Energy Engineering Program

National Graduate School of Engineering

University of the Philippines Diliman

RESIDENTIAL ENERGY AUDIT

The Case of the Madrid Residence

A Paper for the Course:

EgyE 211: Energy Conservation

by

Naason G. Velasco

August, 2013

2

Auditors Page

The auditor has a degree in Bachelor of Science in Chemical Engineering from Saint Louis

University. The auditor has experience in quality assurance for food manufacturing

specifically in edible oils. The auditor has also been employed in a trading company

specializing in pharmaceuticals and cosmetics. He was the Product Scientific Communication

Officer where he conducted research and development activities and relaying it to the sales

team. He also headed the Equipment and Medical Devices section of the said company as

Sales and Marketing Development Officer.

The auditor also worked for the national government at the Philippine Council for Industry,

Energy, and Emerging Technology Research and Development of the Department of Science

and Technology. He was a Science Research Specialist I at the Material Science Section of

the Emerging Technology Development Division. He provided research management

assistance to approved projects and provided Technical Panels assistance in evaluating

project proposals. He was also part of the monitoring team of several research projects

mainly based at the National Institute of Physics, University of the Philippines Diliman.

3

Executive Summary

The eminent problem in energy and climate change is the primary driver of the energy

conservation activities. The activities aim to identify energy conservation opportunities and

formulate sound policies based on energy audits.

The energy audit is conducted using a standard framework where energy cost centers are

identified and simulated. The computed energy consumption where then compared to actual

consumptions based on electric bills. Cost centers where then rank to identify major

contributors. Energy conservation measures were then identified with these cost centers. The

carbon footprint for each process where also identified. The effectiveness of the conservation

measures where measured by different econometrics.

The house has energy intensity of 3696.3 MJ/person and 169.94 MJ/m2 on annual basis. The

major contributors of energy consumption for the area of the study are air conditioning,

refrigeration, lighting and data processing. The energy conservation measures resulted in

135.5664 kWh avoided energy per year that corresponds to 172.9827 lbs of avoided carbon

dioxide emissions per year and yearly savings of P 1,533.26. All of the energy conservation

measures passed the econometrics.

4

Table of Contents

Auditors Page .. 2 Executive Summary . 3 Section 1 Introduction ... 5 Section 2 Methodology . 7 Section 3 Energy Data Gathered . 12 Section 4 Energy and Environmental Analysis ... 16 Section 5 Energy Conservation Measures ... 18 Section 6 Energy Management Plan ... 22 Conclusions and Recommendation 23 References .. 24 Appendix 25

5

Section 1 Introduction

The objectives of the audit are as follows:

Identify energy conservation opportunities

Minimize energy consumption without jeopardizing safety and comfort

Minimize carbon footprint

Evaluate economic feasibility of each energy conservation measures

The area of study is the Unit A of Madrid Residences located in the map below

captured via Google Maps.

Figure 1.1: Location of the Madrid residence within Malanday, Marikina City

Unit A of Madrid Residences is located at the most eastern side of the apartment

building shown in Figure 1.2 below.

Figure 1.2: Location of Unit A within the apartment building

Unit G Unit F Unit E

Unit A Area of Study

6

The apartment unit has two (2) floors and an attic. The layout of the house is

presented in the figures below.

(a) (b) (c)

Figure 1.3: (a) 1st floor; (b) 2

nd floor; (c) attic

The first floor has 27 square meters in area while the second floor and the attic has 30

square meters in area. It should be noted that the air conditioner has been installed at BR 1.

There are 2 adults and 2 children occupying the said apartment unit. The 2 adults occupy the

air-conditioned bedroom. All of the occupants typically leave the house at 8 a.m. for work or

school and they come back at 4 p.m. They occupied the said unit since late 2010.

The materials of construction are similar with normal concrete apartment buildings.

Table 1.1: Materials of Construction

MOC

Roof galvanized iron

Ceiling plywood

Walls painted concrete

Floor tiled concrete

Windows single glass

Doors wood

All of the energy cost centers are appliances and are listed in Section 3 of the paper.

T & B

Terrace

BR 1

BR 2

T & B

7

Section 2 Methodology

The audit conducted is functional as it is expected with residential audits. The audit

was conducted on walk-through basis but developed into energy survey and analysis when

the owner of the house became more comfortable on the process. The data gathering however

was still difficult as the owner of the unit was hesitant in giving information. Several

assumptions were then made while doing the audit, which will be discussed in the succeeding

sections.

The building envelope audit was done very conservatively and assumptions such as

desired room temperature and temperature of rooms affected in the computations were also

assumed.

Figure 2.1: Flowchart of the energy audit

The system boundary was defined and the area of study was delineated. The

dimensions of the house, materials of construction, appliance list, hours of operation, and bill

data were gathered. R-values, area and wattage were then identified to be used in modeling.

For modeling, the following equations were utilized:

Set system boundary

Data gathering

Modeling

Validation of model

Implementation

Forecasting

MOC Appliance

Electric bill

R-values Wattage Actual

Consumption Energy Cost

Centers Computed

Consumption

Corrected Computed

Consumption Conservation Policies

Savings

Area of study Energy balance

Computed and actual

Consumption

Current Consumption

Forecasted Consumption

(with or without conservation)

8

Computed Monthly Power Consumption

where:

P - calculated monthly power consumption in kWh

Pi - monthly power consumption for each process in kWh

n - number of processes

where:

Pi - monthly power consumption for each process in kWh

pi - monthly power consumption for each appliance in kWh

n - number of appliances for each process

In computing for the monthly power consumption, the power company MERALCO

provides an easy to use appliance calculator that involves inputting the type of appliance,

wattage, number of hours used per day, number of days per week, and number of week per

month. The appliance calculator will give an estimate of monthly consumption for each

appliance.

The formula used by MERALCO appliance calculator in estimating monthly power

consumption for each appliance has been utilized in this energy audit because of its

simplicity and its compatibility with the gathered data.

Air Conditioning

where:

pAC - monthly power consumption for air conditioning in kWh

WAC - power rating of air conditioning unit in watts (W)

HAC - number of hours of air conditioning per month

Refrigeration

9

where:

pR - monthly power consumption for refrigeration in kWh

WR - power rating of refrigeration unit in watts (W)

HR - number of hours of refrigeration per month

Other Appliances

where:

pO - monthly power consumption for other appliances in kWh

WO - power rating of other appliances in watts (W)

HO - number of hours the other appliances were used per month

For the computation of cooling load the figure below is considered:

Figure 2.2: Layout of 2

nd floor with adjacent unit

It was assumed that 30 C was the outside temperature and the temperature inside the

house is 27 C while the desired temperature of the room to be air-conditioned is 24 C. The

heat gained by the building envelope was then computed using the standard equation for heat

conduction

. The effects of convective-radiative heat transfer were accounted by

integrating the convective-radiative R-values in the equation. The internal heat gains were

also computed accounting appliances and persons occupying the air-conditioned room.

In determining the carbon footprint, the carbon emissions were computed using the

Philippine Power Mix for 2010 provided by the Department of Energy as basis. After

24 C

27 C

27 C

30 C

27 C

3 m

3 m

10

determining the national average carbon emission per MWh of electricity (1276 lbs/MWh),

the carbon emissions of the house was then computed. The same basis was also used in

computing for the avoided carbon emissions for each energy conservation measures.

Table 2.1: Carbon Emissions by Energy Source

Source GWh MWh lbs CO2/MWh CO2, lbs

oil 7101 7101000 1672 11872872000

hydro 7803 7803000 0 0

geothermal 9929 9929000 0 0

coal 23301 23301000 2249 52403949000

other RE 90 90000 0 0

natural gas 19518 19518000 1135 22152930000

Total

67742000

86429751000

The model was validated by comparing to the actual energy consumption, which was

determined by averaging monthly consumptions based on MERALCO metering.

Using Pareto analysis, the major energy consuming centers that consume 80% of the

total consumption were determined. Energy conservation measures were then provided for

each process basing on the cause-effect diagram. Energy avoided, carbon emissions avoided,

and cost savings were then identified for each process. Each energy conservation measures

were evaluated using economic analysis of energy systems. Several equations were used in

the process.

Simple Payback Period

where:

IC initial capital cost AES annual energy savings Pr price of energy

Return on Investment

Cost of Conserved Energy

11

where:

CRF capital recovery factor

O&M cost of operations and maintenance

Present Value Savings

where

UPVF uniform present value factor

Net Present Value

Benefit-Cost Ratio

For an energy conservation measure to be acceptable SPP should be lesser than n,

CCE should be lesser than Pr, PVS should be greater than IC, NPV should be greater than

zero, and B/C should be greater than 1.

Section 3 Energy Data Gathered

12

Electric Bills

Figure 3.1: Printed bills of Unit A

Figure 3.2: Billing history of Unit A (MERALCO)

Materials of Construction

13

Table 3.1: Materials of Construction of Unit A

MOC

Roof galvanized iron

Ceiling plywood

Walls painted concrete

Floor tiled concrete

Windows single glass

Doors wood

Occupancy

Entire house: 4 persons

Air-conditioned room: 2 persons

Energy Cost Centers

Table 3.2: Ventilation and Airconditioning

Energy Cost

Centers Quantity

Brand/

Type/

Model

Power

Rating

(W)

Usage

(hrs/mo)

Consumption

(kWh/mo) Total

VAC

154.326

Aircon 1

Carrier

(window) 855 180 129.276

Electric

fan1 1 Mikata 65 150 9.75

Electric

fan2 1 Mikata 65 180 11.7

Exhaust

fan 2 Standard 30 60 3.6

Table 3.3: Lighting

14

Energy Cost

Centers Quantity

Brand/

Type/

Model

Power

Rating

(W)

Usage

(hrs/mo)

Consumption

(kWh/mo) Total

Lighting

36.076

CFL1 5 Philips 5 150 3.75

CFL2 1 Osram 20 360 7.2

LED1 1 Landlite 4 4 0.016

CFL3 1 Osram 23 210 4.83

CFL4 1 Osram 23 60 1.38

CFL5 1 Osram 23 270 6.21

LED2 1 Omni 0.5 180 0.09

CFL6 8 Osram 20 45 7.2

CFL7 1 Osram 20 270 5.4

Table 3.4: Entertainment

Energy Cost

Center Quantity

Brand/

Type/

Model

Power

Rating

(W)

Usage

(hrs/mo)

Consumption

(kWh/mo) Total

Entertainment

21.42

TV1 1

Devant

40" LCD 115 120 13.8

TV2 1 TCL

32" LCD 95 60 5.7

Cable Box 2 Cignal 8 120 1.92

Table 3.5: Communications and Data Processing

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Energy Cost

Center Quantity

Brand/

Type/

Model

Power

Rating

(W)

Usage

(hrs/mo)

Consumption

(kWh/mo) Total

Communications

0.375

mobile

phone 5 assorted 5 15 0.375

Data

Processing 32.7

desktop 1 - 200 150 30

broadband

modem 1 Globe 18 150 2.7

Table 3.6: Laundry and Refrigeration

Energy Cost

Center Quantity

Brand/

Type/

Model

Power

Rating

(W)

Usage

(hrs/mo)

Consumption

(kWh/mo) Total

Laundry

11.62

washing

machine 1 Sharp 380 24 9.12

flat iron 1

Fine

Elements 500 5 2.5

Refrigeration

65.1

ref1 1 National 85 720 35.7

ref2 1 Sanyo 70 720 29.4

Table 3.7: Cooking and Beautification

Energy Cost

Center Quantity

Brand/

Type/

Model

Power

Rating

(W)

Usage

(hrs/mo)

Consumption

(kWh/mo) Total

Cooking

23.775

rice cooker 1 Carribean 700 30 21

electric

kettle 1

Kyowa

1.7L 1850 1.5 2.775

Beautification

12

blow dryer 1

Fuller

Home 1200 10 12

Section 4 Energy and Environmental Analysis

16

Current House Profile

Energy Per Occupant: 3696.3 MJ/person (annual basis)

Energy Per Area: 169.94 MJ/m2 (annual basis)

Table 4.1: Actual Energy Consumption and Carbon Emissions

Year Energy, kWh/yr CO2, lbs/yr

2011 3432 4379.232

2012 4019 5128.249

2013 4107 5240.532

The energy consumptions are based on Meralco bill of Unit A. The carbon emissions

were computed for each year using 1,276 lbs/MWh as basis (as per 2010 Philippine Power

Mix).

Table 4.2: Computed Energy Consumption per Process

Process Consumption

(kWh/mo)

VAC 154.326

Refrigeration 65.100

Lighting 36.076

Data Processing 32.700

Cooking 23.775

Entertainment 21.420

Beautification 12.000

Laundry 11.620

Communications 0.375

Total 357.392

The computed monthly energy consumption is 4.424% overestimation of the actual

monthly energy consumption. Since the difference between estimated and actual

consumption is less than 5%, the computed consumption was then accepted.

Table 4.3: Building Envelope Heat Gain

17

Area,

ft2

MOC R-value,

h.ft2.F/Btu

Toutside, F Tinside, F Q, Btu/h Q, W

north

wall 100.98

painted

concrete 1.96 86.00 75.2 556.42 163.07

south

wall 112.98

painted

concrete 1.96 80.60 75.2 311.27 91.23

east

wall 91.98

painted

concrete 1.96 80.60 75.2 253.41 74.27

west

wall 112.98

painted

concrete 1.96 80.60 75.2 311.27 91.23

floor

(2nd) 96.84

tiled

concrete 2.01 80.60 75.2 260.17 76.25

floor

(attic) 96.84

tiled

concrete 2.01 80.60 75.2 260.17 76.25

window 12.00 single

glass 0.91 86.00 75.2 142.42 41.74

door 21.00 wood 2.17 80.60 75.2 52.26 15.32

Total 2147.39 629.34

It should be noted that most of the heat gained through the building envelope was

from the north wall because it is the only wall exposed to the outside environment. The

window is also located on the north wall.

Table 4.4: Internal Heat Gains

Appliances

Q, W

light bulbs 2.50

TV 7.92

Occupants

2 adults 47.62

Total

58.04

The cooling load is 687.39 W.

Section 5 Energy Conservation Measures

18

Pareto Analysis

Figure 5.1: Pareto diagram

The processes that encompassed the 20%-80% criterion were air-conditioning,

refrigeration, lighting, and data processing.

Cause and Effect Analysis

Figure 5.2: Ishikawa diagram for air-conditioning

0

10

20

30

40

50

60

70

80

90

100

0

50

100

150

200

250

300

350

kW

h

Monthly Consumption

19

Figure 5.3: Ishikawa diagram for refrigeration

Figure 5.4: Ishikawa diagram for lighting

Figure 5.5: Ishikawa diagram for data processing

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Energy Conservation Measures

Air-conditioning

As it is imperative that the construction materials and layout of the room that is

affected should not be altered, the easiest way to conserve energy when using air-conditioned

is to install blinds on windows. Blinds add insulation (R-value = 0.29 h.ft2.F/Btu) to the

building envelope decreasing energy consumption.

Conservation Measure: Install blinds

Current: 41.74 W (Qwindow)

After conservation measure: 31.65 W (Qwindow)

Energy avoided: 1.8162 kWh per month

CO2 avoided: 2.3175 lbs per month (Basis: 1276 lbs per MWh national average) Cost Savings: P 20.54 per month (Basis: P 11.31 - Meralco rate)

Refrigeration

Clean the condenser coils at the back or underneath the fridge or freezer 2-3 times a

year as dust and dirt causes the fridge to work harder and run for longer cycles. The energy

consumption can be reduced by 6% per year.

Conservation Measure: Clean condenser coils thrice a year.

Current: 65.1 kWh per month = 781.2 kWh per year

After conservation measure: 734.328 kWh per year

Energy avoided: 3.906 kWh per month

CO2 avoided: 4.9841 lbs per month (Basis: 1276 lbs per MWh national average) Cost Savings: P 44.18 per month (Basis: P 11.31 - Meralco rate)

Lighting

Most exhaustive: CFL6 (20 W) = 7.2 kWh w/ 1100 lm

Conservation Measure: Replace CFL6 with 25 W LED (1800 lm)

8 CFL6 = 5 LED

Energy avoided: 1.575 kWh per month

CO2 avoided: 2.0097 lbs per month (Basis: 1276 lbs per MWh national average) Cost savings: P 17.81 per month (Basis: P 11.31 - Meralco rate)

Data Processing

There is a power surge when turning on computer but this is very minimal as

compared to running computer when not needed. It should also be noted that screen savers

are not energy savers. It is recommended then to do the following:

Turn off the monitor if not using PC for more than 20 minutes.

Turn off both the CPU and monitor if not using PC for more than 2 hours.

The Labour Department of Hong Kong recommends taking 15-minute breaks

between 1-2 hours of continuous computer work to avoid eyestrain. It is therefore assumed

21

that the user of computer in the household takes 20-30 minute breaks for every 2 hours in the

span of his/her usage.

Conservation Measure: Turn off monitor when not using for 20 minutes or above.

Current: 30 kWh per month

After conservation measure: 26 kWh per month

Energy avoided: 4 kWh per month

CO2 avoided: 5.1040 lbs per month (Basis: 1276 lbs per MWh national average) Cost Savings: P 45.24 per month (Basis: P 11.31 - Meralco rate)

Econometrics

Table 5.1: Econometrics

Process IC,

Php

O&M,

Php

AESxPr,

Php/yr

SPP,

yr ROI CRF

CCE,

Php/kWh UPVF PVS NPV B/C Remarks

Airconditioning 750.00 0.00 246.49 3.04 32.87 0.15 5.13 6.71 1653.97 903.97 2.21 ok

Refrigeration 0.00 0.00 530.12 0.00 infinite 0.15 0.00 6.71 3557.15 3557.15 infinite very ok

Lighting 1000.00 0.00 213.76 4.68 21.38 0.15 7.89 6.71 1434.35 434.35 1.43 ok

Data

Processing 0.00 0.00 542.88 0.00 infinite 0.15 0.00 6.71 3642.77 3642.77 infinite very ok

Projection

Figure 5.6: Projected monthly average consumption on or before conservation

To establish baseline, the annual average monthly consumption for the 3 succeeding

years were projected using two period moving average method.

0

50

100

150

200

250

300

350

400

2010 2011 2012 2013 2014 2015 2016 2017

kW

h

Projected Average Monthly Consumption

Baseline

After Conservation

22

Section 6 Energy Management Plan

The energy conservation measures were drafted with the consideration that no

changes on the structure of the house will be made. The resulting energy conservation

measures can be implemented immediately. The blinds can be purchased and installed within

a day so as replacing the concerned light bulbs to LED. Cleaning of refrigeration should be

scheduled every 4 months. The energy conservation measure for data processing is a

behavioral change.

23

Conclusions and Recommendation

The area of study is a apartment unit with 4 occupants. Their average monthly

consumption is 342.25 kWh per month. The biggest contributor to energy consumption is air-

conditioning. The energy savings per process is presented in the table below:

per month per year

Process

Energy

avoided,

kWh

CO2

avoided,

lbs

Cost

Savings,

Php

Energy

avoided,

kWh

CO2

avoided,

lbs

Cost

Savings,

Php

Airconditioning 1.8162 2.3175 20.54 21.7944 27.8097 246.49

Refrigeration 3.9060 4.9841 44.18 46.8720 59.8087 530.12

Lighting 1.5750 2.0097 17.81 18.9000 24.1164 213.76

Data Processing 4.0000 5.1040 45.24 48.0000 61.2480 542.88

Total 11.2972 14.4152 127.77 135.5664 172.9827 1533.26

All of the energy conservation measures are cost effective.

For future studies, it is recommended to use survey equipment e.g. lux meter,

wattmeter if it is permissible. The predicted model would be more accurate and energy

conservation measures can be easily drafted and energy savings can be easily computed.

24

References

Occupational Safety and Health Branch (2010). A Guide to Work with Computers. Labour

Department, Hong Kong.

Randolph, J. and Masters, G. M. (2008). Energy for Sustainability: Technology, Planning,

Policy. USA: Island Press.

Websites:

https://e-services.meralco.com.ph/cmsweb/billing/billslist.jsp

http://energy.gov/energysaver/articles/energy-efficient-computer-use

http://energy.gov/energysaver/articles/tips-kitchen-appliances

http://www.allwallsystem.com/design/RValueTable.html

http://www.horizonservicesinc.com/reference/tips-articles/refrigerator-maintenance-save-

energy

http://www.meralco.com.ph/appcal/formula.html

25

Appendix Sample Computations

Heat Transfer through North Wall

Outside temperature = 86 Inside temperature = 75.2

Cost of Conserved Energy for Air-conditioning

d = 8%

n = 10 years

IC = P 750.00

O&M = P 0.00

AES = 21.7944 kWh

Since 5.13 Php/kWh is lesser than current energy price (11.31 Php/kWh), energy

conservation measure is cost effective.