HVAC System. VRF System. Life Cycle Analysis.

1. Life cycle analysis of multi-split Variable Refrigerant Flow (VRF) system : case study
1
Life cycle analysis of multi-split Variable Refrigerant
Flow (VRF) system : case study
MD. KHURSHID ALAM1 and SHAH ALAM2
1
Al-Falah University, Dhauj, Faridabad, Haryana
2
Jamia Millia Islamia, New Delhi
*E-mail: sm.arzoo111@gmail.com
Abstract
In this paper a building having ground and first floor located in A.M.U. Aligarh has been selected
for HVAC purposes. The total area of building is 18327 square feet. The total cooling load of
ground floor and first floor is 149.5 TR. The total cooling load is ground floor is 89 TR and first
floor is 61 TR. The total HP outdoor units in VRF system is installed load for the diversity of
VRF units is 80 - 90%. The load is calculated on the basis of occupants, electric loads, exposed
area to sun etc. We have found that total HP outdoor unit and TR indoor units are needed. The
total consumption of electricity for running VRF units is also calculated. It is found that units
electricity is consumed 3,30,000 units/year for VRF System and 4,22,500 units/year for split
system. The life cycle analysis has been also done for useful life of 10 years for split units and 12
years for VRF units.The aim is to create thermally controlled environment within the space of a
building envelope by designing and planning a HVAC system for the project with the objective
that the system designed and built is cost-wise economical, energy efficient as well as simple,
flexible with regard to its operation, maintenance. This document mentions the codes, standards
and criteria that will generally be used in the design and constructions of HVAC system for this
project.
Key words : HVAC System, VRF System, Life Cycle Analysis.
1. Introduction
Heating, ventilation, and air conditioning
(HVAC) is the technology of indoor and vehicular
environmental comfort. Its goal is to provide thermal
comfort and acceptable indoor air quality. HVAC
system design is a sub discipline of mechanical
engineering, based on the principles of thermo-
dynamics, fluid mechanics, and transfer.
Refrigeration is sometimes added to the field's
abbreviation as HVAC & R or HVACR, or ventilating
is dropped as in HACR (such as the designation of
HACR-rated circuit breakers).
The primary function of all air-conditioning
systems is to provide thermal comfort for building
occupants. There are a wide range of air conditioning
systems available, staring from the basic window-
fitted unit to the small split systems, medium scale
Invertis Journal of Renewable Energy, Vol. 7, No. 3, 2017 ; pp. 1-6
package units, large chilled water systems and very
latest variable refrigerant flow (VRF) system.
Split type air conditioning systems are one to one
system consisting of one evaporator (fan coil) unit
connected to an external condensing unit. Both the
indoor and outdoor unit are connected through
copper tubing and electrical cabling.
The indoor part (evaporator) pulls heat out from
the surrounding air while the outdoor condensing
unit transfers the heat into the environment.
The advantages of split systems are :
• Low initial cost, less noise and ease of
installation;
• Good alternative to ducted systems;
• Each system is totally independent and has
its own control.
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Md. Khurshid Alam and Shah Alam
Apart from this there are several disadvantages
of this system given as :
• There is limitation on the distance between
the indoor and outdoor unit i.e. refrigerant
piping can't exceed the limits stipulated by
the manufacturer (usually 100 to 150 ft)
otherwise the performance will suffer;
• Maintenance (cleaning/change of filters) is
within the occupied space;
• Limited air throw, which can lead to possible
hot/cold spots;
• Impact on building aesthetics of large
building because too many outdoor units will
spoil the appearance of the building.
VRF System : The term VRF refers to the ability
of the system to control the amount of refrigerant
flowing to each of the evaporators, enabling the use
of many evaporators of differing capacities and
configurations, individualized comfort control,
simultaneous heating and cooling in different zones,
and heat recovery from one zone to another. VRF
systems operate on the direct expansion (DX)
principle meaning that heat is transferred to or from
the space directly by circulating refrigerant to
evaporators located near or within the conditioned
space. Refrigerant flow control is the key to many
advantages as well as the major technical challenge
of VRF systems.
Note the term VRF systems should not be
confused with the centralized VAV (variable air
volume) systems, which work by varying the air flow
to the conditioned space on variation in room loads.
2. Literature Review
Roth et al. (2002)[1] had presented the paper on
VRF installed costs are highly dependent on the
application, construction and lay out of the building
and whether the installation is new or retrofit. Lack
of familiarity with the technology in the U.S will add
to VRF costs. Total costs of VRF systems are likely to
be about 5% to 20% higher than chilled water systems
of similar capacity. Hai, Xiaohong (2006 )[2] et al. had
discussed an effective method to combine the ice-
storage technology with VRV system in commercial
central air conditioning system and the system has
the merits of flexible controls, simple operation and
compact construction, which need not the big space
and difficult construction like the big central ice-
storage system.
William Goetzler (2007)[3] et al. had presented the
paper on VRF systems are not suitable for all
commercial building applications. However, they are
an excellent option for certain projects, and one more
tool for engineers to consider. Johnson (2007)[4] et al.
had presented the paper on Ozone depletion issues
became an increasing concern at that time issues of a
high refrigerant charge of multi split system was
likely a strong negative for the system. Since that time,
refrigerant developments, advances in charge
management, control and inverter technology
Increasing market acceptance of VRF technology.
Morton Blatt, (2008)[5] et al. had presented It observed
to VRF systems are enhanced versions of ductless
multi-split systems. VRF systems are very popular
in Asia and support from major U.S. Main impact of
this system on the electric utility, application
recommendations and technology attributes. John
Rogers, (2008)[6] et al. had presented this paper
reviews The India Low Carbon Growth study is
developing a bottom-up model that covers the
electricity supply, residential, nonresidential
buildings, transport, industry, and agricultural
sectors. In heating/cooling includes like electric water
heater, air cooler, fans, air conditioning. It can be seen
that by 2031 the difference amounts to 135,240 GWh/
year, equivalent to the total output of approximately
thirty eight 500 MW power stations. Qiu Tu (2010)[7]
et al. had presented the paper on the heating control
strategy is key technology for stable and reliable
heating operation of variable refrigerant flow air
conditioning system with multi-module outdoor
units. Li and Wu (2010)[8] et al. had presented the
paper on the heat recovery VRF system can save up
to 17% of the energy consumption compared to a heat
pump VRF system set up. This heat recovery VRF
system offered an additional advantage that it can
provide cooling and heating for different zones at the
same time. Tolga N. Aynur (2010)[9] et al. had
presented the paper on VRF system to control
refrigerant mass flow rate according to cooling and
heating load. This detailed review indicates that the
researchers focus on three main subjects: (a) Control
strategies of the A Review of a HVAC With VRF
System (IJIRST/ Volume 1 / Issue 10 / 003) All rights

3. Life cycle analysis of multi-split Variable Refrigerant Flow (VRF) system : case study
3
reserved by www.ijirst.org.Jignesh M.B. [10] has
designed HVAC System foa a commercial building.
3. Methodology
In this analysis we have taken first floor of a
building located in A. M. U. Aligarh (U.P.). The area
of building is 18327 square feet. First we got the plan
of building. With the help of plan we have calculated
all dimensions like length width of each wall,
partition wall, window, floor area. Then according
to the climate of AMU U.P., we select recommended
outdoor condition with the help of Weather Data
Handbook published by ISHRAE carrier hand book.
We get all the specification such as height of walls,
glasses and ceiling height from architecture drawing
and calculated the area of all walls, partition walls
and windows, of conference room which we can get
fresh air, Dehumidified air and TR. On the basis of
cooling load we have selected air conditioning system.
Basis of Design
Ambient Summer
Conditions : DBT 110°F (43.3°C)
WBT 75°F (23.9°C)
RH 60%
Ambient Monsoon
Conditions : DBT 95°F (35.0°C)
WBT 83°F (28.3°C)
RH 88%
Indoor Temperature : 73 ± 2°F in Office and 74 ± 2°F
in Lift Lobby & Entrance Hall
etc.
RH : RH may exceed 65% in peak
monsoon. Monsoon Reheat is
not considered hence humidity
may increase up to 65-70%
during peak monsoon.
Occupancy : 80 Sq.ft per person in office at
chargeable area, chargeable
area is 22% more than air
conditioned area, 125 Sq.ft per
person in entrance lobby,
Equipment Load : 3.5 W/sq.ft in Office area
Lighting Load : 1.25 W/ft² in Office, 1.25 W/ft²
in Lobby
Fresh Air : As per ASHRAE standard 62.1-
2007 (5 CFM per person+0.06
cfm/sqft) + 30 % higher to meet
LEED requirement for Office
area, lobbies
Design Requirements
It is often a practice to design an Air Conditioning
system for peak load conditions.
However, the average usage of an Air
Conditioning system during a year is between 65%
to 75%
Hence, the proposed system to be adopted for
this project will be planned & selected for
Lowest capital cost.
Flexibility to shut down in the areas that are not
in use
Energy efficiency
Minimum Outdoor unit
The Heat Load of Conference Room is given
below :
Table 1. Heat load calculation

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Md. Khurshid Alam and Shah Alam

5. Life cycle analysis of multi-split Variable Refrigerant Flow (VRF) system : case study
5
The layout of building floor is as given below:
Life Cycle Analysis :
Fig. 1. HVAC layout of first floor of building
(Based on 2500 Hours per year)
VRV System Air Cooled Split Units
1. Total Installed Load 120 TR 130 TR
2. Repair & Maintenance cost per Year 3,50,000/- 2,45,000/-
3 Power consumption/Hour (KWH) 132 Units 169 Units
(@ 1.1 KW per Ton) (@ 1.3 KW per Ton)
4 Total Power consumption (Units Per Year) 3,30,000 Unit 4,22,500 Unit
5 Cost @ Rs 8/- per Unit in one Year 26,40,000/- 33,80,000/-
Total running cost including Maintenance in 1 Years 29,90,000/- 36,25,000/-
9. Difference in running cost/Year -- Approx.6,35,000/-
10 Installation cost Approx. 79.2 Lacs Approx. 52.8 Lacs
11 Difference in Installation cost -- Approx. 26.4 Lacs
Pay Back Period (Using VRV System) Around 4.2 Years
LIFE CYCLE 12 YEARS 10 YEARS

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Md. Khurshid Alam and Shah Alam
Life Cycle Analysis using Annual Cost Analysis method :
C= M+E+I / (P/S, i %, n) – S/ (F/S, i %, n).
F/S = (1+i)n–1, P/S= (1+i)n–1/ i(1+i)n,
Option Installation Maintanance Electric Intrest Year Annual
(Lac) (Lac) consumption (Lac) rate (Lac) expenses (Lac)
SPLIT 52.8 2.45 33.8 0.085 10 42.61193
VRF 79.2 3.5 26.4 0.085 12 0.638348
4. Conclusions
Based on comparative analysis of alternative with
operating cost and life cycle cost, a VRF (variable
refrigerant flow) system is selected for a particular
project of 149.5 TR.
Codes and Standards
NBC - National Building Code
ASHRAE - American Society of Heating,
Refrigeration and Air-Conditioning
Engineers.
ARI - Air-conditioning and Refrigeration
Institute
NFPA - National Fire Protection Association
UL - Underwriters' Laboratories
AMCA - Air Movement and Control
Association
References
[12] Khalil MAK, "Non-CO2 greenhouse gases in
the atmosphere", Annu Rev Energy Environ,
24, (1999) 645-61.
[1] Roth Kurt, et al. "Energy consumption
characteristics of commercial building HVAC
system volume III: energy saving potential"
TIAX LLC FOR DOE, 2002 www.eere.gov/
b u i l d i n g / i n f o / d o c u m e n t s / p d f s /
hvacvolume2finalreport.pdf.
[2] Hai Xiaohong, Tao Zhang, Yun Fanhua and
Jun Shen, "Design and Research of the
Commercial Digital VRV Multi-Connected
Units With Sub-Cooled Ice Storage System"
(2006). International Refrigeration and Air
Conditioning Conference. Paper 759. http://
docs.lib.purdue.edu/iracc/759.
[3] William Goetzler, Member ASHRAE,
ASHRAE Journal, April 2007.
[4] Johnson Spellman" ASHRAE headquarters
building renovation, mechanicals narrative"
June26, 2007. http;//images.ashrae.biz/
renovation/documents/o6js22_mech_design_
narrative_permit%20set_2.pdf.
[5] Ammi Amarnath, "Variable Refrigerant Flow:
An Emerging Air Conditioner and Heat Pump
Technology" Electric Power Research Institute.
Morton Blatt, Energy Utilization Consultant
2008, ACEEE Summer Study on Energy
Efficiency in Buildings.
[6] John rogers, "Residential Consumption of
Electricity in India” Background Paper India:
Strategies for Low Carbon Growth, July 2008
The World Bank.
[7] Qiu Tua b, Ziping Fenga b, Shoubo Maoc,
Kaijun Donga b, Rui Xiaoa b and Wenji
Songa, "Heating control strategy for variable
refrigerant flow air conditioning system with
multi-module outdoor units" Guangzhou
Institute of Energy Conversion, Chinese
Academy of Science, Guangzhou 510640, China
b Key Laboratory of Renewable Energy and
Gas Hydrate, Chinese Academy of Science,
Guangzhou 510640, China c Haier Air-
Conditioning Electronic Co. LTD., Qingdao
266510, China
[8] Li Y.M., Wu J.Y. and Shiochi S., "Experimental
validation of the simulation module of the
water-cooled variable refrigerant flow system
under cooling operation", Applied Energy, 87,
(2010) 1513-1521.
[9] Tolga N. Aynur, "Variable refrigerant flow
systems: A review", Center for Environmental
Energy Engineering, Department of
Mechanical Engineering, University of
Maryland, 3157 Glenn Martin Hall Building,
College Park, MD 20742, USA.