Cost Optimum Design of a Tropical Near Zero Energy House (nZEH)
Corresponding email: lsagita@eng.ui.ac.id
Published at : 25 Apr 2019
Volume : IJtech
Vol 10, No 2 (2019)
DOI : https://doi.org/10.14716/ijtech.v10i2.1781
Latief, Y., Berawi, M.A., Koesalamwardi, A.B., Sagita, L., Herzanita, A., 2019. Cost Optimum Design of a Tropical Near Zero Energy House (nZEH). International Journal of Technology. Volume 10(2), pp. 376-385
| Yusuf Latief | Department of Civil Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
| Mohammed Ali Berawi | Department of Civil Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
| Ario Bintang Koesalamwardi | Construction Engineering and Management, Faculty of Engineering, Universitas Agung Podomoro, Jakarta 11470, Indonesia |
| Leni Sagita | Department of Civil Engineering, Faculty of Engineering, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia |
| Ayu Herzanita | Department of Civil Engineering, Faculty of Engineering, Universitas Pancasila, Srengseng Sawah, Jagakarsa, South Jakarta 12640, Indonesia |
Housing
development, as part of economic development, must be supported by energy
availability in order to achieve sustainable growth. One of the approaches to
supporting renewable energy promotion is to design and build energy efficient
housing. However, the optimal design of such buildings faces two conflicting
requirements, namely the consideration of cost effectiveness and minimum
environmental impact. The high costs of energy efficient buildings, such as the
near Zero Energy House (nZEH), are due to the high price of the materials and
equipment used, such as photovoltaic (PV) panels, insulation and other
supporting materials. Indonesia is situated on the equator and benefits from
sunlight throughout the year. Nonetheless, this potential has not been fully
realized, as the solar-generated energy technology for housing comes at a high
price. Therefore, the objective of this study is to find the cost optimum
combination of validated design variables for an nZEH which suit the tropical
climate conditions of Indonesia. Experiments and a case study are employed in
the study to validate the design variables for an optimum nZEH design, which
include building orientation, PV panels, fenestration, and passive design. The
study finds that the cost optimum nZEH design achieved 72 percent site-energy
savings and 21 percent savings in the total Net Present Value (NPV) of life
cycle costs, with insignificant incremental initial construction costs in
enhancing the design.
Design optimization; Near Zero Energy House; Sequential search
As its population continues to grow, Indonesia is currently facing
increasing demand for housing and electricity production. A by-product of such
rapid development is greenhouse gas emissions. The Centre of Energy Studies at
the University of Indonesia has projected that these emissions will grow
continuously to an alarming level by 2025 (PEUI, 2006) if Indonesia continues
to develop a business-as-usual (BAU) scheme. In the Paris Accord 2015,
Indonesia signed a commitment to reduce its greenhouse gas emissions by up to
29% by 2030 (United Nations Framework Convention on Climate Change, 2016);
however, to date it has only been able to achieve a 1.49% reduction (INDC,
2015). To maintain social welfare by meeting
the basic needs of
adequate housing
and energy and continuing
The energy performance of a building is the key
element in reducing greenhouse gas emissions and making energy savings.
Improving such performance is a cost-effective solution to overcoming climate
change and improving energy security. Energy conservation in the building
sector has attracted the interest and concern of the world community with
respect to environmental conservation (Koesalamwardi, 2014).
In practice, it is very difficult to achieve
zero energy consumption in a building. Buildings that consume just a little
more energy than that generated are called near zero energy buildings (nZEBs),
while an nZEH is a residential building that consumes a little more energy than
it produces. Buildings that can generate energy usually use solar panels on
their roofs and facades. By collecting energy from the sun, an nZEH can use its
own generated energy and minimize energy consumption from outside sources
(Marszal et al., 2011). Indonesia's tropical climate provides the potential for
the development of nZEHs integrated with photovoltaic (PV) panels. However,
this potential has not been fully explored due to the expensive technology of
solar power generation systems (Dhany, 2013).
Reducing energy consumption without compromising
living standards, e.g. indoor room temperature and comfort, is an important
issue in the building construction industry. In addition, this problem also
creates a contradiction for energy-efficient building design, which typically
uses expensive materials and technology, and which directly affects the overall
cost of construction (Milajic et al., 2013). This requires optimal use of green
technology and attention to construction costs, so that energy-efficient
building technologies will be economically feasible.
Buildings with high energy performance, such as
the nZEH, should also be economically viable. Strategies and solutions are
needed to reduce energy consumption for such buildings and to continually
provide energy from renewable sources (Milan et al., 2012). In recent years,
many energy conservation technologies have been developed, but the use of these
tools does not guarantee optimal energy savings. This is because energy
consumption is highly dependent on the combination and use of these tools, so
these factors should be planned and optimized in order to obtain the best
levels of energy saving (Ooka & Komamura, 2009). The purpose of this
research is to develop an nZEH design with optimal costs using a sequential
search optimization algorithm.
To conclude, this study has determined an nZEH design at optimum
cost, using nZEH design variables such as PV panels, azimuth (building
orientation), fenestration (window-to-wall ratio), and glazing for windows. The
design variables were combined and simulated using sequential search numerical
rules, with the help of building performance simulation software. The results
show that common construction materials, e.g. concrete hollow bricks and terracotta
roof tiles, are suitable and represent low-cost heat insulation materials for
tropical houses. Comfortable indoor room temperatures can be achieved with
minimal usage of air conditioning, by positioning the house so it is not
directly facing the sun, and applying 60 cm eaves and overhangs on all windows.
The application of these can also reduce the initial construction cost by not
having to use expensive glazing. The optimum window-to-wall ratio, which ranged
from 15% to 40%, can provide adequate natural lighting, while minimizing heat
radiation from the sun. By applying PV panels, electric consumption can also be
reduced significantly. The electric power generated by the PV panels can also
be exported to the central power grid, thus cutting electricity bills thanks to
the net-metering incentive scheme.
The design optimization algorithm will sequentially search for
the optimum combinations, thus generating maximum cost savings. Therefore, the
optimization process will also eliminate unnecessary, unsuitable, and/or
expensive design variables for tropical climates; for example, boilers, asphalt
roof shingles, fiberglass wall insulations and LED lighting. Based on the cost
optimum design parameter selection, the incremental construction cost for upgrading
the design towards
nZEH design concept is less
than 5% to the initial construction cost of
conventional design. The optimized design of the nZEH shows a significant
annual maintenance and operational cost reduction, resulting in a lower NPV of
cost compared to the conventional house design of up to 21%.
The authors would like to acknowledge the research grant from
the Ministry of Research,
Technology and Higher Education Republic of Indonesia (Kemenristekdikti) as
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