Energy Saving Potential Due to Refurbishment of Federal Public Housing in the UAE

doi:10.4236/eng.2013.51B024

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Engineering, 2013, 5, 132-136

doi:10.4236/eng.2013.51b024 Published Online January 2013 (http://www.SciRP.org/journal/eng)

Energy Saving Potential Due to Refurbishment of Federal

Public Housing in the UAE

Wafa AlAwadhi1, Athari AlNaqbi1, Abeer Manneh1, Ayoub Kazim2, Bassam Abu-Hijleh1

1Faculty of Engineering & I T, The British Universit y in Dubai, D ubai -U AE

2Duba i Inte rnational Academic City, Education Cluster, TECOM Investments, Dubai-U AE

Email: bassa [email protected]

Received 2013

Abstract

This paper, computer energy modeling is used to estimate the potential energy savings of refurbishing existing public

federal housing in the United Arab Emirates. Suc h houses are built by the UAE Ministry of P ublic Works (MoPW) in

five of the seven emirates that make up the UAE federation. T he energy modeling was performed using the Integrated

Environmental Solutions-Virtual Environment (IES-VE) commercial software. The study covered representative

MoPW houses built in the period of 1974-2012. The results indicate po tential ener g y savings upto 30.8% for the case of

model 717 when refurbished to 2 Pearls standards compared to the as built configuration. T he results sho wed little ben-

efit in going from 1 Pearl to 2 Pearls refurbishment level. Thus 1 Pearl seems to be the most practical. This shows the

high potential for energy, and thus environmental, savings should refurbishment be carried out on the homes built by

the MoPW.

Keywords: en ergy m odeling, energy savings , refurbis hment, UAE

1. Introduction

Sustainability features prominently in the UAE’s 2021

vision. T his incl ude s increased det er mina tio n in t he U A E

to reduce CO2 emissions as part of the global effort to

reduce greenhouse gases and mitigate global warming

effects. Although the focus has been on developing and

expanding the use of renewable energy resources, reduc-

ing energy consumption per capita is also an important

aspect. The built environment has been identified as one

of the highest energy consumption sectors in the UAE,

and thus CO2 producers. The focus until now has b een

on regulations for new buildings. As a young country,

UAE compulsory building regulations relating to energy

savings and conservation were introduced only in the

past decade (2003 in Dubai and 2007 in Abu Dhabi).

This means that e ven if all ne w build ings are to ad here to

significantly high energy conservation standards, the

UAE will still have a large stock of buildings, some just

completed, which have excessive cooling loads and thus

are not environmentally friendly. This can be seen from

the data that shows the UAE to have one of the highest

electricity consumption per capita in the world. This re-

flects negatively on the CO2 emissions as the UAE has

the 2nd hi g he st CO2 emi ssions per capita in the world. If

the UAE is to significantly reduce its CO2 footprint the

inefficiencies of the existing building stock needs to be

addr essed.

This paper presents the result of a computer energy mod-

eling study designed to assess the potential energy sav-

ings of refurbishing existing buildings in the UAE. In

particular, public housing buildings built by the UAE

Mini stry of P ub li c W o rks (M oP W ) . The M oP W ha s b ee n

build ing suc h public housing since 1974 and until today.

The existence of detailed data regarding the number and

the construc tion detail s of suc h b uildings mad e them idea

for this study. The study will look at the energy con-

sumption of a representative building in each decade and

see the level of energy reduction that can be achieved

using different refurbishment practices, e.g. extra insula-

tion and changing the gl az ing.

2. Literature Review

The built environment is responsible for approximately

40% of the total primary energy consumption [1]. Al-

though most of the new regulations focus on new build-

ings to be constructed, these new buildings add around

0.5-2% to the total building stock, depending on the type

and the regional economic conditions [2 and 3]. This

means that even if all new buildings have zero CO2

W. ALAWADHI ET AL.

133

emissions, the older inefficient building stock will cause

the CO2 emission levels to remain unacceptably high.

Thus r efurb ish me nt of e xisti ng build ings see ms to be the

most practical way of reducing CO2 emissions in the

short to medium term [4]. T he matur ity of refurbishment

technologies, practices and relatively low costs, makes

refurbishment a better choice for reducing CO2 emis-

sions compared to using more active, and expensive,

renewable energy strategies to meet the high demand of

inefficient build ings. Ma ny studies have b een conducted,

in different countries, to assess the potential and needs

for refurbishment of existing buildings [3, 5-8]. The

scope of these studies covered the environmental, social

and economic aspects of the refurbishment process. In all

cases, the results clearly showed the benefits of refur-

bishing older buildings. The scope of the refurbishment

process is strongly dependent on the age of the building,

building technologies employed in the original build,

building materials used as well as the local climatic con-

ditions and e nvironmental regulation s.

As a young country, the UAE has been late in imple-

menting energy conservation regulations for buildings.

These regulations started with the 2003 Decree 66 in

which Dubai Municipality started enforcing the use of

energy saving practices, i.e. thermal insulation materials

and glazing. Similar regulations were also decreed in

Sharjah in the same year, i.e. 2003. It was not until 2010

that building regulations were decreed in Abu Dhabi.

That is when the Abu Dhabi Urban Planning Council

(UPC) produced the ESTIDAMA building regulations

which included several energy saving requirements.

Form this it is clear that the majority of the buildings in

the UAE were co nstructed with little or no consideration

to energy savings. This is especially true for investment

buildings built by developers for sale rather than rent. In

such situations initial cost savings were the dominate

concern for the developers resulting in cost/corner cut-

ting me as ur es. As a r es ult s uc h b ui ld in gs te nd ed to s u ffer

from high energy operating costs. It is interesting to note

that until 2012 there are no federal building regulations

designed to promote ener gy savi ngs in federal buildings.

This includes all the federally build public houses start-

ing fro m 19 74 until to da y. T he har sh cli mate o f the U AE

coupled with poor thermal characteristics of buildings in

the UAE resulted in very high cooling loads. The highes t

electrical load comes from HVAC equipment which ac-

counts for an average of 40% of the total year around

electrical load and up to 60% of the peak electrical load

during the summer time [9]. Based on this the current

study will focus on the energy saving potential of refur-

bishing exiting buildings in the UAE due to refurbish-

ment of the building envelop in order to improve its

thermal characteristics.

Several federal public housing villas will be studied in

this research to assess the energy saving potential due to

refurb ishment. These federal buildings were chosen due

to the availability of detailed data describing the build-

ings construction characteristics as well as numbers and

years of built. Five different villa models were chosen

for this study. The models were chosen were the most

popular model built by the MoPW in each of the past 5

decades, i.e. from 1974 until 2012. . Table 1 shows a

summary of the main data for these villas. The new ES-

TIDAMA thermal insulation and glazing requirements

are used to guide the level of refurbishment applied for

the different villas. ESTIDAM has five certification le-

vels ranging from 1-5 Pearls [10]. Two refurbishment

levels will be used in the current study, those corres-

ponding to 1 and 2 Pearls. Table 2 lists the minimum

ESTIDAMA thermal requirements for 1 and 2 Pearls

certification.

Table 1. S ummary data of the five villa modles used in the

curr ent study.

Model

number

Decade

built

Villa

Configuration

Total floor

area (m2)

Window/wall

ratio (% )

C73 1970s

G 108

B74 1980s

G 114 3.7

670 1990s

G 351 6.7

717 2000s

G+1 394 11.5

762 2010s

G+1 472 11.1

Table 2. Mi nimum ESTIDAMA thermal requirements for 1

and 2 Pearls certificat ion.

1 Pearl 2 Pearls

Wall U-value (W/m C

)

0.32

0.29

Roof U-value (W/m Co)

0.14 0.12

Glazing U-va l ue (W/m2 Co)

2.2 1.9

Glazing Solar Heat Gain Coefficient

(S HGC)

0.4 0.3

Maximum Window/Wa ll area rati o

(%)

15% 10%

3. Methodology

Computer modeling has proven to be a powerful tool

among building professionals and researchers, whether

they are used for drawing, rendering, evaluating or opti-

mization. A Computer simulation modeling program si-

mula te s a n abstr a ct mo d el o f a p ar ticular building a nd ca n

be used to explore and gain new design ideas, technolo-

gical products and verdicts. Computer energy modeling is

a subset of this category and is used to enhance buildi ngs’

desi gns and systems through a ssessing and estimating the

performance of a building and its integrated systems.

W. ALAWADHI ET AL.

134

Such p rogra ms and models are used when systems are too

complex for an analytical assessment. This type of mod-

eling assists designers in processing building regulations,

simulate solar analysis, thermal analysis, acoustic analysis,

ventila tion and air flow, create shading designs and light-

ing designs within a 3D model. There is a wide range of

energy simulation software available that have been used

by researchers including; Energy plus [11], DOE-2 [12

and 13], Ecotect [14 and 15], and IES [16 and 17]. For

this work, the Integrated Environmental Solutions – Vir-

tual Reality (IES-VE) software was chosen due to high

level of accuracy and ran ge of capa bil i ties.

Five different MoPW built villas were selected for this

study The MoPW built several models in each decade

since 1974 and until today. The villas chosen were the

most popular models built in each decade.

Each villa was modeled in IES based on the design data

provided by the MoPW. This included architectural,

structural and material components. Figure 1 shows a

sample t he IE S villa model ( model 717). IE S was used to

calculate the energy consumption of the different villas.

This was done for the ori ginal configuration of the villas,

i.e. as built, as well after the virtual refurbishment of the

villas by adding additional insulation or upgrading the

existing glazing. The effectiveness of the refurbishment

was assessed by looking at the percentage change in the

energy consumption of the refurbishment villa compared

to the energy consumption of the original villa. These

results will be shown and discussed in the following sec-

tion.

After taking a closer look at the layout and plans of the

different models, it became clear that models C73 and

B74 are es s entially the same in t erms of configuration and

build technology. Thus model C73 was not simulate d.

Figur e 1. T he IES co mpute r model of villa model 717.

4. Results and Discussion

IES energy modeling computer modeling software was

used to simulate the total energy load of each of the four

villa models over an entire year. Each model was simu-

lated as per built configuratio n them after refurbishing it

to EST IDAMA’s 1 and 2 Pear l standards. Note that the 2

Pearls standard requires a window/wall ration of less

than 10%. Still not change in the models w/w was made

as per of the virtual refurbishment exercise as this was

deemed unpractical in real-life refurbishment. Also fro m

Table. 1 shows that only models 717 and 762 had a w/w

ratio greater than 10% but not by much.

Table. 3 show the total annual energy load (TAEL) for

the four villa models and how this changes with refur-

bishment levels. It is interesting that all four models ex-

hibit similar trends and even values in terms of energy

reduction due to refurbishment. The refurbishment to 1

Pearl level r esulted in a significant 27. 5-29.8% reduction

in total energy. Going to 2 Pearls level did not improve

the ener g y performance much over the 1 Pearl level, only

an addition 0.7-1.1%. This is clear indica tion that 1 P earl

insulation levels are good enough for the UAE climate

and further enhancements in these values have little in

terms of return.

Table 3. Cha nges in the total energy consumption d ue to

upgrading the models’ ther mal chatacteristics .

Mo de l n umbe r

Total Annual

Energy Load

(MWh)

Change in TAEL

compared to

based model (%)

Normalized

TAEL

(kWh/m2)

B74 (base)

54.7

480

B74 (1 Pearl)

28.7%

342

B74 (2 Pearls)

38.6

29.4%

339

670 (Base)

188.5

537

670 (1 Pearl)

134.7

28.5%

384

670 (2 Pearls)

132.7 29.6% 378

717 (Base)

237.2

602

717 (1 Pearl)

166.4

29.8%

422

717 (2 Pearls)

164.1

30.8%

416

762 (Base)

174.9

371

762 (1 Pearl)

126.8

27.5%

269

762 (2 Pearls)

125 28.5% 265

Table. 3 also show the normalized total annual energy

load per m2 of the models gross floor area. This is an

indic ator of the e nerg y effi cienc y of t he di fferent models

(TAEL). It is interesting to note that between the 1980s

(B74) and the 2000s (717), the energy consumption per

m2 has gone up. The increase in window/wall ratio dur-

ing that period (Table. 1) coupled with poor thermal

W. ALAWADHI ET AL.

135

glazing characteristics, all models had single pan glass

windows, resulted in high solar heat gain loads and thus

the increase in the normalized TAEL. Model 762 has the

lowest normalized TAEL although it has a high 11.1%

w/w glazing but the glazing used has much better ther-

mal characteristics than the other models, U-glazing for

model 762 is 2.83 W/m2K compared to 4.83 W/m2K

from model 717. Note that the val ue o f t he U-glazing for

model 762 is close to that required by the 1 Pearl regula-

tions, Table. 1.

Figure. 2 gives a better idea as to the impact of upgrad-

ing the thermal envelop of the different models. Figure.

2 shows the monthly total energy load for the three con-

figurations of villa model 670. The biggest reduction

occurs during the hot summer months. This is when the

effect of the extra thermal insulation is strongest. It is

interesting to note that the extra insulation actually re-

sulted in a slight increase in the energy consumption

during the relatively cool months of December and Jan-

uary. The energy modeling done did not account for us-

ing natural ventilation when the outside temperature is

low. T hus the extra insul atio n tra pped the heat insi de the

villa and did not allow for proper heat rejection to the

surroundings during the colder nights of December and

January. Similar trends were also noted for the other

three models i n th is study.

Figure. 2 The monthly total energy consumption for the

villa model 670.

5. Conclusions

Computer energy modeling was used to assess the ener-

gy savings that could result from enhancing the thermal

insulation characteristics of public housing in the UAE.

Four models repr esenti ng publ ic housi ng buil t duri ng the

past five decades were chosen for this study. Two levels

of virtual refurbishment were done for each of the four

models. T he results sho wed annual energy savings rang-

ing from 27.5%-30.8%. here was little extra energy con-

sumption reduction when going from 1 Pearl to 2 Pearls

thermal requirements. Thus upgrading to 1 Pearl re-

quirements seems to be the most practical and economi-

cal course of action.

6. Acknowledgemen t

This work was supported by the Emirates Foundation,

ExxonMobil and GASCO under Grant 2011/157.

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