The value of reducing energy consumption in buildings has increased worldwide. This is because the consumption of fossil fuels for the full-fledged operations of a building is as high as it is in other industries.
Therefore, the adoption of energy efficiency techniques during the construction and operation of buildings would play a crucial role in the creation of sustainable cities in the future.
Energy efficiency is the use of less energy in a building to perform the same operation as buildings that consume energy inefficiently. It should be considered during the design stage, selection of construction materials, construction process, and operation of the building. Adopting passive solar house design strategies at the design stage is the first step toward an energy-efficient structure.Â
Low-energy building materials and less energy-consuming construction equipment must be used during the construction process. As far as building operation is concerned, utilities for renewable energy systems have to be integrated into the building for water heating, photovoltaic electrification, etc.
Why is Energy Efficiency in a Building Important?
Efficient energy consumption in buildings is one of the most affordable ways to lessen the detrimental effects of climate change and health-related problems.Â
It reduces household expenses and decreases carbon dioxide emissions. There was a special emphasis on reducing CO2 emissions by the 26th UN Climate Change Conference of the Parties (COP26) in Glasgow held on 31 October – 13 November 2021.
Moreover, energy-efficient buildings decrease indoor air pollution as they provide cleaner combustion and better ventilation than conventional buildings. As a result, the possibility of air pollution-related diseases such as asthma and lung cancer will be reduced.
It saves lives, reduces medical treatment’s financial and social costs, and increases the value of buildings.
What is Energy Efficiency in a Building?
The energy efficiency in a building can be explained by its main aspects, which are discussed below:
1. Nearly Zero-Energy Passive Building Design
The design of a nearly zero-energy passive building involves adopting all solar passive strategies at the design stage before actual construction begins. For instance, passive solar heating/cooling, building daylighting, and provision for rainwater harvesting.Â
The passive building does not need complex design, but requires a knowledge of solar geometry, local climate, and window technology. The passive solar design strategies should be selected based on the climatic condition of the project site.Â
In a hot and dry climate, passive cooling designs, such as wall and roof cooling, solar refrigeration, and earth water heat exchangers should be integrated into the building.Â
In the cold zones, passive heating designs should be adopted, such as air handling units, sunspace, trombe wall, etc.
2. Utilization of Low Embodied Energy Building Materials
The usage of low embodied energy materials for building construction is important for reducing the impact of global warming and making the building energy-efficient. The embodied energy is the energy used by all processes related to the construction material’s mining, manufacturing, transporting, and administering.
Some of the examples of low embodied energy construction materials are fly ash bricks, fiber-reinforced bricks, woods, stabilized adobe blocks, cement-replacement materials such as silica fume, slag, and fly ash which is mostly by-products in factories. These materials are constantly becoming popular and widely used by contractors worldwide, especially in the Middle East, Europe, the USA, the UK, and India. Table-1 presents embodied energy for different building materials.Â
Table-1: Embodied Primary Energy of Building MaterialsÂ
| Construction material | Primary energy input, MJ/kg | Ranking |
| Fly ash, volcanic ash, sand, aggregate, adobe, soil | >0.5 | Low energy |
| Timber (sawn) | 0.1–5 | Medium energy |
| Sand-lime brick | 0.8–1.2 | |
| Precast | 1.5–8 | |
| Blocks | 0.8–3.5 | |
| In situ concrete | 0.8–1.5 | |
| Gypsum plaster | 1–4 | |
| Clay bricks and tiles | 2–7 | |
| Lime | 3–5 | |
| Plasterboard | 8–10 | High energy |
| Cement | 5–8 | |
| Glass | 12–25 | |
| Lead, zinc | 25+ | |
| Steel | 20–60 | |
| Stainless steel | 100 | Very high energy |
| Copper | 100+ | |
| Plastics | 50–100 | |
| Aluminum | 200–250 |
3. Usage of Energy-Efficient Equipment
This involves using energy-efficient equipment in a building that requires the lowest possible energy, such as LED lights, fans, air-conditioners, and refrigerators. Energy star-approved fluorescent bulbs are highly desirable because they are more durable, and their maintenance cost is 75% less than conventional bulbs.
Moreover, using a lighting control mechanism improves energy efficiency because it automatically turns off lights and eliminates waste of energy. Finally, use a thermoset to regulate heating water and room temperature.
4. Integration of Renewable Energy Technologies in Different Applications
Integrating renewable energy technologies in the building is another way to reduce energy consumption and reduce carbon footprint.
Solar water heaters, small wind turbines to generate electricity, solar photovoltaic electricity generation are examples of renewable energy technologies installed in a building to reduce operational energy consumption.
Other renewable energy sources like hydroelectricity, biomass, and biofuels can also be used. Roofs and facades of buildings are suitable for the placement of solar thermal collectors and photovoltaic panels.
Renewable energy offers great advantages, such as cost-effectiveness, sustainability, and security of energy supply, in addition to increased employment, and long life for energy systems. It also replaces the highly expensive and imported conventional energies such as oil, gas, coal, and nuclear fuel for certain countries.   Â
FAQs
Energy efficiency is the use of less energy in a building to perform the same operation as buildings that consume energy inefficiently.
The efficient use of energy in buildings is one of the most affordable ways to lessen the detrimental effects of climate change, health problems, unemployment, and poverty. It reduces household expenses, infrastructure costs, and reduces CO2 emissions.
The value of reducing energy consumption in buildings has increased worldwide. This is because buildings' operational energy has become the third-largest consumer of fossil energy after industry and agriculture.
Fly ash, volcanic ash, sand, aggregate, adobe, and soil are low-energy materials with less than 0.5 primary energy input.
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