5.1.3. Energy Efficient Built Environment

An energy efficient building "offers an appropriate environment for habitation with minimal energy consumption and wastage of energy, thereby maximizing energy conservation" and "balances all aspects of energy use in a building by providing an optimized mix of passive solar–design strategies, energy-efficient equipment, and renewable sources of energy" (Sustainable Fuel Technologies Handbook, 2021).

Energy efficient buildings are designed to provide a comfortable living environment while using the least possible amount of energy. This is achieved through a combination of strategies. For example, passive solar design makes use of natural sunlight for lighting and heating, reducing reliance on artificial light and heating sources. Energy-efficient equipment includes appliances and systems (like HVAC) that consume less energy while still providing the same level of service. Finally, incorporating renewable sources of energy, such as solar panels, can further reduce the energy footprint of a building.

Consider a house that has large south-facing windows. During the day, sunlight shines through these windows, warming the interior and reducing the need for heating. At night, energy-efficient LED lights minimize energy consumption, showcasing how smart design reduces energy use without sacrificing comfort.

Life Cycle Assessment (LCA) based on ISO14040 (2006) is being increasingly adopted in architectural design and construction, as it CA enables decision-making processes, such as, evaluating and selecting environmentally-friendly products and optimizing construction processes.

Life Cycle Assessment (LCA) is a systematic approach that evaluates the environmental impacts of all stages of a building's lifecycle, from material extraction to disposal. By assessing the energy and resources required throughout the lifecycle of a building, architects and builders can make informed decisions about materials and processes that have a smaller ecological footprint. LCA helps in selecting sustainable materials early in the design process to optimize overall performance and reduce costs over the lifespan of the building.

Imagine planning a road trip. You would want to consider not only the cost of gas (current fuel) but also the wear and tear on your car (resources consumed) and the potential for needing repairs along the way (disposal and after-use). LCA helps builders take a similar approach, considering the entire journey of the building materials and processes.

From a life cycle perspective, the environmental impact and energy consumption of buildings are closely linked to the choice of materials.

Each building material has an 'Embodied Energy' or 'Embodied Carbon', which is the total energy used in the extraction, production, and transportation of that material, as well as any emissions it produces over its lifecycle. This is significant because it helps in determining not just the operational energy demands (how much energy a building uses while in use) but also the environmental costs of materials used in construction. A well-rounded approach considers both embodied energy and operational energy to optimize energy efficiency throughout the building's life.

Think of building a gaming setup. If you opt for lightweight, energy-efficient parts, your electricity bill (operational) might remain low. However, if those parts were made with a lot of energy-intensive processes, the embodied energy cost adds up too. Thus, both purchasing decisions and usage matter.

Lupíšek, et al. (2015) innumerate the Design strategies for reduction of embodied energy and embodied carbon (Subtask 4 of Annex 57) in three steps: 1. Reduction of amount of needed materials throughout entire life cycle 2. Substitution of traditional materials for alternatives with lower environmental impacts 3. Reduction of construction stage impact.

These three strategies focus on minimizing the overall environmental footprint of a building by first reducing the total weight or amount of materials needed, which in turn lessens the energy and resources required for their production. The second strategy encourages the use of materials that have a lesser environmental impact, such as recycled or renewable options. Lastly, reducing the impacts during the construction phase includes efficient project management to minimize waste and emissions from machinery and transport.

Consider how a chef might reduce waste during meal prep. Instead of using many ingredients that require extensive travel and processing, they might choose a few local, in-season vegetables. This not only minimizes the carbon footprint but ensures fresher meals. Similarly, construction can prioritize local and sustainable materials.

A large number of building materials are reusable and recyclable (Kralj & MariČ, 2008), such as, Wood and untreated timber, and Earthen Materials (reusable/recyclable/biodegradable); Metals, mainly Steel, Aluminium, Iron, Copper, Masonry and Bricks, and Glass and ceramic (reusable/recyclable); Asphalt and Concrete (may be crushed and recycled).

Recycling building materials is essential for reducing the overall waste generated during construction and demolition processes. Many materials can either be reused directly, like reclaimed wood and metal, or recycled into new products, thereby reducing the need for new raw materials and lowering environmental impacts. This helps to conserve natural resources and minimizes the energy used in producing new building materials.

Imagine clearing out your attic and finding old furniture. Instead of throwing it away, you could refurbish it or sell it to someone who needs it. Similarly, recycling building materials prevents them from ending up in landfills and gives them a new life in upcoming projects.

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