Designing a Near Zero Energy Building with Renewable Resources in Australia

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