Analysis of Windows Element for Energy Saving in a Tropical Residential Buildings in Order to Reduce the Negative Environmental Impacts

Journal of Environmental Treatment Techniques

2021, Volume 9, Issue 1, Pages: 1-6

J. Environ. Treat. Tech.

ISSN: 2309-1185

Journal web link: http://www.jett.dormaj.com

https://doi.org/10.47277/JETT/9(1)6

Analysis of Windows Element for Energy Saving in

a Tropical Residential Buildings in Order to

Reduce the Negative Environmental Impacts

Aidin Nobahar Sadeghifam *, Iman Kiani , Nurul Noraziemah Mohd Pauzi , Saman

Mostfapour ²

Faculty of Engineering and Science, Curtin University Sarawak, Malaysia

Faculty of Civil Engineering, Department of Construction Management, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia

Received: 02/06/2020

Accepted: 30/09/2020

Online: 05/10/2020

Abstract

In the contemporary milieu of today, sustainability and environmental concerns have become a great subject of debate. Matters

related to sustainability are often linked to other crucial concerns like energy consumption. Energy is a key factor in ensuring continuous

economic growth and development. One of the highest energy consuming systems in buildings – specifically residential homes in tropical

regions – is the air conditioning system. Windows have been identified as the weakest link in the fabric of a building as they serve as

thermal holes. Thus, the selection of proper window materials is crucial to reduce energy usage by minimizing the cooling and heating

requirements of the building. The aims of this paper are analysis of energy performance for diverse types of window’s glazing with

different frames in order to find the most optimized window materials for the tropical residential buildings. The selected case study in

this paper is modeled and then simulated by Building Information Modeling (BIM) application, which is appropriate for energy analysis.

For simulation, some factors of the window materials were taken into consideration including, four physical properties of the U-factor,

solar heat gain coefficient, visible transmittance, and emissivity. The result was shown windows types 02 and 03 were the most optimized

of window materials and led to 10% energy saving into the base model and the windows type 05 was high U-factor, results in a greater

transfer in internal zones and led to high energy consumption.

Keywords: Sustainability, Energy, Tropical countries, Residential buildings, Windows, BIM application

Introduction and Background

The past two decades had witnessed the parallel increase in

energy usage and population growth, thus causing the incessant

hike in energy prices as well as excessive emissions of CO2 and

greenhouse gas (1,2). The International Energy Agency (IEA)

had indicated a 48% hike in global energy intake in the last 20

years (3). The major increase in energy consumption has led to

other critical issues including supply shortage, energy resource

diminution, and grave environmental effects such as ozone

depletion, climate change and global warming. Despite rising

demands against the exploitation of energy and natural

resources, environmental and sustainability concerns remain a

leading global issue (4).

A number of critical issues related to the construction

industry demand solutions in the form of global persistent

efforts to change and adapt our actions to be more

environmentally friendly. The construction of buildings require

approximately 50% raw materials, 71% electricity intake and

Figure1: Overall Electricity Consumption in Malaysia from 2000 to

2018 (7)

The highest energy intake comes from the building sector,

which accounts for over one-thirds of the total energy intake

and one-half of the total electricity usage globally (8). The IEA

delineates energy efficiency as the “fuel” that reinforces the

change towards establishing an energy system that is more

sustainable. Along with this is the substantial untapped

prospect of improving energy efficiency in the building sector

to up to 80% (3). The rise in population is expected to increase

the demands for building comfort and services including the

need for higher energy consumption, parallel with the increase

in the amount of time spent indoors. Energy consumption in

the context of residential buildings in tropical regions is mainly

contributed by the usage of air conditioning systems, which are

used to control indoor temperatures and provide the occupants

with thermal comfort. The aforesaid comfort is delineated as

6% water reserves while generating 40% landfill-bound

wastes (5), all of which pose a heavy toll on the environment.

The operations of buildings are also responsible for 50% carbon

dioxide (CO2) emission and 18% indirect material usage and

transferal (6). As a developing nation with rapid economic and

technological growth, Malaysia is experiencing higher levels of

energy intake than ever before. Figure 1 shows the overall trend

of electricity usage in Malaysia over the past 18 years, with a

significant surge from 53 Billion kWh in 2000 to the current

33 Billion kWh (7).

Journal of Environmental Treatment Techniques

2021, Volume 9, Issue 1, Pages: 1-6

the “condition of mind that expresses satisfaction with the

thermal environment” (4). Yu et al. (2009) highlighted a

number of issues related to the usage of air conditioning

systems. A majority of buildings in tropical regions have air

conditioning units that run on electricity generated from

primary energy sources including oil, coal, and natural gas.

These sources release CO2 and greenhouse gases into the air;

on a wide and prolonged scale, these emissions can deplete the

ozone layer and cause grievous health risks for humans and

other living beings. Therefore, reducing energy consumption

for indoor cooling purposes can significantly help in energy

conservation and environmental protection (9,10). In this

context, sustainable strategies for residential buildings are

capable of solving such problems i.e. by effectively controlling

and reducing the amount and the ways of energy consumption

and improvement of thermal comfort at the same time in

residential buildings. Reducing energy consumption for indoor

cooling purposes can substantially contribute to energy

conservation and environmental protection (10).

The solutions offered by the Building Information

Modelling (BIM) give architects and engineers the opportunity

to come up with sustainable designs through the proper

analysis, simulation and visualization of building performance.

Energy simulation is a practical way for analysing various

systems including the manufacturing system in a construction

process (11). The Autodesk Revit and other BIM applications

facilitate designers in designing, simulating, visualizing and

collaborating on projects that can capitalize on the benefits

offered by the interrelated data in the BIM model. Computer

simulation also helps in analysing the energy usage in

buildings. The amount of energy intake in buildings can be

efficiently examined using BIM’s simulation applications

including Ecotect, EnergyPlus and Transys (12,13,14).

EnergyPlus offers a broad and comprehensive simulation

setting for the ephemeral simulation of various systems

including buildings with multiple zones (15,16).

can be determined by the window’s properties and the

location’s climatic conditions (17).

In the past decade, many studies had been carried out in

analysing the energy performance of windows according to

their various properties (20, 21). G.F. Menzies and J.R.

Wherrett examined four buildings and rated their levels of

comfort and sustainability by looking at the various types of

multi-glazed windows and their architectural design (22).

Singh an Garg (2009) studied the effect of a building’s floor,

roofs, walls, and building zones in terms of their thermal

transference capacity on the building’s overall energy savings

by looking at the different types of windows. The authors

developed an equation for calculating the total amount of

energy savings per window. They found that the energy saving

capacity of a window relies on its type, the building’s

dimensions, the climate as well as the wall and roof’s thermal

transferral. The last two factors were found to save energy the

most (23). Banihashemi et al. (2012) examined the capacity of

double-glazed windows in reducing heating and cooling loads

throughout a year of extremely cold weather. The authors found

that the double-glazed windows in the aforementioned context

cause extra cooling loads on buildings i.e. an outcome that is

negligible when compared to the savings in heating load (24).

Ihara et al. (2015) indicated that energy demand could be

reduced by minimizing the solar heat gain coefficient and

window U-value as well as increasing the solar reflectance of

the opaque components (25). Meanwhile, He et al. (2019)

studied 20 typical and prospective glazing alternatives in

predicting possible energy savings in various buildings with

similar orientations situated in various climate zones in China.

Taking into consideration the multiple parameters and other

elements, the authors found that the Low-E window glazing

showcased the best energy performance for all the climate

zones; however, it approximates traditional glazed windows in

terms of energy savings capacity, which hinders its current

adoption (26).

In terms of energy usage, the main consideration is on the

materials required for the main components and envelope of the

building. According to Sadeghifam et al. (2019), the energy

intake for residential buildings in tropical areas can be

A holistic review of the previous literature and despite the

public and governmental demands for energy-saving methods,

there are rare investigations on the analysis of the potential

window's glazing and frame alternatives together to investigate

the potential energy savings for residential buildings in tropical

countries. Therefore, the overarching aim of this study is to

analyze the energy performance of potential windows

alternatives (various types of window’s glazing with different

frames) in order to find the most optimize windows materials

for the tropical humid climate residential buildings in Malaysia.

significantly

reduced

choosing

the

right

components/materials for the ceiling, windows, walls, roof, and

floor (4). A building would require high levels of cooling if the

envelope has extreme heat transmission. The design for the

building envelope includes the shell as well as the walls, floors,

roofs, and windows (17). On average, thermal loss quantities in

the country’s prevailing residential buildings are: 35% for

walls, 7.5% for floors, 7.5% for ceilings, and 50% for windows

Case study

(

18).

A properly designed glazing decreases the need for cooling

.1 Location and climate

A case study of a double story building with one unit on each

and heating thus decreasing overall energy intake. The frame

design could benefit from the use of sustainable materials as

well as materials with the least possible embodied energy like

timber and aluminium covered timber. Normally, windows are

constructed at the front façade and the back, serving as natural

lighting and ventilation outlets-inlets: heat from the sun can

easily enter the indoor space and becomes trapped inside due to

restricted openings (19). Hence, windows are crucial

components of all buildings as they provide natural light and

ventilation as well as protect against the weather. Nevertheless,

windows have also been identified as thermal holes i.e. the

weakest link in the fabrication of a building. They cause

significant heat loss and thermal discomfort resulting from

insulation properties such as the glass material that conducts

heat. Hence, installing double-glazed windows can reduce

energy loss via windows. The energy performance of windows

floor which was selected for simulation of duelling the

conventional kind of residential building in Johor BahruJohor

Bahru city is situated in south Malaysia, specifically latitude

1.48° N and longitude 103.73° E. The city is relatively humid

(

ranging between 82% and 86%) with high temperatures

throughout the year. On average, it experiences dry-bulb

temperature ranging between 21.9°C and 32.8°C, with monthly

precipitations of 196 mm. Throughout the year, the city

typically receives wind speed fluctuations of between 0 m/s and

m/s (calmly to moderately breezy), and occasionally goes

beyond 7 m/s (Table 1).

Journal of Environmental Treatment Techniques

2021, Volume 9, Issue 1, Pages: 1-6

Table 1: Climate data for Johor Bahru

3.1 Modelling of the Case Study

At this stage, the buildings in the selected case studies are

modelled or simulated using the Autodesk Revit i.e. one of the

most useful software in BIM for dynamic building simulation.

In simulating the case buildings, CAD drawings were imported

to Autodesk Revit entailing explicit parametric design features.

Table 2 shows the characteristics of the materials used in the

original model, which are important in establishing the energy

consumption baseline of a standard house.

.2 Energy Simulations and Analysis of the Case Study

This step is to simulate and analyze the model considering

the energy factor. This step entails the simulation and analysis

of the model taking into consideration the energy factor. Energy

Plus i.e. a prominent software used in studies on energy

analysis was chosen as the platform for measuring the cooling

loads. Accurate analysis requires the usage of variables such as

building type, building orientation, and climatic data for the

building’s location. The weather was simulated by referring to

the weather report for Johor Bahru. Energy intake was

simulated by considering each room in the building as a zone

with distinct thermal properties. In this study, the building’s

model was separated into 7 zones for each level, each having

its own set of specifications with respect to behaviour activity,

HAVC systems, and comfort temperature. To ensure thermal

comfort, the thermostat was fixed at 22 °C - 26 °C according to

the ASHRAE standards. Both levels 1 and 2 use the same data

as shown in Table 3 for level 1.

.2. Description of the case study buildings

As a scope limitation, the chosen building is assumed to

represent the residential building constructed using commonly

found materials in Malaysia. A case study is a double story

building with one unit on each floor and each unit of this

residential building has the main living space including the

kitchen, living room, two bedrooms with their toilet, and

bathroom along to corridor. The total area of the building is 152

m2 and the total windows area ratio to the total floor area is

0%. This house has two levels of similar designs that are

divided into fourteen thermal zones, which have separate

thermal properties on each level. The division of building in

different zones in the simulated model is shown in (Figure 2).

Table 3: Occupant Profiles for the different zones for each unit

Area

Comfort

Band

22-26

Zone

Activity

HAVC System

(

m²)

Living Room

Bedroom 1

Bedroom 2

Kitchen

Bathroom

Toilet

Sedentary

Cooking

Sedentary

ACꢀ

Natural ventilation

None

Corridor

Figure 2: The layout of building in separate zones in the simulation

model

3.3 Energy Evaluation of the Window Alternatives

Finally, eight types of window glazing in various frames

commonly used in residential buildings in Malaysia were

selected to be compared (Table 4). For the simulation, attention

was given on the physical properties of U-factor, solar heat gain

coefficient (SHGC), visible transmittance (VT) and emissivity

in the selection of the sample windows (27). The eight types of

window materials utilized for the component were then tested.

Next, based on the data analysis, the most optimized window

materials were determined to be used in residential buildings in

Malaysia. Table 4 shows the chosen window properties for

simulation. In measuring the effect of the window types on the

cooling loads, the properties of the other components i.e. walls,

roofs and others were maintained whilst the simulations were

conducted by changing the window properties. Lastly, all the

simulations were carried out to determine the selected

buildings’ annual loads.

Research Methodology

Methodology wise, this study compared the physical

specification alterations of the building’s window components

focusing on the simulated model’s energy performance as

analyzed by the BIM. The research scope was limited by

assuming that the base model is a representation of a residential

building constructed with commonly used window materials in

the context of Malaysia.

Table 2: Component properties of simulated building

Component

Floor

Layer Name

Concrete (medium density)ꢀCast concrete (Dense) (10

cm) + tile (1.2 cm)ꢀ

External

walls

Cement sand render (1.3 cm) + brick (22 cm) + gypsum

plastering (1.3 cm)ꢀ

Internal

walls

Brick (11 cm) + inner/outer gypsum plastering (1.3 cm)

Alum framed window, single glazing (6 mm)ꢀ

Acoustic tile suspended (10 mm)ꢀ

3 Results and Discussion

In order to analyze the energy consumption of the building

used as a case study, a model was created in a BIM application.

The case study as a base model was modelled by using the

Autodesk Revit software and ready for energy simulation

through EnergyPlus to calculate the cooling loads. The output

of the Autodesk Revit software with scaled dimensions and its

particular details are presented in Figure 3.

Window

Ceiling

Roof

Wooden batons (20 cm) + air gap (10 cm) + clay tiles (3

cm)