Sustainable Construction and the Environment
Global warming is an alarming issue in the present day. The increment in the global temperature created an excessive temperature increment in the tropical and semi-tropical regions.
This increment in temperature has increased the use of conventional cooling systems in these regions. This has increased the carbon emissions from conventional cooling systems, which is creating an adverse effect on the global environment (Lübken, 2013).
Most of the global countries are trying to reduce the carbon emission from the conventional cooling system through implementing a passive cooling system in the buildings.
Recently, QGBC—Qatar Green Blinding Council and the SIJ—Solar Institute Julich have joined hands to create an environmentally friendly sustainable housing project (Qf.org.qa, 2014).
The Qatar government declared its intention to implement environmentally friendly passive cooling by deciding to install solar cooling systems in all the stadiums for the World Cup (Marsh, 2014).
The tropical and the semi-tropical region geographically positioned within the cancer 23º27´N to the Capricorn 23º27´S (Sciencedirect.com, 2014).
The regional temperature in this area is much higher than in other areas across the globe. According to the study by Chaussinand (2014), the average temperature difference ranges from 10º C to 15º C. Therefore, the use of conventional cooling systems is very wide in this section.
The emerging economic condition has increased the construction of individual and industrial buildings in these areas, especially in India, Singapore, Malaysia and Qatar Li et al. (2013).
This economic growth has increased the use of cooling systems within this region. This increment in the conventional cooling system has increased the demand for power generation.
The cumulative effect of these two has increased carbon emissions in the environment. This higher carbon emission has worked as a catalyst for the warming of the temperature in these areas (Fang, 2014).
In Qatar according to the study by Suljic (2014) the power consumption has increased by approximately 9.30%. However, according to the majority portion of this higher incremental demand has come from the higher installation of the conventional cooling system.
A study by Biswas (2014) clearly demonstrated that the structure and materials used to develop a building majorly increase the inside temperature.
This study has also showed that the faulty design and the selection of the wrong material contributed in the 70% growth of the internal temperature.
Therefore, the main issue is to deliver a design that will help the houses decrease the inside temperature, and this decrease in temperature will slow down the use of conventional cooling systems in the houses.
The passive cooling concept states that it is a preventive measure that will help prevent the overheating of the interior sections inside the building.
According to Liu et al. (2013), the passive cooling strategy involves a three-step cover-up in the structural aspect of the building. These three aspects are:
- A mechanism should be developed so that the inside temperature does not increase. In doing this, the measures that can be taken are solar shading of the roof, use of the reflective elements in the construction of the building and use of color that helps in reducing the generation of the heat.
- The structure should be constructed that it remains able to keep the balance within the heat generation and heat emission for the building. In doing this, the structure should provide ample space for the airflow and incoming of the sunlight during the daytime.
- The implementation of the air infiltration mechanism to reduce the interior heat generation. To achieve this energy efficient material should be used and should use such interior color that reduces the heat generation (Ni and Zhao,2013).
3.0 Different available designs
According to S.K. Ng et al. (2013), the most acclaimed and most practical designs that are available recently are the:
- ZCB- Zero carbon building
- ZEB- Zero energy building
However, in recent days a hybrid system has been developed that uses the renewable energy to run the cooling systems installed in the building.
However, according to Gholami et al. (2014) the development of the captive house has larger potential to implement the passive cooling but the implementation cost is very high.
In the UK and USA, the implementation of the ZCB and ZEB-based building has evolved very smoothly. However, in Qatar and the Asian countries, the initiative is very low.
According to the MoU between the Qatar Green Blinding Council and the Solar Institute Julich, the latter will help implement lower-carbon-emission buildings in Qatar (Qf.org.qa, 2014).
According to Chávez and Melchor (2014), ZCB is the most suitable strategy for building a zero-carbon building.
However, according to him, designing this kind of building is very complex. The main theme of this construction is to construct a house that is capable of responding to the climate.
According to Halirova et al. (2014), the cooling season difference between Qatar and London is very high. Because of this, the fundamental design of this kind of building is to block the direct heat coming from the sun and let the air flow freely within the building.
Moreover, it develops a natural ventilation system that maintains a balance between the optimum temperature and the inside heating. Natural ventilation can more efficiently reduce overheating than a mechanical ventilation system.
Qi et al. (2013) the development of the large open area helps in reducing the temperature very efficiently along with the proper airflow provisions.
The south-facing design development allows the flow of air more freely than the other structures. The following figures demonstrate some of the most widely used airflow maintenance systems within the buildings.
5.0 Zero Energy Building Design
At the early design stage, the energy simulation of the whole building can be conducted, which can help predict the ZCB’s energy consumption. Then, the renewable energy system and building energy system were rebuilt using the results for neutralization.
The effectiveness of the different design strategies can be evaluated at the design phase, and in that phase, the energy demand and loads can also be strategically reduced.
Thus it can help in using the standard cost-benefit analysis for making the decisions regarding the design in architecture and engineering of the design.
Here the simulation tool can be used for building the energy simulation. The main inputs that are required are ZCB building designs (building systems and architectural elements) and hourly weather databases.
Here the Typical Meteorological Year can be used as well for the determination of the weather years.
5.0.1 Base Design
It is evident that the base design of the building is very important in order to make it more energy efficient. To make the buildings energy-efficient, it is very important to consider the Building Energy Codes (BEC) for new buildings.
The code can implement the designs of best practices for all the building developments in the region. The Overall Thermal transmittance value is regulated by the BEC regulations, and it can also provide guidelines for the use of escalators, lighting, electricity usage, air-conditioning, etc.
Thus, the regulations form the design targets and baselines for the practitioners. This can also help achieve the main aims and objectives of using ultra-low energy, and the baseline performance can be surpassed by such low-energy and ZCB designs.
In the following diagram the distribution of energy that is predicted for the baseline model is shown. The energy use intensity (EUI) is between 25-350 kWh/m2 for a typical existing building, and the BEC is around 157 kWh/m2 for a typical building. Thus it can be said that the energy can be effectively reduced in a building by adopting the BEC requirements.
5.0.2 Energy performance
The following table summarizes the key parameters of ZCB and the design values. The energy model was used here as one of the design cases. The predicted ZCB and EUI are 45% lower than the compliant baseline building, at 86 kWh/m2.
As a result of intensive application and mixed uses, the CIC ZCB is more energy-intensive. Thus it can be said that the energy performance of the building structures in the country can be significantly improved by using the specific design.
Performance of Facade Thermal:
It is very important to minimize the envelope loads for lowering the build-up heat. It is calculated that the approximately 163 W/m2 is the value of the peak load cooling but mostly the cooling load is approximately 80 w/m2.
Reduction of the Window-to-wall Ratio:
It is evident that solar heat can be gained nearly ten times more through windows than through opaque facades.
There can be a dramatic impact of the solar heat gain due to the minimization of the extent of glazing. It is very important to consider the angle of the sun in various times of the day and how it can maximize or minimize the requirement of heat and light at home during those times.
It can help in optimizing the benefits and can help in deciding on the position of the windows.
Facade Insulation and Envelope Absorptivity:
It is important to minimize heat flow with opaque walls. Two steps can help reduce such effects.
First, the flow of heat through the walls can be stopped by adding insulation in the walls.
Secondly, the surface temperature can be reduced as wall by reducing the absorption of the façade which can help in reflecting the heat away. Here the absorptivity can reduced below 0.3 by using the glazed finishes and the white walls.
Conclusion
Global warming has increased the temperature of tropical and semi-tropical regions, increasing the demand for conventional cooling systems.
However, due to the excessive use of these conventional cooling systems, carbon emissions have increased, which has adversely affected the environment.
Therefore, to maintain the balance between the comfort and the environmental safety the implementation of the ZCB and the ZEB will be much effective for the residential buildings.
On the other hand, for the industrial buildings the implementation of the combination system will help to reduce the carbon emission from the cooling system.
However, the implementation of solar panels and the use of biodiesel will help to reduce carbon emissions largely.
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