TECHNO-ECONOMIC AND ENVIRONMENTAL VIABILITY OF RETROFITTING … · 2020-02-01 · VIABILITY OF...

http://www.iaeme.com/IJMET/index.asp 527 [email protected]

International Journal of Mechanical Engineering and Technology (IJMET)

Volume 10, Issue 12, December 2019, pp. 527-540, Article ID: IJMET_10_12_050

Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=12

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication

TECHNO-ECONOMIC AND ENVIRONMENTAL

VIABILITY OF RETROFITTING IN PUBLIC

MULTI-STOREY BUILDINGS

Gbadega Peter A

Department of Electrical Electronic and Computer Engineering,

University of KwaZulu-Natal, King George V Avenue, Durban, 4041, South Africa

Inambao Freddie L

Department of Mechanical Engineering,

University of KwaZulu-Natal, King George V Avenue, Durban, 4041, South Africa https://orcid.org/0000-0001-9922-5434

[email protected], [email protected]

ABSTRACT

Multi-storey buildings are becoming a common feature in several campuses and

major cities in Nigeria. This study investigated the pattern of energy consumption of

an existing multi-storey building, namely, the Senate building, University of Lagos. In

this case study, the electrical facilities of the Senate building of University of Lagos

were audited with the aim of improving the energy efficiency of these facilities. The

aim of this study was to assess the pattern of energy consumption and at the same time

investigate the cost effectiveness and environmental-benefit analysis of retrofitting, in

a multi-storey building. The cost effectiveness of different lighting technology

alternatives were considered. The present lighting technology and four other energy

efficient lighting technology alternatives were compared based on their electricity use.

CO2 emissions associated with the Senate building of the University’s electricity use

would be reduced by about 10 %, if the technology alternatives that saved the most

electricity were installed. From the economic analysis point of view, T8-E and CFL

were seen to be cost-effective due their low lamp cost price and life cycle cost

compared to other lighting technology alternatives. This project recommends the

adoption of standards, energy efficiency and conservation measures to ensure

building sustainability within Universities.

Keywords: Energy consumption, cost effectiveness, energy efficiency, economic

analysis, conservation measures, lighting technology.

Cite this Article: Gbadega Peter A and Inambao Freddie L, Techno-Economic and

Environmental Viability of Retrofitting in Public Multi-Storey Buildings.

International Journal of Mechanical Engineering and Technology 10(12), 2020, pp.

527-540.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=12

Gbadega Peter A and Inambao Freddie L


1. INTRODUCTION

The most important aspect of the world is energy. Its functions include powering various

types of vehicles, heating and cooling of homes and lighting of the cities as well as many

other applications. Everything done by people is linked to energy source in one way or

another [1, 2]. Since the industrial revolution in the 18th

and19th

centuries the main source of

energy has been fossil fuels. The success of many inventions are as a result of the substantial

contribution of the various types of fossil fuels. This is mainly due to relatively high-energy

content and flexibility in how they can be used. Regrettably, fossil fuels are non-renewable

and, more significantly, owing to their emission of harmful gases to the atmosphere, they

cause pollution [3, 4]. To reduce the effect of these gases, researchers are seeking to

determine the effectiveness of alternative energy sources to meet energy demands. Thus,

renewable energy sources are being considered, harnessed and transformed into usable forms

of energy. Another way to reduce these emissions is to efficiently and effectively make use of

the available energy in order to reduce the environmental effect of energy wastage.

Consequently, it is advised that techniques for energy efficiency improvement be devised and

subsequently applied to multi-storey buildings. This can significantly reduce their energy

demands as well as their carbon footprint [5, 6]. Furthermore, improving the energy efficiency

of homes, businesses, schools, governments, and industries is one of the most constructive,

cost-effective ways to address the challenges of high energy prices, energy security and

independence, air pollution, and global climate change [7].

The most damaging environmental consequence of fossil fuel combustion is the

production of CO2, a gas which affects global heat balance, and contributes to global warming

[8, 9]. In addition to environmental consequences, the rise in energy use is expensive because

more plants need to be built to serve the loads [10, 11]. For many years, it has been suggested

that a cost effective means to reduce the amount of energy used by the human population

would be the adoption of energy efficient technologies, particularly within the industrial and

commercial sectors [10, 11]. Studies indicate that improvements in energy efficiency will

reduce local and regional energy related environmental challenges, and that the widespread

adoption of energy efficiency measures will result in significant reductions in CO2 emissions

globally [1, 4, 8]. Energy wastage is rampant in society today, hence, this study investigates

how energy can be used efficiently to reduce wastage and greenhouse gas emissions. Many

studies have been carried out on the economic viability of Energy Efficient Measures (EEM)

in developed countries. In developing countries such as Nigeria, indiscriminate energy-use

still exists even in new buildings. This is due to the ignorance of consumers and energy

providers on the advantages of EEM. Therefore, this study evaluates the cost effectiveness

and environmental benefits of applying EEM in an academic environment [12, 13]. The aim

of this study is to assess the pattern of energy consumption and at the same time investigate

the cost effectiveness and environmental-benefit analysis of retrofitting, in a multi-storey

building.

This paper is organized in the following way: section 2 is an overview of the mitigation

devices for minimizing energy consumption patterns. Section 3 describes the results and

analyses of various energy management schemes and the economic analysis of various

technologies for cost effective energy consumption. Section 4 concludes the study.

2. MITIGATION DEVICES FOR MINIMIZED ENERGY

CONSUMPTION PATTERNS

The goal of energy efficiency, energy management and energy conservation is to reduce the

consumption of energy. This is usually accomplished by means of data analysis of an energy

audit. Evaluation of energy saving measures is done by creating a list of cost-effective energy

Techno-Economic and Environmental Viability of Retrofitting in Public Multi-Storey Buildings


conservation measures and determined by using both economic analysis and energy savings

analysis [12, 14]. Firstly, a predefined list of energy efficiency and conversation schemes is

prepared, after which the energy savings due to the various energy conservation measures

related to the building are estimated [5]. The installation or initial costs needed to employ the

energy conservation measures are evaluated and the cost effectiveness of individual energy

conservation measure are explicitly assessed. Steps are then taken to minimize energy

consumption such as lighting improvements, which involves retrofitting of lamps and

utilizing of lighting control systems. Following an initial review of similar projects paying

attention to the challenges faced, execution was logically broken down to the following:

energy audit, demand side management, energy efficiency, cost-effectiveness and

environmental impact (benefits) analysis of energy efficiency measures (schemes), energy

conservation [10, 13].

2.1. Methods Adopted to Carry out the Research

For the purpose of fair presentation and clear understanding of this exercise, this subsection is

concerned with the method of collecting, classifying and processing information gathered

from a field survey. To evaluate the energy consumption pattern in a multi-storey building, a

case study of the University of Lagos Senate house is presented. A walkthrough audit was

implemented to [19, 20]:

Take note of the kind of lighting being used by the consumers.

Observe the kind of air cooling systems used in the building.

Acquire the power ratings of each equipment (theoretical values) and measure the

actual amount of power they consume (experimental value).

Evaluation of the amount of power consumed by the electrical motors (lifts) on a daily

basis in the building was carried out. The energy consumption of lifts typically represents 3%

to 8% of the total energy consumption of buildings, depending on the structure and usage of

the building, the type and the number of lifts [9-11].

2.2.1. Categorization of Rooms

Table 1 Room categories and the 20 room types identified in the energy survey

Room categories Room types

Group 1 Office

Group 2 Portal’s unit

Senate house maintenance annex

Council affairs unit

Information unit

Maintenance unit

Electronic data processing unit

Legal unit

CITS (annex)

Reconciliation unit

Student’s records annex

Enquiry unit

Group 3 Ground floor fittings

Building basement

Group 4 Expenditure control

Staircase and lobby



Group 5 Senate chamber

UNILAG radio

Conference room

Security unit

A survey of every room in the Senate building of University of Lagos was carried out to

know the number of 1.2 m fluorescent fixtures, incandescent lamps, LED lamps, cooling

technology, heating equipment etc. During the course of the survey, information about the

hours of operation of these electrical appliances were gathered. The rooms were divided into

categories, containing 20 types of room, which were identified within the study buildings as

shown on Table 1. Therefore, based on the operating hours per day, room categories 1 to 5

were defined.

2.2.2. Estimation of Electricity Consumption and Cost

Energy consumption of the light fittings is the product of the number of retrofits, power

consumption and operating hours of a lamp. The annual energy consumption or the amount of

energy consumed yearly by existing lighting technology was computed mainly for individual

room categories. The estimates are expressed as follows:

(

) (1)

Where

= The number of fixtures.

= The power used per fixture in watts.

= The number of operating hours per year [10].

The results for different fixtures were cumulated to estimate a total kWh/yr value for each

room category. The cost of the electricity used by existing fixtures was also calculated for

each of the five room categories within the buildings using Eq. (2). Electricity cost was

calculated by estimating the percentage of operating hours, demand charge and annual fixed

charge. An example of the calculation is shown below for a particular room category:

( ) *(

)+ (2)

Where

= The annual fixed charge.

= The number of operating hours per year.

= The electricity charge.

At the case study location, the peak charge is N13.61 /KWh. The total electricity costs are

multiplied by N1.3210 to account for the demand charge. The electricity consumption and

cost was calculated for four energy efficient lighting technology alternatives. These four

technology alternatives were chosen due to the fact that they are easy to install, and have the

potential to save significant amounts of energy. For each of the four alternatives, Eq. (1) was

adopted to calculate the amount of electricity consumed yearly in each category. Eq. (2) was

utilized to calculate the annual cost of the electricity utilized by individual lighting technology

alternatives in each room category.



Table 2 The four lighting technology alternatives assessed in this study [2]

Light technology Lamp

ratings

(Watt)

Lamp life

span

(Hours)

Advantages

Electronic ballast 18 7500 Rugged due to its

hard structure

CFL 8 10000 Environmentally

friendly

T8 Electronic 32 8000 cheaper

T5 21 8000 It’s more robust

Table 2 shows the four lighting technology alternatives illustrating the lamp ratings, lamp

life span and the advantages of adopting each of the technologies in the study.

2.2.3. Economic Analysis

Based on the walk-through audit (energy survey) that was carried out, an economic analysis

of the energy consumption pattern was estimated. The results obtained were used to estimate

the cost effectiveness of installing various lighting technology alternatives. In order to

actualize this, the installation cost and 20-year cash flows were calculated for individual

technology alternatives in each room category. The disposal costs, material (including

ongoing maintenance costs) and electricity costs were also considered. The 20-year time span

denotes the life cycle of 1.2 m and 2 m fluorescent lighting systems, which are the longest

lived components (ballasts). This study utilized three economic analyses techniques in order

to determine the cost effectiveness of various lighting technology alternatives, namely: cost of

conserved energy (CCE), net present value (NPV), and simple payback time (SPT) [2, 10].

2.2.3.1. Simple Payback Time

The SPT measures the amount of time required to recuperate the additional investment on

efficiency improvement through lower operating costs. SPT is the time it takes for an initial

investment to be recouped and is found by using the following equations:

(3)

(4)

Although the SPT technique is insufficient for ranking investments based on their anticipated

profitability [19], this technique was adopted due to the fact that it is still globally utilized as a

benchmark for accepting or rejecting potential investments [10, 18].

2.2.3.2. Net Present Value

The NPV technique estimates the present value of an investment n years into the future. NPV

is known as a sound technique for jointly assessing a number of investment opportunities with

different initial investment amounts and differing cash flow patterns [21]. Eq. (5) was used to

calculate the NPV:

∑ ( )

(5)

Where

= The annual cash flow in year t.

= The discount rate.



= The investment time in years.

= The initial investment amount.

The discount rate adopted in the NPV evaluations was calculated to be 8 %. This value

was selected due to the fact that it is within the rate of returns usually expected by commercial

and industrial organizations for an investment in energy efficient lighting technology [12, 16].

NPV can be mathematically expressed as:

(

) (

) (6)

(

)

( )

( ) (7)

Where

= 8 % (discount rate).

= The number of years.

2.2.3.3. Cost of Conserved Energy

The CCE analysis technique estimates the cost of conserving one-kilo-watt-hour (kWh) of

electricity. If the installation of energy efficient technology results in a CCE, which is less

than the price paid for one kWh of electricity, the project may be considered cost effective.

CCE is described in more detail in [19, 20]. Eq. 8 was used to determine the CCE that related

to a particular investment:

(

(8)

Where the change in annual maintenance cost can be either positive or negative and

annual energy saving is expressed in kWh. CRR is the capital recovery rate, and is used to

annualize the investment. CRR is expressed as:

( ) (9)

Where d is the discount rate and n is the length of the investment in years.

2.2.3.4. Life Cycle Cost

The evaluation of the cost of a system or product over its entire life span is known as life

cycle cost (LCC). Life cycle cost analysis is a method of determining the entire cost of a

structure, product, or component over its expected useful life. The cost of operating,

maintaining, and using the item is added to the purchase price. In this study, LCC was utilized

to estimate the cost of energy efficiency enhancement of the lighting system based on design

options. The LCC is the sum of investment cost (PC) and the annual operating cost (OC)

discounted over the lifetime of the product. The LCC is evaluated using Eq. (10) [17, 20]:

(10)

2.2.3.5. Energy Savings

Energy saving (ES) is the difference between energy consumption of existing (EC existing)

and retrofit lighting (EC retrofitting) a system. The following equation was used to calculate

energy savings [14, 15].

(11)



2.2.3.6. Electricity Consumption and CO2 Emissions

Carbon dioxide emissions related to the electricity consumed by existing 1.2 m and 2 m

fluorescent lighting fixtures were estimated for the whole Senate building of University of

Lagos. For these calculations, it is assumed that the generation of 1 kWh of electricity

produces 1.3 kg of carbon dioxide [18, 19]

3. RESULTS AND DISCUSSION

The site for this study was the Senate building of University of Lagos. This building was

chosen as the study site because the building serves as the heart of the institution where

various activities take place, hence the need for constant supply of electricity. More so, most

of the lighting technology installed in the building is high energy consuming (1.2 m

fluorescent lamps, incandescent lamps and a few LED lights). Generally, AC consumes a lot

of energy compared to modern technology. As a result, there is a dire need to make the

building energy efficient by installing new energy efficient technology (alternative technology

for lighting and cooling). The total energy consumption by all the facilities in the Senate

building of University of Lagos are illustrated by the pie chart in Figure 1. From Figure 1 it is

clear that the facilities that consume the bulk of the energy are cooling (36.4%) and lighting

(26.4%). The energy survey assessed that the lighting system had the greatest potential to save

electricity and reduce electricity related CO2 emissions and was assessed by comparing four

energy efficient lighting technology alternatives. The cost effectiveness of each lighting

technology alternative was estimated.

Figure 1 Pie chart illustrating the energy utilized by all the building facilities

The results of the lighting survey for the room categories are presented in Figure 2. In general,

most lighting fixtures are found in room categories 1 and 3, although room categories 2 and 4

contain most of the single lighting fixtures.



Figure 2 Annual Energy consumption by the lighting technologies

From Figure 2 CFL consumed the least energy compared to the other lighting technology

alternatives. E-ballast also consumed less energy compared to the existing lighting

technology. As a result, CFL and E-ballast are energy efficient lighting technologies which

when installed would make the building more energy efficient.

3.1. Electricity Consumption and Cost

Figure 2 shows the electricity consumption by the 1.2 me and 2 m fluorescent lights in each

room category for each lighting technology alternative. In all cases, room categories 1

(offices) and 2 (Annex and units) consume the most electricity, even though rooms in

category 3 contained the second largest number of globes. This is due to shorter operating

hours within room category 3, and indicates that operating hours is an important factor in the

electricity consumption of 1.2 m and 2 m lighting fixtures. Furthermore, it is obvious that the

CFL lighting technology alternative is by far the most energy efficient alternative.

Undiscounted life cycle costs for various lighting technology alternatives are shown in Figure

3. The costs are divided into electrical costs, initial costs and ongoing maintenance costs. It

can be seen that although ongoing maintenance costs change to some degree, initial costs

change noticeably between the lighting technology alternatives. It is worth noting that T8-E

Electronic is the only technology alternative with low initial costs. Therefore, annual cost

saving and annual electricity costs are shown for each lighting technology alternatives.

Electricity savings are calculated in kWh so that results can be easily compared with respect

to other studies.

Table 3 The electricity cost/use per year of various lighting technology alternatives

Lighting

technologies

EXISTIN

G

Million

(Naira)

CFL

Million

(Naira)

T5

Million

(Naira)

E-BALLAST

Million

(Naira)

T8 –

ELECTR

ONIC

Million

Electricity

cost/year (N)

0.862 0.395 0.826 0.554 0.944

Electricity used

(kWh/yr)

0.197 0.0089 0.188 0.126 0.216

Electricity saved

(kWh)

N/A 0.108 0.0082 0.0712 -0.019



From Table 3 it is evident that CFL has the least electricity cost/year, followed by E-

ballast; this shows that CFL serves as the best lighting technology alternative when cost of

energy-use is being considered. Electricity savings of CFL is the highest of all the lighting

technology alternatives. In view of this, it is expedient to install CFL since it is more

economical.

Figure 3 Life cycle cost for a duration of 20 years

Figure 4 Breakdown of LCC components

From Figure 3 it is evident that CFL has the least life cycle cost which makes it cheaper in

terms of operating costs for a duration of 20 years; this makes it the best lighting technology

alternative from an economic point of view.



Figure 5 Energy savings by the lighting technology alternatives

From Figure 5 it can be seen that CFL and E-ballast save the highest amount of energy

compared with other lighting technologies, therefore installing these two lighting technologies

in a typical building will makes the building more energy efficient.

3.2. Economic Analyses

The results of the economic analysis are shown in Table 4 and indicates that all of the lighting

technology alternatives assessed represent good investment choices if all room categories are

considered together, so they are all economically viable.

Table 4 The estimated net present value of the lighting

Net Present Value

Existing NPV

Million

(Naira)

Installation /Initial

Cost (Million)

Replacement

Cost (Million)

(Naira)

Maintenance

/operating

Cost (Million)

CFL 40.12 3.67 3.67 0.48

T5 55.7 5.11 5.11 0.48

E-ballast 48.16 4.42 4.42 0.48

T8-E 25.53 2.32 2.32 0.48



Figure 6 Chart showing the net present value of lighting technologies

From Figure 6 it can be seen that T8-E has the least NPV of an investment 20 years into

the future due to its low lamp price; in view of this T8-E is the most economically viable.

Figure 7 Chart showing the simple payback time

The SPT measures the amount of time needed to recover the additional investment on

efficiency improvement through lower operating costs. From the analysis, T8-E has the least

payback time, followed by T5, and CFL has the longest payback time. If we are to base our

cost-effectiveness analysis on the time the investment would pay back, then T8-E would be

the best choice to make.



Figure 8 Chart representation of CCE (C/kWh)

The above analysis shows that CFL, E-ballast and T8 are most cost effective, since the

cost of conserved energy is less than the price paid for one kWh of electricity, which is

N13.61.

Figure 9 Chart representation of CO2 emitted per year

From the analysis, CFL has the least amount of CO2 emitted per year, which means it is

the most environmentally friendly lighting technology. Figure 9 shows that more than half of

the CO2 emitted by existing technology can be avoided by the use of CFL.



Figure 10 Energy savings for cooling system

The cooling technology alternatives proposed are Panasonic (IS 85.3 W) and LG series

(188.2 W). Both technology alternatives are energy efficient based on the fact that they save

more energy which invariably reduces the energy operating cost. From Figure 10 it is evident

that LG series and Panasonic (IS) save more energy compared to the existing cooling system.

4. CONCLUSION

This work is a detailed analysis of the mitigation techniques of minimizing energy

consumption patterns. To start with, various energy management measures were investigated

critically to gain an overview and better understand the scope of energy management

schemes. After this, various economic analyses were carried out to investigate the cost

effectiveness of the various technologies proposed. From the results obtained, CFL and T8-E

are the best lighting technologies in terms of energy efficiency and cost effectiveness

measures. This project recommends the adoption of standards, energy efficiency and

conservation measures to ensure building sustainability within Universities.

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