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Performance metrics for room air-conditioners: energy, comfort and environmental impacts Cover

Performance metrics for room air-conditioners: energy, comfort and environmental impacts

Buildings and Cities
Volume 2 (2021): Issue 1
By: Nidhi Rai Jain,  Rajan Rawal,  Vishnu Vardhan and  Shubhashis Dey  
Open Access
|Jul 2021

Figures & Tables

Table 1

International standards that calculate room air-conditioner (RAC) performance metrics.

CONTINENT/COUNTRYRAC STANDARD
USAHRI 210/240-2008
AustraliaAS/NZS 3823.2-2013
ChinaGB/T 7725-2004
EuropeEN 14825-2012
IndiaISO 16358-1-2013 (CSPF)
JapanJISC 9612:2013, JRA 4046

[i] Note: CSPF = cooling seasonal performance factor.

Table 2

Summary of objectives, methods and outcomes.

LITERATURE REVIEWDATA COLLECTIONCALCULATIONS
ObjectiveTo identify metrics to quantify thermal comfort, energy efficiency and the environmental impact of RACsTo prepare a database of variables affecting RAC performance and to analyse their relationshipsTo propose a method to quantify the metrics of thermal comfort, energy efficiency and environmental impact and to establish a correlation between them
Methods

  • Analysing international adaptive thermal comfort indices

  • Analysing international energy efficiency standards

  • Analysing GWP, LCCP and TEWI to identify the metric for this study

  • Selecting Indian cities based on temperature bin hours, available weather files and climate type

  • Selecting RAC devices based on a survey of the Indian RAC market

  • Referencing outdoor temperature bin hours for 24–43°C as per the BEE

  • Calculating CSPF as per ISO 16358-1 (2013)

  • Calculating annual energy consumption for a static setpoint of 24°C and adaptive setpoint as per IMAC

  • Calculating TEWI using equation (12)

Outcome

  • ISEER with variable reference temperature bin hours

  • Energy consumption (kWh) with variable temperature bin hours for 12 months

  • TEWI score to calculate the total emissions throughout the lifespan of RAC

  • 55 Indian cities

  • Five test cases of 1.5 TR with varying COPs and refrigerants R32 and R410-A

  • Temperature bin hours for 55 Indian cities

  • ISEER

  • CSEC (kWh)

  • TEWI (CO2e)

[i] Note: For definitions, see the list of abbreviations.

Table 3

Specifications of the five room air-conditioner (RAC) cases.

CASESOURCEMANUFACTURERREFRIGERANTCAPACITY (TONS OF REFRIGERATION)ENERGY PERFORMANCE
1Kumar et al. (2018b)CR410a1.53.65 (EER)
2Kumar et al. (2018b)AR321.55.20 (ISEER)
3Coolselector2BR410a1.53.68 (COP)
4Coolselector2BR410a1.53.69 (COP)
5Coolselector2BR410a1.53.58 (COP)

[i] Note: For definitions, see the list of abbreviations.

bc-2-1-127-g1.png
Figure 1

Calculating cooling seasonal performance factor (CSPF) (also known as the Indian seasonal energy efficiency ratio—ISEER) as per ISO 16358-1 (2013).

Table 4

Assumptions for the calculation of total equivalent warming impact (TEWI).

PARAMETERASSUMPTIONREFERENCE
Leakage rate10%Chaturvedi et al. (2015)
Recovery factor5%, 10% and 15%Chaturvedi et al. (2015)
15%Kumar et al. (2018b)
System operating life10 yearsZhao et al. (2015)
8–10 yearsWu et al. (2019)
Refrigerant charge0.21 kg/kWKumar et al. (2018b)
Indirect emission factor0.82 kg CO2/kWhCentral Electricity Authority (2018)
Table 5

Rated energy performance and standard room air-conditioner (RAC) metrics for the five cases.

CASERATED ENERGY PERFORMANCEISEERCSEC (kWh)TEWI (CO2e)
13.65 (EER)1.9298713,382
25.20 (ISEER)2.488999,686
33.68 (COP)3.517039,982
43.69 (COP)3.826489,529
53.58 (COP)3.736639,654
bc-2-1-127-g2.png
Figure 2

Variation of standard cooling seasonal energy consumption (CSEC) and total equivalent warming impact (TEWI).

bc-2-1-127-g3.png
Figure 3

Variation of outdoor temperature bin hours.

bc-2-1-127-g4.png
Figure 4

Localised Indian seasonal energy efficiency ratio (ISEER).

bc-2-1-127-g5.png
Figure 5

Localised cooling seasonal energy consumption (CSEC).

bc-2-1-127-g6.png
Figure 6

Localised total equivalent warming impact (TEWI).

Table 6

Variation of Indian seasonal energy efficiency ratio (ISEER) for five room air-conditioner (RAC) cases for selected cities compared against the ISEER calculated using the standard methodology.

CASESTANDARD ISEERMAXIMUM ISEERMINIMUM ISEERISEER VARIATION
11.922.301.590.71
22.483.101.961.14
33.514.102.951.16
43.824.363.271.10
53.734.263.201.06
Table 7

Variation of cooling seasonal energy consumption (CSEC) for five room air-conditioner (RAC) cases across 55 Indian cities.

CASEMAXIMUM CSEC (kWh)MINIMUM CSEC (kWh)CSEC VARIATION (kWh)
15,1492,2322,917
24,6152,1242,491
33,6161,5682,048
43,3361,4161,920
53,4151,4471,968
Table 8

Variation of total equivalent warming impact (TEWI) for five room air-conditioner (RAC) cases across 55 Indian cities.

CASEMAXIMUM TEWI (CO2e)MINIMUM TEWI (CO2e)TEWI VARIATION (CO2e)
146,44322,52223,921
239,20418,78120,423
333,86717,07516,792
431,57215,83215,740
532,22016,08116,139
bc-2-1-127-g7.png
Figure 7

Comparison of Indian model for adaptive comfort (IMAC) air-conditioned (AC) and mixed-mode (MM) comfort bands against the static setpoint of 24°C.

Table 9

Reduction in cooling seasonal energy consumption (CSEC) and total equivalent warming impact (TEWI) due to adaptive methodology.

SETPOINTCSEC (kWh)REDUCTIONTEWI (CO2e)REDUCTION
Static1,416–5,149–15,832–46,443–
Adaptive (AC)1,126–4,7454–23%13,450–43,1263–22%
Adaptive (MM)753–4,01812–50%10,018–37,16710–47%
bc-2-1-127-g8.png
Figure 8

Variation of room air-conditioners (RAC) performance parameters for static and adaptive (air-conditioned, AC; and mixed-mode, MM) setpoints.

ACair-conditioned
BEEBureau of Energy Efficiency
CDMClean Development Mechanism
CO2ecarbon dioxide equivalent
COPcoefficient of performance
CSECcooling seasonal energy consumption
CSPFcooling seasonal performance factor
CSTLcooling seasonal total load
ECBCEnergy Conservation Building Code
EERenergy efficiency ratio
EUIenergy use intensity (kWh/m2/year)
GHGgreenhouse gas
GWPglobal warming potential
HFCshydrofluorocarbons
HVACheating, ventilation and air-conditioning
IMACIndian model for adaptive comfort
ISEERIndian seasonal energy efficiency ratio
LCCPlife cycle climate performance
MEPSminimum energy performance standards
MMmixed mode
NBCNational Building Code
NVnaturally ventilated
RACroom air-conditioner
RHrelative humidity
S&Lstandards and labelling
SEERseasonal energy efficiency ratio
TEWItotal equivalent warming impact
TMYtypical meteorological year
TRtons of refrigerationa
TSItropical summer index
DOI: https://doi.org/10.5334/bc.127 | Journal eISSN: 2632-6655
Journal RSS Feed
Language: English
Submitted on: Mar 22, 2021
|
Accepted on: Jun 25, 2021
|
Published on: Jul 21, 2021
Published by: Ubiquity Press
In partnership with: Paradigm Publishing Services
Publication frequency: 1 issue per year
Keywords:
air-conditioning,
energy efficiency,
environmental impact assessment,
global warming potential,
indirect emissions,
room air-conditioners,
thermal comfort,
India

© 2021 Nidhi Rai Jain, Rajan Rawal, Vishnu Vardhan, Shubhashis Dey, published by Ubiquity Press
This work is licensed under the Creative Commons Attribution 4.0 License.

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