Energy Qualification and Geothermal Energy

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The Energy Qualification of buildings in symbiosis with Geothermal Energy.

The Energy Qualification of existing properties, whose entry into force is expected in the near future, not only constitutes an essential tool to boost the sector of buying, selling and renting housing, but it is also a unique opportunity to save energy and therefore , economic.

According to the results of the SPAHOUSEC study, carried out by the IDAE, the existing housing stock in Spain shows an average Spanish household consumption of about 10,500 kWh per year. Previous studies carried out by the IDAE and the former MITyC yielded data of about 0.85 toe. According to this report, block dwellings (flat type) in the Mediterranean area are those with the lowest energy consumption, this being 0.53 toe per year. On the other hand, and at the other extreme, single-family homes in the continental sector present an average value of energy consumed of 1.69 toe / year. Globally, single-family homes consume 2 times more energy than flat-type homes.

The Energy Qualification of single-family homes as a result of the Energy Certificate is a unique opportunity to detect energy saving measures that will lead to improved labeling and a significant reduction in energy consumption and associated cost.

The average consumption of single-family homes is 17,012 kWh / home (0.061 TJ), which represents almost double the consumption of the average national home. In this type of housing, the use of the heating service predominates with an average value of 64% compared to 47%.

The Single-family homes lend themselves, due to their construction characteristics and air conditioning systems, to the use of low-temperature systems based on radiant floor terminal units.. Renewable energy systems are routinely integrated into single-family homes, primarily solar thermal energy for DHW generation, the prevalence of these systems being much higher than in block homes. Energy labeling will lead to the detection of savings opportunities in single-family homes, which use natural gas or diesel as their main fuel.

The Geothermal energy Low temperature is based on the fact that for a depth greater than about 15 meters 20 m a stable temperature is maintained regardless of the season of the year and the meteorological conditions. This constant temperature makes the ground an ideal focus to work with a water-water heat pump, using the ground as an evaporator (winter) or as a condenser (summer). Unlike an air-water type heat pump, the evaporator temperature (used for heating) is not influenced by the outside air temperature, which makes the COP much higher. This advantage decreases as we approach areas closer to the coast, where the temperature is much more uniform throughout the year, being in this case not very competitive due to its high initial cost. After carrying out the energy rating of a single-family home, a simple study can be carried out on the feasibility of installing a low-temperature geothermal energy system using a geothermal heat pump.

Considering an average energy consumption according to the SPAHOUSEC study, of 17,012 kWh / year, the energy consumption for heating will be 10,888 kWh, Table I.

Table I. Annual energy consumption

For a typical house of 150 m² It will be necessary, on average, a vertical sounding with a total length of about 160 meters, corresponding to three soundings of about 53 meters. The typologies of single-family homes allow, in a simple way, to integrate this technology due to the little floor space occupied. The annual cost of the heating system is calculated for the general parameters indicated in Table II.

Table II. Unit costs and returns

Assuming an annual CPI value of 4% in the case of diesel and 3.20% in the case of electricity, the operating costs are shown in Table III.

Table III. Operating costs

The accumulated cost and the savings obtainable will be more than € 28,000, thus being a very profitable investment in the medium term with a return on investment of about 10 years.The installation, without any subsidy, will cost approximately about € 10,800 including geothermal heat pump.

Table IV. Savings in 20 years.

Figure 1. Cumulative cost in 5 years

Figure 2. Cumulative cost in 10 years

Figure 3. Cumulative cost in 20 years

It is surprising, in these times of economic scarcity, see figures as shocking as that in 20 years of life in a home we will spend more than € 50,000 on heatingThis being an expense that will not generate any tangible material good. Having an efficient system will report a saving of more than € 28,000, a not inconsiderable figure that can be used to buy a vehicle, food or education, among others. The energy rating obtained from the Energy Certificate is presented as a unique option to detect these savings opportunities and to give added value to properties that have these systems. It is important to note that the problem in these facilities is the initial investment, showing that as always, everything that has to do with energy efficiency is a financial problem, not an economic one. That credit flows again becomes a necessity for our economy but also to improve our energy model.