1. Introduction to incorporation of sustainable systems in residential projects
Sustainability has become a very critical issue in today’s construction sector especially due to the increasing global problem of climate change (Oduyemi & Okoroh, 2016). In this context, sustainability refers to use of high efficiency construction materials and processes and which are environmentally friendly throughout a building’s lifecycle. This means that sustainable buildings have lower environmental impacts throughout their lifetime while providing the desired functionality and comfort level for occupants. Globally, buildings account for about 40% of primary energy (Ghaffarianhoseini, et al., 2013). There are a wide range of sustainability features that are being integrated in buildings to improve their environmental performance. These features aim at reducing energy and water use in buildings without compromising their functional requirements and comfort of occupants (Ahn, et al., 2013). They are integrated into buildings to reduce their environmental impacts through their lifecycle, i.e. during design, construction, operation, maintenance and renovation.
2. Sustainable building systems
There are three main sustainable building systems that can be integrated in residential projects: energy systems, water systems and waste systems. This report discusses energy systems.
2.1. Energy systems
Sustainable energy systems aim at reducing the amount of energy consumed by the building throughout its lifecycle without compromising the comfort of occupants. Some of these systems include the following:
2.1.1. Passive design systems
These are systems aimed at capitalizing on natural resources for indoor heating, cooling, ventilation and lighting (Omer, 2008) during the operation stage of a residential development project. Some techniques of achieving this include: proper orientation of the building, appropriate design of building envelope, proper sealing of the building, proper building insulation, glazing, shading and use of locally available construction materials with suitable thermal mass. With these techniques, the building can be completely illuminated with natural light during the day and the cooling and heating loads during summer and winter seasons reduce because flow of heat into and from the building is properly controlled.
The main advantages of passive design systems are: reduced energy demand and consumption, minimal space requirements, lifetime operating and maintenance cost savings, (Tobias, 2016) improved comfort for occupants and minimal environmental impacts. Their disadvantages include: higher initial/upfront costs, performance can be altered by weather conditions and the efficiency and reliability of some of these design systems largely depend on external conditions (Rinkesh, 2017).
2.1.2. Energy efficient equipment
A lot of energy in buildings is used by lighting fixtures, heating and cooling systems and electrical appliances (Mehta & Wiesehan, 2013). As a result of this, using energy-efficient lighting fixtures (such as light-emitting diode – LED lights), heating and cooling systems and electrical appliances reduces the total amount of energy consumed. So energy consumption can be reduced by purchasing electrical equipment and appliances that are more energy efficient. Advantages of using energy efficient equipment are: reduced energy demand, reduced environmental impacts and decreased energy bills. Their main disadvantage is higher upfront costs.
2.1.3. Renewable energy systems
There are many residential development projects that are relying on renewable energy to reduce energy costs at different stages of the project. Renewable energy is unlimited and available for free, making it suitable for residential development projects. Types of renewable energy that can be used include: solar panels, wind energy, biomass, geothermal energy and hydroelectric energy, depending on the location of the project. The main advantages of renewable energy systems include: reduced energy bills and lower environmental impacts (Chel & Kaushik, 2017). Disadvantages of these systems are: higher initial costs and unreliability due to fluctuating renewable energy resources.
2.1.4. Automation systems
Energy wastage largely contributes to increased energy bills in many residential buildings. The most effective and economical way of resolving this problem is through automation. Building management systems (BMS) can be used to monitor, control and, optimize energy consumption in buildings. BMS ensures that energy is only consumed when needed by switching on luminaries and electric and electronic appliances only when necessary. BMS achieves this by use of different integrated control strategies such as optimum on/off, duty cycle, operating hours, night purge and cycle, holiday mode, etc. Additionally, BMS help building owners or operators to identify equipment malfunction or defects early and rectify them to avoid inconvenience of occupants, equipment damage and high energy consumption.
Advantages of automation systems include: reduced energy wastage, improved comfort level of occupants, reduced maintenance costs, increased lifetime of equipment, reduced energy bills, and lower environmental impacts. Disadvantages of these systems include: higher upfront costs and need for skilled personnel to oversee the automation systems.
In general, all the above mentioned energy systems have environmental, economic and social benefits. Environmental benefits include: reduce harmful emissions, improve water and air quality, conserve natural resources, minimize solid waste, and protect biodiversity & ecosystems. Economic benefits include: water and energy savings, reduce operating cost, improve employee productivity, and increase property value. Social benefits include: improve occupant health and comfort, improve acoustic and thermal environments, and improve quality of life, among others.
3. Cost of incorporating sustainable systems in residential projects
The cost of different energy systems discussed above depend on different factors such as size of the project and its location. Some of the systems cost more than others. For example, ensuring proper orientation of the building to reduce energy consumption costs less than developing an onsite wind energy plant. Passive systems have been estimated to increase cost of building projects by 7-15% (Freeman, 2017). Generally, incorporating sustainable energy systems in a residential development project requires more upfront costs. However, some of these costs can be eliminated or significantly reduced if there is proper planning, design and consultation from the early stages of the project. The costs are also continuing to reduce as new systems are being developed and more people are become familiar with them (Penny, 2012). After construction, the costs of running and maintaining these systems are very low resulting to shorter payback period. In other words, long-term savings realized from sustainable energy systems counterbalance upfront costs (Knox, 2015). With time, the cost of incorporating sustainable systems in buildings is expected to be the same or less than that of traditional buildings.
Stakeholders in the building and construction industry are now more concerned and informed about sustainability because of the impacts on the environment, people and economy as a whole. Implementation of sustainable building products and processes in residential developments is a major step towards reducing environmental impacts associated with these developments. One of the most effective ways of improving sustainability of residential developments is to integrate sustainable energy systems. Doing so will reduce the amount of resources that residential developments consume throughout their lifecycle. This will lead to environmental conservation, economic growth and improved quality of life.
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