a new method about the evaluation of indoor … · a new method about the evaluation of indoor...

International Journal on Architectural Science, Volume 3, Number 2, p.72-76, 2002

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A NEW METHOD ABOUT THE EVALUATION OF INDOOR COMFORTABLE ENVIRONMENT A.R. Tao Jiangsu Textile Industry Design & Research Institute, Nanjing 210009, China (Received 13 December 2001; Accepted 22 May 2002) ABSTRACT A new method about the evaluation of indoor comfortable environment is introduced in detail, and relevant experiments indicate that the index CPD (comprehensive percentage dissatisfied) has good reliability and mensurability, and can be used to evaluate and control the indoor comfortable environment. 1. INTRODUCTION The time, which a person spends indoors, is about more than 80 percent of his whole life, and indoor environment conditions have direct influences on every person’s health, spirit and efficiency [1,2]. With the development of economy and the progress of society, better indoor environment conditions are demanded. Relevant researches show that there are many factors which can influence the comfort condition of an indoor environment, such as temperature, humidity, air velocity, noise, concentration of CO2 and etc. These factors can be mainly divided into such parts as following approximately. The first could be called thermal parameters such as temperature, humidity and etc., and related famous evaluation indices PMV and PPD are suggested by Fanger [3,4]. The second is mainly the noise parameter, and related index NPD (noise-caused percentage dissatisfied) is suggested [5,6]. The third could be called IAQ (indoor air quality) parameters, and related index QPD (quality-caused percentage dissatisfied) is suggested [7]. The others could be about visual parameters such as lighting quality and level. As the first-stage task, this paper tries to study the comprehensive influences of thermal, noise and IAQ parameters on an indoor comfortable environment by experiments, and introduces an evaluation index called CPD (comprehensive percentage dissatisfied). Of course, visual parameters are also important, and it will be the next-stage task to study the comprehensive influences of related parameters including visual factor and others on an indoor environment. 2. CPD 2.1 Principle Here the comfort sensation co-influenced by thermal, noise and IAQ parameters is called

comprehensive comfort sensation. Corresponding-ly, the index CPD (comprehensive percentage dissatisfied) can be defined as following: CPD = α1· TPD + α2· NPD + α3· QPD (1) Hereinto, TPD means therm-caused percentage dissatisfied with the same meaning as the index PPD (predicted percentage dissatisfied) [4]; NPD means noise-caused percentage dissatisfied [5]; QPD means quality-caused percentage dissatisfied [7]; α 1, α 2 and α 3 are weight coefficients respectively. 2.2 TPD (therm-caused percentage dis-

satisfied) According to the research made by Fanger [4], there is: TPD = PPD = 100 − 95exp(-(0.03353PMV4 + 0.2179PMV2)) (2) Herein PMV means predicted mean vote. In this paper, PMV value is calculated by use of relevant tables in ISO-7730, and when the indoor air temperature Ta is not equal to mean radiant temperature Tmrt or indoor air relative humidity is not equal to 50%, related PMV value should be adjusted. In the process of calculation, the mean radiant temperature Tmrt is calculated by: Tmrt = (T1A1 + T2A2 + … TiAi + … + TNAN)/ (A1 + A2 + … + Ai + … + AN) (3) Herein, Ti means temperature of wall surface, and Ai means related wall acreage. 2.3 NPD (noise-caused percentage dis-

satisfied) According to the research made by Clausen [5], there is:

International Journal on Architectural Science

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∫ ∞−

−−=

noiselevel 2 dx))0.13

6.58x(exp(35.4NPD (4)

x means the class of noise in dB. 2.4 QPD (quality-caused percentage dis-

satisfied) According to the research made by Fanger [7], there is:

)C

11298.5exp(QPD 4−= (5)

Here C means IAQ sensation value, and can be calculated by C = CO + 10G/Q, while CO means the perceived value of outdoor air quality with unit decipol, G means the intensity of indoor air pollution source with unit olf, and Q means the flow rate of fresh air with unit l/s. 2.5 α1, α2, α3

Weight coefficients α1, α2 and α3 are defined making use of gradation analysis method. The gradation analysis method is put forward by an American scientist in 1970s, which is usually used in such regions as prediction, evaluation and etc. [8]. Considering a factor set U = {U1, U2, U3}, herein U1, U2 and U3 represent TPD, NPD and QPD respectively, and the key step of gradation analysis is to determine a suitable evaluation matrix in the light of Table 1. Table 1

Value Meaning

1 In comparison with Ui, Uj is as important as Uj

3 In comparison with Ui, Uj is a bit important

5 In comparison with Ui, Uj is obviously important

7 In comparison with Ui, Uj is quite important

9 In comparison with Ui, Uj is extremely important

2,4,6,8 Medium value of 1-3, 3-5, 5-7 and 7-9

reciprocal Uij = 1/Uji

According to references [5,6], variable 1 oC of operative temperature may give the same influence on comfortable sensation as variable 2.4 decipol of IAQ or variable 3.9 dB of noise, and within near-comfort sensation scope, effect caused by variable

1 decipol is equal to that by variable 1.2 dB of noise. Thus the following evaluation matrix is defined as: U1 U2 U3

3

2

1

UUU

134/13/115/1

451P

= (6)

Then character vectors ξ is calculated as following: ξ= (ξ1, ξ2, ξ3)

=

∏∏∏===

33

1jj33

3

1jj23

3

1jj1 u,u,u

= (2.7144,0.4055,0.9086) (7) and the coefficient α matrix can be obtained as:

α = (α1, α2, α3) =

ξ

ξ

ξ

ξ

ξ

ξ

∑∑∑ i

3

i

2

i

1 ,,

= (0.6738,0.1007,0.2255) (8) 2.6 Comment Scale After calculation, the value of CPD is in a range of 3.37 to 100. If a five-point comment scale is adopted [2], the relevant evaluation standard is shown in Table 2. Table 2

CPD (%) Comment Value < 20 Comfortable 20 ~ 40 A bit uncomfortable 40 ~ 60 Obviously uncomfortable 60 ~ 80 Quite uncomfortable 80 ~ 100 Extremely uncomfortable

3. TEST 3.1 Target Environments Target A: a usual room neighboring to street with dimensions of 12 m (L) x 6 m (W) x 3 m (H). Target B: an air-conditioned room with dimensions of 6 m (L) x 5 m (W) x 2.8 m (H). 3.2 Outdoor Environments Mean dry ball temperature: 8.2 oC. Mean relative humidity: 44%.


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3.3 Number of Test People 10 ~ 12 people. 3.4 Instruments portable surface thermocouple. psychrometer. ND model noise level meter. QDF-2A model thermal ball electric

anemometer. 3.5 Steps i. Get ready instruments. The measuring dot is

in the center of the room, and persons who make evaluations are stationary.

ii. Write down the measuring values of

temperature, relative humidity, velocity and noise level. In the meantime, comfortable

sensation value of each person is given. As for the IAQ sensation value, concentration of CO2 is mainly considered, and the original value is defined 0.1 decipol with the increasing rate of 0.05 decipol per ten-minute. In addition, physical activity and clothing are defined 58 w/m2 and 2.0 clo respectively.

iii. After 10 minutes, repeat steps i and ii. iv. Analyse test data. Compare calculation values

with sensation values. 3.6 Result Tables 3 to 6 are the measuring values of related parameters, and Tables 7 to 10 are the comparison of calculation values and sensation values.

Table 3: Parameters of environment A1~A6

Temp Radi temp

Relative humidity

Velocity Activity Clothing Noise IAQ sensationEnvironment

Time

oC oC % m/s w/m2 clo dB decipol A1 15:30 10.5 9.1 60.5 0.08 58 2.0 58 0.1 A2 15:40 11.8 10.3 50 0.07 58 2.0 62 0.15 A3 15:50 12.0 10.7 49 0.1 58 2.0 50 0.2 A4 16:00 13.0 11.5 45 0.09 58 2.0 57 0.25 A5 16:10 12.3 11.0 43 0.11 58 2.0 54 0.3 A6 16:20 13.1 11.5 48 0.13 58 2.0 43 0.35

Table 4: Parameters of environment B1~B6

Temp Radi temp

Relative humidity


Time

oC oC % m/s w/m2 clo dB decipol B1 18:40 19.2 16.1 57 0.15 58 2.0 28 0.1 B2 18:50 19.7 16.5 59 0.13 58 2.0 32 0.15 B3 19:00 20.0 16.7 56 0.11 58 2.0 21 0.2 B4 19:10 20.6 17.4 52 0.16 58 2.0 24 0.25 B5 19:20 21.0 17.7 53 0.20 58 2.0 30 0.3 B6 19:30 21.3 18.0 51 0.17 58 2.0 35 0.35

Table 5: Parameters of environment A7~A12

Temp Radi temp

Relative humidity


Time

oC oC % m/s w/m2 clo dB Decipol A7 12:00 15.0 13.2 56 0.1 58 2.0 43 0.1 A8 12:10 15.1 13.3 57 0.06 58 2.0 46 0.15 A9 12:20 15.7 14.0 52 0.09 58 2.0 40 0.2

A10 12:30 15.9 14.2 50 0.12 58 2.0 39 0.25 A11 12:40 15.4 13.7 49 0.08 58 2.0 51 0.3


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A12 12:50 15.8 13.9 47 0.11 58 2.0 53 0.35 Table 6: Parameters of environment B7~B12

Temp Radi temp

Relative humidity


Time

oC oC % m/s w/m2 clo dB Decipol B7 18:20 17.1 14.3 52 0.12 58 2.0 31 0.1 B8 18:30 17.9 15.1 52 0.14 58 2.0 23 0.15 B9 18:40 18.3 15.6 50 0.13 58 2.0 28 0.2

B10 18:50 18.6 15.7 49 0.12 58 2.0 32 0.25 B11 19:00 19.0 16.3 50 0.15 58 2.0 26 0.3 B12 19:10 19.1 16.2 48 0.16 58 2.0 22 0.35

Table 7: Comparison of calculation and sensation of CPD (A1~A6)

Calculation value Sensation value Environment CPD

(%) Evaluation Test

person Uncomfort-able person

Uncomfortable ratio (%)

Evaluation Comp

A1 33.1 A bit un-comfortable 12 4 33.3 A bit un-

comfortable Accordant

A2 29.13 A bit un-comfortable 12 4 33.3 A bit un-


A3 21.55 A bit un-comfortable 12 3 25 A bit un-






A6 14.92 comfortable 12 3 25 A bit un-comfortable

Not accordant

Table 8: Comparison of calculation and sensation of CPD (B1~B6)


(%) Evaluation Test

personUncomfort-able person


Evaluation Comp

B1 4.17 comfortable 12 1 8.3 comfortable AccordantB2 5.61 comfortable 12 2 16.7 comfortable AccordantB3 6.13 comfortable 12 2 16.7 comfortable AccordantB4 6.65 comfortable 12 1 8.3 comfortable AccordantB5 7.84 comfortable 12 2 16.7 comfortable AccordantB6 9.07 comfortable 12 2 16.7 comfortable Accordant

Table 9: Comparison of calculation and sensation of CPD (A7~A12)


(%) Evaluation Test



Evaluation Comp

A7 7.85 comfortable 10 1 10 comfortable AccordantA8 8.04 comfortable 10 1 10 comfortable AccordantA9 7.52 comfortable 10 0 0 comfortable Accordant

A10 6.81 comfortable 10 3 30 A bit un-comfortable

Not accordant

A11 9.8 comfortable 10 1 10 comfortable Accordant


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A12 9.91 comfortable 10 1 10 comfortable AccordantTable 10: Comparison of calculation and sensation of CPD (B7~B12)


(%) Evaluation Test



Evaluation Comp

B7 4.27 comfortable 10 0 0 comfortable AccordantB8 3.85 comfortable 10 1 10 comfortable AccordantB9 4.37 comfortable 10 0 0 comfortable Accordant

B10 4.57 comfortable 10 1 10 comfortable AccordantB11 4.96 comfortable 10 1 10 comfortable Accordant

B12 4.92 comfortable 10 3 30 A bit un-comfortable

Not accordant

According to the above data, accordant ratio of calculation values and sensation values of the index CPD is about 87.5%. 4. CONCLUSION The method based on the index CPD can be used to evaluate and control an indoor comfortable environment co-influenced by thermal, noise and IAQ factors. Of course, the weight coefficients α1, α2 and α3 should be adjusted in accordance with different conditions of an indoor environment, and deeper studies are needed. REFERENCES 1. D.A. McIntyre, Indoor climate, Applied Science

Publishes Ltd. (1980).

2. A.R. Tao, “Research on the Fuzzy-evaluation-based thermal comfort index FCE of air-conditioned environments”, Proceedings of the 2nd International Symposium on Heating, Ventilation and Air Conditioning, Beijing, China (1995).

3. International Standard (ISO-7730), Moderate thermal environments determination of PMV and PPV indices and specification of the conditions for thermal, International Standard Organization, Switzerland (1984).

4. P.O. Fanger, Thermal comfort, New York, McGraw-Hill (1970).

5. G. Clausen, “A comparative study of discomfort caused by indoor air pollution, thermal load and noise”, Indoor air, Vol. 3, pp. 255-262 (1993).

6. P.A. Hancock and J.O. Pierce, “Combined effects of heat and noise on human performance: A review”, American Industrial Hygiene Association Journal, Vol. 46, pp. 555-556 (1985).

7. P.O. Fanger, “ Introduction of the olf and the decipol units to quantify air pollution perceived by humans indoors and outdoors ” , Energy and Building, Vol. 12, pp. 1-6 (1988).

8. H.Z. Zhao, Gradation analysis method, Chinese Science Press (1986).

a new method about the evaluation of indoor … · a new method about the evaluation of indoor...

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