How to get a higher score in the energy efficiency test of your home

Reforms facilitated by subsidies from European funds will raise the current poor ratings of the buildings

The energy letter has conditioned the sale and rental of housing in recent years, although only for the most environmentally responsible consumers. Now, the scale from A (higher energy efficiency) to G (lower) is becoming more important in buildings to be rehabilitated with subsidies from the Next Generation Funds.

In order to scale up an energy rating or letter, it is necessary to start from a good base and, unfortunately, we do not have the most suitable one due to the defective housing stock. At present, according to the Ministry of Transport, Mobility and Urban Agenda (Mitma), more than 81% of existing buildings are rated E, F or G in terms of emissions, with this percentage rising to 84.5% of buildings in terms of energy consumption, which shows the significant potential for energy rehabilitation. The buildings that achieve the best rating, the letter A, do not reach 0.3% of the total in the case of emissions and stand at 0.2% in terms of energy consumption.

What would have to be done to climb the rating ladder? “In reality, there is no recipe that can be extrapolated to all the buildings and dwellings on which we need to intervene. No two buildings are the same, so intervention programs are needed that are tailored to each case and take into account both the life cycle of the building and its potential for improvement,” reasons Marta Vall-llossera, president of the Higher Council of Architects’ Associations of Spain (CSCAE).

The letter is associated with an energy certification and does not have to coincide exactly with the certificate of the building with that of the house that integrates it, although obviously the considerations of the global certificate directly condition the individual one. That is, “a house could not easily jump several letters in an energy rating – because, for example, you can not modify the facade – so it is necessary to intervene in the entire building,” says Alfredo Sanz, president of the General Council of Technical Architecture of Spain (CGATE).

To gain a letter on the rating scale, the first action will always be to reduce the building’s energy demand, that is, to improve the insulation of facades, roofs and, if possible, also the exterior carpentry. “If it is technically possible, it is important to insulate the sill (the floor that is in contact with the ground). This is like when you go outside in winter, when you put on your hat, coat and good boots,” says Paula Rivas, technical director of the Green Building Council Spain (GBCe).

Next, say the experts, the performance of heating, hot water and cooling installations should be improved and, finally, if the building allows it, try to incorporate some renewable energy generation (solar photovoltaic…).

However, to undertake these actions well, it is important not to take a wrong step. According to Emilio Linzoain, managing partner of ATEC Aparejadores, “it is essential to have good technicians to help make decisions, since the investment can become an expense without a good strategy and planning; it would not be the first time that you have to intervene twice on the same element after a bad decision”.

Let’s talk numbers. According to data from the Institute of Construction Technology of Catalonia (ITeC), collected in the Citizen’s Guide to boost rehabilitation, edited by the Observatory 2030 of the CSCAE, investment in a building to move from the letter E to C or from E to B would mean savings of up to 80% in energy costs for heating and cooling. In any case, this is not an exact value. “In economic terms, it is difficult to predict the numbers in a general way, as it will depend on the climate zone, the fuels and the contracts that the community of owners has, but for a typical building of 20 homes, this could easily reduce its bill to 50%,” says Sanz.

EOS Energy, as an ESCO (Energy Services Company) and rehabilitation agent, extends this percentage: for a block of apartments with an average of approximately 100 residents, with gas or oil boilers and construction prior to the implementation of the Technical Building Code (2006), the savings from a comprehensive energy rehabilitation, which will end up paying for a large part of the investment, can be as high as 75%.

One of the most striking cases of the 21 projects that this company has, through its subsidiary Eoszenit Energy, is a work in a town of Lleida, Tàrrega, where a community of 51 neighbors has been granted a grant of more than one million euros, which will allow them to climb from the letter E to the highest rating, A, thanks to the reduction in demand for fossil fuels, with which they can reach 83% savings.

Atec Aparejadores has also just started work on the Iwer building in Pamplona, a project that has received a European award as well as a grant; it is a refurbishment for different uses (commercial, nursing home, offices…), which, after its intervention, will be able to donate energy to 400 existing homes in the San Pedro district of Pamplona.

Circular economy

Likewise, Gbce, promoter of the green certification tool, has many examples of rehabilitations of residential buildings in which A ratings are being obtained. They are including renewable energies and significantly improving the performance of the building, both in terms of energy, health and circular economy. Two good cases are a residential building in Rosalía de Castro street in Barcelona and another one in Turia street, 63, in Valencia.

The energy rating of a building has an expiration date: it is valid for 10 years except for the worst of them, the letter G, which is 5 years. And although it is not usual, the letter can be de-escalated: “It can happen due to a bad choice of materials (due to their degradation); due to stationary inefficiencies due to pathologies derived from a bad hygrothermal performance (humidity that degrades the insulation) or due to a bad execution of the work, which makes the behavior of the constructive elements not act in the way they have been designed”, concludes Emilio Linzoain.

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