
tions for DR index and PPD index are satisfied. For unit 1, PPD index increases and DR index decreases as the thermal length LT increases. It is certainly due to the variation of the separation distance of the cold horizontal wall jet. For unit 2, placed in the centre of the false ceiling, PPD and DR indices decrease with thermal length LT because the four directions of supply air provide a good repartition of the air velocity in the occupied zone but also large values of the air velocity turbulence. 3.4. Global approach Fig. 5 shows for unit 1 and tests Nos. 1–3, the values of the PPD, DR, ADPI and NR indices in the occupied zone. Fig. 5 also shows the compounded electric power of fan, pumps and compressor, Pe. With Archimede’s number as reference, it can be seen that the comfort parameters including electric power do not vary in the same way. Thus PPD index, ADPI index and electrical consumption increase as NR and DR indices decrease. This points out the difficulty to get an optimum for the local comfort with occupant’s preferences.
3.2. Air performance index The measured Effective Draft Temperature EDT [12] and ADPI index [13] distribution in the climate chamber are shown in Fig. 3. For unit 1 the value of the ADPI fluctuates with the mechanical configuration of the fan-coil. Considering the same supply flow rate, but not a different mechanical parameter, the APDI value is roughly divided by 2. For unit 2 the influence of the mechanical configuration is very small and the ADPI value for test No. 11 is close to the optimum 3.3. Thermal comfort
Fig. 3. EDT distribution and ADPI values.
Fig. 4 gives the percentage of locations in the test room where the ISO 7730 [14] standard recommenda-
Table 3 Percentage of locations for the NR index and for unit 1 Test No.
1 2 3 4 5 6
NR index o30
[30,35]
0% 0% 94% 0% 0% 94%
0% 50% 6% 0% 50% 6%
435 100% 50% 0% 100% 50% 0%
Fig. 4. PPD and DR distributions vs thermal length.
ARTICLE IN PRESS Percentage of locations in the test room ( %) and electrical power (W)
E. Rutman et al. / Building and Environment 40 (2005) 29–37
PPD (%)
120
DR (%)
0
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Table 4 Family of actions Action Nos.
Description
NR (%) 80
ADPI (%)
60
Pe (x10) W
40 20 0 0.000
0.001
0.002
0.003
0.004
0.005
unit 1
unit 2
a11 a12 a13 a14 a15 a16
a21 a22 a23 a24 a25 a26
Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical
parameter parameter parameter parameter parameter parameter
1 1 1 2 2 2
and and and and and and
high speed medium speed low speed high speed medium speed low speed
Ar0
Fig. 5. Global comfort criteria vs initial Archimede’s number (unit 1, test Nos. 1–3).
The objective of this study is to define operating rules for coherent air conditioning systems, with a requirement for quality of indoor environment. Since classical methods cannot answer the problem, a multi-criteria method is used in order to analyse the experimental results.
4. Multi-criteria analysis Firstly, the different steps of the multi-criteria method are described. Then, this method is applied to analyse the experimental results. 4.1. Methodology The multi-criteria analysis approach is used to propose a panel of solutions in concordance with a specific problem. With this method the Roy g theory [15] can be managed: ‘‘How to classify solutions from the best to the worst’’. The Usual European methods developed by Bernard Roy since 1968 [15] with the ELECTRE method ‘‘ELimination Et Choix Traduisant la Realite´ (ELECTRE)’’ is presented. Then to optimise the presentation of the ELECTRE method, the five steps defined by Blondeau [6] are used. Step No. 1: Listing of potential actions. In accordance with Vinckle [16], setting the potential actions is the most difficult step of the analysis. For this study, the whole potential action is relative to the cold water inlet temperature, water flow rate, air flow rate and the mechanical parameters described previously (see Section 2). Nevertheless, the two fan-coil units tested in this study usually work with a fixed inlet temperature and the cooling power is controlled with the air flow rate. Due to these reasons, it was decided to consider the airflow rate and the mechanical parameters as the potential actions. The six actions selected are given in Table 4.
Step No. 2: Definition of criteria family and weight level. According to Gilles d’Avignon [15], nothing exists to quantify and to qualify a group of independent criteria for a specific topic. Nevertheless and with reference to industrial activities, i.e. to select the criteria family in accordance with standards, ISO 7730 [14] with PPD index and DR index were applied for thermal comfort. Concerning the acoustical comfort, the ISO recommendation [11] has been chosen and the quality of air diffusion is based on the ASHRAE 113-1990 standard [13]. The lowest energy consumption was selected as the economical criteria. Concerning the DR index, actions which satisfy between 95% and 90% of occupants are encouraged. Whilst for PPD index, actions which satisfy between 92.5% and 95% are encouraged. Finally, for NR level actions with an NR index value less than 30 are encouraged. In accordance to their range of validity, a weight for each criterion has been added. Although the choice of the weights is arbitrary, the guiding idea is to encourage the best actions. Thus, a non-linear scale has been chosen for the weights namely value 10 for the higher level (the best action), 5 for the middle level and 1 for the lower level (the worst action) as shown in Table 5. Moreover, from Table 5 it can be seen that the ranges of weights are not disjoint. Once again, it is because we want to encourage the best actions. Thus, a good action could be weighed by two or three values whilst a bad action will be weighed once only. Step No. 3: Definition of the performance matrix. For each criterion the percentage of locations in the occupied zone where the standard levels are satisfied is calculated. For the PPD index, it is the percentage of locations where the PPD index value is less than 10%. Concerning the DR index, it is the percentage of locations where the DR value is less than 15%. The percentage of locations relative to the NR index we considered, is a value less than 35. ADPI index is already a percentage of locations and for economical criteria, the compounded electrical consumption of fan, pumps and compressor is selected.
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E. Rutman et al. / Building and Environment 40 (2005) 29–37
Table 5 Criteria and their weight Criteria
Range
Weight
C TH1 : Draft sensation (DR) C TH2 : Draft sensation (DR) C TH3 : Draft sensation (DR) C TH4 : Predicted Percentage of Dissatisfied (PPD) C TH5 : Predicted Percentage of Dissatisfied (PPD) C AI : Air Diffusion Performance Index (ADPI) C AC1 : NR level C AC2 : NR level C EC : Economical criteria
[0%, ]5%, ]0%, [5%,
5%] 10%] 15%] 7.5%]
10 5 1 10
]5%, 10%]
1
[0%, 100%]
10
p30 ]0, 35] Minimal
10 1 10
Step No. 4: Elimination of non-acceptable actions. The main goal of this step is to delete the actions which are non-acceptable for one or several criteria. Hence, the occupant complaints have been taken into account. The draft sensation is the most unpopular discomfort sensation in air-conditioned offices. So, an action with the DR index value above 15% for more than 30% of the locations in the occupied zone is not acceptable. An action with the PPD index value above 10% for more than 50% of the locations in the occupied zone is eliminated and for acoustical comfort, the actions with a NR value above 35 for more than 50% of the locations in the occupied zone are not selected. Step No. 5: Definition of concordance and discordance indices to analyse the performance matrix. To put in order the actions with the ELECTRE II method, the concordance index is calculated with an auto-regulation of these indices. For that, the performance matrix from which we determine the maximum cmax , the average cmoy and the minimum cmin values were calculated. Then, three concordance ranges with c1 ; c2 and c3 thresholds were selected and given by cmax þ 1 c1 ¼ max 0:9; ; ð1Þ 2 cmax þ cmoy c2 ¼ max 0:7; ; ð2Þ 2 cmoy þ cmin c3 ¼ max 0:5; : ð3Þ 2 Furthermore, for each criteria two discordance indices were selected. To take into account the difficulties due to the range of variation of criteria C TH1 ; C TH2 ; C TH4 and C AC1 , value 1 is used for both discordance indices. Concerning the criteria C TH3 ; C TH5 and C AC2 the value 0.1 for the first discordance index and 0.6 for the second were used. For air diffusion performance criteria C AI and economical criteria, the values of the two discordance indices are equal to 0.10 and 0.60, and 0.50 and 0.66, respectively.
A strong outclass SO, a low outclass lo and an incomparability criteria I between all actions are given in Table 6. 4.2. Application to unit 1 and unit 2 The multi-criteria analysis has been applied to unit 1 and unit 2 with and without elimination of nonacceptable actions for the former, and with all the actions for the latter. 4.2.1. Unit 1 with elimination of non-acceptable actions In relation with the criteria family and the results given in Table 7, actions a11 and a14 are eliminated because, in both cases, the DR index value is above 30% and the NR value is above 50%. For this case, the performance matrix is given in Table 8. These results are used to obtain the concordance matrix given in Table 9 and Table 10 gives the discordance indices for this unit. In accordance with Tables 9 and 10, the outclass graph is built (see Fig. 6). Considering all these results, the up and down classifications are:
Up classification
Down classification
Position 1: a13 Position 2: a16 a12 Position 3: a15
Position 1: a13 Position 2: a16 a12 Position 3: a15
As the two classifications are identical, the final classification is:
Table 6 Definition of outclass relation between two actions 1
c1
c2
c3
SO
SO
lo
I
SO
lo
lo
I
I
I
I
I
0
d1 d2
Table 7 Non-acceptable actions for unit 1 Action No.
DR415% PPD410% NR435
a11
a12
a13
a14
a15
a16
32 24 100
21 24 50
8 24 0
49 26 100
29 28 50
12 50 0
ARTICLE IN PRESS E. Rutman et al. / Building and Environment 40 (2005) 29–37 Table 8 Performance matrix for unit 1 without non acceptable actions Criteria
C TH1 C TH2 C TH3 C TH4 C TH5 C AI C AC1 C AC2 C EC
Action No.
Final classification Weight
a12
a13
a15
a16
276% 145% 79% 605% 76% 550% 0% 50% 6364 W
474% 191% 92% 605% 76% 750% 940% 100% 8465 W
276% 112% 71% 566% 72% 250% 0% 50% 6364 W
526% 118% 88% 263% 50% 260% 940% 100% 8465 W
10 5 1 10 1 10 10 1 10
a12 a13 a15 a16
0.19 1.00 0.45
One supply direction for airflow Inlet air flow: 366 m3 =h Inlet temperature: 12:5 C Room temperature: 24:6 C
a13
a15
a16
1.00
0.53 0.00
0.55 0.53 0.81
1.00 0.83
Position 1: a13 Position 2: a16 a12 Position 3: a15 So, the best use of unit 1 is:
Table 9 Concordance matrix for unit 1 without non acceptable actions a12
35
0.14
It can be noticed that the action listed first has the lowest air flow rate. In this study, indoor air quality is not considered. However, it is assumed that the indoor air quality is satisfied due to fresh air mixed with the total air flow rate. For an office occupied by two persons, the maximum French standard value of the fresh air flow rate is equal to 60 m3 =h [17]. 4.2.2. Unit 1 with all actions Using all the actions, the performance matrix is given in Table 11. This matrix allows to calculate the concordance matrix given in Table 12 and the outclass graph is built (see Fig. 7). In this case, the up classification and the down classifications are:
Table 10 Discordance indices for unit 1
C TH1 C TH2 C TH3 C TH4 C TH5 C AI C AC1 C AC2 C EC
a12
d1
d2
1 1 0.3 1 0.3 0.3 1 0.3 0.5
1 1 0.6 1 0.6 0.6 1 0.6 0.66
Table 11 Performance matrix for unit 1 with all actions Criteria Action No. a11 C TH1 C TH2 C TH3 C TH4 C TH5 C AI C AC1 C AC2 C EC
Weight
a12
a13
a14
a15
a16
145% 276% 474% 237% 276% 526% 118% 145% 191% 39% 112% 118% 68% 79% 92% 51% 71% 88% 605% 605% 605% 684% 566% 263% 76% 76% 76% 74% 72% 50% 580% 550% 750% 24% 250% 260% 0% 0% 940% 0% 0% 940% 0% 50% 100% 0% 50% 100% 3837 W 6364 W 8465 W 3837 W 6364 W 8465 W
10 5 1 10 1 10 10 1 10
a13 Table 12 Concordance matrix for unit 1 with all actions a11
a15
a16
Fig. 6. Outclass graph for unit 1 without non-acceptable actions.
a11 a12 a13 a14 a15 a16
0.53 0.19 0.66 0.62 0.45
a12
a13
a14
a15
a16
0.47
0.81 1.00
0.34 0.34 0.17
0.55 0.53 0.00 0.81
0.64 0.55 0.53 0.81 0.81
0.19 0.83 1.00 0.45
0.83 1.00 0.83
0.36 0.19
0.14
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a11
Table 13 Performance matrix for unit 2 with all actions
a12
Criteria Action No. a21
a14
a13
a15
a16
C TH1 C TH2 C TH3 C TH4 C TH5 C AI C AC1 C AC2 C EC
a22
Weight a23
a24
a25
a26
10% 120% 90% 10% 0% 3% 60% 80% 150% 35% 55% 21% 38% 60% 65% 38% 43% 62% 380% 540% 610% 330% 340% 53% 54% 68% 75% 57% 54% 67% 868% 724% 868% 882% 987% 910% 0% 0% 0% 0% 0% 0% 0% 0% 1% 0% 0% 73% 7378 W 6364 W 8773 W 7378 W 8032 W 8773 W
10 5 1 10 1 10 10 1 10
Fig. 7. Outclass graph for unit 1 with all actions.
Final classification
Up classification Position Position Position Position
1: 2: 3: 4:
a13 a11 a12 a16 a15 a14
Down classification Position Position Position Position
1: 2: 3: 4:
a13 a12 a16 a11 a15 a14
Thus, the final sorting out is:
Position Position Position Position
1: 2: 3: 4:
a23 a26 a22 a25 a21 a24
So, the best use of unit 2 is: Toward the ceiling ða23 Þ or toward the floor (a26 ) Inlet air flow: 570 m3 =h ða23 or a26 ) Inlet temperature: 16:3 C ða23 Þ or 14:5 C ða26 Þ Room temperature: 24:7 C ða23 or a26 ).
Final classification Position Position Position Position Position
1: 2: 3: 4: 5:
a13 a16 a12 a11 a15 a14
This classification is nearly similar to the previous one and the best use of unit 1 is the same. Actions a13 ; a12 and a16 are on top and the elimination of action a14 is justified due to its last position. The position of action a11 has to be discussed. Previously, this action was eliminated due to the NR value and the DR index value. Nevertheless, the DR index value is very close to the upper boundary for an acceptable action. Therefore, in spite of a poor acoustical level, this action takes position 3 in the sorted list.
4.2.3. Unit 2 without elimination of non-acceptable actions Because of the poor acoustical comfort measured for this unit (see Section 3.1), the classification for unit 2 is built with all the actions without considering nonacceptable actions. Using the same method as previously and the performance matrix given in Table 13, the following final classification is obtained:
5. Conclusions The results presented in this paper have shown that the multi-criteria method can be used for a global analysis of the indoor environment of an air-conditioned office. In that way, the ELECTRE II method was used and has allowed to select working conditions for two air terminal devices considering various indices. However, this method has to be used with a special care for the non-acceptable conditions especially close to the boundaries of the indices. The results of this study will be applied in order to select HVAC systems in accordance with the improvement of the indoor environment.
Acknowledgements This study was supported partly by the Research and Technology National Agency (ANRT), the Environment and Energy Management Agency (ADEME) and Electricity of France (EDF). References [1] Fanger PO. Thermal comfort analysis and applications in environmental engineering. New York, USA: McGraw-Hill; 1980.
ARTICLE IN PRESS E. Rutman et al. / Building and Environment 40 (2005) 29–37 [2] Rutman E. Contribution a` l’e´valuation de la qualite´ des ambiances inte´rieures climatise´es. The`se de Doctorat, Universite´ de la Rochelle, France. 2000. [3] Rutman E, Inard C, Allard F, Bailly A. Relationship between horizontal cold air jets induced by a real HVAC system as a fan coil and the indoor comfort. In: Proceedings of Roomvent’00, Reading, UK; 2000. p. 517–22. [4] Le Te´no JL. De´veloppement d’un mode`le d’aide a` l’e´valuation et a` l’ame´lioration de la qualite´ environnementale des produits de construction. The`se de Doctorat, Universite´ de Savoie, France, 1996. [5] Michel P, Guarracino G. Evaluation of the global performance of ventilation fans in the re´sidential sector. In: Proceedings of the Second International Confe´rence of Indoor Air Quality, Ventilation and Energy, Conservation in Buildings, Montre´al, Canada; 1995. p. 567–74. [6] Blondeau P. Contribution a` l’e´valuation de la qualite´ globale des ambiances habite´es. Roˆle de la ventilation en pe´riode estivale. The`se de Doctorat, Universite´ de la Rochelle, France, 1996. [7] ASHRAE. Thermal environmental conditions for human occupied. ANSI/ASHRAE standard 55, Atlanta, USA, 1992. [8] Etheridge D, Sandberg M. Building ventilation. Theory and measurement. Chichester, UK: Wiley; 1996.
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[9] Rajaratnam N. Turbulent jets. Amsterdam, Netherlands: Elsevier Scientific Publishing Company; 1976. [10] Beranek L. Noise reduction. New York, USA: McGraw-Hill; 1960. [11] ISO. Assessments of noise with respect to community response. Technical committee ISO/TN43, Geneva, Switzerland, 1971. [12] Koestel A, Tuve G. Performance and evaluation of room air distribution systems. ASHRAE Transaction 1955;61:533–50. [13] ASHRAE. Method of testing for room air diffusion. ANSI/ ASHRAE standard 113, Atlanta, USA, 1990. [14] ISO. Moderate thermal environments. Determination of the PMV and the PPD indices and specifications of the conditions for thermal comfort. ISO standard, Geneva, Switzerland, 1995. [15] Scha¨rlig A. De´cider sur plusieurs crite`res. Panorama de l’aide a` la de´cision multicrite`re. Lausanne, Suisse: Presses polytechniques et universitaires romandes; 1985. [16] Vinkle P. L’aide multicrite`re a` la de´cision. Paris, France: Ellipses Edition; 1989. [17] CSTB. Practical guidance to meeting the requirements of the thermal and ventilation regulations for non residential buildings. Cahiers du CSTB, No. 2286, Paris, France, 1988.
Building and Environment 40 (2005) 29–37 www.elsevier.com/locate/buildenv
A global approach of indoor environment in an air-conditioned office room Emmanuel Rutmana, Christian Inardb,, Andre´ Baillya, Francis Allardb a
CIAT Research and Development Center, Culoz, France LEPTAB, University of la Rochelle, La Rochelle, France
b
Received 6 January 2003; received in revised form 20 February 2004; accepted 20 May 2004
Abstract This study presents a multi-criteria method used for analysing the quality of an air-conditioned indoor environment. Indoor air flow induced by an actual Heating Ventilation and Air Conditioning system was experimentally studied under various conditions. The attention was focused on thermal comfort, acoustical comfort and indoor air distribution by considering spatial statistic studies of comfort indices. The compounded electric power of fan, compressor and pumps was measured in order to get information about energy consumption. A first analysis of these parameters showed that indoor comfort cannot be described by a general law. Thus, to reach the objective of a global approach of comfort by a spatial statistical study of the various discomforts, a multi-criteria analysis based on ELECTRE II method adapted to the comfort of air-conditioned indoor environment was applied. In this way the operating rules for coherent air conditioning systems can be defined, with a requirement for quality of indoor environment. r 2004 Elsevier Ltd. All rights reserved. Keywords: Thermal comfort; Acoustical comfort; Air-conditioned; Building; Multi-criteria analysis
1. Introduction Since 1973 and the first fuel shortage, the French government has conducted actions for a reduction of building energy consumption. First, building actors worked on insulation, then on equipment energy consumption reduction. In the last 10 years, the CIAT laboratory staff has been working on indoor environment quality in accordance with the European and international preoccupations. Fanger [1] showed that the occupants of offices are submitted to various local discomforts, due to temperature, draft and noise. In order to improve comfort, different types of HVAC systems can be applied. Rutman [2] carried out an experimental work to link the cold air jet characteristics and a global approach of comfort, which takes into account thermal and acoustical comforts. Furthermore, Corresponding author. Fax: +33-5-46-45-82-41.
E-mail address: [email protected] (C. Inard). 0360-1323/$ - see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2004.05.006
Rutman et al. [3] showed that the comfort criteria such as the PPD, DR, NR and ADPI indices do not vary in the same way with Archimede’s number as reference. Thus, PPD index and ADPI index increase as NR level and DR index decrease. Lastly, they pointed out the difficulties of improving local comfort with occupants. In another way, many building designers use the multicriteria analysis in their results [4] and some authors [5,6] have started using these tools to improve the ventilation of buildings. That is why, a multi-criteria method has been used to analyse the experimental results in this study.
2. Methodology and test conditions The measurements [2] were carried out in the CIAT’s laboratory located in Culoz, France. The longitudinal section of the experimental test chamber is shown in Fig. 1. The volume was equal to 5:2 4:0 2:5 m3
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Nomenclature A0 ADPI aij Ar0 C AC1 C AC2 C AI C EC ck C max C min C moy C TH1 C TH2 C TH3 C TH4 C TH5
supply area, m2 Air Diffusion Performance Index actions with i ¼ unit 1 or unit 2 and j ¼ 1; 2; 3; 4; 5 or 6 inlet Archimede’s number acoustical criteria No. 1 acoustical criteria No. 2 air diffusion performance criteria economical criteria concordance indices (k ¼ 1; 2 or 3) maximum of concordance indices minimum of concordance indices average of concordance indices thermal criteria No. 1 for the DR thermal criteria No. 2 for the DR thermal criteria No. 3 for the DR thermal criteria No. 1 for the PPD thermal criteria No. 2 for the PPD
bounded on five sides by air volume controlled at a constant temperature level. The sixth side is submitted to the influence of a climatic housing, where external air temperature can be simulated. For the present experiments, the value of external temperature was set at þ30 C. Real internal heat loads were simulated with a computer and two dummies. These thermal heat loads were balanced by a fan-coil unit mounted on the ceiling. Two fan-coil units, unit 1 and unit 2, were tested as shown in Figs. 1 and 2. For each unit, six tests with various supply conditions were carried out including two mechanical configurations of the fan-coil unit. For unit 1, the air jet had one supply direction (mechanical parameter 1) or three directions for the airflow (mechanical parameter 2). For unit 2, the direction of the jet was toward the ceiling (mechanical parameter 1) then toward the floor (mechanical parameter 2). In all the tests, the cold water temperature level was constant ð6 C=12 CÞ and it was possible to select five air flow rates. In order to study the overall band of the air flow rate, the tests were carried out with three air flow rate values (low, medium and high) and the two mechanical parameters for each unit. For all the tests, the operative temperature in the occupied zone was equal to 24:5 1:5 C. Tables 1 and 2 give the parameters used for the experiments. The air velocity, the relative intensity of velocity turbulence, and temperature in the occupied zone of the room were measured with a thermoanemometric sensor (type DANTEC 54T21) placed at 76 different locations in the occupied zone. Vertical test points were located from the floor at 0.1 m for the feet, 0.6 m for the hips, 1.1 m for the head of an occupant in the sitting position and 1.7 m for the head of
dk DR I LT lo NR Pe PPD Q0 Re0 SO T0 DT 0 U0
discordance indices (k ¼ 1 or 2) draft rating incomparability thermal length, m low outclass noise rating electrical power, W predicted percentage of dissatisfied, % air flow rate, m3 h1 initial Reynolds number strong outclass inlet air temperature, C inlet excess temperature, C inlet air velocity, m s1
Greek letters m r
viscosity, kg m1 s1 density, kg m3
an occupant standing up [7]. This probe calibrated by DANTEC, is characterized by a precision of 0:02 m=s for the air velocity and 0:2 C for the air temperature. The inner wall surface temperatures were measured with thermocouples type K calibrated with a precision of 0:25 C at the CIAT laboratory. The acoustical level was measured with a microphone sensor with a precision of 3 dB type Bruel & Kjaer 4189 and a frequency analyser type Kontron FFT-AD3524. To calibrate the microphone, a pistonphone type Bruel & Kjaer 4231 was used. For the acoustical measurements, the probe was placed at 36 different locations in the occupied zone. 2 Archimede’s number, Ar0 ¼ gb DT 0 A0:5 0 =U 0 , Rey0:5 nolds number Re0 ¼ rU 0 A0 =m and thermal length LT ¼ ðA0 =Ar0 Þ0:5 [8] define the supply conditions. The square root of the supply area A0 was used because the ratio effective length ðl 0 Þ/effective width (h0 ) is equal to 13 for unit 1 and more than 4 for unit 2. So in accordance with Rajaratnam [9], these values are characteristic of a three-dimensional jet. The mean value of the inlet temperature T 0 was measured with a Newport Omega, 0.051 mm diameter, K-type thermocouple calibrated with a precision of 0:25 C at the CIAT laboratory. For the velocity U 0 , a Dantec laser doppler anemometer unidirectional system was used.
3. Experimental test results The main results presented here consist in the spatial statistical studies of comfort indices and energy consumption.
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Fan-coil unit1 Unit1 Climatic guard T = +25 ˚C Climatic Housing T =+ 30 ˚C
Dummies
Lights
One supply direction
2.5 m
Computer on table
Unit1
Climatic guard T =+ 25 ˚C Three supply directions
5.2 m
Fig. 1. Longitudinal section of the test cell and unit 1.
Fan-coil unit2 Climatic guard T = +25 ˚C Climatic Housing T =+ 30 ˚C
Unit2
Dummies
Lights
Toward the floor
2.5 m
Computer on table
Toward the ceiling
Climatic guard T =+ 25 ˚C 5.2 m
Fig. 2. Longitudinal section of the test cell and unit 2.
Table 1 Experimental conditions for unit 1 Test No.
Number of supply directions
Q0 ðm3 =hÞ
U0 (m/s)
T0 ð CÞ
1 2 3 4 5 6
1 1 1 3 3 3
732 537 366 722 532 366
5.5 4.5 3.0 5.6 4.2 2.9
14.1 11.0 12.5 11.8 12.1 11.5
DT 0 ð CÞ 9.1 12.5 12.1 11.8 12.7 13.5
Ar0 ð103 Þ
Re0
LT (m)
0.91 1.87 4.05 1.14 2.17 4.85
30517 24969 16646 31072 23304 16091
5.7 3.9 2.7 5.0 3.7 2.4
Table 2 Experimental conditions for unit 2 Test No.
Supply direction to
Q0 ðm3 =hÞ
U0 (m/s)
T0 ð CÞ
DT 0 ð CÞ
Ar0 ð103 Þ
Re0
LT (m)
7 8 9 10 11 12
Ceiling Ceiling Ceiling Floor Floor Floor
684 623 570 725 623 560
5.8 5.2 4.7 5.6 5.1 4.2
15.6 16.3 16.3 14.5 14.1 14.5
8.5 7.8 8.4 9.1 9.3 10.2
0.97 1.08 1.44 1.64 2.07 3.27
41050 37063 33240 58620 52887 44090
3.6 3.4 2.9 4.1 3.6 2.9
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3.1. Acoustical comfort The assessment of acoustical comfort was made using the Noise Rating (NR) index. This index came from the Beraneck [10] experimental studies. The author produced a network of curves called Noise Criteria (NC) which give the sensibility of the ear to the noise for various acoustical pressure levels and the sound frequencies audible by a human being. Based on this work, complementary studies allowed to obtain the NR curves which are used by the International Standard Organisation (ISO) [11]. The NR index is the value of the NR level for a sound frequency equal to 1000 Hz. Following the ISO recommendations, the maximum value of the NR index in an office has to be in the range [30,35]. Table 3 gives the percentage of locations in the occupied zone where the NR index value is lower than 30, between 30 and 35, and higher than 35 for the unit 1. From Table 3 it can be seen that the NR index is lower than 35 everywhere for tests No. 3 and No. 6. For tests No. 2 and No. 5, only 50% of the values are lower than 35 and any value is less than 30. All the values are higher than 35 for tests No. 1 and No. 4. The experiments carried out with the unit 2 result in a poor acoustical comfort since the index NR values are higher than 35 everywhere and for all the tests.
tions for DR index and PPD index are satisfied. For unit 1, PPD index increases and DR index decreases as the thermal length LT increases. It is certainly due to the variation of the separation distance of the cold horizontal wall jet. For unit 2, placed in the centre of the false ceiling, PPD and DR indices decrease with thermal length LT because the four directions of supply air provide a good repartition of the air velocity in the occupied zone but also large values of the air velocity turbulence. 3.4. Global approach Fig. 5 shows for unit 1 and tests Nos. 1–3, the values of the PPD, DR, ADPI and NR indices in the occupied zone. Fig. 5 also shows the compounded electric power of fan, pumps and compressor, Pe. With Archimede’s number as reference, it can be seen that the comfort parameters including electric power do not vary in the same way. Thus PPD index, ADPI index and electrical consumption increase as NR and DR indices decrease. This points out the difficulty to get an optimum for the local comfort with occupant’s preferences.
3.2. Air performance index The measured Effective Draft Temperature EDT [12] and ADPI index [13] distribution in the climate chamber are shown in Fig. 3. For unit 1 the value of the ADPI fluctuates with the mechanical configuration of the fan-coil. Considering the same supply flow rate, but not a different mechanical parameter, the APDI value is roughly divided by 2. For unit 2 the influence of the mechanical configuration is very small and the ADPI value for test No. 11 is close to the optimum 3.3. Thermal comfort
Fig. 3. EDT distribution and ADPI values.
Fig. 4 gives the percentage of locations in the test room where the ISO 7730 [14] standard recommenda-
Table 3 Percentage of locations for the NR index and for unit 1 Test No.
1 2 3 4 5 6
NR index o30
[30,35]
0% 0% 94% 0% 0% 94%
0% 50% 6% 0% 50% 6%
435 100% 50% 0% 100% 50% 0%
Fig. 4. PPD and DR distributions vs thermal length.
ARTICLE IN PRESS Percentage of locations in the test room ( %) and electrical power (W)
E. Rutman et al. / Building and Environment 40 (2005) 29–37
PPD (%)
120
DR (%)
0
33
Table 4 Family of actions Action Nos.
Description
NR (%) 80
ADPI (%)
60
Pe (x10) W
40 20 0 0.000
0.001
0.002
0.003
0.004
0.005
unit 1
unit 2
a11 a12 a13 a14 a15 a16
a21 a22 a23 a24 a25 a26
Mechanical Mechanical Mechanical Mechanical Mechanical Mechanical
parameter parameter parameter parameter parameter parameter
1 1 1 2 2 2
and and and and and and
high speed medium speed low speed high speed medium speed low speed
Ar0
Fig. 5. Global comfort criteria vs initial Archimede’s number (unit 1, test Nos. 1–3).
The objective of this study is to define operating rules for coherent air conditioning systems, with a requirement for quality of indoor environment. Since classical methods cannot answer the problem, a multi-criteria method is used in order to analyse the experimental results.
4. Multi-criteria analysis Firstly, the different steps of the multi-criteria method are described. Then, this method is applied to analyse the experimental results. 4.1. Methodology The multi-criteria analysis approach is used to propose a panel of solutions in concordance with a specific problem. With this method the Roy g theory [15] can be managed: ‘‘How to classify solutions from the best to the worst’’. The Usual European methods developed by Bernard Roy since 1968 [15] with the ELECTRE method ‘‘ELimination Et Choix Traduisant la Realite´ (ELECTRE)’’ is presented. Then to optimise the presentation of the ELECTRE method, the five steps defined by Blondeau [6] are used. Step No. 1: Listing of potential actions. In accordance with Vinckle [16], setting the potential actions is the most difficult step of the analysis. For this study, the whole potential action is relative to the cold water inlet temperature, water flow rate, air flow rate and the mechanical parameters described previously (see Section 2). Nevertheless, the two fan-coil units tested in this study usually work with a fixed inlet temperature and the cooling power is controlled with the air flow rate. Due to these reasons, it was decided to consider the airflow rate and the mechanical parameters as the potential actions. The six actions selected are given in Table 4.
Step No. 2: Definition of criteria family and weight level. According to Gilles d’Avignon [15], nothing exists to quantify and to qualify a group of independent criteria for a specific topic. Nevertheless and with reference to industrial activities, i.e. to select the criteria family in accordance with standards, ISO 7730 [14] with PPD index and DR index were applied for thermal comfort. Concerning the acoustical comfort, the ISO recommendation [11] has been chosen and the quality of air diffusion is based on the ASHRAE 113-1990 standard [13]. The lowest energy consumption was selected as the economical criteria. Concerning the DR index, actions which satisfy between 95% and 90% of occupants are encouraged. Whilst for PPD index, actions which satisfy between 92.5% and 95% are encouraged. Finally, for NR level actions with an NR index value less than 30 are encouraged. In accordance to their range of validity, a weight for each criterion has been added. Although the choice of the weights is arbitrary, the guiding idea is to encourage the best actions. Thus, a non-linear scale has been chosen for the weights namely value 10 for the higher level (the best action), 5 for the middle level and 1 for the lower level (the worst action) as shown in Table 5. Moreover, from Table 5 it can be seen that the ranges of weights are not disjoint. Once again, it is because we want to encourage the best actions. Thus, a good action could be weighed by two or three values whilst a bad action will be weighed once only. Step No. 3: Definition of the performance matrix. For each criterion the percentage of locations in the occupied zone where the standard levels are satisfied is calculated. For the PPD index, it is the percentage of locations where the PPD index value is less than 10%. Concerning the DR index, it is the percentage of locations where the DR value is less than 15%. The percentage of locations relative to the NR index we considered, is a value less than 35. ADPI index is already a percentage of locations and for economical criteria, the compounded electrical consumption of fan, pumps and compressor is selected.
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E. Rutman et al. / Building and Environment 40 (2005) 29–37
Table 5 Criteria and their weight Criteria
Range
Weight
C TH1 : Draft sensation (DR) C TH2 : Draft sensation (DR) C TH3 : Draft sensation (DR) C TH4 : Predicted Percentage of Dissatisfied (PPD) C TH5 : Predicted Percentage of Dissatisfied (PPD) C AI : Air Diffusion Performance Index (ADPI) C AC1 : NR level C AC2 : NR level C EC : Economical criteria
[0%, ]5%, ]0%, [5%,
5%] 10%] 15%] 7.5%]
10 5 1 10
]5%, 10%]
1
[0%, 100%]
10
p30 ]0, 35] Minimal
10 1 10
Step No. 4: Elimination of non-acceptable actions. The main goal of this step is to delete the actions which are non-acceptable for one or several criteria. Hence, the occupant complaints have been taken into account. The draft sensation is the most unpopular discomfort sensation in air-conditioned offices. So, an action with the DR index value above 15% for more than 30% of the locations in the occupied zone is not acceptable. An action with the PPD index value above 10% for more than 50% of the locations in the occupied zone is eliminated and for acoustical comfort, the actions with a NR value above 35 for more than 50% of the locations in the occupied zone are not selected. Step No. 5: Definition of concordance and discordance indices to analyse the performance matrix. To put in order the actions with the ELECTRE II method, the concordance index is calculated with an auto-regulation of these indices. For that, the performance matrix from which we determine the maximum cmax , the average cmoy and the minimum cmin values were calculated. Then, three concordance ranges with c1 ; c2 and c3 thresholds were selected and given by cmax þ 1 c1 ¼ max 0:9; ; ð1Þ 2 cmax þ cmoy c2 ¼ max 0:7; ; ð2Þ 2 cmoy þ cmin c3 ¼ max 0:5; : ð3Þ 2 Furthermore, for each criteria two discordance indices were selected. To take into account the difficulties due to the range of variation of criteria C TH1 ; C TH2 ; C TH4 and C AC1 , value 1 is used for both discordance indices. Concerning the criteria C TH3 ; C TH5 and C AC2 the value 0.1 for the first discordance index and 0.6 for the second were used. For air diffusion performance criteria C AI and economical criteria, the values of the two discordance indices are equal to 0.10 and 0.60, and 0.50 and 0.66, respectively.
A strong outclass SO, a low outclass lo and an incomparability criteria I between all actions are given in Table 6. 4.2. Application to unit 1 and unit 2 The multi-criteria analysis has been applied to unit 1 and unit 2 with and without elimination of nonacceptable actions for the former, and with all the actions for the latter. 4.2.1. Unit 1 with elimination of non-acceptable actions In relation with the criteria family and the results given in Table 7, actions a11 and a14 are eliminated because, in both cases, the DR index value is above 30% and the NR value is above 50%. For this case, the performance matrix is given in Table 8. These results are used to obtain the concordance matrix given in Table 9 and Table 10 gives the discordance indices for this unit. In accordance with Tables 9 and 10, the outclass graph is built (see Fig. 6). Considering all these results, the up and down classifications are:
Up classification
Down classification
Position 1: a13 Position 2: a16 a12 Position 3: a15
Position 1: a13 Position 2: a16 a12 Position 3: a15
As the two classifications are identical, the final classification is:
Table 6 Definition of outclass relation between two actions 1
c1
c2
c3
SO
SO
lo
I
SO
lo
lo
I
I
I
I
I
0
d1 d2
Table 7 Non-acceptable actions for unit 1 Action No.
DR415% PPD410% NR435
a11
a12
a13
a14
a15
a16
32 24 100
21 24 50
8 24 0
49 26 100
29 28 50
12 50 0
ARTICLE IN PRESS E. Rutman et al. / Building and Environment 40 (2005) 29–37 Table 8 Performance matrix for unit 1 without non acceptable actions Criteria
C TH1 C TH2 C TH3 C TH4 C TH5 C AI C AC1 C AC2 C EC
Action No.
Final classification Weight
a12
a13
a15
a16
276% 145% 79% 605% 76% 550% 0% 50% 6364 W
474% 191% 92% 605% 76% 750% 940% 100% 8465 W
276% 112% 71% 566% 72% 250% 0% 50% 6364 W
526% 118% 88% 263% 50% 260% 940% 100% 8465 W
10 5 1 10 1 10 10 1 10
a12 a13 a15 a16
0.19 1.00 0.45
One supply direction for airflow Inlet air flow: 366 m3 =h Inlet temperature: 12:5 C Room temperature: 24:6 C
a13
a15
a16
1.00
0.53 0.00
0.55 0.53 0.81
1.00 0.83
Position 1: a13 Position 2: a16 a12 Position 3: a15 So, the best use of unit 1 is:
Table 9 Concordance matrix for unit 1 without non acceptable actions a12
35
0.14
It can be noticed that the action listed first has the lowest air flow rate. In this study, indoor air quality is not considered. However, it is assumed that the indoor air quality is satisfied due to fresh air mixed with the total air flow rate. For an office occupied by two persons, the maximum French standard value of the fresh air flow rate is equal to 60 m3 =h [17]. 4.2.2. Unit 1 with all actions Using all the actions, the performance matrix is given in Table 11. This matrix allows to calculate the concordance matrix given in Table 12 and the outclass graph is built (see Fig. 7). In this case, the up classification and the down classifications are:
Table 10 Discordance indices for unit 1
C TH1 C TH2 C TH3 C TH4 C TH5 C AI C AC1 C AC2 C EC
a12
d1
d2
1 1 0.3 1 0.3 0.3 1 0.3 0.5
1 1 0.6 1 0.6 0.6 1 0.6 0.66
Table 11 Performance matrix for unit 1 with all actions Criteria Action No. a11 C TH1 C TH2 C TH3 C TH4 C TH5 C AI C AC1 C AC2 C EC
Weight
a12
a13
a14
a15
a16
145% 276% 474% 237% 276% 526% 118% 145% 191% 39% 112% 118% 68% 79% 92% 51% 71% 88% 605% 605% 605% 684% 566% 263% 76% 76% 76% 74% 72% 50% 580% 550% 750% 24% 250% 260% 0% 0% 940% 0% 0% 940% 0% 50% 100% 0% 50% 100% 3837 W 6364 W 8465 W 3837 W 6364 W 8465 W
10 5 1 10 1 10 10 1 10
a13 Table 12 Concordance matrix for unit 1 with all actions a11
a15
a16
Fig. 6. Outclass graph for unit 1 without non-acceptable actions.
a11 a12 a13 a14 a15 a16
0.53 0.19 0.66 0.62 0.45
a12
a13
a14
a15
a16
0.47
0.81 1.00
0.34 0.34 0.17
0.55 0.53 0.00 0.81
0.64 0.55 0.53 0.81 0.81
0.19 0.83 1.00 0.45
0.83 1.00 0.83
0.36 0.19
0.14
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a11
Table 13 Performance matrix for unit 2 with all actions
a12
Criteria Action No. a21
a14
a13
a15
a16
C TH1 C TH2 C TH3 C TH4 C TH5 C AI C AC1 C AC2 C EC
a22
Weight a23
a24
a25
a26
10% 120% 90% 10% 0% 3% 60% 80% 150% 35% 55% 21% 38% 60% 65% 38% 43% 62% 380% 540% 610% 330% 340% 53% 54% 68% 75% 57% 54% 67% 868% 724% 868% 882% 987% 910% 0% 0% 0% 0% 0% 0% 0% 0% 1% 0% 0% 73% 7378 W 6364 W 8773 W 7378 W 8032 W 8773 W
10 5 1 10 1 10 10 1 10
Fig. 7. Outclass graph for unit 1 with all actions.
Final classification
Up classification Position Position Position Position
1: 2: 3: 4:
a13 a11 a12 a16 a15 a14
Down classification Position Position Position Position
1: 2: 3: 4:
a13 a12 a16 a11 a15 a14
Thus, the final sorting out is:
Position Position Position Position
1: 2: 3: 4:
a23 a26 a22 a25 a21 a24
So, the best use of unit 2 is: Toward the ceiling ða23 Þ or toward the floor (a26 ) Inlet air flow: 570 m3 =h ða23 or a26 ) Inlet temperature: 16:3 C ða23 Þ or 14:5 C ða26 Þ Room temperature: 24:7 C ða23 or a26 ).
Final classification Position Position Position Position Position
1: 2: 3: 4: 5:
a13 a16 a12 a11 a15 a14
This classification is nearly similar to the previous one and the best use of unit 1 is the same. Actions a13 ; a12 and a16 are on top and the elimination of action a14 is justified due to its last position. The position of action a11 has to be discussed. Previously, this action was eliminated due to the NR value and the DR index value. Nevertheless, the DR index value is very close to the upper boundary for an acceptable action. Therefore, in spite of a poor acoustical level, this action takes position 3 in the sorted list.
4.2.3. Unit 2 without elimination of non-acceptable actions Because of the poor acoustical comfort measured for this unit (see Section 3.1), the classification for unit 2 is built with all the actions without considering nonacceptable actions. Using the same method as previously and the performance matrix given in Table 13, the following final classification is obtained:
5. Conclusions The results presented in this paper have shown that the multi-criteria method can be used for a global analysis of the indoor environment of an air-conditioned office. In that way, the ELECTRE II method was used and has allowed to select working conditions for two air terminal devices considering various indices. However, this method has to be used with a special care for the non-acceptable conditions especially close to the boundaries of the indices. The results of this study will be applied in order to select HVAC systems in accordance with the improvement of the indoor environment.
Acknowledgements This study was supported partly by the Research and Technology National Agency (ANRT), the Environment and Energy Management Agency (ADEME) and Electricity of France (EDF). References [1] Fanger PO. Thermal comfort analysis and applications in environmental engineering. New York, USA: McGraw-Hill; 1980.
ARTICLE IN PRESS E. Rutman et al. / Building and Environment 40 (2005) 29–37 [2] Rutman E. Contribution a` l’e´valuation de la qualite´ des ambiances inte´rieures climatise´es. The`se de Doctorat, Universite´ de la Rochelle, France. 2000. [3] Rutman E, Inard C, Allard F, Bailly A. Relationship between horizontal cold air jets induced by a real HVAC system as a fan coil and the indoor comfort. In: Proceedings of Roomvent’00, Reading, UK; 2000. p. 517–22. [4] Le Te´no JL. De´veloppement d’un mode`le d’aide a` l’e´valuation et a` l’ame´lioration de la qualite´ environnementale des produits de construction. The`se de Doctorat, Universite´ de Savoie, France, 1996. [5] Michel P, Guarracino G. Evaluation of the global performance of ventilation fans in the re´sidential sector. In: Proceedings of the Second International Confe´rence of Indoor Air Quality, Ventilation and Energy, Conservation in Buildings, Montre´al, Canada; 1995. p. 567–74. [6] Blondeau P. Contribution a` l’e´valuation de la qualite´ globale des ambiances habite´es. Roˆle de la ventilation en pe´riode estivale. The`se de Doctorat, Universite´ de la Rochelle, France, 1996. [7] ASHRAE. Thermal environmental conditions for human occupied. ANSI/ASHRAE standard 55, Atlanta, USA, 1992. [8] Etheridge D, Sandberg M. Building ventilation. Theory and measurement. Chichester, UK: Wiley; 1996.
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[9] Rajaratnam N. Turbulent jets. Amsterdam, Netherlands: Elsevier Scientific Publishing Company; 1976. [10] Beranek L. Noise reduction. New York, USA: McGraw-Hill; 1960. [11] ISO. Assessments of noise with respect to community response. Technical committee ISO/TN43, Geneva, Switzerland, 1971. [12] Koestel A, Tuve G. Performance and evaluation of room air distribution systems. ASHRAE Transaction 1955;61:533–50. [13] ASHRAE. Method of testing for room air diffusion. ANSI/ ASHRAE standard 113, Atlanta, USA, 1990. [14] ISO. Moderate thermal environments. Determination of the PMV and the PPD indices and specifications of the conditions for thermal comfort. ISO standard, Geneva, Switzerland, 1995. [15] Scha¨rlig A. De´cider sur plusieurs crite`res. Panorama de l’aide a` la de´cision multicrite`re. Lausanne, Suisse: Presses polytechniques et universitaires romandes; 1985. [16] Vinkle P. L’aide multicrite`re a` la de´cision. Paris, France: Ellipses Edition; 1989. [17] CSTB. Practical guidance to meeting the requirements of the thermal and ventilation regulations for non residential buildings. Cahiers du CSTB, No. 2286, Paris, France, 1988.