AES BIOFLUX: Advances in Environmental Sciences - International Journal of the Bioflux Society
An assessment of
sustainability of a green residential building
in an urban setting: focus in Pueblo
de Oro, Cagayan de Oro City
1Rey D. Galua, 2Ermelinda G. Tobias
College of Engineering and Architecture, Mindanao University of Science and Technology, Cagayan de Oro City, Philippines; 2 Department of Biological Sciences, College of Science and Mathematics, MSU-Iligan Institute of Technology, Iligan City, Philippines. Corresponding author: R. D. Galua, rgaluasds@gmail.com
Abstract. A study of the technical, economic,
environmental and architectural aspects of green residential
building situated in an urban location has been performed. The results of the
study revealed the following: the
building has been observed to be properly oriented with minimum levels of
lighting consumption and sufficient
lighting designs, and that with the implementation of the green rooftop, restoration and plantation of different
species of plants a considerable amount of carbon has been offset for the growing of the plant at
approximately 470 tons of carbon for the 20-year time horizon. As to the elements of sustainable energy use, the
energy usage of the green building has been compared with that of the traditional building. The results have indicated
that green building has reduced
its energy consumption of approximately 40% per unit
of floor area when compared with that of the traditional building design. In terms of energy savings, it has been
projected that due to the use of the foregoing
strategies, the green building can save up to 1,800 kilowatt-hours of
energy annually, and the increased construction
cost due to the application of these strategies may be recovered at
approximately eleven years of
operation of the building. In the selection and conservation of resources
associated to the construction of the
green building, the study revealed that when compared to the traditional
building, it has the potential to
reduce approximately 40% associated carbon dioxide emissions and 40% primary energy for the construction of the green
building. The calculated estimates reveal that with this strategy, it can mitigate approximately 21,000 kg of
carbon dioxide emitted to the environment and approximately 2,100 gigajoule of primary energy is
avoided; as to building’s indoor environmental quality, the results of the study indicates that the resulting
design have achieved the maximum natural ventilation possible. As to acceptability of the green building,
the survey results as per statistical analyses revealed high level of acceptance of respondents in terms of the
overall satisfaction features, the general and the specific features
and the given psychological indicators of the design.
Key Words: Energy consumption, green building, carbon,
LEED, architecture.
Introduction. There is a global
consensus that anthropogenic emission of greenhouse gases in the atmosphere causes the increase of temperatures on
the surface of the earth and that
this has facilitated climate changes faster than normal (Stern 2007). These emissions caused by anthropogenic enormous
growth and development heavily rely on carbon-based
fossil fuels to supply these developments. At present, the effects of climate change due to global warming has been recognized and that there have been actions at all
levels, i.e. government, private enterprises and professional to mitigate the
impacts of these man-made
climatic changes or even to adapt
with the current climactic changes.
Emissions of carbon dioxide from fuel combustion, in conjunction with
that emitted from cement factory are
responsible for more than 75% of the increase in atmospheric carbon dioxide since the pre-industrial 18th century (Solomon
et al 2007). The construction and occupation of buildings
is a substantial contributor of carbon dioxide
emissions, with almost a quarter
or 25% of the total carbon dioxide
emissions attributable to
energy use in buildings (Metz et al 2007). A further 5% can be attributed to the manufacture of cement which is a
principal component of building construction
material. Thus, there is really a great interest in this area to reduce the energy demand
and the consequential carbon emissions attributed to buildings construction and operation.
The aim of this study is to compare the standard or traditionally-designed residential building with that of a
proposed set-up which is designed as a modern green residential building situated in the local setting. This study focused on the present
research gap, which is to answer whether indeed there is an
environmental benefit in the design
and construction of green buildings. Problems associated with each key element
of sustainable developments shall be addressed
in details, such as site selection and development, energy use, water conservation, environmental quality and social or community acceptability. In site
development and selection it is expected that issues related to proper building orientation and indoor air quality
shall be addressed; in energy use,
key problems related to increase in energy demand as the building size
increased shall be discussed, and key issues related to improved indoor air quality
shall be investigated and ecological parameters
were measured and monitored for three months.
Foremost to the study is to determine whether the expected green
building shall pass social and community acceptability.
Material and Method. The global
consensus that the present trends in the construction of building which of a considerable portion are residential
units cannot be sustained without
inflicting damage to the environment. Residential units, be it in the
construction stage or in the
operation stage, contribute significantly to the overwhelming demand of energy and thus demand for fossil fuels.
In the field of architecture, the culprit of this dilemma is the omission or perhaps failure in the field of
looking for another element in any
architectural design which consider the “fragility of the Earth”. As of now,
the gap in the design of standard or
traditionally-designed units is clear that previous trends does not account the environmental impacts of
building constructions and/or operations for a
variety of reasons, the most obvious is the costs associated when such
element is totally addressed.
In line with the overall objective of quantifying the advantage of
sustainable housing unit compared with traditionally designed
residential unit, the conceptual framework emphasizes the need to subject
the standard architectural design into five major
sustainable test standards namely: (a) sustainable site and development, (b) water
use, (c) energy use, (d) material and resource use and (e) indoor environmental quality.
In the evaluation whether what constitutes sustainable designs, the work combined the standard features
of sustainable architecture and globally accepted
standards for determining sustainable designs such as Leadership in Energy and Environment
Designs (LEED).
The design concept as shown in Figure 1 shall be subjected to
technical, economic, environmental and architectural assessment to determine whether it is within the scope of the standard scheme of constructing
residential buildings. As an added feature, the research methodology incorporate social acceptability measure so
as to ensure that the implemented
design shall be socially acceptable to the public. Survey questionnaires shall be given to random participants and their
comment shall be made basis for revising the
design plan during the implementation process and if necessary, as an
adjustment after the construction stage.
Results and Discussion
Site
selection and development. In the construction of the green building
the research has chosen the
following practical design and research strategies: (1) proper orientation of the residential unit, (2) site selection that improves the existing site, (3) site development
which incorporates carbon abatement strategies, i.e. green rooftop and site tree planting as part of the residential design. An analysis,
evaluation and calculation as to how much carbon
is abated by using these strategies was made; the calculation was done by estimating the amount of carbon in
each individual strategy has abated during the construction up to the whole lifespan
of the green residential building.
For
comparative purposes, the same strategy is applied to a traditionally-designed building
in the same subdivision, i.e. carbon footprint comparison, others.
Figure 1. The research
conceptual framework.
Figure 2. Measured energy gains on the site.
Figure 2 shows the calculated
energy gains for a three month period, while Table 1 shows the amount of equivalent carbon derived
in incorporating the green rooftop and the plantation of plants
on the site.
Table 1
Equivalent carbon emission derived from employing the research strategies
 |
Calculation of equivalent carbon dioxide
|
Solar energy gain |
5.82 kw-hr x 3.6
MJ/kw-hr |
20.95 |
|
Biomass energy converted |
20.952 MJ/m2 x 250 m2 x 0.067 |
350.95 |
|
Mass of biomass |
350.94 MJ/8 MJ/kg biomass |
43.87 |
|
Mass of carbon |
43.87kg x 40% |
17.55 |
|
Mass of carbon
dioxide |
17.55 x 3.667
kg CO2/kg C |
64.34 |
|
Yearly mass of carbon dioxide in kg |
64.34 x
365 days |
23,484 |
Equivalent carbon
dioxide for 20-year
time horizon in tons
23,484 kg CO2/year x 20 years 470
The calculation of equivalent carbon dioxide taken from the atmosphere for the consumption of biomass may reach approximately 23,000 kg of carbon dioxide
yearly or a total of 470 tons for a 20-year time
horizon. From a global point of view, the amount of carbon dioxide reduced
may be insignificant and obviously
the economics of the increased
cost associated with the employment of site selection
and development strategy may not be quantifiably
justified. However, it may be safely argued that there is a true test of sustainability in these
site selection and development strategies as it is apparent from the calculation that the impact of construction of
buildings in terms of carbon dioxide
and in terms of primary
energy has been mitigated and reduced respectively.
Energy
use. Daylighting and the use of efficient energy consuming lighting and
air conditioning features
were employed for the green building to reduce the energy consumption of the building.There is a growing
body of literature on embodied energy
and carbon in the construction of houses. Studies typically use a
process based Life Cycle Analysis (LCA) methodology (bottom
up) rather than an input–output (top-down) methodology.
Individual process based studies have used different parameters, factors, datasets and boundaries. In addition,
values of embodied energy, and consequential
emissions of carbon, vary by country due to: the energy mix;
transformation processes; the
efficiency of the industrial and economic system of that country; and how these factors
vary over time (Sartori & Hestnes 2007).
As shown in the Table 2, there is a substantial difference at
approximately 40% in energy usage for the green building
design based on energy usage per size of floor area,
i.e. in watts electricity used per square meter of floor area. This means that the building is approximately 40% more efficient than
that of the traditionally designed building in
terms of operation of the building. Nässén et al (2007) summarized the
results of 20 process-based
(predominantly Scandinavian) studies published prior to 2001. The studies showed similar results with a range of
1.3–7.3 GJ/m2 primary energy for residential buildings.
Table 2
Comparison of energy use between the green building and the traditional building design
|
Parameter |
Traditional design |
Green residential design |
|
Total electric load |
11,550 kW |
11, 393 kW |
|
Total floor area |
247 m2 |
404 m2 |
|
Electric load/floor area |
46.7 W/m2 |
28.02 W/m2 |
|
% of electrical reduction |
- |
39.69% |
There is a
growing concern about energy use and its implications for the environment. Recent reports by the Inter-governmental
Panel on Climate Change (IPCC) have raised public awareness
of energy use and the environmental implications, and generated a lot of interest in having a better
understanding of the energy use characteristics in buildings, especially their correlations with the
prevailing weather conditions (IPCC 2007; Levine et al 2007). It was estimated that in 2002 buildings worldwide
accounted for about 33% of the global
greenhouse gas emissions (Levermore 2008). In their work on climate change and comfort standards
(Kwok & Rajkovich 2010), reported that the building sector
accounted for 38.9% of the total primary
energy requirements (PER) in the United States,
of which 34.8% was used for heating, ventilation and air-conditioning (HVAC).
In China, building stocks accounted
for about 24.1% in 1996 of total national energy use, rising to 27.5% in 2001, and were projected to increase to about
35% in 2020 (Yao et al 2005).
Although carbon emissions per capita in China are low, its total emissions are
only second to the US. When the life
cycle energy use and emissions footprint are considered, buildings account for a significant proportion of the energy-related
emissions (Jiang & Toveyl 2010).
In order to quantify the environmental benefits derived by employing
strategies that reduced
energy consumption, an evaluation of the amount of carbon dioxide equivalent due to the reduction in energy
usage has been computed. Table 3 shows the results
of the computation, as shown in the table, the total energy saving for the
selected 20-year time horizon
approximately reached 36,000 kilowatt hours. Using internationally accepted standard conversion factors this
energy savings is translated into approximately almost 12,000 kg of coal or approximately 12 metric tons of
coal is avoided to be combusted in
coal-fired power plants. On average, a kilogram of coal is 70% carbon thus for every kilogram
of coal combusted there is approximately an equivalent emission
of
2.6 of carbon dioxide equivalent that is emitted into the atmosphere.
Thus, as shown in Table 3, the
resulting energy savings due to the application of daylighting designs and efficient
lighting features has avoided approximately 30,000 kg of carbon dioxide
equivalent for the 20-year lifetime horizon.
Table 3
Amount of carbon dioxide
avoided
 |
Environmental analysis
Annual energy savings 1,800
kWh Total energy savings (20 years) 36,000 kWh
Amount of coal avoided (in kg per kWh of energy) 0.333* Total amount of coal avoided 11,988
kg
 |
Total amount of carbon dioxide avoided (kg CO2) 30769.2
* - Standard conversion factor
(IPCC Report 2007).
Material selection and
conservation of resources. In evaluating sustainability the carbon impact and primary energy input for
the construction of the buildings were evaluated.
As shown in Table 4, the results
of the detailed calculation for both the traditionally-designed
building and the green residential building indicated a significant difference when the size of occupancy in
terms of floor area of the building is considered. As presented, total kg carbon associated with the traditional
design is approximately 33,500 kg of
carbon dioxide, almost similar in quantity with that of the green building at approximately 33,300 kg of carbon dioxide.
However when the results are made in the same
dimensional index, i.e. amount of carbon dioxide per unit area, the green
building design is almost 40% less
compared with that of the traditionally-designed residential building. Total overall primary energy for
both building designs are obtained using the
calculated material weights,
the accepted emission
factors and the total energy consumption of the building
for an assumed 20-year time horizon. A recent report
estimated the waste reduction
through substitution of traditional methods
with prefabrication systems to
be between 20 and 40%, the greater the pre-fabrication the greater
the savings (WRAP 2008).
Carbon impact for both designs
Parameter Traditionally- designed building
Green building
Table 4
Total kg carbon dioxide (kg CO2) Total
floor area, in square meters Amount of CO2 per unit floor area,
kg CO2/m2
%
reduction relative to traditionally- designed
building
33,499.95 33,297.35
247.63 404.34
135.38 82.35
- 39.13%
Figure 3 shows the total primary energy input for both designs in terms of
megajoule per unit of floor area
(MJ/m2). The total primary energy is the sum of the primary energy input used to produce the material needed
in the construction plus the energy expended
or consumed by the building
over the specified lifespan
of the building.
Figure 3. Calculated total primary energy input.
Analysis of
the evaluation reveals positive results for the green residential building as compared to that of the traditional
building. As shown in the calculated results, total primary energy needed including the primary energy associated
with the consumption of electricity
can reach as much as 2,700 gigajoule for the green building and approximately 3,000 gigajoule for the traditional
building respectively. In terms of primary energy per unit of floor area, results of the calculation indicate a much
bigger advantage for the green building
design. As shown in the calculation, total primary energy can be approximately
7,000 MJ/m2 for the green building and approximately 12,000 MJ/m2
for the traditional building
respectively. Thus, the green building consumes approximately 40% less in terms of overall primary
energy as compared with that of the traditional building.
Improved
environmental quality. The use of natural ventilation design and proper orientation of the building
were integrated into the design of the green building.
Simulations were made to determine the optimum level of daylight and
some features of the design utilize
insulation features to stabilize the indoor air temperature of the building. The climatic parameters such as
prevailing wind speeds, solar insolation levels, relative humidity and pressure differences were measured to
obtain proper ventilation of the building. Figure 4 shows
temperature measurements of the building.
Figure 4. Measured indoor
and outdoor temperature of the green building.
As illustrated
in the graph and observed in the green building, indoor temperature is almost stable during the measuring periods
in spite of rapid variations in the outside air temperature. The foregoing results can be attributed to a number
of factors inherent in the green
building design. One of such factor is the efficient natural ventilation
occurring in the building and the use of proper insulation materials that reduces
energy gain coming from the roof during the day time. Temperature
measurement were not taken during the
period starting 7:00 PM up to 7:00 AM, nonetheless is safe to assume from observation of the building occupants that
temperature drops below of that measured at 7:00
PM in the previous day. It has been
observed that due to prevailing indoor air speeds inside the building,
considerable number of the windows
and doors in the northern portion of the house is closed to
maintain a comfortable temperature inside the
house.
Social
acceptance. In order to measure the social acceptability of the green
building, survey questionnaires were
administered to a number of varied respondents on the following aspects: as to overall satisfaction, specific features
and some psychological features.
Figure 5 shows the perceived level of acceptability of the human factor
of the sustainable building design in
terms of overall satisfaction. As illustrated in the statistical analysis
there is a very high level of acceptability as to the present impression
of the building, the orientation and
location of the building and layout of the building, the construction cost and the energy usage, water use and materials selected
for the construction.
Figure 5. Mean perception of respondents in terms of overall satisfaction.
Figure 6 shows the percentage responses
of the respondent in terms of overall
satisfaction. As shown in the graph, approximately 65% responded highly
acceptable with, 29% of the
respondents responded very acceptable and about 6% responded slightly
acceptable in terms
of the five indicators evaluating overall satisfaction.
Figure 6. Percentage responses of respondents in terms of overall satisfaction.
Conclusions. A sustainable strategy in
the selection and site development integral to
design, construction and implementation of green building
has been developed. In the site selection and development, the
following are the strategies; the proper orientation of the green residential building; the incorporation of the green roof top and the restoration/plantation
of different species of plants within the site. The results reveals the following: that the building has been
observed to be properly oriented with minimum
levels of lighting
consumption and sufficient lighting designs, and that with the implementation of the green rooftop and
restoration and plantation of different species of plants a considerable amount of carbon has been offset for the
growing of the plant at approximately
470 tons of carbon for the
20-year time horizon.
In the use of water, the results indicated that with the incorporation
of a water storage tank and the
consequential use of rainwater, the dependency of the residential building for commercial water has
been significantly diminished. It has been observed that the normal amount of rainfall can supply the needed
requirement of supplying adequate
amount of water to sustain the plants in the green rooftop and that of the planted
trees and other species in the
site.
For the construction and implementation of a green building that
consumes less energy and reduced
cooling loads, the sustainable strategies includes the use of daylight and the use of highly efficient electrical
features. The results have indicated that green building has reduced its energy consumption of approximately 40%
per unit of floor area when compared
with that of the traditional building design. In terms of energy savings, it has been projected that due to the use of
the foregoing strategies, the green building can save up to 1,800 kilowatt-hours of energy annually, and the
increased construction cost due to the application of these strategies may
be recovered at approximately eleven years of operation of the building.
The study further
reveals that in terms of environmental
benefits, the green building may abate the associated equivalent carbon emissions to the atmosphere as much as 30
tons of equivalent carbon dioxide for the 20-
year assumed life span.
With respect to the selection and conservation of resources associated
to the construction of the green
building, the parameters considered are the associated carbon dioxide
emissions in the construction and operation of the green building and the associated primary energy needed as input
into the construction. The study reveals that
when compared to the traditional building, it has the potential to
reduce approximately 40% associated carbon dioxide emissions
and 40% primary energy for the construction of the green building. The calculated estimates reveal that
with this strategy, it can mitigate
approximately 21,000 kg of carbon dioxide of emissions to the environment and approximately 2,100 gigajoule of primary energy is
avoided.
A sustainable strategy which improved the environmental indoor quality
of the residential building has been
employed in the construction of the green building which is the most critical component of the study.
The strategies involved are the incorporation of design features that utilizes natural air circulation and the
use of such features combining with
advanced ultra-high efficient cooling units that achieved the maximum natural
ventilation possible. This has been evident with the resulting stability
of the indoor air temperature and the achievement of thermal comfort
even at the normal relative
humidity prevalent in tropical climate.
As to acceptability of the green building, the survey results as per
statistical analyses reveals
high level of acceptance of respondents in terms of the overall
satisfaction features, the general and the specific features and the
given psychological indicators of the
design.
Thus, consistent with the research
direction and the specific objectives, the advantages of the
green residential building has been quantified in terms of architectural, technical, economics and its benefit to
the environment. Its social acceptability has been proven as indicated
in the survey results. Hence, it can be concluded
that the construction and operation of a truly sustainable house has been achieved.
References
IPCC 2007 (Intergovernmental Panel on Climate
Change) Climate Change 2007: Mitigation, contribution of working group
III to the Fourth Assessment Report. Cambridge, Uk: Cambridge
University Press.
Jiang M. P., Tovey N. K., 2010 Overcoming barriers
to implementation of carbon reduction
strategies in large
commercial buildings in china. Build Environ 45(4):856–864.
Kwok A. G., Rajkovich N. B., 2010 Addressing climate change in
comfort standards. Build Environ 45(1):18–22.
Levermore G. J., 2008 A review of the IPCC assessment report four,
part 1: the IPCC process and
greenhouse gas emission trends from buildings worldwide. Building Services
Engineering Research and Technology 29(4):349–361.
Levine M., Ürge-Vorsatz D., Blok K., Geng L., Harvey D., Lang S., Levermore G., Mongameli
Mehlwana A., Mirasgedis S., Novikova A., Rilling J, Yoshino H., 2007 Residential and commercial buildings. In:
Contribution of working group III to the fourth
assessment report of the intergovernmental panel on climate change, 2007. Metz B., Davidson O. R., Bosch P. R., Dave
R., Meyer L. A. (eds), pp. 387–446, Cambridge University Press, Cambridge, U.K.
Metz B., Davidson O. R., Bosch P. R., Dave R., Meyer L. A., 2007
Climate Change 2007: Mitigation of
Climate Change: Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental
Panel on Climate Change, 2007. IPCC Fourth Assessment Report (AR4). Cambridge: Cambridge University Press.
Nässén J., Holmberg
J., Wadeskog A., Nyman M., 2007 Direct
and indirect energy
use and carbon emissions in the production phase of buildings: an input–output analysis.
Energy 32(9):1593–1602.
Sartori I., Hestnes A. G., 2007 Energy use in the
life cycle of conventional and low- energy buildings: a review article. Energy and Buildings 39(3):249–257.
Stern N., 2007 The economics of climate change: The
stern review. Cabinet Office HM Treasury.
Solomon S., Quin D., Manning M., Chen Z., Marquis M., Averyt K. B.,
Tignor M., Miller H. L., (eds) 2007
Climate Change 2007: The Physical Science Basis. In: Contribution of Working
Group I to the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change. IPCC Fourth Assessment Report (AR4). Cambridge University Press, Cambridge, U.K.
WRAP 2008 Waste Minimisation Through
Offsite Timber Frame Construction, Waste Resources and Action Programme, pp. 14.
Yao R., Li B., Steemers K., 2005 Energy policy and standard for built
environment in China. Renew Energy 30(13):1973–1988.
Rceived: 12 May 2014. Accepted: 09 January 2015. Published online:
11 February 2015.
Authors:
Rey Diegas Galua, Mindanao University of Science and
Technology, College of Engineering and Architecture, Philippines, Cagayan de Oro City, Lapasan Highway,
9000, e-mail: rgaluasds@gmail.com
Ermelinda Goc-ong Tobias, MSU-Iligan Institute of
Technology, College of Science and Mathematics, Department of Biological Sciences, Philippines, Tibanga,
Iligan City, Andres
Bonifacio Street, 9200,
e-mail: egtobias2008@gmail.com
This is an open-access article distributed under the
terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium,
provided the original
author and source
are credited.
How to cite this article:
Galua R. D., Tobias E. G., 2015 An assessment of sustainability of a green
residential building in an urban
setting: focus in Pueblo de Oro,
Cagayan de Oro City. AES Bioflux 7(1):60-69.
Comments
Post a Comment