Green Energy Efficiency in the Construction Industry

Mario HonrubiaEnergy

Written by Jesús Del Val In October 2018, ennomotive launched an innovation challenge to find an alternative solution to lime to dry wet soil in road construction works. For 6 weeks, 54 engineers from 30 countries accepted the challenge and submitted different solutions. After a thorough evaluation, the solutions that best met the evaluation criteria were submitted by Jesús Del Val, from Spain, and Andrés Alonso Quintanilla, also from Spain. ennomotive asked Jesús to write an article about a topic he likes and here are his views on clean energies that can be used in construction.   We often hear about the influence of humans on global warming because we produce the greenhouse effect gases, mainly CO2. We all have thought about how to contribute to the fight against global warming. Well, we have a close possibility with housing since it produces 7% of the harmful gases that accelerate global warming. Here are some currently available techniques and solutions that the general user might not know yet. It is important to be aware of these solutions to select, among the wide range of possibilities, which one is the best one concerning energy management in a house.

Key Considerations

There is no question that, regarding energy, both the location of the house, the use, its construction criteria, and materials are vital to properly manage the necessary energy. We must take all these aspects into consideration when making decisions about new construction, purchase or renovation.

Considerations about the Construction

LOCATION AND DIRECTION Obviously, the location of the house is very important because it affects the variation of the power/m2 of irradiation that reaches the ground depending on the latitude. The direction, regarding the North-South axis, also has great importance whether we want to use the radiation or avoid it. SINGLE-FAMILY OR COLLECTIVE HOUSING This aspect is important because of the energy implications, more specifically the size of the solar collector and other possibilities. STRUCTURAL OR ENCLOSURE MATERIALS People usually focus on the type of materials but it is also important to look into the lifecycle of the products. There is a major debate among the advocates for wood, steel, concrete, and other not-so-usual materials. It is important to take several factors into account like durability, maintenance, influence regarding accidental agents (fire, water, insects, tornadoes, etc.) and characteristics that directly improve weather conditions (thermal insulation, thermal inertia, etc.). The debate and the selection of one material are not easy, in fact, the combination of multiple materials is not rare. CONSTRUCTION CRITERIA ABOUT ENERGY DEMAND This aspect has evolved significantly over the past few years since the invention of the LEED, BREEAM standards to the more demanding nZEB and PASSIVHAUS. For instance, if we take a closer look, the construction criteria for the last one (heavy insulation, staunchness, elimination of thermal bridges, use of heat during air renewal) are very logical, especially under extreme weather conditions.

Available Techniques

Here is a summary of the most commonly-used techniques around primary and renewable energy management. However, we must bear in mind that, because of their variability and temporality, renewable energies need proper management of that energy. To achieve that, it is necessary to reject it, transfer it or store it, always considering the inherent problems of each of them. For this reason, a combination of more than one renewable is frequently used.
    • This is the oldest solar energy technique used in housing.
    • It is a simple technique, but controlling it is not that easy due to the heat surplus generated during the high solar radiation season.
    • Some inter-seasonal energy storage systems have been developed, but the investment must be thoroughly assessed.
    • These storage systems can be combined with heat pumps.
    • Read more about solar heating and cooling in this article.
    • With this technique, electricity is generated directly.
    • Although it is easier to manage this type of energy, its transmission and application are very high.
    • To maximize the efficiency of this renewable energy, it is usually combined with heat pumps, and even with aerothermal and geothermal energy.
    • Read in this article about some examples of energy-efficient houses that use photovoltaic, among other techniques.
    • The success of this system lies in the fact that, on average, and contrary to the Joule effect (electrical resistance), these machines generate 70% more thermal energy than the electricity they use, a concept called coefficient of performance (COP).
    • These numbers are very variable and depend on the source of the cold being the air (aerothermal energy) or a more thermally stable source like the underground (geothermal energy).
    • Read more about how heat pumps work here.
    • The goal is to extract the heat contained in the air outside the house and inject it inside.
    • This system works as air/water and can be used to power the heating and warm water.
    • The usual warm water temperature is 60ºC.
    • Read the description of a real house that uses aerothermal energy here.
    • This technique uses the same heat-pump system as aerothermal energy but the source of the heat comes from below the ground.
    • There are multiple types of geothermal energy depending on how deep the heat is found.
    • It is not always possible to implement a geothermal system due to the physical characteristics of the housing.
    • This type of energy is very interesting, compared to aerothermal energy, because of its stability and energetic performance improvement.
    • Read more about geothermal energy in this article.
    • Biomass is a renewable energy system that uses wood or wood waste and is linked to circular economy. However, the combustion process generates CO2 within the (not fossil) lifecycle.
    • Unburnt composites or different suspended microscopic particles may appear and good management of the ashes becomes necessary.
    • The use of this type of energy is related to single-family housing and community facilities.
    • Read about biomass in this brochure from the European Union about introducing bioenergy in your business.  
    • Hydrogen is not a primary energy source, but the interest about what it can do and its applications is increasing rapidly.
    • Hydrogen does not exist in nature, it must be generated by electrolysis of water.
    • Hydrogen-based energy storage systems are often considered for houses and facilities isolated from the grid.
    • Hydrogen technology is still not widespread, even though it is technically reliable and it is thought to have a wide implementation.
    • Read more about the Hydrogen House, North America's first regulation-approved solar-hydrogen powered residence.
  • Personal actions and decisions do have an impact in the fight against climate change.
  • Energy priorities shift depending on the type of housing, whether it is new construction or renovation.
  • In new construction, the decision must be about the conditioning system. However, this is not too important since considerations about isolation, habitability, etc. already appear in the regulations and are quite progressive, although there is always room for improvement (NZEB, Passivhaus).
  • It is crucial to undergo renovation taking into account energy management, which involves several elements: windows, shutters, doors, staunchness, additional insulation, materials, and heating/cooling systems. It is clear that renovation must be focused on using as little primary energy as possible on the constructive elements, mainly around the house’s perimeter. This can be very complex, trust experts.
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