LCC Optimization of Different Insulation Materials and Energy Sources Used in HVAC Duct Applications

  • Dileep KumarEmail author
  • Intizar Ali
  • Muhammad Hakeem
  • Awais Junejo
  • Khanji Harijan
Research Article - Mechanical Engineering


The heating, ventilation and air conditioning (HVAC) ducts distribute the conditioned air to different zones. They are installed outside in a harsh environment which escalates the energy loss due to heat transfer. This study aims to estimate the economically feasible and environmental amiable insulation thickness for HVAC duct using life cycle cost (LCC) and environmental assessment method. It deems five insulation materials for the duct and eight energy sources for chiller operation in selected countries. It uses the design and operating parameters of the duct installed in a renowned pharmaceutical company at Jamshoro/Pakistan. An apropos mathematical model is developed using the collected parameters to calculate optimum insulation thickness (OIT), LCC, maximum energy savings (ES) at minimum payback period (PP) and emission reduction in the insulated duct. It examines the effect of insulation thickness on economic and environmental outcomes using the linear slope line regression method. The results revealed that the use of EP and natural gas has minimum LCC of 13.66 $/m-year (− 0.484), 95% ES (0.248) corresponding to OIT (64.64 mm) with minimum PP of 1.2 years (decreasing at a rate of − 3.69 with insulation thickness). Fuel consumption reduces dramatically (− 0.79) and once OIT is achieved, further increasing insulation thickness has a negligible impact on fuel savings (− 0.041). Higher fuel cost produces maximum ES in the duct and reduces PP of insulation cost in selected countries but they do not affect the variation in fuel consumption and CO, \(\hbox {CO}_{2}\) and \(\hbox {SO}_{2}\) emission. Additionally, OIT of EP for duct reduces CO and \(\hbox {CO}_{2}\) emission at a maximum rate of -0.134 in case LPG (96%) and − 0.484 (95%) in the case of natural gas, respectively.


Optimum insulation thickness Energy saving Life cycle cost analysis HVAC duct Energy Sources 

List of Symbols


Duct’s external surface area \((\hbox {m}^{2})\)


Cost (US$)


Diameter of the duct (m)


Height of the duct (m)


Convective heat transfer coefficient (\(\hbox {W/m}_{2}\hbox { K}\))


Thermal conductivity (W/m K)


Length of the duct (m)


Mass flow rate (kg/s)


Nusselt number (–)


Prandtl number (–)


Heat gain (W)


Reynolds number (–)


Radius (m)


Thermal resistance (K/W)


Temperature (\(^{\circ }\hbox {C}\))


Velocity (m/s)


Width of the duct (m)


Thickness (m)


Quantity of insulation material (\(\hbox {m}^{3}\))

Greek Letters

\(\vartheta \)

Kinematic viscosity (\(\hbox {m}^{2}/\hbox {s}\))

\(\eta \)

Efficiency (%)

\({\ddot{\varvec{\iota }}}\)

inflation rate (–)

\({\acute{\iota }}\)

Interest rate (–)

\(\mathcal {C}\)

Cost (USD/m-year)

\(\hbox {SV}\)

Salvage value (–)

\(\Delta {T}\)

Operating hours (h)

\(\hbox {MR}\)

Ratio of maintenance cost to initial investment (–)



Date palm residue


Engineering equation solver


Expanded polystyrene


Fiberglass (24 \(\hbox {m}^{3}/\hbox {kg}\))


Fiberglass (48 \(\hbox {m}^{3}/\hbox {kg}\))


Fuel oil


Energy saving (%)


Heating value (kJ/kg or \(\hbox {kJ/m}^{3}\))


Liquefied petroleum gas


Life time (years)


Natural gas


Optimum insulation thickness (mm)


Payback period (years)


Rice husk

















Investment cost



ins, opt

Optimum insulation


Outside, exit or surrounding






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The authors thank Engr. Sanjay Kumar and Engr. Muhammad Haris Khan, Lecturer, Dept. of Mechanical Engineering, MUET Shaheed Zulfiqar Ali Bhutto Campus Khairpur Mir’s and Engr. Rasikh Tariq Facultad de Ingeniería, Universidad Autónoma de Yucatán, Av. Industrias No Contaminantes por Anillo Periférico Norte, Apdo. Postal 150, Cordemex, Mérida, Yucatán 97000, Mexico, for their help to revise this manuscript. The authors would like to thank the reviewer for their wise suggestion to enhance the quality of this paper.


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Copyright information

© King Fahd University of Petroleum & Minerals 2019

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringMehran University of Engineering and TechnologyKhairpur Mir’sPakistan
  2. 2.Department of Mechanical Engineering TechnologyThe Benazir Bhutto Shaheed University of Technology and Skill DevelopmentKhairpur Mir’sPakistan
  3. 3.Department of Industrial Engineering and ManagementMehran University of Engineering and TechnologyJamshoroPakistan
  4. 4.Department of Mechanical EngineeringMehran University of Engineering and TechnologyJamshoroPakistan

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