5.1.3.2.1.1.2. Optimization of structural system

Therefore, the selection of appropriate materials, which is often emphasized as a directive for energy-efficient design, becomes a critical decision factor in the design process. It is recommended to consider material selection as early as possible, as it not only impacts the operational energy performance of the building but also influences the total embodied energy and potential environmental impact.

Choosing the right materials for construction is crucial. These materials affect how much energy a building will use during its lifespan. If materials are chosen wisely at the beginning of the design process, it can lead to lower energy consumption during the building's operation and a smaller environmental footprint. The embodied energy, which is the total energy consumed in making a material and transporting it, is also affected by these choices.

Think of material selection like choosing ingredients for a recipe. If you pick fresh, organic ingredients, your dish not only tastes better but is also healthier. Similarly, selecting high-quality, energy-efficient materials helps create a building that is not only sustainable but also reduces energy costs over time.

Operating energy, which includes energy for HVAC, domestic hot water, lighting, appliances, and building maintenance, is easily quantifiable and can account for up to 85% of total energy consumption and 70-90% of the environmental impact.

Operational energy is the energy a building needs to function on a daily basis. This includes heating, air conditioning, hot water, lighting, and running appliances. In fact, this type of energy demand can represent a huge portion of a building's total energy use and its environmental impact. Understanding how much energy these systems consume can help builders and designers find ways to improve efficiency.

Imagine a person who buys an energy-efficient refrigerator. Initially, they might pay a bit more, but over time, the lower electricity bills will save them money. Just like choosing energy-efficient appliances, buildings can significantly reduce their operational energy by optimizing systems to use less power.

From a life cycle perspective, the environmental impact and energy consumption of buildings are closely linked to the choice of materials. However, there is often a lack of alignment between the service life of materials (which determines the intervals for material renewal) and the service life of buildings (the duration of the operational phase). This can result in a trade-off between material selection and building energy demand and so, requires a holistic approach (Heeren et al., 2015) that considers the effects and trade-offs.

Both embodied energy and operational energy are important when evaluating a building's environmental impact. Embodied energy refers to the energy used to produce and install materials, whereas operational energy is about how much energy the building uses once it is operational. Designers must balance these two aspects, as some materials may save energy during use but have high embodied energy costs, leading to complicated decisions about what materials to use.

Consider the choice between driving a fuel-efficient car that costs more upfront and an older, less efficient car that is cheaper initially. The first car will save money over time due to less fuel usage, but the material choices in a building have a similar consideration; long-lasting materials may mean fewer replacements, saving embodied energy, whereas cheaper materials might require frequent replacement.

For example, in a residential building, since the ‘wood variant’ is susceptible to solar and internal gains, and the ‘concrete variant’ isn’t, the energy spent on demand for space cooling of wood is higher than concrete in spite of wood having lower environmental impact than concrete. However, for cool climates, a wooden structure and this very same property will be beneficial and energy-saving.

The choice between wood and concrete for building a house can significantly affect energy consumption. In hot climates, wood may absorb more heat, requiring more energy for cooling compared to concrete. Yet, in cooler climates, wood acts as a natural insulator, keeping heating costs down. This shows that the context, like climate, plays a crucial role in material selection and energy efficiency.

Think about wearing a thick sweater in summer versus winter: in the summer, it makes you hot and uncomfortable, but in winter, it keeps you warm. Similarly, material choices should consider local environmental factors to optimize energy efficiency.

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