Abstract
Heating and cooling consume a high amount of energy, which is today mainly provided by fossil fuels. To save fossil resources and simultaneously reduce pollutants and CO2, heating and cooling energy consumption should be reduced. Geothermal energy is a clean, inexhaustible source of energy that is available all year round because it does not depend on the weather. Nevertheless, the use of tempered subsoil air has been used as a traditional air conditioning strategy; however, nowadays, its use has been questioned by the discovery of the leaks of radon gas from the ground. The investigation searches a heat exchange system with the subsoil which prevents the introduction of radon gas into living spaces. The system that is exposed increases the performance of aerothermal heat pumps by means of thermal exchange with tempered air in the sanitary chamber. This exchange is more favorable than air at the outside temperature, increasing the COP of the machine. This system complies with the regulations for protection against radon, protecting the building from this radioactive gas.
TopIntroduction
Heating and Cooling Consume of CO2. Emission Reduction Strategies
The growing concern for environmental sustainability and the fragile balance in which many of the ecosystems are found has substantially increased the need to reduce the impact of energy consumption on our planet. A significant part of this contribution to energy consumption lies in the construction sector (Zeiler & Boxem, 2009). The Global Situation Report of (2018) establishes the guidelines for efficient, resilient and emission-free construction and buildings. The built environment, which is one of the main drivers of the world economy, accounted:
- •
39% of total CO2 emissions in 2017 of carbon dioxide related to energy, where 28% of global energy-related CO2 emissions and another 11% of CO2 emissions from the energy sector.
- •
36% of global final energy; this consumed almost 125 exajoules (EJ) in 2016, or 30% of total global final energy use and building construction, including the manufacture of materials for its construction, represented an additional consumption of 26 EJ (almost 6%) in the overall estimated final energy use.
Although buildings and construction sector emissions appear to have levelled off since 2015, they still represent the largest rate of total energy-related CO2 emissions:
“If we don’t make buildings more efficient, the increase in energy use will affect us all, whether through lack of access to affordable energy services, poor air quality or higher energy bills,” says Dr. Fatih Birol, Executive Director of the International Energy Agency (IEA).
Building standards must change to reflect the urgency of buildings that are more resilient to climate change, with lower energy needs or mainly near-zero energy buildings, and their progressive decarbonization or mainly carbon-neutral buildings. Thus, global dialogue is supporting progress in developing policies for sustainable buildings and countries are continuing to implement and update building energy codes and certification policies. From here arose the Net Zero Carbon Buildings Commitment officially that launched at the Global Climate Action Summit on 13th September 2018 (C40 Cities, 2018). The aim is to reach net zero carbon in operation for all assets under their direct control by 2030, and to advocate for all buildings to be net zero carbon in operation by 2050 (ADEME, 2018). Unfortunately, investment in energy efficiency in buildings has slowed in 2017, with the slowest rate of increase in recent years.
The shift towards this desirable double new situation is promoting interest in passive geothermal cooling and heating and natural ventilation techniques in order to decrease energy consumption and carbon footprint (Soltani et al., 2018). The use of the high heat capacity of earth´s soil enable us to preheat the air in winter cold days and cool it in summer hot days (Wachenfeldt & Bell 2003). Moreover, there are various passive systems that combine strategies for passive cooling, passive heating as well as heat storage, aided or not by mechanical means. Thus, with earth air heat exchangers, it´s posible to capture heat from the ground or dissipate to it, preheating the air inside the buildings in winter and cooling it in summer (Peretti et al., 2013). The use and application of such mechanical ventilation systems in search, of low-energy buildings is the main aspect for creating a desirable level of indoor air quality, IAQ (Balvers et al., 2008). Several studies collect the latest advancements with different combinations of earth air heat exchangers and their thermal performance (Kaushal, 2017), (Bordoloi, 2018).
Key Terms in this Chapter
Passive Air Conditioning System: Passive air conditioning systems take advantage of the building's constituent elements such as windows, walls, or floors to obtain thermal energy and use it to heat or cool the building. The general objective of these design strategies is to take advantage of the climatic conditions to minimize the use of active air conditioning systems and thus reduce energy consumption and CO 2 emissions.
Carbon Footprint: The Carbon Footprint, defined in a very general way, represents the amount of greenhouse gases (GHG) emitted into the atmosphere derived from the activities of production or consumption of goods and services, and is considered one of the most important tools to quantify the emissions of these gases. GHGs, defined in the Kyoto protocol in 1997, form a permanent layer in the middle part of the atmosphere that prevents all solar radiation that is returned by the earth from leaving, thereby causing the temperature under the layer to increase ( Espíndola & Valderrama, 2012 ).
APTAE System: Pre-tempered aerothermal air exchange system between the living space and the subsoil without mixing. This system benefits from taking advantage of the constant temperature that the ground has at shallow depth, while avoiding radon gas leaks inside, favouring its ventilation to the outside.
Parietodynamic Wall: Enclosure that takes advantage of solar energy to preheat the external ventilation air. Generally, it is made up of a factory inner sheet, an air chamber and a glazed or metallic outer sheet that absorbs solar radiation. Air circulation can be natural (thermosyphon) or forced (CTE-DB-HE0, 2019).
Aerothermal Heat Pump: The heat pump is a thermal machine capable of pumping heat from a cold source to a hot one. In the case of aerothermal heat pumps, they extract natural environment (air) through the evaporator and transfer it to the interior of a building through the condenser.