Near Zero Energy Buildings: Introduction and Background Analysis

This report provides an in-depth introduction and background study on Zero Energy Buildings (ZEBs), emphasizing their growing importance in environmental and energy conservation. It defines ZEBs, highlighting their reduced energy demands through renewable sources and high energy efficiency. The report explores the global context, focusing on the significant energy consumption of conventional buildings, particularly for HVAC systems. It discusses the Australian government's initiatives in promoting ZEB technologies, including the installation of rooftop photovoltaic systems. The report also outlines research questions, objectives, and methodologies, including the use of SOLIDWORKS and ANSYS FLUENT for design and simulation. It examines passive and active design strategies, the motivation for the research, and the potential benefits of ZEB design, such as reduced reliance on fossil fuels and decreased environmental impact. Specific objectives include the design and simulation of natural ventilation, building materials, natural daylight distribution, and solar heating systems. The report highlights the potential of ZEB design to optimize energy consumption and promote sustainability in the building industry.

Introduction and Background of Study
With increasing knowledge in environmental and energy
conservation, the concept of zero energy technology in construction of
buildings has gained a global attention in the recent past and forecast as
a design goal in the building industry. The wide international acceptance
of this design technology is due to its low associated energy demands
and main dependence in renewable sources of energy compared to the
large demands created by the use of conventional buildings (Marszal, et
al., 2011). On a global scale the primary uses of energy in domestic and
commercial households is air conditioning (heating and cooling of air), for
cooking and also in lighting; about 50% (Perez-Lombard, et al., 2008) or
more of the total energy demand goes to the heating, ventilation and air-
conditioning (HVAC), necessarily for thermal comfort to the occupants.
This therefore, calls for a critical consideration in the energy efficiency in
the construction of buildings to help reduce the energy burden to the
producers.
Zero Energy Buildings (ZEBs) can be defined as a type of building
design (both residential and commercial) for which there is a great
reduction in the energy demands due to the use renewable sources of
energy and high energy efficiency gains such that the annual net total
amount of energy consumed within the building is approximately equal to
the renewable energy created on-site or at some other place (Torcellini,
et al., 2006). In such definitions the zero energy only considers the
energy consumption for the effective operation of the building i.e. energy

for heating, for cooling and lighting; while not considering the energy
consumption during the construction of the building, thus a net – ZEB
(Hernandez & Kenny, 2010).
In the design of such buildings, the architects and construction
engineers’ focus on the impact of the building to greenhouse gas
emissions, the overall global warming and the adverse global climatic
change, thus endeavor to shift focus from the overstretched use of the
non- renewable fossil fuels to the adoption of green energy building code.
The design of Green energy buildings considers environmental
friendliness and sustainability, the use and conservation of clean
renewable energy. Thus for an acceptable zero energy building operating
on a green energy code the energy consumed should be efficiently
conserved such that the energy input to the building equals the energy
output from the building, without energy spills (Hootman, 2012). This
would thus reduce the burden on the consumption of fossil fuel which is
ever increasing in cost, become scarce and has high emissions to the
environment.
The Australian government has taken the lead role in
implementing zero energy technologies both for large-scale (commercial
institutions like factories) consumption and small- scale consumption (e.g.
in residential houses) through the giving of grants and various incentives
on installation of rooftop photovoltaic systems (Fechner, et al., 2015). To
that effect the total PV power capacity installed in the country by March
2016 showed a record of 4918MW for the small- scale residential sector,
connecting about 320000 homes, thus lowering the national grid power
demand burden (NSW Government, 2015). The use of rooftop PV models
in most Australian commercial buildings and households in Queensland

were modelled and analyzed using the PVSYST software in which the
carbon dioxide emissions, the cost incurred on investment and the
financial proceeds from such an investment were also studied. It was
found that maximum power harnessing could be realized if the panels
were installed at a slope of 200 to 250 for a time period of between 9 am –
4 pm (at maximum sun intensity) during the day. This resulted in 15%
decrease in the annual CO2 emission in Australia and a ploughed-back
profit percent of 20% of the total energy bill (Liu, et al., 2012). Fig. 1
below shows an array of 175W photovoltaic panels installed at a slope of
200 on the roofs of residential houses in Sydney.
Figure 1: Rooftop Photovoltaic panels installed in households in Sydney
(Odeh & Behnia, 2009)
According to (Steven Winter Associates Inc, 2016) inefficiently
designed buildings in the United States takes the largest share of the of
the national energy consumption annually. This is due to the over-
dependence on the use of now-renewable energy such as fossil fuels,
increased domestic demand from the national grid and the large-scale
ignorance on the efficient use of the

non-renewable thus increasing the annual energy bills. The use of
national grid connection has been applied in some cases where the total
energy demand within the ZEB is not fully supplied by the on-site
renewable source. Conversely, the renewable energy source may
produce energy in excess of the site requirement thus the surplus is
feedback to the national grid (hence called an energy-plus building) to
help offset a future excess energy demand of energy leading to a zero
consumption of the net energy produced (Steven Winter Associates Inc,
2016).
Some of the renewable energy sources used in the near zero
energy buildings (nZEB) include the use of solar water heating
technologies, photovoltaic power generation, natural ventilation and
lighting, and the use of small-scale wind turbines. The efficient use of
biomass (wood, charcoal and other agricultural wastes) for space and
water heating, in improved cookstoves and burners has also proved
helpful and rewarding (Hernandez & Kenny, 2010). There are two design
strategies used in the design of nZEB to help meet its energy loads: the
passive and active design strategies. The passive strategies are usually a
supplement of the active design strategies by reducing the size of the
heating and cooling system to be used within the building, through the
conservation of the entrained heated or cooled air within the building.
Such include building design to effectively use the natural ventilation, use
of windows for daylighting, air sealing, building orientation (for maximum
use of the solar power from the sun) and the use of continuous insulation
(through the use of effective insulation building materials) (Marro, 2018).
Motivation for the research
The fossil fuel reserves are depleted with time, there is an over-stretch in its
demand by various consumers and its effluents like the compounds of carbon,
nitrogen and sulphur, have a remarkable detrimental effect on the atmosphere by

causing global warming. The adverse climatic conditions have caused a decrease
on the depth of water resources hence hydro-electric power produced cannot fully
supply the demanded energy. There is a need for an alternative source of power
that is first clean, then cheap, readily available and renewable in nature. The freely
available solar, wind and geothermal power have proven the best alternatives to
provide such clean energy with increased human comfort and no global warming
effects. The design of the nZEBs focus on the use of these alternative sources as
well as efficiency of use. They are
designed to harvest maximum natural light during the day, provide free
natural ventilation, conserve the heated or cooled air within the room and
also supplement its additional energy requirements from the renewable
sources.
The design of such buildings provide an interesting field of
research by investigating the sustainability and efficiency of technologies
used in such a design. Through computer aided design and simulation
this project will help develop an optimal design for the selected region
based on the available resources and the overall life cycle costing
analysis. Skills in Computational fluid dynamics (CFD) and the use of
ANSYS FLUENT will be used in the analysis of the natural ventilation,
distribution of natural light, the efficiency of solar water heaters as well as
the use of advanced building materials with improved insulation.
Research Questions
To achieve its goals and guide the research into this project the
following research questions will be considered:
• What are the environmental and economic effects of the continued
used of conventional buildings operating on the non-renewable
sources of energy? The negative effects of the use of fossil fuels
will be investigated from previous researches and its effects to the
economy and the global climate.

• What technological advancements are there in the design and
commercialization of the zero energy buildings? The current
advancements in the ZEB technology will be assessed to
determine their advantages and disadvantages and also identify a
possible gap not satisfied by such technologies.
• What technologies will be used in this new design to help ensure a
near zero net energy and what will be their efficiencies? Here the
report will propose the key technologies that will be adopted in
various parts of the building to help realize a net zero energy
consumption i.e. the use of solar collectors, PV systems, natural
ventilation and natural light distribution.
Objectives
Main objective
• The main objective of this project will be to design a near zero
energy low rise building based on the available renewable energy
resources and weather conditions of Australia.
Specific objectives
To help achieve the main objective this proposal will consider four areas
of improvement in the near zero energy building as shown below.
• Natural ventilation
• To carry an in-depth research on the current technology and
design used to effect natural ventilation in the nZEBs and
assess its efficiency.
• To design the proposed natural ventilation system in SOLIDWORKS.
• Simulate the performance of the ventilation design in terms of
the air exchange rate using ANSYS software.
• Building materials

• To assess the various types of current building materials used
in nZEB technology and their thermal performances.
• To design a model of the wall and roof material used in nZEB using
SOLIDWORKS.
• To carry out a CFD simulation of the designed model using
ANSYS fluent to determine the effect of its heat transfer
properties with the wall thickness, its thermal mass and heat
conservation properties.
• Natural daylight distribution
• To investigate the current designs used in nZEBs for effective
propagation of the natural light within the room during the day and
during moonlight.
• To design the rooftop light distribution panels in Solidworks and
assign the right type of material for improved performance.
• To analyse the light distribution panel for efficiency and durability in ANSYS.
• Solar heating and power generation
• Conduct extensive research on the application of flat
plate solar heaters in the design of nZEB
• Design a 3D model of the FPSH in the CAD software SOLIDWORKS
• Use ANSYS Fluent to illustrate the application of a FPSH in
heater water to be used in the household.
• To design the PV panel for a roof of an area 200 km2 and
determine the effective inter-panel gap, size of the panels
and the sun intensity and duration in Australia.
Project Design and Methodology
The design work will be carried out using SOLIDWORKS software
whereas the computation fluid analysis will be carried out using ANSYS

workbench package, mainly using the fluent module due to the fluid flow
involved in the ZEB.
The SOLIDWORKS software will be able to present the simulation
of the buildings adherence to the zero energy from the different
components. This software will be able to combine the different aspects
of residents, buildings, services, infrastructure, mobility and commerce to
achieve the zero energy. The interconnection of all these factors must be
achieved for a building to achieve the ZEB category and requirements.
The simulation will be able to show the energy production as well as
energy consumption for the building. This will be achieved through
simulation of the input factors and output and energy consumption rate
for the building (Voss and Musall, 2011). The simulation is done to
demonstrate the balance between energy production and consumption
for the building. The choice of the SOLIDWORKS software is meant to
arrange the building according to usage. This software is able to provide
the proper design for estimating the zero energy through balancing of the
energy production and usage. Additionally, the software which is part of
the Autodesk package allows the users to create a building with correct
choice library of materials and pre-created constructs.
Additionally, the fluids play a critical role in achieving ZEB.
Therefore, the analysis of the fluids inflow and outflow is important to
understand the level of zero energy value for a building. This is why the
ANSYS workbench package will play a critical role in understanding the
buildings achieving of zero energy. Fluid flow plays a critical factor in
energy production and usage in a building (Asdrubali, et al, 2019 p.461-
470). Using ANSYS will help to simulate the energy production at
different parts in a building. Combining it with the SOLIDWORKS
software will help develop a complete system of balancing the energy

production and usage. This criterion will help to visualize the ZEB in the
structure in a clearer way.
Design parameters
Some of the design parameters that will be considered in the design
of the building are as shown below:
• Design of the ventilation system
The ventilation system will be designed to ensure optimal air
exchange in and out of the room with a means of regulating the flow rate.
It will mainly use the windows, main doors and the wall partitions. The
following will be considered:
• The number of doors and windows required per compartment,
their size and height above the floor.
• The material used to make the doors and windows i.e. its thermal
properties.
• The maximum number of occupants in the building, their
gender and probable occupations.
• The wind conditions of the surrounding region to the nZEB i.e. speed and
direction.
• The humidity of the area that will affect the density of the air and thus
human comfort.
• The climatic condition of the region i.e. a cold or hot climate
will affect the need or degree of ventilation required.
• Design of the daylight distribution system
The light distribution system should ensure that the sunlight is
efficiently distributed to all corners of the room/building during sunny days
with a regulated intensity that besides cutting on the lighting bill will also
provide comfort to the occupants. Here are some of the design
parameters to be considered in such a design:
• The optical properties of the material used for daylight distribution.

• The cost of such materials.
• The average intensity and duration of the sunlight per day within the region.
• The size of the room and the activity to be taken within such rooms i.e.
study, etc.
• Design of the roof and wall
The retention or emission of the temperature of the air within the ZEB
will be primarily determined by the type of material used in the design of
the roof, wall and floor of the building. For cold regions (such as China)
the walls should have a high thermal mass material that will effectively
absorb and retain the temperature of the air and hence facilitate in
warming the room, whereas for hot regions the materials should be good
emitters and reflectors of heat ensuring a cool space for the occupants.
The following design parameters will guide the design:
• The average temperature of the surrounding region i.e. hot or cold.
• The thermal mass of the wall material (Trombe walls) and roof material.
• The thickness of the walls and the height of the roof above the floor.
• The type of paint used within and without the building. Should be
reflective (for warm regions) or dull for cold regions.
• The thermal properties of other building materials used for the wall i.e. brick
and concrete
• The overall cost of the materials and their durability.
• Design of the solar heater and power generation
A flat plate solar water heater will be used within the building to cut on
the amount of power required for water heating purposes while
photovoltaic solar panels will be installed at the rooftop to cater for the
electric power generation used in lighting and other appliances. The
following design parameters will be considered during the design.
For the solar heater:
• The absorption ability of the water tubes used in the design.

• The thermal properties and durability of the glass material used in the flat
plate assembly.
• The solar intensity and duration.
• The thermal insulation of the tube materials used in transporting
the heated water as well as the effectiveness of the heat
exchanger used in the water heater.
For the PV panels:
• The type of PV material to be used i.e. crystalline or amorphous
and their corresponding efficiency.
• The capacity of the photocells used in storage of the accumulated solar
power.
• The energy requirements of the building i.e. lighting, heating, cooling and
cooking.
• The sunlight duration, intensity and length.
Proposed Chapters of the Report ( Naser )
It is proposed that the final report will have the following chapters:
• Executive Summary (Abstract)
• List of Figures
• List of Tables
• List of Acronyms
• Introduction
• Background and Motivation of the Study
• Research Objectives
• Research Scope and Questions
• Research Plan and Methodology
• Expected Outcomes
• Project Report Structure

• Literature Review
• Existing Zero Energy Buildings in Australia and the rest of the world
According to statistics, about 40% the total energy is used in buildings. This factor
combined with the climate change and the limited resources in energy productions has led to an
increase in embracing of the Zero Energy Buildings (ZEB) concept in the whole world to
mitigate the high production of CO2 (Srinivasan et al., 2012, p. 302 and Krarti & Ihm, 2016
p.120). The ZEB concept is being embraced in the whole world. This concept holds that the
amount of energy used within a building per year is roughly equal to the amount of energy
created on site. Many researchers over the world have worked under International Energy
Agency (EIA), Heating and Cooling Program (SHC), Task 40/Energy in Buildings and
Communities (EBC) in order to make the ZEB viable (Sartori, Napolitano & Voss, 2012, p.225).
All these joint organizations show how the ZEB concept is important not only to Australia but
the whole world.
• Designs of Building Wall Materials
The design process plays a critical part in the ZEB concept achievement. For the
design to achieve the ZEB concept, it should ensure reduction in energy consumption will
promoting building energy production. The design of the wall plays a critical role in insulation
process. Wall materials should be able to prevent energy loss. Glue laminated timber has low
carbon footprint and is usually utilized instead of steel and concrete to achieve the goals of ZEB
(Kapsalaki, Leal, & Santamouris, 2012, p.765-774). The timber also reduces the weight of the
structure and therefore reducing damages during disasters. Additionally, hollow blocks for walls